text:
Records used for genealogy research are, unfortunately, riddled with errors, especially the spelling of names. These incorrect names create major challenges for family historians as they search for earlier generations.
Name errors occur for varied reasons. Sometimes names have variations and individuals were not concerned which version was used. Sometimes names were written down incorrectly in the original record. Also, handwriting on old records is often hard to read or in old-fashioned script, leading to errors when the names are transcribed for a census or name index, for example.
Genealogists learn to spot names in the records that might be the ancestors they are seeking — even when outrageously misspelled –and then work to prove or disprove their theory.
My search for my paternal third great-grandparents – parents of Sherman A. Bradley — is an instructive example. To celebrate Father's Day 2009, here is a look at my quest for my Bradley forefathers, focusing on the challenges of misspelled names!
When my paternal second great-grandfather Sherman A. Bradley married in Milwaukee on 6 Jan 1859, he was recorded as born in Connecticut "near New Haven" with parents Leman H. Bradley and Mary C. Bradley. When he married for a second time on 11 Jan 1882, the official asked for a maiden name for his mother, so Sherman's parents were listed as L. H. Bradley and Mary Simons.
An exhaustive review of all Leman, Lemon, Leming and Lyman Bradley men of the right period to have a son born in or about 1835 in Connecticut turned up no relevant results. Nor could an 1850 Census record with Leman, Mary and Sherman be found — anywhere.
Two intriguing records turned up, however, in Litchfield, Litchfield County, Connecticut, a place about 40 miles from New Haven:
> Leaming Hawkins Bradley b. 10 Oct 1808 in Litchfield to Horace Bradley and Hannah Hawkins
> Seyming Bradley m. 18 Sep 1830 in Litchfield to Mary Simons.
The name Leaming could be mistakenly recorded as Leman — and there was a middle name starting with H. And if those who created the Barbour Collection of Vital Records for Connecticut towns misread the capital L as a capital S, then the marriage record could be Leyming Bradley m. Mary Simons. Leyming is yet another way a clerk might think to write down Leaming, and marriage at age 22 was typical in those days.
This was the closest I had come to a match for the names Sherman gave as his parents. But could I prove this was right? Several records and books kept me focused on this family.
First, Leaming H. Bradley turned up in the 1840 Census in Washington Township, Litchfield County, Connecticut, with two sons in the 5-9 age range. Sherman would fit in that family.
Second, a Pedigree Resource File at FamilySearch.org for Leaming's younger brother John showed that he, another brother Clark and father Horace were in Dodge County, Wisconsin, not far from Milwaukee, in the 1850 Census. Here was an exciting Wisconsin connection with a date not long before Sherman arrived in 1857-58.
Third, among the books on Ancestry.com I found one with the genealogy of this Bradley family line going back to New Haven in the 1640s. It showed that Leaming Bradley, the first child of Horace Bradley and Hannah Twitchell [her correct surname], had married Mary Simonds and they "had several sons." Here was good confirmation of the Litchfield marriage record and a match to the two young males in Leaming's household in the 1840 Census.
[The book is Genealogical and Family History of Central New York, Vol. III, by William Richard Cutter. See page 1224.]
Attempts to find a birth record for Sherman A. Bradley were not successful, even with efforts by the Litchfield Historical Society and the Town Clerk for Washington, Connecticut. Such a record is always the best proof. I was pretty sure I had the right family, but felt I need some added records for confirmation.
I turned to the Milwaukee City Directories for the 1860s and 1870s to see if Sherman's father or parents might have come to Milwaukee as well. In the microfilms of those directories, on a day not long ago, I found the proof I was looking for: Leaming H. Bradley had come to Milwaukee where his son Sherman was married and working. You can imagine my excitement!
His name was recorded in various ways in the directories, and I share them all to show again the challenge of misspelled names:
> 1862: L. H. Bradley
> 1863: Leming H. Bradley, proprietor of L. H. Bradley & Co.
> 1865: Seamey H. Bradley, same address as Leming H. in 1863.
> 1866: Leaming H. Bradley, his name spelled correctly!
> 1867: L. H. Bradley
> _PHONE_: Lyman H. Bradley
Leaming's consistent use of his middle initial H. helped identify him, no matter how his first name was mangled.
The home address for all but one of these entries was on 8th Street, helping show that these are listings for the same man, just various spellings of of his name. And the location was about four blocks from the home of Benjamin Church where his daughter Hannah lived with her husband Sherman A. Bradley.
Also, in many of these years his occupation listed was pumpmaker, including the final listing when his name was spelled Lyman. Sherman A. Bradley had the same occupation. [Note: In that era, water pumps were made out of wood, so Sherman's career move to pumpmaker from carpenter makes sense.]
Two more clues helped confirm that Leaming Hawkins Bradley and Mary Simons were Sherman's parents. Written on a Bradley family tree were two notes: one, that Sherman had an ancestor in the Revolutionary War and, two, the ancestral name Abernathy, connection unclear. Books showed the parents of Horace Bradley as Aaron Bradley — who served in the Revolution as a youthful blacksmith and guard — and Lorrin Abernethy, daughter of Dr. William Abernethy.
All the pieces of the genealogical puzzle fell into place, at last.
But why was a Bradley male child born in 1808 given the first name Leaming? That name honors his great-grandfather Leaming Bradley who first brought the family to Litchfield from Middletown, Connecticut, and also his third great-grandmother Jane Leaming, daughter of Christopher Leaming and Hester Burnet, who married the first in the line of men named Abraham Bradley. But those are stories for another day.
Using the surname Leaming was a given name did indeed honor our Leaming ancestors, but also created a genealogy brickwall that was very strong, but has finally tumbled down!
This is one in a series of genealogy and family history research articles to help you find your family and ancestors, often for modest or no cost.


Gender: Female
Origin: American
Meaning: Little Child
The name Alanna means Little Child and is of American origin. Alanna is a name that's been used primarily by parents who are considering baby names for girls.
From Irish. Or from the name ALAN
Variations include: Alanah, Alannah
People who like the name Alanna also like the names: Abigail, Amelia, Arianna, Arabella, Ava, Ella, Aurora, Alexander, Liam, Jackson, Gavin, Benjamin, Ethan, Adam
Stats for the Name Alanna
checkmark Alanna is currently #68 on the Baby Names popularity charts
checkmark Alanna is currently #529 in U.S. births


text:
The trees around your house provide similar services in your neighborhood that trees do in a forest.
To learn more about the environmental benefits of
trees in urban and suburban environments, you can
use various tree benefit calculators based on i-Tree.
i-Tree is a software suite, from the U.S. Forest Service, that consists of tools that calculate the value
of trees in urban areas and your home.
A tree's value is expressed in terms of services it provides and the value of these services. This information helps communities strengthen the structure and management of their urban forests as well as advocacy efforts to build and preserve urban forests.
By determining what services trees can provide for urban ecosystems, people can increase environmental quality and livability of urban areas.
Use one of the following calculators to determine the monetary value of individual trees on your property.
Mobile App: _URL_
The simplest calculator, for a quick estimate of the value of one tree. (Requires Flash and will not work in Firefox or Google Chrome)
The most up-to-date and accurate calculator, that also allows you to see the value of multiple trees.
(Requires Flash, and works in most non-mobile browsers)
Sponsored by iTree.

source: HuggingFaceFW/fineweb-edu


text:
Friday, April 1, 2016
BUILDING LOCAL FOOD SYSTEMS
A new resource from USDA can help communities make the economic case for investments in local food. "The Economics of Local Food Systems: A Toolkit to Guide Community Discussions, Assessments and Choices" will help local food stakeholders–including farmers markets, food hubs, and other local food outlets–tell the story of how investing in strong local and regional food systems can revitalize rural and urban economies across the country. The toolkit allows communities to conduct reliable economic impact assessments of investing in local food system initiatives. The Toolkit uses real-world projects, experiences, and applied research, making it a practical and useable resource for community leaders, businesses, and others.
Source: USDA, 3/24/16, Local Food Systems

source: openbmb/Ultra-FineWeb


Build Status
The SafeYAML gem provides an alternative implementation of YAML.load suitable for accepting user input in Ruby applications. Unlike Ruby's built-in implementation of YAML.load, SafeYAML's version will not expose apps to arbitrary code execution exploits (such as the ones discovered in Rails in early 2013).
If you encounter any issues with SafeYAML, check out the 'Common Issues' section below. If you don't see anything that addresses the problem you're experiencing, by all means, create an issue!
Add this line to your application's Gemfile:
gem "safe_yaml"
And then execute:
$ bundle
Or install it yourself as:
$ gem install safe_yaml
Configuring SafeYAML should be quick. In most cases, you will probably only have to think about two things:
 1. What do you want the YAML module's default behavior to be? Set the SafeYAML::OPTIONS[:default_mode] option to either :safe or :unsafe to control this. If you do neither, SafeYAML will default to :safe mode but will issue a warning the first time you call YAML.load.
 2. Do you want to allow symbols by default? Set the SafeYAML::OPTIONS[:deserialize_symbols] option to true or false to control this. The default is false, which means that SafeYAML will deserialize symbols in YAML documents as strings.
For more information on these and other options, see the "Usage" section down below.
Suppose your application were to use a popular open source library which contained code like this:
class ClassBuilder
 def []=(key, value)
 _USER_ ||=
 _USER_.class_eval <<-EOS
 def #{key}
 def create
Now, if you were to use YAML.load on user input anywhere in your application without the SafeYAML gem installed, an attacker who suspected you were using this library could send a request with a carefully-crafted YAML string to execute arbitrary code (yes, including system("unix command")) on your servers.
This simple example demonstrates the vulnerability:
yaml = <<-EOYAML
---!ruby/hash:ClassBuilder
"foo; end; puts %(I'm in yr system!); def bar": "baz"
> YAML.load(yaml)
I'm in yr system!
=> #>
With SafeYAML, the same attacker would be thwarted:
> require "safe_yaml"
=> true
> YAML.load(yaml, :safe => true)
=> {"foo; end; puts %(I'm in yr system!); def bar"=>"baz"}
When you require the safe_yaml gem in your project, YAML.load is patched to accept one additional (optional) options parameter. This changes the method signature as follows:
 - for Syck and Psych prior to Ruby 1.9.3: YAML.load(yaml, options={})
 - for Psych in 1.9.3 and later: YAML.load(yaml, filename=nil, options={})
The most important option is the :safe option (default: true), which controls whether or not to deserialize arbitrary objects when parsing a YAML document. The other options, along with explanations, are as follows.
 - :deserialize_symbols (default: false): Controls whether or not YAML will deserialize symbols. It is probably best to only enable this option where necessary, e.g. to make trusted libraries work. Symbols receive special treatment in Ruby and are not garbage collected, which means deserializing them indiscriminately may render your site vulnerable to a DOS attack (hence false as a default value).
 - :whitelisted_tags: Accepts an array of YAML tags that designate trusted types, e.g., ones that can be deserialized without worrying about any resulting security vulnerabilities. When any of the given tags are encountered in a YAML document, the associated data will be parsed by the underlying YAML engine (Syck or Psych) for the version of Ruby you are using. See the "Whitelisting Trusted Types" section below for more information.
 - :custom_initializers: Similar to the :whitelisted_tags option, but allows you to provide your own initializers for specified tags rather than using Syck or Psyck. Accepts a hash with string tags for keys and lambdas for values.
 - :raise_on_unknown_tag (default: false): Represents the highest possible level of paranoia (not necessarily a bad thing); if the YAML engine encounters any tag other than ones that are automatically trusted by SafeYAML or that you've explicitly whitelisted, it will raise an exception. This may be a good choice if you expect to always be dealing with perfectly safe YAML and want your application to fail loudly upon encountering questionable data.
All of the above options can be set at the global level via SafeYAML::OPTIONS. You can also set each one individually per call to YAML.load; an option explicitly passed to load will take precedence over an option specified globally.
Supported Types
The way that SafeYAML works is by restricting the kinds of objects that can be deserialized via YAML.load. More specifically, only the following types of objects can be deserialized by default:
 - Hashes
 - Arrays
 - Strings
 - Numbers
 - Dates
 - Times
 - Booleans
 - Nils
Again, deserialization of symbols can be enabled globally by setting SafeYAML::OPTIONS[:deserialize_symbols] = true, or in a specific call to YAML.load([some yaml], :deserialize_symbols => true).
Whitelisting Trusted Types
SafeYAML supports whitelisting certain YAML tags for trusted types. This is handy when your application uses YAML to serialize and deserialize certain types not listed above, which you know to be free of any deserialization-related vulnerabilities.
The easiest way to whitelist types is by calling SafeYAML.whitelist!, which can accept a variable number of safe types, e.g.:
SafeYAML.whitelist!(FrobDispenser, GobbleFactory)
You can also whitelist YAML tags via the :whitelisted_tags option:
# Using Syck
SafeYAML::OPTIONS[:whitelisted_tags] = [",2002:object:OpenStruct"]
# Using Psych
SafeYAML::OPTIONS[:whitelisted_tags] = ["!ruby/object:OpenStruct"]
And in case you were wondering: no, this feature will not allow would-be attackers to embed untrusted types within trusted types:
yaml = <<-EOYAML
---!ruby/object:OpenStruct
 :backdoor:!ruby/hash:ClassBuilder
> YAML.safe_load(yaml)
=> #"baz"}>
Known Issues
If you add SafeYAML to your project and start seeing any errors about missing keys, or you notice mysterious strings that look like ":foo" (i.e., start with a colon), it's likely you're seeing errors from symbols being saved in YAML format. If you are able to modify the offending code, you might want to consider changing your YAML content to use plain vanilla strings instead of symbols. If not, you may need to set the :deserialize_symbols option to true, either in calls to YAML.load or--as a last resort--globally, with SafeYAML::OPTIONS[:deserialize_symbols].
Also be aware that some Ruby libraries, particularly those requiring inter-process communication, leverage YAML's object deserialization functionality and therefore may break or otherwise be impacted by SafeYAML. The following list includes known instances of SafeYAML's interaction with other Ruby gems:
 - ActiveRecord: uses YAML to control serialization of model objects using the serialize class method. If you find that accessing serialized properties on your ActiveRecord models is causing errors, chances are you may need to:
 1. set the :deserialize_symbols option to true,
 2. whitelist some of the types in your serialized data via SafeYAML.whitelist! or the :whitelisted_tags option, or
 3. both
 - Guard: Uses YAML as a serialization format for notifications. The data serialized uses symbolic keys, so setting SafeYAML::OPTIONS[:deserialize_symbols] = true is necessary to allow Guard to work.
 - sidekiq: Uses a YAML configiuration file with symbolic keys, so setting SafeYAML::OPTIONS[:deserialize_symbols] = true should allow it to work.
The above list will grow over time, as more issues are discovered.
My intention is to eventually adopt semantic versioning with this gem, if it ever gets to version 1.0 (i.e., doesn't become obsolete by then). Since it isn't there yet, that means that API may well change from one version to the next. Please keep that in mind if you are using it in your application.
To be clear: my goal is for SafeYAML to make it as easy as possible to protect existing applications from object deserialization exploits. Any and all feedback is more than welcome!
SafeYAML requires Ruby 1.8.7 or newer and works with both Syck and Psych.
If you are using a version of Ruby where Psych is the default YAML engine (e.g., 1.9.3) but you want to use Syck, be sure to set YAML::ENGINE.yamler = "syck" before requiring the safe_yaml gem.


text:
The Nonprofit Team You Need to Succeed in 2021
Webinar on Demand
- Hanna Thomas Uose, Principal Consultant, Align
- Carys Afoko, Director Of Advocacy, Mozilla
- Chris Thomas, VP Nonprofit, Salesforce
COVID taught nonprofits that digital is essential. In order to rise to the challenge in 2021, nonprofits are examining their digital strategies, their technology choices, and how to organize their teams to fully adopt and embrace tech across their operations.
What is the impact on digital (and non-digital) teams? As organizations move to implement new systems, how do they ensure that the mission and other strategic objectives of the organization benefit — and even transform — as a result of the right people in the right places? Digital leaders are on the rise in all business sectors. What is their role in nonprofits, and how do they structure the teams that they lead?


An Improbable Definition of Faith
Today's problematic definition of 'faith' comes from Loftus, himself, as he expands his description of faith as "an irrational leap over the probabilities." While emailing a Christian friend, he offered the following definition:
In my opinion faith is what fills in the gaps of the probabilities. If, say there is a 70 % probability something is the case then to conclude more than that 70% probability is faith, and I reject faith based reasoning like that. To reject that kind of faith is to live and operate based on the probabilities. If there is a 70 % chance of something then that's all I can conclude and that's all I can use to base my decisions on. And so I could never give my whole life over to a 70% probability. I could only give 70% of my life over to a 70% probability. This is Lessing's ditch when applied to the past, as you know. Kierkegaard responded by acknowledging Lessing's point and therefore decided faith must go beyond what the evidence calls for. And that's what I must reject.
Loftus's Christian interlocutor replied that he thought the phrase "faith is what fills in the gaps of the probabilities" was spot-on and a great way to encapsulate Hebrews 11:1. I can't speak to the exegesis, but I sure as heck have an issue with this treatment of probability.
Loftus is essentially saying that, when we aren't certain, we have to hedge our bets, but that can be the wrong way to reason. Let me give an example. I tell you that I have a weighted coin — it is 60% likely to come down heads and 40% likely to come down tails. Plenty of people, given this data, will conclude that they should call out 'heads!' 60% of the time and 'tails!' 40% of the time. They'll lose out to the people who call 'heads!' every single time you play with enough iterations.
If you're doing a math test, you're going to mark down a lot of probabilities that aren't zero or one, but, when you're taking action, you pick the best option you know of and commit to it. It doesn't matter that you think there's a only a 70% chance that you're right, instead of a 99%. If you think it's the best choice, you're only self-sabotaging by hedging.
What that 70% means is that you need less new evidence to change your mind about this action than you would if you were truly 99% confident. But, absent that new evidence, there's no reason you shouldn't stay the course. Instead of half-heartedly committing to the choice you've made, you should just stay vigilant that you don't discount new evidence in either direction, because you've started thinking of your current confidence level as an important part of your identity, one that it would hurt you to lose.
I've been framing this in terms of choosing actions, but it goes for beliefs also. The main difference here is that there's less obviously a moment of 'choosing.' When your estimate hits some critical level, you believe. You can't change your belief by an act of will, or a "jump over the probabilities." You can only change what you profess to believe, so that you don't feel like you're betraying the side. But check out the link in the previous sentence to see how different belief looks from belief-in-belief.
*I'd like to preempt one objection I think may come up in the comments. People are going to ask some variant on the Abraham question: "What if I'm very confident that the right thing to do is the wrong thing?" I think you're describing your reasoning incorrectly. The choice that's before you isn't sundered from all the other data/priors you have; a good Bayesian is factoring them in. Those qualms (or, more precisely, the evidence that causes your qualms to trigger) count as evidence against the choice that scares you.
About Leah Libresco
 - _URL_ Gilbert
 I don't think this disagreement tracks the Christianity/atheism-devide, but I'll take this opportunity to mention I reject your entire epistemology.
 Probabilities live on probability spaces and are meaningless without those probability spaces specified at least implicitly. Assigning probabilities to all our beliefs doesn't make sense because we don't even know the sample space. And in fact we don't do that. Our beliefs just aren't real numbers. Now some people cling to platonic idealizations of themselves whose beliefs would be real numbers ("perfect Bayesians"), but I have no need of that hypothesis. In reality "X% sure" is most of the time a figure of speech and not a mathematical statement. And that is good.
 On a more practical level, beliefs are mostly not changeable by single acts of the will, but eventually masks tend to shrink on and biases are heavily influenced by what we wish to believe. In the long run that makes beliefs much more voluntary than most people's self-image would admit them to be.
 And while we're at comforting pop-psychological explanations of disagreement, you only talk about this "belief in belief" thing because you're angry at God.
 - _URL_ J. Quinton
 No one is saying that you have to have exact probabilities to think like a Bayesian, you just have to be aware that all events have multiple explanations, and some explanations are more likely than others given approximate probabilities. For example, the phrase "extraordinary claims require extraordinary evidence" makes perfect sense if you think in terms of Bayes theorem; anyone who follows that advice is a Bayesian to some degree. Yet, how do you figure out what "extraordinary" means? You would have to have some ballpark "low probability" figure.
 You might say that Leah is "angry at god" but, if you thought like a Bayesian, you would at least attempt to look at the multitude of reasons for why she writes what she does and not stick with the "angry at god" reason.
 - _URL_ Gilbert
 I have nothing against the Rev. T. Bayes' theorem. It is a useful calculation tool for probability spaces. I just object to using it as a universal hammer turning everything into nails shaped like probability measures. And my main objection is not the faux precision, bad as that is, but the blotting over of the issue of the undefined sample space.
 Being aware that "all events have multiple explanations" has absolutely nothing to do with statistical ideologies and, unless you misunderstand "likely" in too technical a way (which would be question begging) neither does awareness that "some explanations are more likely than others". The "given approximate probabilities" probably (haha) does count as thinking "like a Bayesian", but I don't see how that should be a good thing. The way real people actually think we don't have even approximate probabilities for most of our beliefs and neither should we. Of course that needn't hinder us from using probability as a figure of speech. But then it's a figure of speech, not an approximation.
 "Extraordinary claims require extraordinary evidence" makes sense if we take "extraordinary claims" to mean "claims against which we already have substantial evidence". In that case it reduces to "look at all the evidence", something quite understandable without pseudo-mathematical voodoo. But in common practical usage it's more of a rhetorical battle-cry than of a sound epistemological principle.
 As for the last paragraph the snark doesn't quite seem to have carried through, so I will have to work on my unsubtlety.
 - deiseach
 "I could only give 70% of my life over to a 70% probability."
 Given that this is the week of Cheltenham, has the man ever bet on a horse in his life? Even in the usual workplace sweepstakes where you join in not because you expect to win, but just for the craic?
 This Loftus bloke must be great fun at family gatherings and other social occasions.
 Suppose I am stuck on the top floor of my house, which is on fire. If I stay in the room, the best thing that will happen is that I will suffocate due to smoke inhalation (the worst thing is that I will be burned alive while conscious). However, if I jump out my window, there's probably a 70% chance I'll break at least one leg, maybe both.
 Is there anyone who would stick 70% of their body out the window and keep 30% inside? Or who would not jump out the window, even though they can't be 100% sure they'll walk away unhurt?
 - InvincibleIronyMan
 Ooh, nice! I've been folowing John's posts on this subject, and this is by far the best objection I have seen to anything he's said. I bet there are quite a few theists out there who are kicking themselves wishing that they had come up with this!
 - Patrick
 I can't see why this would be so. Is this a psychological claim? Are you using "belief" to mean "certain enough that I treat the possibility of err as negligible?"
 - Jay
 Leah,


text:
Mapa - Interactive Milan Map
Information about the map
Check out the main monuments, museums, squares, churches and attractions in our map of Milan. Click on each icon to see what it is.
To help you find your way once you get to your destination, the map you print out will have numbers on the various icons that correspond to a list with the most interesting tourist attractions. This way, you'll be able to see where each attraction is.
Icons on the Milan interactive map
The map is very easy to use:
- Check out information about the destination: click on the color indicators.
- Move across the map: shift your mouse across the map.
- Zoom in: double click on the left-hand side of the mouse on the map or move the scroll wheel upwards.
- Zoom out: double click on the right-hand side of the mouse on the map or move the scroll wheel downwards.


Show this cartoon to the Climate Deniers – Why 'Laudato Si' is prophetic
Randall Munroe is a genius scientist/cartoonist. He is renowned the world over, amongst comic and cartoon buffs, as the artist behind xkcd.
Munroe combines his training as a physicist with his ability as an artist to simplify complex matters and present them in a way that even a child can understand.
Below, he has created a Climate History cartoon chart that measures global warming between -4 degrees and +4 degrees Celsius, beginning 20,000 years Before the Christian Era (BCE) and progressing to the present day. Back then the city of Boston was buried under a mile of ice.
Shortly after 9,000 BCE the temperature crosses the 0 degrees Celsius line, with rising seas cutting off the land bridge between North America and Asia. By 8,500 BCE cattle are domesticated. Around 8,000 BCE the temperatures began to level out, slightly above the _PHONE_ average levels. And they remain remarkably stable until around 3,000 BCE when temperatures begin to drop slightly until the 1,900s AD. After that, Munroe's cartoon leaves little doubt that something dramatic has intervened as the rise of temperature is alarming and way outside the very gentle and gradual natural pendulum.
This is a cartoon to ponder. Along the way you'll encounter the builders of Stonehenge (2500 BCE); Solomon (1000 BCE); Confucius (600 BCE); Jesus (1 CE); Buddha 500 (CE); Muhammad (600 CE); Ghengis Khan (1200 CE); Shakespeare (1600 CE) and many more.
When we reach the mid 1800s we encounter the Industrial Revolution, followed by, in the 1900s: Airplanes, World Wars, Nuclear Weapons, Internet, Fossil Fuel, and the rapid increase of CO2 Emissions. Beginning in 2016 Munroe projects three scenarios for a reduction in global temperatures by 2100: a "Best-Case Scenario assuming immediate, massive action to limit emissions"; a "Optimistic Scenario", a slowing down of warming; and the third scenario – we continue towards catastrophe.
And suddenly we realise how prophetic 'Laudato Si' is and why Pope Francis told the American actor and environmentalist, Leonardo Di Caprio, to 'pray for humanity'.
Following is a 10-minute journey through 22,000 years of history and the very gentle natural fluctuations of global temperatures until human activities dramatically intervened.
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Working with Dates in IBM BPM
Many of us (ibm bpm developers) are wondering on perform certain operation like comparing dates, find difference between dates and such stuff as Date not a simple type but is complex system object. But thanks to bpm suite, the implementation to do these operations are all already in place and if we give simple syntax which we use with simple types it will do the job. Here a some of the operations which I would like to illustrate in this post.
How to Comparing date1 and date2?
Comparing dates is as simple as comparing two integers.
Suppose I have two date variables tw.local.date1 and tw.local.date2.
In order to compare dates we just have to use the statements as shown below.
 tw.local.date1 > tw.local.date2 or
 tw.local.date1 < tw.local.date2
Above statement will be evaluated to true or false in the similar way when used with integers.
Above statements will consider time stamp as well. If you want to check this irrespective of time, then first set the hours, min and seconds for these dates to same values and then compare. You have to first set hours, seconds and then milliseconds.
How to Compare date to current date?
For this, first we need to get the current date and store it in a variable.
var currentDate= new TWDate();
then set currentDate and hours, seconds and milliseconds to same value and then compare like above.
To set the hours, minutes and seconds you can use script similar to the one shown below.;
How to increase the 'n' no of days to a date?
You can just get the date from and add number of days and set that value to again. This will increase the number of days automatically.Refer to below script. + X number of days)
Below scenarios will be automatically taken care when we add days.
scenario1: if = 3/12/2013, if we want to add 3 days to this date, the final date will become 6/12/2013
scenario2: if = 31/12/2013, if we want to add 3 days to this date, the final date will become 3/1/2014. We don't have to explicitly Change the month and year.
scenario2: if = 31/10/2013, if we want to add 3 days to this date, the final date will become 3/11/2013. We don't have to explicitly Change the month.
Hope you find it use full.
 1. Hi Anna
 please explain what is dojo toolit, how it is related with coach view
 2. Hi
 i can't able to set the hours and minutes and seconds value as you defined previously.
 var currentDate= new TWDate();
 Try this:
 var currentDate = new TWDate();"Current Date: " + currentDate);
 currentDate.setDate(currentDate.getDate() + parseInt(tw.env.Days)); = currentDate;
 currentDate.setMinutes(currentDate.getMinutes() + parseInt(tw.env.Mins)); = currentDate;"xxx: " +;


text:
Dollar cost averaging sounds like a terribly complex term, but we're going to break it down and make it very simple for anyone to understand. In a nutshell, dollar cost averaging is buying an investment little by little over a period of time. Now that doesn't sound so complex does it?
Dollar Cost Averaging: A Little More Detail
Now that you have the general idea, we will expound on that principle a little bit. When we say buying little by little, that means that the investor has a system in place of buying at certain timing intervals. For example, some people buy weekly, monthly, or even quarterly. They generally have a set amount that is going to be invested over a period of several months or even years.
Why Dollar Cost Average?
The idea is to reduce the risk to the investor. By making small purchases over an extended period of time, the investor creates a buffer of protection against changes in the market price. Let me illustrate this with an example:
Let's say that stock A is selling for $20, $22, $17, and $16 respectively each quarter that you purchased 100 shares. That gives you an average price of $18.75, which is the price the stock would have to return to in order to break even. However, had you bought all 400 shares at $20, you would need to have the price return to $20 per share to break even.
While dollar cost averaging with a single stock is obviously a wonderful tool to protect yourself, there is an additional measure of security that you can implement as well. Try dollar cost averaging with mutual funds. A mutual fund is basically a fund that spreads the investment over a myriad of stocks, which will throw diversification into the picture. You've heard the phrase, "Don't put all your eggs in one basket."
How to Implement the DCA Strategy
A written plan is always the way to go when you are implementing any strategy.
- Determine the amount of money that you intend to invest and the systematic interval. Make sure that it is a realistic amount that you will be able to fulfill.
- Decide what investment that you want to put your money into. Make sure that it is something that you will be willing to hold onto for five to ten years.
- Regularly buy your selected investments. If you use a broker or mutual fund company, and they offer automatic purchases or an automatic investing program, it may be a good idea to use it. This will keep you faithfully adhering to your timing intervals.
That's dollar cost averaging! If you notice, this is an investment strategy commonly used when you invest in a 401k or other employee retirement plan. Your 401k account can be set up to automatically deduct money from your paycheck on a regular basis for investing in stocks or mutual funds that you've selected. This is just one more tool to use in your investing career.


, the better; provided that it doesn't contain any unnecessary 'gibberish'.
You should provide one or more images on your blog article and they should contain title attribute too. But there is no way you can insert an image in a YouTube video description. I believe the thumbnail used on a video serves the purpose of it's SEO.
In case of a blog article, you should provide a meta description which has to contain the focus keyword. But there is no such option on a YouTube video (the metadata of a YouTube video is a lot different scenario. Below is the link to an article which describes what metadata is for a YouTube video and also how it can be misleading).
The focus keyword should be present in the url of the blog article, which doesn't apply for a YouTube video. Again, in case of a blog article you should provide internal links, like those to other articles on your blog. Whereas, you shouldn't possibly put links to other videos of your channel in the video description. This should be done by using cards.
Use AdWords to find suitable keywords and tags
Although there are other tools and web services to find suitable keywords and tags for your YouTube videos and blog articles, but I would strongly suggest you to use 'Google AdWords' instead. It is the best keyword finding tool not only in my view, but also to most other SEO experts. Let us now learn how to use it.
First you have to sign in to your AdWords account. Recently they have made changes in the dashboard interface. You should go to the portion with three vertical dots and click on it. A menu will open where you'll be clicking on 'Keyword planner', then a page will open in a new tab.
A portion of AdWords dashboard to do SEO
Can you see the three vertical dots?
Now you need to click on the link saying 'Search for new keywords using a phrase, website or category'. You'll be provided with a few blank spaces, where you need to type your options. In most cases, typing the title of your YouTube video or blog article is just enough. And you have to do it in the box that says 'Your product or service'.
You're about to enter your desired keywords for SEO purpose
After that you have to hit the blue 'Get ideas' button below, and you will have some search results. You could be using some of the results as tags in your YouTube video or blog article (I'm going to do the same for this article). Also when I'll be preparing a YouTube video with the same title and content, I'll be using some of these tags – the most popular ones.
Choose the best and the most popular keywords to serve SEO
Now that you know how to find keywords related to your particular YouTube video or blog article, you have to choose the best and the popular related keywords. Out of these, choose one as your SEO keyword (aka focus keyword) which you are going to focus in video description or article copy. The rest popular keywords could be used as tags.
For your information, I previously ran a search on AdWords using keywords like SEO and keyword planner. I had some results out of which I chose SEO as the focus keyword. Now after selecting my article title and running a search with that, I'm going to use a few results as tags on this article. If you're a YouTuber, you could use such keywords as tags on your video, as I previously mentioned.
The keywords with most search numbers like 10K-100K or 1K-10K are supposed to be the most popular ones. Nevertheless, keywords which have low search frequency but are very close to your particular theme, could be selected as well. Besides the search frequency, there is another option which shows competition: low, medium or high. In ideal situation, you should be selecting keywords with low or medium competition, for reasons I'll be describing may be in a future article. (FYI, I prefer to cover the first three pages of search results)
list of SEO keywords showing search frequency and competition level
SEO keywords you shouldn't choose
In my opinion, you shouldn't choose more than 15 tags for a YouTube video and 20/25 keywords to use as tags for a blog article. Also once you have the search results on AdWords, you might see some mouth watering and frequently searched keywords which are remotely related with your copy (article or video description). You shouldn't choose these as tags for your copy, because choosing so may harm the SEO status of your article and lead your YouTube channel to termination.
For example, upon running an AdWords search on the title of this article, I too found some mouth watering keywords as 'youtube hot videos 2016' with search frequency of 10k-100k. But I didn't select this as a tag, because this search keyword is no way related with my current article. Also I found another keyword name 'youtube generator' with a good search frequency. But I didn't accept this as a tag either, because I was not sure whether this one was relevant to my article or not. You should keep these points in your head while selecting keywords/tags for your YouTube channel/blog article.
That's all for this article. If you have properly gone through this, then I believe you should be able to learn to SEO both your YouTube videos and blog articles correctly.
You may also likeYouTube cards: How to set and use them
How YouTubers Get Paid! – How To Get Paid without Adsense on YouTube!
It is probably an age old question as to exactly how YouTubers get paid and how much do they actually earn. These are good questions. As a full-time YouTuber myself I can understand that we have really weird jobs that couldn't have existed even 5 or 6 years ago. I'm here to explain exactly how the whole thing works, from how we get paid and how much we get paid, to how you can get paid doing this.
how youtubers get paid - in multiple ways
How YouTubers get paid
Your average YouTube channel generates money every single time a viewer watches an advertisement on one of your videos. This means that they don't have an ad-blocker turned on and they watch an skippable ad for at least 30 seconds. Once a user has watched the advertisement for 30 seconds or seen other smaller ads such as banner ads, YouTube will then generate a payment for that and split the money between you and YouTube itself. You get the 55% of it, while YouTube gets the rest 45% (in case of AdSense). The money generated per view is less than 1 cent, however we will get to how much that turns out to later. (This article is on how youtubers get paid)
Sponsored deals
Another way a YouTube channel can get paid is through sponsored deals. This is usually offered to only bigger YouTube channels that take part in more hands on networks. But occasionally smaller channels will have them as well. It's just that the sponsor will pay them specific amount of money either per view or per click to the company's link, or to make a video about a product, often some kind of other YouTube channel or video game.
It's worth nothing that it's required by law for the YouTuber to tell people that it's a sponsored video in the video's description. So if you ever watch a video that you think might be a sponsored one, check the description to know for sure. Sponsored deals range from extremely shady to where they buy off people's opinion to sell games, to completely legend them, or they just want the person's honest opinion on it while doing a video to show the game off to new players. Sponsored deals generate much more money than regular advertisements. (This article is on how youtubers get paid)
Through Patreon : Receive donations from viewers
The last way to make money on YouTube isn't directly attached to YouTube, but it's so common and extremely efficient that it's worth bringing out. You see that a lot of YouTubers myself included use Patreon. It is a website where content creators can receive donations monthly from fans and give optional rewards in return. Patreon then takes 10% of the donations for themselves and gives you the rest 90% of what was sent. Not every viewer is going to donate every month, still it's a much more stable income than YouTube itself. Yes, YouTubing is such a weird job that most channels with Patreon make more money from donations every month than they do from their actual paychecks from AdSense or MCN partnership. (This article is on how youtubers get paid)
How much YouTubers get paid
As a YouTuber, how much you get paid actually depends on three factors: how many viewers you get, how many of them use ad-block and if you do sponsored videos. Let's look at the number of views first. Many Multi-channel networks will attempt to have you signed a contract with them by saying that you're going to earn $3-$10 per thousand views, where the reality is that it is not possible to pay you more than $2 for each 1000 views. That is assuming that most of your viewers are from USA, UK, Canada. If most viewers are from developing countries like India, you'd be paid much less than $2 for one thousand views.
Well, you have to be very careful before you sign a contract with an MCN. There are some contracts which won't let you go before 5 years have finished. They do this in the hope that one day your channel will really earn a lot of revenue for them. So, if you're going to choose an MCN, then choose one that will not


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The CO2 Analyser is a Analytical instrument that measures the concentration of CO2 gas in the process. The CO2 Analyzer use multi-component analysis by using Non Dispersive Infrared (NDIR) sensor technology for consistent, precise process gas measurement.
The Non Dispersive Infrared (NDIR) detection method is based upon the absorption of infrared radiation at specific wavelengths as it passes through a volume of sample. Non-Dispersive Infrared (NDIR) techniques for the measurement of various gases rely on the energy absorption characteristics of a particular gas in the infrared region. In a simple NDIR instrument, Infrared energy passes through two identical tubes and falls on a detector. The first tube is the reference cell and is filled with a non-absorbing gas such as nitrogen. The second tube is the measurement cell and contains the gas sample to be analyzed.
The IR Source continuously sends an IR waves through the gas tubes and detector measures the intensity of two different wavelengths, one at the sample gas absorption wavelength and the other is at reference gas absorption wavelength. As the reference gas generally contains nitrogen so the detector receives 100% signal. If the CO2 gas is present in sample gas means the received signal will be attenuated at the detector side. The detector measures these two signals and their difference is proportional to the amount of absorbing gas in the sample cell.i.e. CO2 gas. So Finally the CO2 gas concentration is measured with the difference in absorption of IR radiation in the sample and reference cells. CO2 gas concentration measuring unit is ppm.
Also See: NDIR Gas Analyzer Animation


Question: What Are The Main Rules Of Cricket?
What is the maximum runs scored in one ball?
Crazy Cricket Record: 286 Runs Were Scored Off in Just 1 Ball in Australia..
How many hours should I practice cricket?
For a pro player, quality practice/training of 5–6 hours split in 2 sessions is necessary. This includes fitness, fielding, batting and bowling. Playing competitive cricket takes much more than skill development.
Who is the father of cricket?
William Gilbert GraceW. G. GracePersonal informationFull nameWilliam Gilbert GraceBorn18 July 1848 Downend, near Bristol, EnglandDied23 October 1915 (aged 67) Mottingham, Kent, EnglandNicknameW. G., The Doctor, The Champion, The Big 'Un, The Old Man20 more rows
Can you score 7 runs in cricket?
New Delhi: A batsman can get a maximum of 6 runs on a ball, well, unless there has been an error from the bowling or fielding side. … The total hence resulted in 7 runs being scored from 1 ball.
What are the 10 basic rules of cricket?
Basic Rules Of CricketHitting the wickets with the ball when bowling.Catching a batsman's shot on the full.Hitting the batsman's leg in front of the wicket (LBW)Or hitting the wickets before the batsmen can run to the other end of the pitch.Jan 12, 2017
What is the LBW rule?
What are the basic rules of cricket?
Cricket is played by two teams of 11, with one side taking a turn to bat a ball and score runs, while the other team will bowl and field the ball to restrict the opposition from scoring. The main objective in cricket is to score as many runs as possible against the opponent.
What is the first law of cricket?
The first written Laws of Cricket in 1744 were: The rules shall choose from amongst the rich batsmen present. The twoumpires who shall absolutely decide all disputes.
Can 2 wickets fall in 1 ball?
Who hit the first six in cricket?
Joe DarlingThe first six in international cricket was hit by Australian batsman Joe Darling in 1898, almost 21 years after the first Test was played. Back then, a six had to be hit out of the ground as hits over the boundary counted as five. Darling, born on November 21, 1870, went on to hit two more sixes in his innings.
Can a bowler bowl two consecutive overs?
3 Answers. No, it is not allowed to bowl chain overs in any Cricket matches. … Another bowler shall complete the over from the same end, provided that he does not bowl two overs consecutively, nor bowl parts of each of two consecutive overs, in that innings.
Can batsman hit ball twice?
A player can hit the ball twice in order to prevent it from hitting his/her stumps but not with a hand that is not in contact with the bat and not if doing so prevents a catch being taken (in which case they would be out obstructing the field). The bowler does not get credit for the wicket.
Why is pitching outside leg not lbw?
So consider if it is out even if pitches outside leg stump, then the bowlers job would be pretty easy, and the batsman can hardly stand. But if the bowler bowls from the off side of the batsman, it is his bat comes first then the leg, hence outside off stump LBW is considered OUT." … That's why LBW is not given."
What is the weight of cricket ball?
What is the lowest score in one day cricket?
TeamScoreOppositionPakistan71v West IndiesNew Zealand73v Sri LankaPakistan74v EnglandNew Zealand74v Pakistan34 more rows
What are the latest rules of cricket?
No fans. The anticipatory roar ahead of the first ball of a contest, the deafening noise every time a wicket falls or a boundary scored will be absent. … No Saliva. … COVID-19 Substitution. … Non-Neutral Umpires. … Additional DRS Reviews. … Logos. … Sanitisation Breaks And No Sharing.Jul 8, 2020
Is Virat better than Sachin?
In comparison, Virat has so far played 86 Tests (114 less than Sachin), since his Test debut in Kingston vs the West Indies in June 2011. He has so far scored 7240 runs (8681 runs behind Sachin), at an average of 53.62. … In ODI cricket however, the numbers show that Virat is very close to Sachin's centuries' record.
Who found cricket?
What are the 42 rules of cricket?
How do you score runs in cricket?
Run (cricket)If the ball hits the ground before hitting or passing the boundary, then four runs are scored.If the ball passes or hits the boundary without first bouncing, then six runs are scored.


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~ The Library Ghost in the video game.
~ The Library Ghost after her book bats are destroyed by the ghostbusters.
The Library Ghost (aka The Grey Lady, Gray Lady, Librarian Ghost) was a supporting antagonist in Ghostbusters, and a supporting antagonist in Ghostbusters: The Game.
She was the ghost of librarian Eleanor Twitty and the very first ghost that the Ghostbusters encountered. She appears to be a very odd reader as she likes to stack books up in the air. A team of three paranormal scientists managed to destroy her shield and trap Eleanor, but then some realize that it was to easy to the point it seem to them that she wanted them to have it.
She was portrayed by Ruth Oliver.
Early Life
Eleanor Twitty was born before the 1920s, and became the head librarian of the New York Public Library in New York. According to the newspaper article that Winston Zeddemore researches in 1991, Eleanor was seduced by Edmund Hoover, who was also known as "The Collector" and was a rare book collector. Eleanor was unaware that Hoover was using her to get rare books, including the Gozerian Codex.
When Eleanor realized this, she broke off their relationship and their engagement, but he murdered her in a secret section of the library that was constructed by Ivo Shandor. In 1924, Eleanor was the fifth woman to go missing under mysterious circumstances, and Hoover was caught and hanged before declaring that he would return as Azetlor the Destroyer. Eleanor became a spirit and was cited to be seen by 1924, and she continued to roam the library.
In 1984, the Library Ghost was disturbing the library, and later scared the librarian Alice in the opening of the film. Ray Stanz, Egon Spengler and Peter Venkman, three paranormal scientists, were brought to investigate the disturbance. The three came into contact with the Library Ghost, and when Ray told the group to "get her", she changed into her frightening form and scared them away. It's assumed that Twitty continued to roam the public library, and it's hinted that the Ghostbusters attempted to capture her before 1991.
Ghostbusters: The Video Game
In 1991, The Ghostbusters hear of a ghost outbreak happening at the library while going to the Museum, an decided to settle the score and capture the Grey Lady. The outbreak of ghosts also happened because of a paranormal wave caused by Shandor's descendent, and the mandala nodes in New York.
Ray, Egon, Winston and the new recruit go the library, and come across the Grey Lady after fighting ghosts that could manifest books to attack them. Winston goes to the archives and gives the others information on the Grey Lady's past, and tells them of The Collector and the Gozerian Codex. The information shocks Ray, who has held a grudge against Twitty for scaring them in 1984.
The Ghostbusters continue to look for the Grey Lady, and she is seen reading books, looking over books, and shushing the group when they speak. However, she shows her irritation towards the group by separating them, manifesting books to attack them, and screams "Quiet" to the Rookie when he is separated from Egon and Ray. The Library Ghost takes them deeper into the library, and they found her to an unground room reading the codex, and apparently shows how she was killed when the book attacks her. The Grey Lady allows the Rookie to take the codex, and quietly disappears, causing Ray to believe that she has passed over after they have taken the book, and has let go of her hatred for them.
However, she returns and changes into her "scary form" to fight the Ghostbusters, but is easily defeated and trapped after the group destroy Gozerian books that she was using to generate an energy shield. Ray realizes that the battle was too easy to the point that it seemed that she wanted them to have the codex, and a portal to an alternate dimension appears. Egon reveals the portal is a result of the energy produced from their battle with Twitty, and has caused a dimensional rip.
Ray, Egon and the Rookie go through the dimension, battling other ghosts, and surmise that Twitty did this to lead them to The Collector, who has become Azetlor. Also, Egon and Ray realize that Ilyssa Selwyn is connected to the paranormal events that have happen recently, notably the hotel, the return of Stay Puff, and the ghosts at the library. The Ghostbusters return to the library, but where the membrane of the dimension is still part, and defeat The Collector. After returning to the public library and reuniting with Winston, the group see a Mandala node, seeing one of them closing.
Though Egon and Ray were correct that Twitty allowed them to take the book, but it's possible that she wanted them to defeat The Collector to get her revenge. That being said, she also could have done so presuming that the Ghosbusters and The Collector would die fighting each other. Towards the last act of the video game, Ivo unleashes the Ghostbusters' containment unit to get an alternate energy source, thus releasing every ghost the group had trapped. It's assumed that the Grey Lady escaped, and returned to the public library, went onto the afterlife, or wasn't in the containment unit.
 - She was meant to have an iconic "Quiet!" line, which originated from the artist Berni Wrightson, but it was deleted for a roar in the film. In the video game, the Library Ghost is heard screaming the line.
 GhostbustersTitle.png Villains
Video Games


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A few animals and many flowers have more than bilateral symmetry. A daisy or a starfish has radial symmetry from its centre. Crystals also form symmetrical shapes such as octahedra and cubes. A snowflake is a crystal of ice with 6-fold radial symmetry and it is particularly elegant. How does it acquire its shape?
The snowflake begins its life as a minute hexagonal crystal forming in a cloud. The origins of this structure lie in a lattice arrangement of the water molecules which form the ice. During its passage from the clouds to the ground, it experiences a sequence of changes in temperature and humidity which cause it to grow at varying rates. Its history is recorded in the variations of thickness in its six petals as it grows. This process ensures that each petal is almost identical to any other and accounts for the snowflake's symmetry.
When a snowflake is rotated through an angle of 60 degrees about its centre, it returns to a position where it looks the same as before. Its shape is said to be invariant (meaning unchanged) under such a transformation. It is invariance which characterises symmetry in mathematics. The shape of the snowflake is also invariant if it is rotated through 120 degrees. It is invariant again if it is turned over. By combining rotations and turning over it is possible to find 12 different transformations which leave its shape invariant (including the identity transformation which does nothing). We say that the order of the snowflake's symmetry is 12.
Consider now the symmetry of a regular tetrahedron. That is a solid shape in the form of a pyramid with a triangular base for which all four faces are equilateral triangles. The shape of a regular tetrahedron is invariant when it is rotated 120 degrees about an axis passing through a vertex and the centre of the opposite face. It is also invariant when rotated 180 degrees about an axis passing through the midpoints of opposite edges. If you make a tetrahedron and experiment with it, you will find that it also has a symmetry of order 12. But the symmetry of the tetrahedron is not quite the same as that of a snowflake. The snowflake has a transformation which must be repeated six times to restore it to its original position and the tetrahedron does not.
Mathematicians have provided precise definitions of what I meant by "not quite the same". The invariance transformations or isometries of any shape form an algebraic structure called a group. You can consider composition of transformations as a kind of multiplication. For example, two isometries of the snowflake are a rotation of 60 degrees clockwise (call it a) and a reflection about the vertical axis (call it b). The transformations are composed by doing one and then the other, a followed by b. The result is a reflection about a different axis set at 30 degrees to vertical which is also an isometry (call it c). This composition is expressed algebraically as ab = c, as if it were a multiplication. The algebraic structure defined by these elements of symmetry is the group. The order of the symmetry is the number of elements in the group. Two groups are isomorphic if there is a one-to-one mapping between them which respects the multiplication. Two groups which are isomorphic are often regarded as essentially the same thing. The symmetry group of a snowflake is not isomorphic to that of a tetrahedron but it is isomorphic to that of a hexagon. Groups can be considered to be a mathematical abstraction of symmetry. Many of them have symbolic names. The symmetry group of the snowflake and hexagon is called D6 while that of the tetrahedron is called A4.
The historical origins of group theory can be traced back to tragic events of May 30th 1832. That morning a young Frenchman named Évariste Galois died in a dual. At 21 years old his life was already a tale of rejection and failure as a mathematician, yet the night before he met his death he wrote a letter which brought about a revolution in abstract thought. Galois developed a theory about which polynomial equations could be solved exactly using simple arithmetic operations such as addition, multiplication and square roots. Polynomials up to degree four could be solved in this way but quintic equations had been proven insoluble by the Norwegian mathematician Niels Abel in 1823. Galois found that the answer lay in the group of permutations of the solutions of the equations. A permutation is a way of rearranging or shuffling an ordered set of objects. Suppose, for example, that there are six numbered objects in numerical order 1, 2, 3, 4, 5, 6. A possible permutation would be 3, 4, 1, 6, 5, 2. It can be shown as a diagram,
It is not really the numbers which are important. It is the arrows which permute them. There are 720, (6! = 1 x 2 x 3 x 4 x 5 x 6) different possible permutations of six objects.
A rotation of a snowflake can be regarded as a permutation of its arms. Number them clockwise and look at the 60 degree rotation.
This is a permutation of the arms
Likewise a reflection about the vertical axis is another permutation
Any of the twelve transformations which leave the shape of the snowflake invariant can be shown as a permutation. To appreciate the algebraic structure of the group formed by the transformations we need to see how they can be combined. This is how it works for the rotation followed by the reflection
So combining permutations by joining the arrows is equivalent to performing one isometry followed by another. This is the same as multiplication in the group of isometries.
Like ordinary multiplication of numbers this kind of multiplication is associative, i.e. a(bc) = (ab)c for any three transformations a, b and c, but unlike ordinary multiplication it is not always commutative (ab)!= (ba). There is always an identity which has the property, a1 = 1a = a. Each element has an inverse, aa-1 = a-1a = 1. These algebraic rules are taken as the definition of a group.
Permutations, symmetry and groups all go together. A permutation is just a one-to-one mapping from some set to itself. A symmetry is a subset of permutations which leaves something (like shape) invariant. The algebraic structure of symmetries and the ways they combine is a group. To complete the triangle any group can also be seen as a collection of permutations of its own elements because multiplication by any element of the group is a one-to-one mapping onto itself.
The geometric symmetries of the snowflake and tiger are just one type of symmetry which leaves the shape of an object invariant. The permutations on a set of n objects also form a group which is called the symmetric group of the set or Sn for short. All these things are very important in physics but the theory of groups and symmetries also has its own intrinsic power and beauty which makes it interesting to mathematicians.
Permutations are not only applied to finite sets. There are also infinite order symmetries described by infinite groups and permutations of infinite numbers of objects. The simplest example is the group of rotations in a plane about the origin. It describes part of the symmetry of a circle and is known as U(1).
The next important example is rotation symmetry. The laws of physics are invariant under rotations in space about any axis through some origin. An important difference between the translation symmetry and the rotation symmetry is that the former is abelian while the latter is non-abelian. An Abelian group is one in which the order of multiplication does not matter, they commute (ab = ba). This is true of translations but it is not true of rotations about different axis.
If the laws of physics are invariant under both rotations and translations then they must also be invariant under any combination of a rotation and a translation. In this way we can always combine any two symmetries to form a larger one. The smaller symmetries are contained within the larger one. Note that the symmetry of a snowflake is already contained within rotation symmetry. Mathematicians say that the invariance group of the snowflake is a subgroup of the rotation group. They are both subgroups of the full group of permutations of points of space which leave the distance between any two points invariant.
Such symmetry is important because we can use it to test new theories of physics. Once we have accepted that certain symmetries are exactly observed in nature we can check that any set of equations looks the same after applying the transformations under which physics is supposed to be invariant. If they are not then they cannot form any part of the laws of physics. Mathematicians often go much further than this and work out all possible forms the laws of physics might take to respect the symmetry. Given translational and rotational symmetry we know that the equations can be expressed using scalars, vectors, tensors and spinors; quantities which can be combined in certain ways such as using vector and scalar multiplications. Nature has been kind to physicists. With these rules they waste much less time dreaming up useless theories of physics than they would if there was no symmetry. The more symmetry they know about, the better physicists can do. This is one of the secret of their success.
It was the Copernican revolution that changed all that. Nicolaus Copernicus described a cosmology in which the Earth had no special place and initiated a new freedom of thought taken up by Galileo. Newton, in response to Galileo, discovered his law of gravity which could at the same time account for falling objects on Earth and the motion of


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Oil Exploration…in the Food & Beverage Industry
In the 1970s, the use of filtration in air quality management in pharmaceutical production, hospitals, and medical device manufacturing facilities became increasingly important and increasingly of interest to regulatory agencies. The air quality field was growing. From the air moving into and out of clean rooms to the protection of surgical environments to the expansion of the global medical drug industry, compressed air began to play a larger role—a role that continues undiminished (and, in fact, has increased substantially) today. This helped spur larger growth in the compressed air field, including the use of air testing, which was already expanding due to attention in SCBA fire fighting and SCUBA diving air management and NFPA's work with healthcare facilities moving into the 1980s.
However, one of the key aspects of compressed air management rests in understanding that there is a huge difference between how the use of compressed air is overseen in pharmaceutical or other facility types and how breathing air quality is regulated. Breathing air requirements can be defined narrowly by guidelines such as OSHA 1910.134 and CGA Grade D + Moisture. But the compressed air quality needed for operations like bottle blowing is not the same as for a facility that manufacturers implantable devices.
Today's plant engineers must recognize this necessary inability to establish a "hard and fast" air quality standard beyond personal safety. And they must develop site-specific quality management and testing protocols that keep them in compliance with standards, even in the absence of exact standards for their applications, and operating efficiently. The pharmaceutical industry's development has really provided a good template here.
The food and beverage industry has had a very similar arc in its compressed air usage. It too exists in something of a gray zone, despite the heavy quality controls in modern manufacturing. In food and beverage, the need for compressed air is enormous and the compressed air is or can be used in all aspects of production, transport and storage.
The site-specific nature of product-production air quality, however, has put food and beverage companies in a state of question. Compressed air is a significant source of facility energy consumption, which impacts operational efficiency and cost. It is also a point at which facility owners must evaluate the level of risk involved in any compressed air quality levels they use. In the absence of clear rules, beyond needing some repeatable protocol, they often shoot higher than needed.
Setting the Bar Too High
Mark Fenstermaker, Qualification Services Division Manager of Bethlehem, Pennsylvania-based Micro-Clean, Inc., notes that the questions about compressed air quality, particularly for issues such as oil and other non-viables, have grown as the FDA has dedicated more time to learning about compressed air practices in food and beverage facilities. Essentially, the FDA is looking at how facilities are monitoring their compressed air quality—what guidelines are plant engineers consulting, what guidelines are available to them, how are they gathering samples, how are they verifying the compressed air quality, etc.
It's the same challenge as in the pharmaceutical field.
Fenstermaker says he's seen an uptick in recent years in the number of food and beverage companies seeking out additional support for compressed air quality analysis. In addition to various testing services, Micro-Clean also provides training to multiple industries about the standards and guidelines available to them and how others in their sector are responding.
"If a company is involved with something like SCUBA gear," Fenstermaker says, "they're looking at positive pressure or suits or something like that. They have to do breathing air. They fall under certain regulations. But if they are a large beverage company—now the FDA is asking 'Do they test?'"
They do, but the degree to which they test varies wildly. The FDA is looking at air that blows out bottles, for example, and making sure no contamination emanates from that compressed air source. But there's no regulation specific enough to the application to follow.
"They have to determine their risk analysis," Fenstermaker says. "What level of testing do they really want to perform at their location? A lot of them are taking the most stringent regulation they can find, like 8573-1, and they are using those recommended levels and testing to the lowest possible limit."
This decision is increasingly common, but puts these operations at a fairly inefficient level of operation. ISO 8573-1, even at its lowest levels in oil and particulate control, is still far higher than food and beverage facilities generally need.
"In terms of oil testing," Fenstermaker says, "they don't have to be '0.000001' or anything like that. For what they do, 0.01 may be perfectly appropriate, so long as the oil from their system is not contaminating the product."
For food and beverage right now, oil contamination identification and prevention are key areas of air quality focus.
But Where Is Your Oil Coming From?
Oil contamination can be an extremely difficult contaminant to pinpoint when it is discovered in your compressed air system. Even brand new systems can yield oil contamination upon more detailed air analysis. Some common sources for potential contamination include:
Piping. "If it's cast iron, for example," says Fenstermaker, "maybe there was oil coating on the cast iron to protect it in storage….And if it wasn't cleaned properly before assembling, now they have a contaminant in the line." The fittings used to connect pieces of a compressed air system might have some sort of oil on them as well. As the flow continues through from the compressor system, the actual generator, it can release those contaminants. "That's one of the main ways," Fenstermaker says.
Oil-based compressors. Some compressors are oil compressors that require the input of oil for lubrication. Usually these are food grade-based or food-based oils, so they may be considered edible. "That oil can get into the system if there's a breakdown in the compressors," Fenstermaker says. With the constancy of this oil's addition to the system, it increases contamination potential. Ways to test for it include Draeger tubes, air testing kits supplied by independent laboratories, and various analytical methods.
Lack of filtration. If the appropriate filtration, such as a point-of-use filter that may be beneficial to achieving an air quality goal, is not installed, oil can get pulled right into a compressor. It may sound simple, but it's less so. Again, issues such as the type of piping or fittings and how they were stored may impact performance here. If the contamination is already in the pipes but you haven't looked for it before, it may take you some time to figure out the source.
Contamination in the tanks. When you are dealing with massive industrial tanks at a food and beverage operation, it's entirely possible that some contaminant is present in the tank. In this situation, even installing a new system will not correct the contaminants you are finding in your testing. The investment in new, clean piping, new compressors, new desiccant driers, and everything else will not yet help you meet your goals if turning the system on stirs up the pre-existing contaminants in your tanks.
The systems used on a commercial scale in food and beverage operations can be incredibly elaborate. From 200 gallon tanks to 5000+ gallon tanks, multiple compressors, multiple driers to lower dew points, etc., there are many points at which oil mist and particulate contamination can enter a system.
This is exactly why the FDA is asking about how facilities in this industry test the vast compressed air networks necessary to production.
This information has been shared courtesy of TRI Air Testing, Inc. (_URL_).
While independent compressed air testing laboratories and consultants cannot tell you what you should do, their outside perspective can significantly help plant engineers identify where in the process the system is wasting energy and operational time or money to achieve a level of air quality that is well beyond industry practices. These independent partners can also help identify what type of contaminants, such as a particular level or type of oil has gotten into the product.
Sampling kits, such as those distributed by TRI Air Testing, Inc. in Austin, Texas help plant engineers economically acquire samples right at the source that are sent out for independent verification to a lab. Micro-Clean's business model, in fact, provides not just its own testing capabilities but a close network of additional independent labs when analyses sought by companies require particular levels of analysis or an additional independent check.
It's all part of fine-tuning in the food and beverage field, just as pharmaceutical facilities have done over the past 40 years.
"Oil is a big issue right now [in food and beverage]," Fenstermaker says. "Industry-wise, pharmaceutical is still the biggest area. But we are starting to get more calls from soft drink companies and other companies like that."
Chris Kelsey writes for Geosynthetica on energy, engineering, and the environment. He would like to thank Mark Fenstermaker (_URL_) and Dr. Ed Golla (_URL_) for sharing their time and insight.
To read more System Assessment articles, please click here


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Massive poverty reduction, middle-class expansion from major development gains in Africa, Asia, Latin America
Mexico City, 14 March 2013— The rise of the South is radically reshaping the world of the 21st century, with developing nations driving economic growth, lifting hundreds of millions of people from poverty, and propelling billions more into a new global middle class, says the United Nations Development Programme's (UNDP) 2013 Human Development Report.
"The rise of the South is unprecedented in its speed and scale," the 2013 Report says. "Never in history have the living conditions and prospects of so many people changed so dramatically and so fast."
This phenomenon goes well beyond the so-called BRICs, middle income countries often represented by Brazil, Russia, India and China, the 2013 Report stresses. The Report shows that more than 40 developing countries have made greater human development gains in recent decades than would have been predicted. These achievements, it says, are largely attributable to sustained investment in education, health care and social programmes, and open engagement with an increasingly interconnected world.
ABOUT THIS REPORT: The Human Development Report is an editorially independent publication of the United Nations Development Programme. For free downloads of the 2013 Report in ten languages, plus materials on the Report's indices and regional implications, please visit: _URL_.


}{\epsilon_0}} \frac{\gamma}{i\,\omega\,\mu}\right|^2} $
Now the time averaged power per unit area incident on the interface (by calculating the Poynting vector) is:
$\frac{1}{2}\sqrt{\frac{\epsilon_0}{\mu_0}} |E_i|^2$
so that the momentum transferred to the metal for each unit of incident energy is:
$\frac{2\,\mathrm{Im}(\gamma)\,\sigma}{\omega\,\mathrm{Re}(\gamma) \left|1 + \sqrt{\frac{\mu_0}{\epsilon_0}} \frac{\gamma}{i\,\omega\,\mu}\right|^2} \sqrt{\frac{\mu_0}{\epsilon_0}} $
This is the ratio we seek. For the case $\sigma\rightarrow \infty$ this ratio approaches $\frac{2}{c}\frac{\mu}{\mu_0}$. For $\mu = \mu_0$, this is twice the value calculated in methods 1 and 2 because the infinite conductivity excludes the field from the metal, there is no loss and light is reflected without loss. So, just as there is an impulse $2\,p_z$ transferred to a wall by an elastic bounce of a ball initially with momentum with component $p_z$ into the wall, so too the impulse transferred to the mirror from energy $W$ is twice the momentum of the incoming light, i.e. $\frac{2\,W}{c}$.
Now we let $\sigma\rightarrow 0$ so that $\gamma\approx -i \,\omega\,\sqrt{\mu\,\epsilon} + \frac{1}{2}\sqrt{\frac{\mu}{\epsilon}} \sigma$. I'll finish this case later, but it yields the same answer as methods 1 and 2 when $\mu = \mu_0$ and $\epsilon = \epsilon_0$, i.e. the light passes without reflexion into a weakly conducting medium and is absorbed.
Maxwell's equations are not consistent with Galilean relativity. They are implicitly relativistic. In relativity, the definition of mass is $m^2=E^2-p^2$. For a ray of light, $m=0$, so $E=|p|$.
 - $\begingroup$ So, just for the OP's benefit (although this OP seems to lose interest in his questions and not give too much feedback), there never was a version of electromagnetism that had to be upgraded to account for relativity. Indeed, historically, EM's Lorentz covariance that jarred with everything else and forced special relativity to be born. $\endgroup$ – Selene Routley Sep 29 '13 at 10:00
Your Answer


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Why Fingers & Toes Get Pruney in Water
Those pruney toes may have helped our ancestors get better footing in wet conditions, and today the wrinkles help us grip objects, scientists have found.
CREDIT: Brian Chase | Shutterstock
Fingers may wrinkle when wet to help people grip wet objects, find researchers, who say the pruney feature may have helped human ancestors do the same in wet conditions.
When a person's hands and feet are soaked in water, wrinkles eventually develop on the tips of fingers and toes. Scientists once thought this puckering resulted from the outermost layer of skin absorbing and swelling with water, but recent studies revealed the nervous system actively controlled this wrinkling by constricting blood vessels below the skin.
That the nervous system controls this behavior suggests these wrinkles served a purpose. Now researchers find these wrinkles could help fingers and toes grip wet surfaces.
"A phenomenon that everybody is familiar with is not just some kind of side effect of the nature of the skin on fingers and toes, but a functional feature that has very likely been selected for by evolution," researcher Tom Smulders, an evolutionary biologist at Newcastle University in England, told LiveScience.
Smulders and his colleagues had 20 volunteers pick up wet marbles and small lead weights of different sizes. Volunteers attempted the task either with normal, dry hands or after their fingers had wrinkled following a 30-minute soak in warm water. The participants picked up wet items 12 percent faster with wrinkled fingers. [10 Odd Facts About the Human Body]
"We have shown that wrinkled fingers give a better grip in wet conditions," Smulders said. "It could be working like treads on your car tires, which allow more of the tire to be in contact with the road, [which] gives you a better grip." Another possibility is that wrinkling causes changes in skin properties, such as its flexibility or stickiness, which help the fingers and toes perform better when wet.
"The most surprising thing to me was how the effect was there in all 20 participants, independent of how fast they were on average," Smulders said. "I never expected the effect to be so strong and obvious."
As a potential explanation of why this effect might have evolved, Smulders said, "it could have helped with gathering food from wet vegetation or streams. And as we see the effect in our toes, too, this may have been an advantage as it may have meant our ancestors were able to get a better footing in the rain."
Wrinkled fingers apparently made no difference when it came to picking up dry objects.
"This raises the question of why we don't have permanently wrinkled fingers, and we'd like to examine this further," Smulders said. "Our initial thoughts are that this could diminish the sensitivity in our fingertips or could increase the risk of damage through catching on objects."
Future research should analyze what other primates or non-primate animals might also show this phenomenon to shed light on when and why it evolved, Smulders said.
"Which other animals share this trait? And is the link among species that share it phylogenetic — that is, they're all related — or environmental — that is, they all deal with submerged objects, for example?" Smulders said.
The scientists detailed their findings online Jan. 9 in the journal Biology Letters.
MORE FROM LiveScience.com


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Simplified Internal arc - Structural simulation
Paper i proceeding, 2011
The impact of pressure rise due to an internal arc (IA) event on the structure of a switchgear cubicle is of great importance for a safe design. Switchgear panels are designed for withstanding an internal arc incident as per the testing conditions defined by IEC 62271-200 standard. This paper reports on a calculation procedure employing computational fluid dynamics (CFD) and structural finite element method (S-FEM). The approach is targeting a reduced numerical complexity, straight forward modelling, and stressing as little assumptions as possible. In the proposed method, time varying electric power is used as input along with other parameters for solving mass, momentum and energy equations by CFD. The peak pressure and rise time delivered by transient CFD simulation is needed to perform structural simulation. The structural calculation is performed using dynamic load factor.


Category: Social Sciences
Quest to understand motherly love
Researchers find that motherly grooming, even after being independent, has unprecedented benefits to young chimps for life. Saugat Bolakhe explores the evolutionary advantages maternal love and shares how the 'alpha male' is often wrongfully portrayed in human culture.
Drawing of a hand holding a phone with an instagram model promoting diet pills. Artwork by Maria Clara Liuzzi
A bad influence?
The promotion of diet pills, laxative teas and weight-loss supplements is now the norm on social media. Siobhan McGeechan explores this phenomenon in relation to social media influencers, specifically how their promotion of these products may be affecting not just the mental health but also the physical health of their followers.


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RoboBlox is a 4X4 3D Blox artwork which comprises of a sculptural frieze, interactive artwork and a 'making of RoboBlox' video (see below). While the artwork is inspired by Thieri Foulc's 2D-Morpholo Tile Game and the Oulipo French Movement, the muse of RoboBlox's sculptural frieze is the windy Brisbane/Maiwar river. The artwork uses rules and constraints to trigger the creation of the blocks which also serves as the basis of interactive creative engagement between the public and artwork. To create the individual block designs, QUT Design Robotics and UQ researchers coded a novel computational workflow into an industrial robotic arm to hotwire-cut polystyrene into the desired designs.
The making of RoboBlox Video
As robots will be commonly used in design education and fabrication, this artwork is an exploration into finding novel ways to communicate robotic design processes. This is important as designers and architectural manufacturers are likely to rely on robotic systems for the production of design and architectural work in the coming future. In keeping with this approach, a video which explains the design and manufacturing process of RoboBlox was placed within the exhibition. It elaborates on the workflow where open-source plug-ins were used particularly to develop a web-based interactive design platform and code that translates 2D graphics into 3D forms. It further documents the eventual robotic fabrication of the frieze pieces.
RoboBlox was exhibited in Brisbane, Australia at:
- Brisbane Art Design (BAD) festival from 10 May – 11 August 2O19
- Robotronica 2019 on 18th August 2019.
More on RoboBlox and related work:


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If your intended audience will view your finished program on a TV, preview the program on a TV monitor as you work. Elements that appear satisfactory on a computer screen may be unacceptable when viewed on a TV because computer monitors and TV monitors display images differently. The outer edges of the image may be cropped, colors may bleed, and horizontal details may appear to flicker. However, once you are aware of a problem, it's easy to take steps to correct it.
The Safe Title and Safe Action margins in the Monitor panel designate the title's visible safe zones. These margins are displayed by default when the Monitor is in title-editing mode.
Safe zones are useful when editing for broadcast and videotape. Most consumer TV sets use a process called overscan, which cuts off a portion of the outer edges of the picture, allowing the center of the picture to be enlarged. The amount of overscan is not consistent across TVs, so to ensure that titles and important actions fit within the area that most TVs display, keep text within the safe title margins and all other important elements within the safe action margins.
If you are creating content for the web or a CD, the safe title and safe action margins do not apply to your project because the entire image is displayed in these mediums.
A. Safe title margin B. Safe action margin
You can adjust the sizes of the Title Safe area, the Action Safe area, or both (for example, to customize them for displays with less overscan).


to predict the image position of an object, formed by a spherical interface (refer to light bulb image above):
$ n\ \sin \theta_1 = n'\ \sin \theta_2 $
$ \sin \theta_1 \approx \sin a + \sin b \approx {h \over S_o} + {h \over R} $
$ \sin \theta_2 \approx \sin b - \sin c \approx {h \over R} - {h \over S_i} $
$ {n \over S_o} + {n' \over S_i} = {(n'\ - n)\over R} $
Note that equation does not depend on angle a!
Massaging this equation gives three possible relationships between $ S_i $ and $ S_o $:
There's no need to memorize these relationships; they just serve to show the different behaviors of light as it passes through the spherical boundary. We will see these behaviors again when we look at lenses having two spherical boundaries in the next section.
20.309 130819 RefSphere2.png
a) Light converges
$ S_o > {n\ R \over (n'\ - n)}\ \Rightarrow S_i > 0 $,
b) Light is collimated
$ S_o = {n\ R \over (n'\ - n)}\ \Rightarrow S_i \to + \infty $,
c) Light diverges
$ S_o < {n\ R \over (n'\ - n)}\ \Rightarrow S_i < 0 $
Note the sign convention is that if $ S_i < 0 $, the light diverges, and a virtual image is formed at a distance $ |S_i| $ in front of the lens, on the same side of the lens as the light source (virtual images will be discussed more in a following section).
Let's put two spherical interfaces together to make a spherical lens. Each lens consists of two spherical interfaces with radii of curvature $ R_1 $ and $ R_2 $. Its focal length $ f $ is where the image is formed when an object is at infinity.
Types of spherical lenses
20.309 130819 TypeLenses.png
A practical note: to minimize spherical aberrations, the general rule is to position the curved side of the lens toward the collimated/straight light.
Lens maker's formula
Using the equation we derived earlier to find the image position after light passes through one spherical boundary, we can apply the formula twice--once for each spherical boundary of a simple lens, to calculate where the image will form after light passes through the entire lens. If we maintain our thin lens approximation, and take the image from the first refraction as the object for the second one, we can derive the lens maker's formula:
An example of light passing through a biconvex lens
The lens maker's formula
This formula shows us that the focal length of the lens is a characteristic of the lens, based on its radii of curvature and relevant indices of refraction.
Ray tracing
Based on what we've learned about how light is redirected when passing through lenses, we can come up with a set of rules to simplify our analysis of optical systems. With the technique of ray tracing, we can figure out where images are formed, whether they're upside down, magnified, etc.
20.309 130822 RayTracing1.png Rule 1: Rays passing through the center of a lens are unaffected by the lens.
20.309 130822 RayTracing2.png Rule2 : Rays that are parallel to the optical axis pass before hitting a lens pass through the focal point after the lens and vice versa. 20.309 130822 RayTracing3.png
20.309 130822 RayTracing4.png Rule 3: Parallel rays (any angle to optical axis) pass through the same point in the focal plane after refraction and vice versa 20.309 130822 RayTracing5.png
Image formation with a lens
When an object gives off its own light (like a light bulb) or is illuminated, we can imagine that the object is made up of many point sources, where each point on the object is emitting or scattering light in all directions. After refraction, all the rays from a single point in the object plane reach the same location in the image plane, forming an image. The image can be either real or virtual. A real image is one that can be seen if you put a screen on the image plane. A virtual image cannot be seen if a screen is at the image plane since there is no place the rays actually come together; it needs another lens (such as your eye) in order to view it. More examples of real and virtual images are described in a following section.
Let's look at a ray tracing example of a single lens producing a real, inverted image:
Step 1: Pick a ray that you know how to trace (here we pick a point at the top of the object and use Rule 1)
Step 2: Pick more rays emanating from the same point that you can trace based on our rules (here we use Rule 2). See where they converge to form an image
Step 3: Pick rays from a different point on the object (this time we pick a point on the bottom and use Rule 1 again).
Step 4: For completeness, let's look at more rays emanating from the second point we picked to see where they converge. Here, we use Rule 3.
Exercise for the reader: Can you use ray tracing to demonstrate the lens equation geometrically? You'll probably need to use similar triangles. Remember, that the lens equation is the relationship between the focal length of the lens, the object distance, and the image distance:$ {1 \over S_o} + {1 \over S_i} = {1\over f} $
Using this relationship, you can see why light going through a converging lens can produce three different results (this is similar to what we saw earlier for light passing through a spherical boundary). Whether the light converges, diverges, or is collimated depends on where the object is relative to the focal length of the lens:
Examples of real and virtual images
Let's use ray tracing to walk through a few examples of real and virtual images. In these examples we will consider the lens of your eye and the image formed on the retina.
Example 1: Real, inverted image. This is like the ray tracing example shown in the previous section. Don't worry if you can't draw all the rays shown below; there are rays you can draw based on our rules that will show you the same result (you should be able to identify those rays).
20.309 130819 EyeImage1.png
 - The eye's optical system focuses the light from each point of the object on to a point on the retina to create an image. Although the image is inverted on your retina, your brain does the work for you to see the image in the right orientation.
Example 2: Real image. This time the image is not inverted. This scenario is taking the image of one lens and making it the object of the second lens (your eye). Since the image gets inverted after each lens, it is at the original orientation after passing through the second lens.
20.309 130819 EyeImage3.png
 - You can view a real image directly. In this optical system the image of the first lens acts like the object of the next.
Example 3: Observing a real image on a screen.
20.309 130819 EyeImage2.png
 - This is an overview diagram demonstrating how we observe images from a projector. Let's break this down and look at the rays going through each lens.
Example 4: Observing a virtual image. An object placed within the focal distance of a lens produces a virtual image that can be observed through a second lens (like your eye). This is how a magnifying glass works.
20.309 130819 EyeImage4.png
 - This is an overview diagram demonstrating a lens before the eye acting as a magnifying glass. Let's take a closer look below with some ray tracing to understand how this happens.
 - In the virtual image, each light ray from a point on the object appears to originate from a different point in space.
 - Unlike a real image, you cannot position a screen to show the image – there is no place that the rays come together, unless they are refracted by another lens (your eye, in this case).
 - A real image, where light physically converges, is formed on the retina.
 - The image in a magnifying glass is virtual.
More ray tracing examples
Example 1: Relay lens system
Your friend is building an endoscope, where she wants to faithfully extend an image across a long distance. She proposes a system composed of two convex lenses having the same focal length (f) shown below.
A) Trace the rays to check her work and see where the image is formed.
B) Is the final image the same orientation as the original image, or is it inverted?
C) Use the lens equation to find the distance between the final image and the one she started with.
Once you've worked it out on your own, you can check your work here.
Example 2: Compound microscope
There is a cool bacterium you want to study in closer detail so you want to build a microscope to see it. You are told that you can build a microscope by placing two positive lenses (having focal lengths $ f_1 $ and $ f_2 $) at a separation distance equal to the sum of their focal lengths


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Bleeding Control Stations
Remember when applying medical treatment to someone to always wear personal protective equipment (i.e. gloves, glasses)
What to do when someone is bleeding.
- Attempt to stop the bleeding by applying a 4x4 dressing to the affected area and apply pressure.
- If the bleeding continues but slows, apply additional 4x4 dressings. (Do not remove previous dressings)
- If the bleeding continues and DOES NOT slow, apply a tourniquet 4" or higher to the affected limb.
If a tourniquet is applied, be sure to check for a pulse to ensure it does not exisit. This will mean the tourniquet was properly applied. *use the sharpie to write the time the tourniquet was applied on the white strap of the tourniquet and notify EMS.
Throughout Campus you'll find our Bleeding Control stations. Each station is equipped to treat 8 patients.
- Building 5400 (Cafeteria hallway)
- Building 3100 (enter the left automatic door and on the left wall past the registration computers)
- Building 1400 (Gym)
- Building 1000 (beneath the staircase)
- Building 3100 LRC (to the right of the main front door)


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An ultra-flexible grouping system
The DemoS grouping unit offers the possibility to freely arrange containers by defining spacings both in the running direction and crosswise. This allows to simply create any grouping in order to meet all production needs.
A simple and efficient way to feed downstream equipments
Once prepared, groupings are delivered on a belt with a very precise positioning.
This belt can directly feed :
- a gripping head for direct case packing in one move,
- the lapping station of a shrink-wrapper,
- a wrap around case packer.
Optimum protection of your containers
The DemoS grouping unit uses comb-shaped guides instead of conventional bar guides. This system ensures a smooth and positive guiding, without friction and without having one container ever pushing another one.
It allows an efficient mechanization of unstable containers with maximum protection of the containers themselves as well as of their labels.
Suitable for high outputs and multiple formats
The DemoS grouping unit can manage up to 100 rows per minute and thus reach an output of 50 000 bph.
A quick set-up process and container turning option at machine's infeed also allow the DemoS grouping unit to manage multiple formats.