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3. Gentoo/Alt Technotes Guide
3.a. General Structure
Handling Users
There are differences between users in a Gentoo/Linux system and the ones in other Gentoo/Alt systems. These differences are usually a side problem that does not invalidate most of the work. Still, it's better to pay attention.
The first thing to check is to never use the root group. The group with id 0, called root on Linux is instead wheel on BSD and Darwin, (and probably other classical unices); while wheel group on Linux has GID 10. When you need to set the default permissions on a file (or a series of files), you should then use the command chown root:0 file instead, so that it takes the right permissions.
Important: This is the only one case where you should refer to a group or an user with its numeric ID instead of the name.
For every other case you should always use the name of groups and users, avoiding specifying them by ID as they can have different IDs on different systems.
Also, it's important to note that every ebuild that makes references to specific users and groups, should add them with enewgroup and enewuser, if it does not depend on the ebuild that adds them. So for example, cronbase adds cron user and group, as they can not be present on the users' systems.
It's not rare to create users that cannot login on a system. To do so, on Linux, the shell of those users is set to /bin/false. Unfortunately, this does not work on BSD-derived systems like Gentoo/*BSD and Gentoo/Darwin, as they use a more sofisticated approach, and /bin/false does not exists. enewuser function provide a simple way to create a disabled user: just use -1 as the shell for the newly created user, this way the function will take care of selecting the right shell for the disabled user, making use of /sbin/nologin where that is present (*BSD, Darwin and Linux using app-admin/nologin) or falling back to /bin/false when nothing else can be used.
Note: As of now eneweruser function fails when using /bin/false or any other direct "disabled" shell as shell for the user, forcing the ebuild developers to use -1 as it should be.
If you need to find out the home directory for a given user, you can't rely on the format of /etc/passwd or on the output of egetent, as they are different on FreeBSD and OSX. To avoid this, the egethome function (provided by portability eclass, but available inheriting eutils), returns the right field making sure that is the home directory for the user:
Code Listing 1.1: egethome usage
inherit eutils
homedir=$(egethome charlie)
3.b. Applications
Bash and shells
Bash is the default shell of Gentoo Linux, and it's on top of this that ebuilds are written. Because of this, Gentoo/Alt projects provides bash in their base system, as /bin/bash.
Ebuilds and scripts can use bashisms without problems as bash is provided, but in case of scripts, it's important that the first line reads as #!/bin/bash instead of just #!/bin/sh, to make sure that they are being executed with bash. The same goes for calling scripts from inside ebuilds, sh somescript is deprecated in favor of bash somescript so that bash is called for sure.
While bash should take care of managing [.. ] tests, it's anyway suggested to use [[.. ]] to run tests also when quoting the arguments correctly. This way, the tests are guarranteed to be expanded by bash internally and do not get executed by /bin/[ instead.
GNU tools and non-GNU userlands
Gentoo/Alt projects, a part from Gentoo GNU/kFreeBSD, aims to have a complete system that uses native versions of all the system's tools, of libc, and so on. However, there are some part of Gentoo's base system that does not work with BSD-like tools (not because they are broken, just because they are strictly POSIX). To work around this problem, we install a series of GNU tools g-prefixed. In a Gentoo/Alt system profile, you can always find these tools: GNU sed (as gsed), GNU make (as gmake), GNU awk (as gawk), GNU patch (as gpatch) GNU diff (as gdiff) and usually GNU cmp (as cmp, for compatibility with a couple other scripts). If you need GNU-style find command, you can also install findutils package that provides gfind and gxargs.
To allow users who prefers the GNU-style tools be comfortable, there is an ebuild sys-apps/userland-gnu that depends on coreutils and other GNU packages, that are always g-prefixed, and then links them inside /usr/libexec/gnu without the g-prefix. After adding them to $PATH, it's possible to use GNU tools in command line.
It's always preferred to use just the POSIX options, to be able to run the same script identical on Gentoo/Linux and Gentoo/Alt. In case you cannot rewrite the code not to use the GNU extensions, just add a dependency over the right package that provides the tool, and then do a simple test:
 1. Check for the g-prefixed tool
 2. Check that it works as expected for a GNU tool (usually this means that it accepts version option and reports GNU, FSF or the name of the package there)
And then select the right one you need.
Important: Inside an ebuild there are a few aliases that are used to make sure that they doen't break apart, so calling make, sed, patch and awk will call the GNU version of the tools.
Warning: The GNU tools' aliases works only if the tools are called by themselves, they won't work inside scripts called by the ebuild, and they won't work if called by find.. -exec or by xargs. In those cases, it's usually better to check for the right tool to call. An important exception is the usage of the sed command to call GNU sed: being widely used and difficult to check or fix, Portage 2.1_pre9 and later provides a wrapper script that calls GNU sed in any case, when used from ebuilds, if the $ESED variable is not set, in which case the called sed will be the one there indicated. This allows the usage of BSD sed when building BSD packages for instance.
To help with porting, there are a few constructs that are usually used out of habit that need to be fixed:
 1. cp -a: this is a GNUism, as the -a option is not present on POSIX cp. Its replacement is told to be -dpPR, but -d is not posix itself, so -pPR is what you should replace -a.
 2. cp --parents: this other GNUism is used to copy a series of files from a tree maintaining their prefix. There's no equivalent option in BSD userland, so this should be avoided. If you need this, instead use the treecopy function in portability eclass, that works exactly as a cp --parents -pPR call.
 3. seq doesn't exist on BSD userland, but there's a quick replacement: jot. Unfortunately its syntax is too variable, and poses a problem to manage. To avoid this, portability eclass has a seq function replacement that calls jot with the right parameters when called on a BSD userland. Still, make sure you're not trying to use some extra options to seq
Note: The -d option does not make a difference in almost all the cases, as it counts only when you have symlinks directly on the command line argument.
Using pmake
There are a few packages that require the use of pmake (parallel make, by NetBSD, the package we use is from Debian) to build on GNU userland, as the makefiles are incompatible with GNU make. As the name of this flavor of make varies depending on the userland you're in (it's pmake on GNU userland, bsdmake in Darwin userland and simply make in BSD userland. To avoid this trouble, you can use get_bmake function from portability eclass.
Code Listing 2.1: using get_bmake
src_compile() {
 $(get_bmake) || die "make failed"
If the package builds using ports-like interface, as done by FreeBSD system packages, bsdmk eclass (currently on Gentoo/Alt overlay) provides a simple way to handle the knobs: just add to ${mymakeopts} the list of knobs to pass during the pkg_setup() function, and then call mkmake and mkinstall to compile and install the packages as specified.
Note about different make
As the make command changes name depending on the system where it's being used, there is an important thing to keep in mind: recursive makefiles are often used to build subdirectories of a source tree, but sometimes they calls directly a new make command. This breaks when the makefiles are called with other versions.
To avoid this problem all the modern make commands sets an automatic variable $(MAKE) that carries the name of the command used to launch the make chain. Instead of calling a generic make, all the makefiles should then call $(MAKE) to be safe with different naming of the command.
Another fortunately less common problem is when a package decides that $(


text:
After the capture of a living Coelacanth, evolutionists realized that this was not a transitional form. So they next settled on depicting the fish E. foordi as a transitional "missing link."
Evolutionists maintained that that the tailed water frog was descended from E. foordi. However, anatomical comparisons of tailed water frog and Eusthenopteron revealed profound differences between the two. This meant that evolutionists had to suppose another transitional form between them. However, no skeleton belonging to this theoretical transition between Eusthenopteron foordi and the tailed water frog Icthyostega has ever been found.
Now, the two favorite subjects for most of the contemporary evolutionary scenarios regarding tetrapod origins are Eusthenopteron (an extinct fish) and Acanthostega (an extinct amphibian). Robert Carroll, in his Patterns and Processes of Vertebrate Evolution, makes comments on these allegedly related forms:
Eusthenopteron and Acanthostega may be taken as the end points in the transition between fish and amphibians. Of 145 anatomical features that could be compared between these two genera, 91 showed changes associated with adaptation to life on land... This is far more than the number of changes that occurred in any one of the transitions involving the origin of the fifteen major groups of Paleozoic tetrapods. 154
154 Maria Genevieve Lavanant, Bilim ve Teknik magazine, April 1984, No. 197, p. 22.

source: HuggingFaceFW/fineweb-edu


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Why Downtown Is Important
- Downtown serves as a good incubator for new small businesses - the success of tomorrow. Strips and malls are often too expensive for new entrepreneurs. Lower rents make downtown a good location.
- Downtown represents independent businesses which support local families, support local community projects such as teams and schools, keep profits in town (chain stores send profits out of town). It helps reduce sprawl by concentrating activity in one area.
- Downtown is a major employer. Often when you count the number of jobs in a community, you will find that downtown is the largest employer.
- Downtown infrastructure is a major public investment. Only healthy businesses in buildings assessed at full value generate taxes that give taxpayers a return on this public investment.
- Downtown revitalization protects property values in surrounding residential neighborhoods.
- Downtown rehabilitation work stimulates the local economy. Materials and labor for new commercial construction often come from out of town.
- Downtown is a symbol of community economic health, the partnership between the private and the public sector, local quality of life, local pride, and community history
- Downtown is the heart of the community, and the site for government, arts, churches, and financial institutions.
- Downtown is an important community space, where members of all segments of the community can meet equally for parades, speeches and other community events.
- Downtown can be a tourist attraction, and is the location of a community's unique businesses and buildings.

source: openbmb/Ultra-FineWeb


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Pedestrian And Traffic Barriers: Regulations, Standards, And Best Practices
Beyond the general duty clause that requires employers to keep workers safe from recognized hazards and 29 CFR 1910.176(a), which requires sufficient safe clearances around mechanical handling equipment and appropriately marked permanent aisles and passageways, the Occupational Health and Safety Administration (OSHA) offers no written regulations surrounding the use of pedestrian and traffic barriers. That's why, in "The Purpose of Pedestrian and Traffic Barriers," a webinar presented by the members of the Protective Guarding Manufacturers Association (ProGMA), best practices for the design and use of these systems were discussed. Additionally, the contents of the newly published standard for crash-testing of industrial guardrails and barriers were explored.
Among the best practices reviewed, the presenters recommended considering safety guarding placement during the earliest phases of a facility design project. Key points included to look for areas where material handling equipment and pedestrians might interact as locations where designated walkways, delineated with guardrails, be established. A plan that segregates forklift traffic areas from pedestrian and other non-traffic areas with guarding should also be considered. Further, when placing equipment—such as machinery or racking—it is important to leave extra space around the system to ensure adequate square footage for guarding to prevent a forklift impact.
To help purchasers be assured that the pedestrian and traffic barriers they install will be sufficiently strong enough to withstand potential impact forces ProGMA recently published a new standard, "ANSI MHI31.2-2021 – Test Method for Crash Testing Industrial Guardrail Barriers and Barrier Posts." The webinar presenters discussed the primary sections of the document, including how the test should be set up for uniform, comparable results; how and why deflection zones are measured; what impact ratings can be given; and which testing facilities are certified.
To conclude the session, key factors for selecting the most appropriate guardrail solution were overviewed. These include:
- What is the environment in which the guardrail will be installed?
- What is to be protected?
- What are the weights and travel speeds of the vehicles used in the facility?
- What are the impact zone heights?
- What is the maximum angle of approach?
- What is the strength of the floor to which the guardrail will be bolted?
- How far away from the protection zone should the guardrail be placed?
Looking for more information about guardrails and protective barriers? The members of the Protective Guarding Manufacturers Association (ProGMA) are available for guidance and recommendations.


procedure.
Comparing the skeleton to the tensor product grid required to approximate $\tilde{f}$ to machine precision, we see that $\tilde{f}$ is numerically of low rank, so Diskfun is effectively compressing the representation. The clustering of sample points near the center and the edges of the disk can be observed in the tensor product grid; low rank methods alleviate this issue in many instances.
plot(f, '.-', MS, 10, LW, 0.3), axis off
title('Low rank function samples', FS, 16), snapnow
[ m, n ] = length(f);
r = chebpts(m);
r = r((m+1)/2: m);
[ tt, rr ] = meshgrid( linspace(-pi, pi, n), r );
XX = rr.*cos(tt);
YY = rr.*sin(tt);
clf, plot(XX, YY, 'k', LW, 0.1)
hold on
plot(XX', YY', 'k', LW, 0.1)
view(2), axis square, axis off
title('Tensor product function samples', FS, 16)
Writing the approximant as in (\ref{eq:lra}) allows us to work with it as a continuous analogue of a matrix factorization. Then, the "column" (radial) slices of $f$ are the collection of Chebyshev interpolants $c_j(\rho)$, and the "row" slices are the trigonometric interpolants $r_j(\theta)$. These can be plotted; doing so we observe that each column is either even or odd, and each row is either $\pi$-periodic or $\pi$-antiperiodic. This is reflective of the BMC structure inherent to the approximant.
title('5 of the 26 column slices of f'), snapnow
title('5 of the 26 row slices of f')
In practice, several basis choices can be used for approximation on the disk (see [Boyd & Yu, 2011]). Diskfun uses the Chebyshev--Fourier basis, and f is fully characterized by its Chebyshev and Fourier coefficients. The command plotcoeffs lets us inspect these details.
[Boyd & Yu, 2011] J.P. Boyd, and F. Yu, Comparing seven spectral methods for interpolation and for solving the Poisson equation in a disk: Zernike polynomials, Logan & Shepp ridge polynomials, Chebyshev & Fourier series, cylindrical Robert functions, Bessel & Fourier expansions, square-to-disk conformal mapping and radial basis functions, J. Comp. Physics, 230.4 (2011), pp. _PHONE_.
[Churchill & Brown, 1978] R.V. Churchill, and J.W. Brown, Fourier Series and Boundary Value Problems, McGraw-Hill, 1978.
[Fornberg 1998] B. Fornberg, A Practical Guide to Pseudospectral Methods, Cambridge University Press, 1998.
[Townsend, Wilber & Wright, 2016] A. Townsend, H. Wilber, and G.B. Wright, Computing with functions in spherical and polar geometries I. The sphere, SIAM J. Sci. Comp., 38-4 (2016), C403-C425.
[Wilber, Townsend & Wright, 2016b] A. Townsend, H. Wilber, and G.B. Wright, Computing with functions in spherical and polar geometries II. The disk, SIAM J. Sci. Comput., 39-3 (2017), C238-C262.
[Trefethen, 2000] L. N. Trefethen, Spectral Methods in MATLAB, SIAM, 2000.


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Thrive by Five welcomes Federal Government investment in preschool access for Indigenous children
5 August 2021 – Thrive by Five has welcomed the Morrison Government's $120 million investment in programs to improve access to preschool for Indigenous children in regional and remote Australia as part of the Closing the Gap implementation plan.
Thrive by Five CEO Jay Weatherill said the announcement was recognition of the importance of high quality and universally accessible early learning.
"We know that high quality early childhood education sets children up for life. When children attend high quality early learning they start school ready to learn and have greater opportunities to fulfil their potential in later life," Mr Weatherill said.
"Currently, one in five Australian children are considered developmentally vulnerable at the time they start school. These children are more than twice as likely to be found in low-income communities as in high-income communities and they are also more than twice as likely to be Indigenous.
"The evidence shows that vulnerable children stand to benefit the most from high quality early learning.
"Thrive by Five welcomes investment to improve access to early learning for Indigenous children in regional and remote Australia."
The investment is an expansion of Minderoo Foundation's Connected Beginnings initiative, which has been adopted by the Government and partners with local organisations and providers in regional and rural communities to determine the best method of early education and care delivery.
"We continue to urge National Cabinet to prioritise overall early learning reform," Mr Weatherill said.
Thrive by Five is calling on the National Cabinet to adopt a five-point plan to reform early learning and childcare.
- Agree to a new Federal-State Agreement to deliver universal three-year-old preschool across the country to match the agreement in place for four-year-old preschool.
- Lift the childcare subsidy to 95 per cent for all children and set agreed fee caps.
- Make the childcare subsidy available to all children regardless of the service type and the income or work status of the parents.
- Start workforce planning for a universal system and fund appropriate pay and conditions for educators to end the problem of skill shortages, high vacancy rates and high staff turnover rates across the sector.
- To achieve these outcomes, we ask that early education and childcare become a part of the National Cabinet reform agenda to deal with complexities of the system and build a true national universal system.


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I have read that holes in semiconductor are nothing but vacancies created by electrons. But how can this vacancy i.e. hole has a mass?
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See physics.stackexchange.com/a/10858/3811 for more details about "what is a hole" than you usually find :-) – Steve B Jul 10 '12 at 22:57
4 Answers 4
A quick answer:
Imagine an array of billiard balls with one missing in the middle of the array; there is a "hole" where the billiard ball is missing. For this hole to "move", a billiard ball must move into that position, leaving a hole at the ball's previous position. Since, in fact, the hole movement is entirely equivalent to the billiard ball movement, we can speak of the mass of the hole even though it is the billiard ball's mass that is physical.
Now, in the case of electrons moving through the unfilled valence band, the effective mass is greater than the mass of a mobile electron so hole mass is typically greater than mobile electron mass.
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While the answers above are correct in essence, the inertia of the hole is due to the electrons that must flow to fill up the hole, there is a simple way to understand what the mass of a hole is in a tight-binding model.
If you have an electron in a lattice, and it can hop from one site to another with amplitude a, then the time evolution of the wavefunction is by
$$ {\partial_t \psi(x)} = a\sum_{\langle y,x\rangle} \psi(y) $$
where the sum is over nearest neighbors of x (not including x). If you redefine the phase of the wavefunction in a time-dependent way $\psi(x)\rightarrow e^{iNat}\psi(x)$$ where N is the number of nearest neighbors, you subtract a term from the right hand side which leads to a standard form of the lattice Laplacian, so you have a discretized Schrodinger equation. The continuum limit of this is the normal Schrodinger equation:
$$ {\partial_t \psi} = a\epsilon^2 \nabla^2 \psi $$
Where $\epsilon$ is the lattice spacing. From this, you can read off the effective mass $m={1\over 2a}$.
The point is that mass of a quantum excitation is just the inverse of the hopping amplitude, so it is universal to describe any localized excitation that moves coherently with an effective mass. The harder it is to hop, the more massive the object is. The result is in principle independent of the actual mass of the fundamental particles--- if you make an optical lattice and place a metal BEC in each optical trap, the electrons have to tunnel from one trap location to the next in order to flow, and the effective mass can be as large as you like. In real materials, the effective mass is usually close to the electron mass, but sometimes can be hundreds of times bigger.
If you fill up all the electron states, and consider one hole, there is an amplitude for the hole to hop to a neighboring location. This gives an effective mass as above, proportional to the inverse hopping amplitude. Unlike in classical systems, you don't have to consider dissipation--- the effective mass description is exact. Further, if the hopping amplitude for a hole is fundamentally the same as the hopping amplitude for an electron to fill the hole from the neighbors.
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I think that the answer should be searched in surface metal (dielectric)free electrons. When an electron start to move it became heavier or easyer throgh absorbtion or radiation of some Planck energy.The change in speed is : speed is increasing if electron go through band gap by absorbtion.(Fourier Generalised Tf. and antenna radiation) In orbital valent position the electrons and the holes in which it is formed a filler.When the electron leave the filler, the filler hole mass is the mass of electrons plus the mass of received energy and other posible interaction with other orbital or nucleous.
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Could you please improve the grammar and/or sentence structure of your answer? It is very hard to understand what you're saying as of right now. – Danu Oct 19 at 8:54
For a very common practically important classical mechanical equivalent, consider a bubble of air in the water. The apparent inertia of the bubble is on order of the mass of water displaced by the bubble, as the water around the bubble has to move for the bubble to move. This is an important consideration for ships, submarines, torpedoes, fish, etc, that end up having considerably more inertia than their own mass, and end up accelerating slower with the engine on.
One time I did mathematics for realistic barrel falling into water in computer game; the apparent 'increase' of the mass, in combination with the conservation of momentum, rather accurately describes a large part of the deceleration of object when it is entering water.
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Lasers to replace quartz technology
In a new discovery, researchers have found that lasers can safely replace years old quartz technology used in wristwatches or to transmit reliable signals to radios.tech reviews Updated: Jul 18, 2014 16:06 IST
In a new discovery, researchers have found that lasers can safely replace years old quartz technology used in wristwatches or to transmit reliable signals to radios.
In lieu of a crystal, researchers at California Institute of Technology (Caltech) have developed a method to stabilise microwave signals in the range of gigahertz using a pair of laser beams as the reference.
"Our new method reverses the architecture used in standard crystal-stabilised microwave oscillators - the 'quartz' reference is replaced by optical signals much higher in frequency than the microwave signal to be stabilised," explained Kerry Vahala, a professor of information science and technology and applied physics at Caltech.
Nearly all electronics require devices called oscillators that create precise frequencies.
For nearly 100 years, these oscillators have relied upon quartz crystals to provide a frequency reference.
Quartz crystals "tune" oscillators by vibrating at relatively low frequencies - those that fall at or below the range of megahertz, or millions of cycles per second, like radio waves.
However, future high-end navigation systems, radar systems and even consumer electronics will require references beyond the performance of quartz.
In the new method called electro-optical frequency division, the optical reference used by researchers is a laser that looks like a tiny disk.
"At only six mm in diameter, the device is very small, making it particularly useful in compact photonic devices - devices powered by photons instead of electrons," said co-author Scott Diddams, a physicist at Maryland-based the National Institute of Standards and Technology.
The study appeared in the journal Science.


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Objective: To report a case of eosinophilic myocarditis with remarkable initial clinical manifestations and outcome. Material and Methods: A 67-year-old woman with hypertension and a history of asthma and drug hypersensitivity was referred to our institution with a diagnosis of acute myocardial infarction on the basis of severe chest pain, ST elevation on an electrocardiogram, and a slight increase in cardiac enzymes. Further diagnostic studies were performed. Results: Echocardiography disclosed left ventricular dysfunction in conjunction with apical asynergy, thinning, and thrombus. The eosinophil count in the peripheral blood was increased only slightly. Coronary angiography showed normal ar-teries and prompted the performance of endomyocardial biopsy, which revealed active eosinophilic myocarditis. After corticosteroid therapy, global and regional left ventricular function returned to normal. Conclusion: This unusual clinical picture and outcome demonstrate that eosinophilic myocarditis may simulate acute myocardial infarction and should be considered in patients with a history of allergies or acute left ventricular dysfunction, even in the absence of pronounced eosinophilia in the peripheral blood. With appropriate medical therapy, recovery for these patients can be complete. 7.
ASJC Scopus subject areas


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It is the first study to look like the relationship between long-term effects of exposure to fine particles in the air and rates of hospitalizations.. Ads written drug information on oxycodone and aspirin by Anna Sophia McKenney.Increased risk of hospitalization Lung, Heart Disease following long-term exposure to air pollutionOlder adults may be at increased risk for lung and heart disease, stroke and diabetes, according to a long-term exposure to fine particulate air in hospital pollution, according a new survey by researchers at the Harvard School of Public Health.
Patterns of Abuse Among Unintentional Pharmaceutical Overdose Fatalities Aron J. MSPH;. Joseph E. PhD, Robin L. James A. MD, PhD, James C.; Danae Bixler, Leonard J. Paulozzi, MPH, JAMA 2008;. 300 :2613-2620 Click here for Abstract.Many colleges and universities of provide resources, their studies. Five students with ADHD a functional point, but we are to first who are looking the effects of drugs to treat symptoms treated. Treated. The results of this study autumn autumn 2010.


The Fitness Generation Pty Ltd
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Environmental Policy
Environmental statement
Understanding the importance of the preservation of our shared environment is of a fundamental importance to the Management and every employee of The Fitness Generation.
Several initiatives have been undertaken to ensure we are leading the way for the health and fitness industry in this area. To date we have:
1. Undertaken a full Carbon Audit to quantify our Carbon Footprint and we have committed to purchase Carbon Credits to offset this quantity;
2. Committed to ongoing annual Carbon Audits;
3. Undertaken to deal with Supplier Companies that have a similar stance on these matters;
4. Introduced in-house environmental training programs for all employees to create a greater awareness of environmental issues, and develop ways to address such issues;
5. Implemented the relevant and required Health and Safety measures for all employees;
6. Undertaken systems, equipment and plans to use all raw materials, energy and water and as efficiently as possible.
The Fitness Generation will make every effort to ensure that our Environmental Performance is as important as other performance indicators within our business by regularly monitoring the environmental performance of all those directly involved with our business.


People work harder when expecting a future challenging task
November 17th, 2009 in Other Sciences / Social Sciences
Consumers will work harder on a task if they're expecting to have to do something difficult at a later time, according to a new study in the Journal of Consumer Research.
In today's fast-paced world, frequently undertake unrelated tasks in a sequence. An individual might make a grocery list, decide whether to take out a home improvement loan, search the Internet for a vacation spot, and choose a dinner location—all before preparing lunch. "It seems reasonable to expect that when consumers know that they will have to work hard on a future task, they will devote less effort to the current task, in order to save energy for the upcoming demanding task. This is not what we found," write authors Anick Bosmans, Rik Pieters (both Tilburg University, The Netherlands), and Hans Baumgartner (Pennsylvania State University).
In a series of five studies, the authors observed that the more difficult a future task was expected to be, the harder consumers worked on a current task. "For example, consumers consulted more information on a web page when they were asked to evaluate a new soft drink when they expected that they would later on have to work on a difficult and demanding task," write the authors. Other participants were better able to come up with weight loss ideas when they believed they would have to work hard on a future job.
The authors titled the the "get ready mindset." "People seem to prepare themselves mentally for upcoming tasks, but in doing so, the resources that are freed up for the future task carry over to current tasks," the authors explain. "We found consistent evidence that if the mind gets ready to perform later, it is set to go now."
The authors found that the "get ready mindset" can be attenuated and even reversed when people are better at separating tasks, either because the situation helps then to do so or because they are habitually better at keeping tasks separate.
"These results imply that the amount of effort that consumers will invest in the decision-making process (such a searching for information, generating ideas, or evaluating alternatives) is dependent upon the anticipated difficulty level of future tasks," the authors conclude.
More information: Anick Bosmans, Rik Pieters, and Hans Baumgartner. "The Get Ready Mindset: How Gearing Up for Later Impacts Effort Allocation Now." : June 2010 (published online October 20, 2009).
Source: University of Chicago (news : web)
"People work harder when expecting a future challenging task." November 17th, 2009. _URL_


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Magnetic Particle Inspections
It is crucial to test any machine or material consisting metal in order to prevent major discontinuities.
Magnetic Particle Inspection (MPI) is a nondestructive testing process that detects discontinuities (seams, laps, grinding and quenching cracks) on surfaces and subsurfaces of iron, nickel, cobalt, their alloys and other ferromagnetic materials.
How Does MPI Work?
A magnetic field is put into the ferromagnetic part and is magnetized by direct or indirect magnetization. If the ferromagnetic part has a discontinuity, then it will interrupt the magnetic field flow and a leakage field will occur. An application called magnetic media is then used to coat the part and form a mark over the discontinuity. The mark can only be visible under proper lighting conditions.
Wet v.s. Dry Magnetic Media Application
Wet– More sensitive since it gives the magnetic particles more mobility because it is a liquid. There are two types of wet particles: One is visible and can be viewed under normal white light while the other is fluorescent and can only be viewed under black light.
Dry– More of a dust that is light and more portable. It comes in a variety of colors so that a color can be chosen that produces a high level of contrast against the background of the ferromagnetic part
Advantages of MPI
- Detects both surface and subsurface defects
- Inspects parts with unusual shapes
- Pre-cleaning is easy and not as critical as other inspection methods
- Fast and cheaper than other methods
- Very portable
If you use ferromagnetic materials make sure to contact CODE STEEL to come and inspect it with the MPI test before it's too late.


text:
by John R. Thelin
"Free college" is a visible and volatile issue in the Democrat candidates' presidential campaign platforms. No Democratic candidate today can afford to ignore the issue, even if it means taking time to impose strict limits.
- Evelyn Brooks Higginbotham on the AP Af-Am Studies Controversy
- 600 African American Studies Faculty Sign Open Letter in Defense of AP African American Studies
- Organization of American Historians Statement on AP African American Studies
- Historians on DeSantis and the Fight Over Black History
- How the Right Got Waco Wrong


text:
This web site contains an algebra-based physics curriculum in which physics concepts are introduced through studies of human physiology. It contains a collection of modules covering a wide range of topics in physics, each using examples from human biological processes. Modules include Biomechanics and Modeling Human Motion, Modeling Human Vision, Modeling Human Speech and Hearing, Circulatory and Respiratory Systems, and more. A key element of the pedagogy is the embedding of mathematical models within practical disciplines, such as physiology and biomedical engineering. Students will engage in "real-world" scenarios to solve inquiry-based physics problems.
These materials are based on an interactive pedagogy and include use of multimedia and mathematical modeling. These resources have been tested in classes and assessed.
%0 Electronic Source %A Wentworth, Christopher %D July 28, 2006 %T The Humanized Physics Project %V 2013 %N 25 May 2013 %8 July 28, 2006 %9 application/pdf %U _URL_
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Most requirements processes mandate that requirements are traced from high level concepts such as Business Drivers, Visions and Goals down to the parts of Components that implement them. For many projects this is an intractable problem because much of the information lives in a set of heterogeneous tools such as word processor documents, spread sheets, diagram tools, corporate presentation tools and more. Some project managers attempt to solve the problem by creating a spread sheet that acts as a register of all the disparate information but the management of this file takes up considerable project resources and is almost impossible to keep up to date. With Enterprise Architect there is the ability to model all of this project information in the one tool and to create easy to maintain and analyzable traces between all the elements from an organization's mission statement right down to the level of programming code if required.
Visualizing Traces in diagrams
Regardless of whether you have entered the project's Requirements using a diagram or using a text based tool like the Specification Manager or imported them from another tool, viewing the requirement traces in a diagram gives an easy to understand view of their relationships. The diagrams can be created easily by dragging and dropping elements from the Project Browser or automatically by using the Insert Related Elements function. This function can be configured and used to draw a graph of elements to any depth and can be restricted to selected element and connector types. It is a powerful productivity tool in a team environment and even modelers with deep knowledge of the domain and the repository are surprised at the connections that are displayed in the diagrams.
Visualizing Traces using the Relationship Matrix
The Relationship matrix is a powerful tool and provides an alternate way of visualizing the relationship between requirements and other elements or even between different levels or types of requirements. It is quite common for some stakeholders to prefer a spreadsheet like view of the Requirements and their relationships and the Relationship Matrix provides an excellent way of presenting the relationships without resorting to a diagram. In Use Case driven requirements methods Use Cases are said to realize one or more Requirements and these relationships can be displayed visually in the relationship matrix. The list of Use Case would appear on one axis of the matrix and the requirements would be listed on the other axis, a marker in the row and column intersection would display if a relationship exists indicating that a particular Use Case realizes a Requirement. Relationships between elements can be created or deleted using the relationship matrix and the matrix can be saved and reopened at any time or saved to a CSV file so it could be opened in a spreadsheet. Documentation can also be created that includes the relationship matrix providing a powerful communication tool for people who do not have access to the model.
Visualizing Traces using the Traceability Window
While diagrams and the Relationship Matrix allow modelers to view traces between requirement elements it is possible that the creators of these views of the repository have deliberately omitted elements from the view. For example a diagram does not need to show all the requirements owned by a particular stakeholder. The Traceability window will however present a complete and unabridged view of the relationships between elements. The element relationships will be displayed regardless of the location of the elements in the Project Browser.
Visualizing Traces using the Relationships Window
Modelers often choose to hide one or more relationships on a diagram for the purpose of making the diagram simpler to understand or to hide detail. The Relationships window is a useful window to have open as it will display all the relationships that exist between the elements in the diagram indicating whether they are visible or hidden in the diagram.
If relationships have been hidden in a diagram they can be made visible by selecting the 'Diagram | Visible Relations...' option from the main menu.


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Kevin Alan Brook
In 1996, an unexpected and remarkable archaeological discovery of Jewish significance was made by an Armenian bishop, Abraham Mkrtchyan. The bishop came upon a number of large inscribed gravestones in a river and an adjoining forest at the edge of Eghegis, in the Siwniq region of southeastern Armenia. These stones, which were shaped from granite into oblong cylinders, contain Hebrew and Aramaic inscriptions and are the first known physical evidence of a Jewish community in Armenia prior to modern times. The community existed contemporaneously with Jewish communities in neighboring regions like Georgia, Iran, Azerbaijan, Dagestan, the Crimea, and Ukraine. It may have consisted of about 150 people, according to Frank Brown, writing in the Jerusalem Report ("Stones from the River"). The stone inscriptions contain dates ranging from the middle of the 13th century to 1337.
An archaeological team was assembled from Israeli and Armenian experts, thanks in large part to Bishop Mkrtchyan. Israeli participants included the archaeologist Michael E. Stone (of the Hebrew University of Jerusalem), the archaeologist David Amit (of the Israel Antiquities Authority), the Armenologist and photographer Yoav Loeff, and the archaeological assistant Sheila Bishop. Igor Dorfmann also participated. Armenians who helped with the research and excavation work included not only Bishop Mkrtchyan but also Mayis Mkrtchyan, Hussik Melkonian, Niwra Hagopian, Gohar Muradyan, Aram Topchyan, and several others. A preliminary survey of the Jewish cemetery took place during October 2000. The second phase of excavation took place in May 2001. The third phase is scheduled to take place in the spring of 2002.
ARCHAEOLOGICAL EVIDENCE FOR ARMENIAN JEWRY
To date, over 62 Jewish gravestones have been located at various sites in Eghegis -- including the Jewish cemetery, the foundation of a mill, and the lower support of a foot-bridge. At the cemetery, some of the stones are positioned on open graves while others are on sealed graves. A number of the stones had magnificent ornamentation. Some of the symbols on the Jewish gravestones -- like a spiral wheel -- were also in use on Armenian Christian stonecrafts around the same time. It is most interesting that the same decorative motifs were shared by Jews and Christians. While some of the inscriptions were worn down over the centuries, a lot of them are decipherable. Here are some examples:
* A gravestone dated the 18th of Tishrei of the common era year 1266 contains an inscription dedicated to the memory of "the virgin maiden, the affianced Esther, daughter of Michael. May her portion be with our matriarch Sar[ah]..." The opposite side quotes "Grace is a lie and beauty is vanity" from Proverbs 31:20 of the Hebrew scriptures and continues with a statement that Esther was "God-fearing". This stone was found in the bank of a flour mill.
* A gravestone in the bank of the same flour mill read "Rachel, daughter of Eli, may her repose be in the Garden of Eden." Rachel's stone also contains geometric ornamentation.
* A gravestone recorded the death of Baba bar David in the month of Tamuz in 1600 (the equivalent to the year 1289 of the common era). The other side of this stone reads "A good memorial and rest for the soul" in Aramaic.
* One gravestone includes a Hebrew blessing of Aaron the Priest from the ancient Jewish Temple in Jerusalem.
* There is a gravestone containing an emotional statement from a father mourning his son's passing. In this inscription, the father claims that the soul is eternal and cites passages from the Book of the Prophet Isaiah that relate to the resurrection of the dead.
It is evident from the gravestones that many typical Hebrew names were in use among the Jews of medieval Armenia.
The archaeologists learned that the cemetery of the Orbelian royal family of Armenia, at the other side of Eghegis, had gravestones made of the same material and in a similar style as the Jewish gravestones. Michael Stone thinks it is possible that an identical workshop had produced both the Jewish and the Christian stones.
At the time of Jewish settlement in Eghegis, the city was an important commercial, cultural, intellectual, and governmental center, serving as a provincial capital. Apparently, Jews were wealthy and important members of the society at Eghegis, though Armenian Christians predominated in the city's population. The Mongols ruled Armenia during the period of Jewish habitation.
On the wall of an Armenian church outside of Eghegis, an inscription mentions that the plot of land where it stands was purchased from a Jew.


Google Translate's Website Translator
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To help these webmasters reach more users, we're reopening access to the Google Translate Website Translator—a widget that translates web page content into 100+ different languages. It uses our latest machine translation technology, is easy to integrate, and is free of charge. To start using the Website Translator widget, sign up here.
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Magma Flow: How Does Temperature Affect the Movement of Magma?
How does temperature affect the movement of magma?
- Teaspoon (5-ml spoon)
- Soft margarine
- Small baby-food jar
- Cereal bowl
- Warm tap water
- Fill the teaspoon (5-ml spoon) with margarine.
- Using your finger, push the margarine out of the spoon and into the babyfood jar so that the glob of margarine is centered in the bottom of the jar.
- Hold the jar in your hand and turn it on its side.
- Observe any movement of the margarine.
- Fill the bowl halfway with warm (slightly hotter than room temperature) tap water.
- Set the baby-food jar in the warm water.
- After three minutes, pick up the jar and turn it on its side.
- Again, observe any movement made by the glob of margarine.
At first the margarine inside the tilted jar does not move much, but heating the margarine causes it to move more freely.
As the temperature of the margarine increased, it became thinner and moved more easily. Molecules in colder materials have less energy, are closer together, and move more slowly than warmer molecules with more energy. These warm, energized molecules move away from each other, causing solids to melt and liquids to thin. Just as the temperature of the margarine affected the way it moved across the surface of the jar, the temperature of magma affects the way it moves up the volcano's vent (the channel of a volcano that connects the source of magma to the volcano's opening). Hot magma is thin and moves easily and quickly up the vent, while cooler magma is thick and sluggish.
- Would a different heating time affect the results? Repeat the experiment, checking the movement of the margarine every minute for six minutes. Use a thermometer to keep the temperature of the water as constant as possible, and replace the warm water each time you make an observation. Quickly replace the jar in the warm water after each testing.
- Does the composition of the material being heated affect the results? Repeat the original experiment using other solids such as butter or chocolate candy with and without nuts.
- Thick liquids are said to have a high viscosity (the measurement of a liquid's ability to flow). Viscous liquids flow slowly, and particles dropped into the liquid fall slowly as well. Liquids such as water, honey, and shampoo can be used to simulate magma of various viscosities. Test the viscosity of each liquid by dropping a marble into a tall, slender glass filled with the liquid at room temperature. The slower the marble falls, the more viscous the liquid is.
- Demonstrate the effect of temperature on the viscosity of the liquids by repeating the experiment above twice. First, raise the temperature of the samples by standing each glass in a jar of warm water. After three minutes, stir the liquids and use a thermometer to determine the temperature of each. Second, lower the temperature of the samples to about 50° Fahrenheit (10°C) by inserting a thermometer in each liquid sample and placing them in a refrigerator. Diagrams and the results of each experiment can be used as part of a project display.
CHECK IT OUT!
The three distinct types of magma—andesitic, basaltic, and rhyolitic—harden into different kinds of rock. Find out more about the characteristics of these magma types. What is their chemical composition? Where are they formed? How does the temperature of each differ? Which is the most common? For information about magma see pages 74-79 in The Dynamic Earth, Second Edition (New York: Wiley, 1992), by Brian J. Skinner and Stephen C. Porter.
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state's handbook of Science Safety.


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What can I do by connecting this unit and a computer by USB?
DJ performances can be conducted using DJ software and tracks can be created, recorded, etc. This unit is compatible with two interfaces: the "USB sound card function" for input/output of digital audio signals with a computer, and the "MIDI interface function" synchronizing the operation of buttons and controls.
1. The output sound (digital) of DJ software on the computer can be input to this unit. (USB sound card function)
2. The output sound (digital) from this unit can be input to DJ software on the computer. (USB sound card function)
3. MIDI signals can be output from this unit to operate DJ software on the computer. (MIDI interface function)
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Joined: 21-January 06
Positive Feedback: 91.3%
Feedback Score: 120
Booze-Soaked Superconductors Provide Hot Physics Results
|A paper that explores the unlikely coupling of warm wine and the electric properties of iron is currently making its rounds on the media circuit—leading us to conclude that people get excited about science when there is alcohol involved.|
"Drunk scientists pour wine on superconductors and make incredibly discovery," declares the (slightly inaccurate) headline on io9. "'Tis the season to be pickling your liver in alcohol," announces the (slightly irrelevant) opening line of a CNET article.
The researchers' experiment—led by Keita Deguchi of the National Institute for Materials Science in Japan—involved first submersing an iron alloy in various hot alcoholic beverages, and then finding the temperature at which the treated alloy starts to display superconducting properties. A superconductor is a material that has no electrical resistivity, allowing electrons to flow through it with essentially zero friction.
The paper abstract, which was published on arXiv, gives an overview of the experiment's findings and method (although there's no mention of beverage consumption that might have inspired these scientific antics):
"We found that hot commercial alcohol drinks are much effective to induce superconductivity in FeTe0.8S0.2 compared to water, ethanol and water-ethanol mixture…. Any elements in alcohol drinks, other than water and ethanol, would play an important role to induce superconductivity."
The researchers tried the experiment with beer, red wine, white wine, Japanese sake, Shochu, and whisky, heating each liquid to 70 degrees Celsius. (Extremely hot beer—yum!) The result: soaking the iron alloy in party drinks made the metal act like a superconductor at higher temperatures than if it was simply soaked it in water and ethanol, and red wine produced the best results. Less sensational things that the researches have recently found to induce superconductivity include moisture and oxygen annealing.
Superconductors are super-cool: Place a magnet above a super-conductor, and it will just stay there, levitating; give it a spin and it will spin like a top that is both immune to gravity held steady by some invisible force (this is called the Meissner effect). Superconducting materials have applications in such modern wonders as particle accelerators, MRI imaging, more efficient power transmission lines, and levitating trains.
The snag in the more sci-fi applications of this technology: superconductors only work when they're really, really cold. The Large Hadron Collider's superconducting magnets, for example, function at about -271 degrees Celsius.
Research—booze-soaked and otherwise—in hot superconduction brings science closer to understanding how superconducting can be induced at warmer temperatures, and how to coax better performance out of superconducting materials. Maybe one day scientists will figure out room temperature superconducting, which would allow for more mundane, large-scale applications.
So what's the next baby step toward a future filled with flying cars and energy efficiency? The team suggests hitting the bottles again:
"To clarify the origin of evolution of superconductivity with hot alcohol drinks, detailed investigation in crystal structure is needed," the paper states.
Partying by scientists is good for science as well as the scientists.
"Time's grey hand won't catch me while the stars shine down;
Untie and unlatch me while the stars shine"


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Curriculum Monitoring Programme
Note: This report was originally intended for release earlier this year, but was postponed due to the global health emergency. We are now making it available online for your information.
In 2018/19, CCEA initiated a curriculum monitoring programme, designed to allow us to hear the views of teachers and other stakeholders about the curriculum.
The purpose of this first stage of the Curriculum Monitoring Programme was to engage with teachers and principals in relation to curriculum, assessment and qualifications and use the responses to inform CCEA's future planning and support.
We sought views on:
- the implementation of the curriculum – the benefits and challenges;
- progression and continuity across key stage transitions;
- the effectiveness and relevance of the Cross-Curricular Skills and Thinking Skills & Personal Capabilities;
- assessing progress; and
- awareness/usefulness of CCEA curriculum support materials and areas to prioritise in the future.
Almost 1,000 teachers provided their feedback. Thank you to those who took part in a range of direct feedback, surveys and focus groups.
We hope to be able to undertake the next phase of research in the 2020/21 academic year and that this will incorporate pupil voice. We will also be seeking detailed feedback on specific areas such as progression from Key Stage 3 to 4.
The Northern Ireland Curriculum was introduced in 2007 and covers all 12 years of compulsory education. It's a curriculum that focuses on the learning process and learners' needs, as well as their knowledge, understanding and skills.
Watch the short video below to find out more.
Assessment is the cornerstone of good learning and teaching. It can make a vital contribution to improving educational outcomes for all pupils. It's about collecting, interpreting and using information to give a deeper appreciation of what pupils know and understand, their skills and capabilities, and what their learning experiences enable them to do.
Watch the short video below to find out more:
We have collaborated with Parentkind throughout the Curriculum Monitoring process and held events across Northern Ireland to ensure that parents' views were captured. The rich feedback and information received is illustrated through the following video:


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5th Grade Oral Language Resources
Students will:• Learn about the concept of whales.
- Access prior knowledge and build background about whales.
- Explore and apply the concept of whales.
Students will:• Demonstrate an understanding of the concept of whales.
- Orally use words that describe different types of whales and where they live.
- Extend oral vocabulary by speaking about terms that describe whales and whale body parts.
- Use key concept words [inlet, humpback, ocean, fins, underwater; submerge, ascend, Baleen, mammal].
Explain• Use the slideshow to review the key concept words.
- Explain that students are going to learn about:
- Where whales live.
- Parts of a whale's body.
Model• After the host introduces the slideshow, point to the photo on screen. Ask students: What kind of animal do you see in this picture? (whale). What do you know about these animals? (answers will vary).
- Ask students: What are the dangers facing whales? (too much hunting, polluted environment).
- Say: In this activity, we're going to learn about whales. How can we protect whales? (not pollute the environment, join groups that are concerned with their safety).
Guided Practice• Guide students through the next two slides, showing them examples of whales and the way whales live. Always have the students describe how people are different from whales.
Apply• Play the games that follow. Have them discuss with their partner the different topics that appear during the Talk About It feature.
- After the first game, ask students to talk about what they think a whale's living environment is like. After the second game, have them discuss what they would like and dislike about having the body of a whale.
Close• Ask students: How do you move in the water?
- Summarize for students that since whales are mammals, they have to come above water to breathe. Encourage them to think about how they breathe underwater.


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The Pre-Casa program at the Montessori School of Sudbury integrates children into the Casa program and is offered to children 30 to 36 months of age either on a full-time or part-time basis.
Our Pre-Casa program provides a natural extension of the comfort of home where each child is nurtured and stimulated to reach his or her full potential. It provides a supportive environment designed to foster independence, language and creativity for children aged 30 to 36 months. The program focuses on the emotional and intellectual needs of each individual child within a secure environment specifically designed to stimulate and engage children in this age group. Confidence and self esteem grow through activities and materials that encourage self-expression and promote cognitive and gross motor development, as well as development of the senses and co-ordination.
The Montessori School of Sudbury's Pre-Casa program is challenging, comprehensive and diverse. It is built on the recognition that children in this age group absorb effortlessly from his/her surroundings, just by living and doing. These children are curious about everything and thrive in our specially designed environment that provides endless opportunities for exploration, discovery and wonderment. Special materials with stimulating visual and tactile elements are literally at their fingertips, quenching their innate thirst to touch and manipulate the objects around them.
Our Pre-Casa Program provides:
- a happy, relaxed and stimulating environment where children develop a willingness to share and the ability to respect the rights of others
- encouragement for each child to develop their potential and individuality
- activities and guidance that will instill an understanding and acceptance of routines and limits
- the ingredients necessary for your child to develop self-confidence, self-respect, self-discipline and a feeling of security
- a model of caring and respect for others regardless of race, colour, gender, religion, nationality or social origin


How do I remove files older than a certain date, like logs and sessions?
The UNIX find utility is disabled for performance reasons. In order to find older files and delete them, one must create a script that performs similar logic.
Below is a way to do this using a PHP script and a HTML form as a cron job alternative.
 1. Notes
 2. The HTML form
 3. The PHP script
Before implementing your script for deletion of older files,know the following:
This is not designed to be used as a cron job. If you want to use as a cron job, do one of the following:
 - Hard code the arguments passed over HTML GET
 - OR
 - Pass the arguments on the CLI and use argv[0] and argv[1].
Example 1
ex1 $dir = opendir("/mnt/stor1-wc1-dfw1/111111/") or die("Could not open directory");
Example 2
ex2 $dir = opendir($argv[0)) or die("Could not open directory");
This form will allow anyone that can access it to delete your content. You'll want to secure it with an.htaccess file. You can also delete the form when you're done with it.
The HTML form
The HTML form that sends the directory and age to the PHP script is as follows:

 Directory:
 Days Old:

The PHP script
The PHP script that takes args from HTML GET query string can be constructed as follows:
 * DISCLAIMER: Use at your own risk. Rackspace claims no responsibility for any loss of data that occurs when using this script.
 * Pass from a HTML form the directory to be searched eg. /mnt/stor1-wc1-dfw1/111111/
 * Pass from a HTML form the age of files to be deleted in days. eg. "10" is any files that have not been modifed in 10 days
$dir = opendir($_GET["dir"]) or die("Could not open directory");
$old = mktime(0,0,0,date("m"),date("d")-$_GET["days"],date("Y"));
echo "Working in ".$_GET["dir"]."";
echo "Deleting files created before ".date("F d Y", $old)."";
while(($dirent = readdir($dir)) != false)
 $cur = filemtime($dirent);
 if($cur < $old)
 echo "$dirent modified ".date("F d Y H:i:s",$cur)."";
 echo "Error deleting file $dirent";
 echo "$dirent modified ".date("F d Y H:i:s",$cur)."";
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See license specifics and DISCLAIMER


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Reference: Shacter, R. D. & Heckerman, D. E. Thinking Backward for Knowledge Acquisition. Fall, 1986.
Abstract: This article examines the direction in which knowledge bases are constructed for diagnosis and decision making. When building an expert system, it is traditional to elicit knowledge from an expert in the direction in which the knowledge is to be applied, namely, from observable evidence toward unobservable evidence - because this direction reflects causal relationships. Therefore, we argue that a knowledge base be constructed following the expert's natural reasoning direction, and then reverse the direction for use. This choice of representation direction faciliatates knowledge acquisition in deterministic domains and is essential when a problem involves uncertainty. We illustrate this concept with influence diagrams, a methodology for graphically representing a joint probability distribution. Influence diagrams provide a practical means by which an expert can characterize the qualitative and quantitative relationships among evidence and hypotheses in the appropriate direction. Once constructed, the relationships can easily be reversed into the less intuitive direction in order to perform inference and diagnosis. In this way, knowledge acquisition is made cognitively simple; the machine carries the burden of translating the representation.


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page > Lesson Plans > Art >
Have a Mobius
Have a Mobius Christmas:
When your class is cutting up strips of paper to make Christmas ornaments, it's a perfect time to introduce them to the Mobius strip. Take a strip of paper about 5 cm wide and 1 meter long, give one end a 180 degree twist, then tape or glue the two ends together. Use scissors to cut down the middle lengthwise of the paper and see what you get, then cut lengthwise AGAIN. Try it again with a complete 360 degree twist on a new piece of paper. Then when you're done, use the paper for Christmas decorations.
|include("/var/www/vhosts/teachnet.com/httpdocs/include/search.txt");?> include("/var/www/vhosts/teachnet.com/httpdocs/include/recent.txt");?>|


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Hydrogen Induced Cracking (HIC), also called hydrogen assisted cracking (HAC) and cold cracking, is a common welding defect when welding heavy steel sections and steels with high carbon content. If you would like to learn more about the causes of HIC read Factors Influencing Hydrogen Induced Cracking.
In the above mentioned article we explained that you need three things in order to have cold cracking: source of hydrogen, susceptible microstructure and a certain level of stress. If you can eliminate one you eliminate the potential for cold cracking. When we ignore this, whether by choice or by ignorance, we are in trouble. However, many weldments fail due to hydrogen induced cracking even when good welding procedures are in place. In this article we list several reasons for hydrogen induced cracking even when proper procedures are being followed.
The list below is not exhaustive. Rather, it is simply a list of some of the most common causes. Most of these involve failing to follow the welding procedure. It is very important to educate welders and supervisor as to the importance to adhering to qualified procedures in order to avoid these costly mistakes.
- Preheat applied but not measured correctly – the preheat temperature must be taken at least 3 inches away from the weld joint. This should not just be done where the weld starts but throughout the entire joint. If the part thickness exceeds 3 inches in thickness then the distance from the joint at which you need to take the measurement should be equal to the thickness of the plate.
- Failing to maintain interpass temperature – if you are welding a PQR plate you will probably be waiting for the plate to cool between passes. Once you apply this welding procedure to production parts you may not notice that the part is now acting as huge heat sink, and instead of have the temperature go up with each pass it is actually dropping below the preheat temperature. Always take the temperature between passes following the same distance instructions as with preheat.
- Not following low hydrogen practices – simply using a low hydrogen electrode does not guarantee low levels of hydrogen in the weld. Electrodes exposed to the atmosphere for long periods of time, especially stick electrodes, flux-cored wires and flux are very susceptible to pick up moisture. This moisture then turns into diffusible hydrogen after welding. Be aware of all sources of moisture including: base material contamination, shielding gas moisture and other sources such as greasy rags or contaminated grinding wheels.
- Cooling too fast – not all parts require post weld heat treatment, but this does not mean that they can cool at any rate. If a weldment is susceptible to hydrogen induced cracking you can bet that the cooling rate must be controlled. This is especially true if you find yourself having to reheat the part between passes to maintain the required interpass temperature. Consider using heating blankets, burying the weldment in sand or any other means to prevent a fast cooling rate.
- Ignoring minimum weld sizes – most fillet welds are used for rigidity and hardly ever transfer the load entirely. Because of this reason they can be extremely small. However, minimum fillet welds are specified for different steel thickness ranges. An example of this is seen in Table 5.7 of AWS D1.1 Structural Welding Code – Steel. If you look at this table you'll see that for a range of ¼ < T < ½ (inches) the minimum fillet weld size is 3/16". This is the case regardless if a 1/8" or 1/16" fillet weld would provide enough strength. The reason for this is that even in this relative thin material we can have excessive cooling rates. A 1/8" fillet weld will not have a high enough heat input to prevent a cooling rate that has the potential of creating martensite (this makes a weld brittle).
- Ignoring special circumstances – If the part temperature is below 0˚F we should not weld, even with preheat. Also, if we weld indoors we do not expect our steel to be cold. However, if the steel is stored outside there is a chance that in the winter months this material will be below the minimum required preheat temperature (32˚F for most steels).
There are many more ways in which you can get in trouble with cold cracking, but the above seem to be the most common (provided an adequate welding procedure is in place).


10 Common Questions for Pop Warner Parents
Signing your child up for Pop Warner football is exciting and overwhelming at the same time.
Like any new adventure, playing Pop Warner football will come with lots of questions. Will my child be safe? How big are the kids playing on my child's team? When can I register? What league will my child play in?
Here are some frequently asked questions first-time Pop Warner parents ask, and some answers to get you started as your child embarks on a great experience.
Is there a league in my area?
Pop Warner has football leagues in 42 states from coast to coast, so chances are there's one in your area. Visit Pop Warner's league finder web page to find information--including contact information and web addresses--of the Pop Warner league near you.
When are sign-ups?
It depends on the league, but usually are in the spring and summer months. Check the website of your local league for more information.
What are the different age groups?
Pop Warner has opportunities for players ages 5-15, and they are separated into nine divisions. The youngest, the Tiny-Mite division, features children ages 5-7. The Bantam division features 13-15 year olds with 16-year olds welcome if they are light enough.
My child has a birthday during the season. How does that affect age placement?
With Pop Warner games being played in the fall, the organization has set up a specific guideline: A child's age on July 31st is his/her age for the entire season. So if your son turns 10 on August 1st, he will still be considered a 9-year old for registration purposes.
Does my child's weight matter?
Yes, it does. Pop Warner combines age restrictions with weight restrictions to make an age/weight scale. It is as follows:
 - Tiny-Mite: Ages 5-7. Must be between 35 and 75 pounds.
 - Mitey-Mite: Ages 7-9. Must be between 45-90 pounds.
 - Junior PeeWee: Ages 8-10 must be between 60-105 pounds. 11-year olds are accepted if they weigh between 60-85 pounds.
 - PeeWee: Ages 9-11 must be between 75-120 pounds. 12-year olds are accepted if they weigh between 75-100 pounds.
 - Junior Midget: Ages 10-12 must be between 85-135 pounds. 13-year olds are accepted if they weigh between 85-115 pounds.
 - Midget: Ages 11-14 must be between 105-160 pounds. 15-year olds are accepted if they weigh between 105-140 pounds.
 - Junior Bantam: Ages 12-14 must be between 120-170 pounds. 15-year olds are accepted if they weigh 120-150 pounds.
 - Unlimited: For 12-15 year olds who weigh more than 170 pounds.
 - Bantam: Ages 13-15 year olds who weight 135-185 pounds. 16-year olds can play if they are between 135-165 pounds.
For more information, check out Pop Warner's Age/Weight structure web page.
Are there any other requirements?
Pop Warner demands academic excellence among its participants. Players must receive a 2.0 grade-point average (or 70 percent average) in school to participate. Exceptions are made through Scholastic Eligibility Forms, which are filled out by that child's school to determine whether Pop Warner football would be beneficial to that child.
Are there tryouts?
No. Everyone is allowed to participate and play. All you have to do is sign up.
Is my child safe playing organized football?
Though injury is always possible in any sport, Pop Warner is quick to point out that injury rates are significantly lower in youth football than in high school or college football. That's partly because of Pop Warner's strict age/weight scale that makes sure all the children are playing against players their own size.
Studies have shown that organized football among children produces fewer injuries than soccer.
How many games will my child play?
The regular season schedule is usually between seven and nine games, between late August and late October. Playoffs will follow in certain divisions, and the best teams will play in the Pop Warner Super Bowl in Florida in early December.
If my child isn't the best player on the team, will he/she just sit the bench all season?
Not at all. Pop Warner has mandatory rules of play that requires everyone be able to participate. That means that every player will get in for several plays every game.
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We believe that current education and extension efforts could be improved by targeting knowledge gaps and misperceptions among current and future streamside landowners in the risk-based context of degraded watersheds. The purpose of the project proposed here is to identify these knowledge gaps through a mental models research approach. Such an approach is based on an in-depth assessment of the web of beliefs, or "mental model" that affects how an individual defines a problem and ultimately makes decisions about issues that are communicated to them.
The results from the research component of the project will be used to develop a targeted watershed-based curriculum with high school educators, which will then be used to remediate knowledge gaps among students and their parents (i.e., current and future landowners in the watershed). Knowledge gaps among the larger community will be remediated through tailored on-going web support of landowner decisions and development of streamside land management plans. It is expected that a better understanding of these gaps, and the associated beliefs and perceptions of stakeholders, may illuminate ways to improve both educational efforts and inform landowner decision making, with the end goal of encouraging land conservation and reducing stream impairment due to habitat alteration.
To design education, extension and outreach efforts that 1) identify knowledge gaps in stakeholder knowledge related to an expert-based model, 2) assist in gap remediation with respect to risk and watershed ecology by more clearly identifying the necessary risk communication messages and designing the associated education and extension efforts, and 3) lead to greater behavior change among stakeholders in the watershed.


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The first English usage of the word "cocktail" for a drink is from 1806
, when it was described as "a stimulating liquor
, composed of spirits of any kind, sugar
, and bitters
" and noting that this "renders the heart stout and bold at the same time as it fuddles the head." Throughout the 1800s, the word was limited to this particular kind of mixture, but at that time the world of mixed drinks
was very small. The 1862
guide by bartender Jerry Nichol says that the cocktail "is a modern invention, and is generally used on fishing and sporting parties, though some patients exist that it is good in the morning as a tonic
." In other words, you would probably not order one in a saloon
Although they gradually gained acceptance over the latter half of the 19th century, the period where cocktails were most popular was the 1920s, during Prohibition in the United States. Mixed drinks were necessary to cover up the low-quality alcohol that was illegally obtained by speakeasies. Commercial bootleggers did not bother with wine or beer, so it was necessary to make spirits palatable to those who would not normally drink them. During this period the American habit of mixing drinks spread across the Atlantic Ocean, even though there were no prohibition laws outside the U.S., because technology was making it easier to keep ice on hand for those which required them.
A bartender writing after the repeal of Prohibition included some of the concoctions in his guide, but noted that "They are published here as a matter of record and as a mirror in which future Americans may see the follies which the enactment of the Eighteenth Amendment produced."
After repeal, simpler cocktails such as the martini replaced the elaborate ones in popularity for a few decades, but fashions change and mixed drinks with more ingredients and different tastes have come back since the 1950s.
Barr, Andrew. Drink: A Social History of America. New York: Carroll & Graf Publishers, Inc., 1999.


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Date of Conferral
Doctor of Nursing Practice (DNP)
Marisa L. Wilson
The literature indicates that serving as a preceptor for new nurse graduates can be challenging and stressful without proper training in this role. Many organizations appoint preceptors without providing training and support for the role, which negatively impacts both the new nurse and the preceptor. Evidence shows that a preceptor workshop can cultivate the knowledge and skills needed to train and precept new nurse graduates. Further, there is evidence that preceptorship programs ease new graduates' transition to practice, increase employee satisfaction, and improve the quality of care provided to clients. The purpose of this developmental project was to develop a preceptor workshop to prepare registered nurses to serve in the capacity of preceptors within a local agency to ease the transition for new nurse graduates into practice, increase employee satisfaction, increase retention rates, and promote higher quality of care within organizations. The preceptor workshop proposed in this project incorporates Watson's caring theory, Benner's novice-to-expert model, and Wright's domain-specific competency assessment model. These theoretical frameworks served to guide the curriculum and design of an eight-module workshop. This workshop will be shared with the partnering organization with the recommendation for implementation and evaluation within the next year. Development of an effective training program for preceptors will result in positive social change by improving outcomes for preceptors, preceptees, the organization, and the clients. Implementing this workshop will have a positive impact on the quality of care provided to clients within the organization by the affects on retention rates, satisfaction, and transition to practice.


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The San Diego Union-Tribune
Author makes case for a gene-spirituality link
November 4, 2004
'The God Gene: How Faith Is Hard-Wired Into Our Genes" asks why spirituality is such a powerful and universal force. Why do so many people believe in things they cannot see, smell, taste, hear or touch?
Dean Hamer, a molecular geneticist, argues persuasively that genes predispose humans to believe that "spirituality is one of our basic human inheritances," and that, indeed, there is a specific individual gene associated with faith. "I propose," he writes, "that spirituality has a biological mechanism akin to birdsong, albeit a far more complex and nuanced one."
Genes, Hamer adds, do not tell the whole story. Humans' genetic predisposition for spiritual belief is expressed in response to personal experience and the cultural environment, and it is shaped by them.
But the genes, he says, "act by influencing the brain's capability for various types and forms of consciousness, which become the basis for spiritual experiences."
In other words, an inclination toward religious faith is no accident.
What captured Hamer's attention was a gene, called VMAT2, that controls the flow of mood-regulating chemicals called monoamines in the brain. Crucial to making the connection was a scale called "self-transcendence," which, the author writes, "provides a numerical measure of people's capacity to reach out beyond themselves – to see everything in the world as part of one great totality."
Convinced that the brain chemicals controlled by the "God gene" influenced spirituality by altering consciousness, he studied DNA samples from volunteers, trying to identify sequences of DNA that might be involved in the degrees of spirituality observed from one person to the next.
Hamer is best known for a 1993 study linking male homosexuality to a region of the X chromosome. Other researchers tried to replicate the findings in 1999 but were unable to do so.
Hamer writes that while he found an apparent association between VMAT2 and spirituality, the gene is not the only one to affect spirituality.
"It plays only a small, if key, role," he writes. "Many other genes and environmental factors also are involved. Nevertheless, the gene is important because it points out the mechanism by which spirituality is manifested in the brain."
Needless to say, many geneticists are skeptical. When Hamer told his former boss at the National Institutes of Health that he was writing this book, her suggestion was, "Wait until you've retired."
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© Copyright 2004 Union-Tribune Publishing Co.


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The Science of Scent
Please join us Tuesday, May 31 at 7pm at the LGBT Center's Belardo Road Food Bank as Board Certified Internal Medicine physician, Dr. Alex Del Rosario opens a discussion that explores such questions as:
- Do humans respond to pheromones?
- What role does odor play in male-male attraction?
- How do male pheromones affect gay and straight men differently?
- Can it influence partner selection and mating success?
- What does the scent of your sweat reveal about you and how does it influence male mating behavior?
Learn about the genetic and immense system role in male scent and the role it plays in mate selection.
This event takes place in the LGBT Center's Food Bank space, located behind the Sun Center at 610 S Belardo, Suite 500.


I observed. If the AD8397 cannot survive a short circuit without the series resistor, there are other op amps that are short circuit protected and might offer better overall performance. Another option would be a more elaborate protection scheme. A final (low cost) compromise might to move the resistor outside the feedback loop—especially if you only plan to use higher impedance conventional headphones (not BA IEMs).
 - Improve High Frequency Stability: There's enough evidence the Mini3 might be marginally stable to consider some improvements or at least investigate further. The AD8397 is a fast op amp and it demands very careful implementation. The AMB Mini3 History page describes having oscillation problems during development—I'm not surprised. The Mini3 is roughly 20 times faster than it needs to be. I would add a compensation capacitor to the feedback loop creating a dominant pole to greatly improve stability. AMB runs this AD8397 "wide open" for bandwidth when there's no arguable benefit, and only risk, in doing so. I'd also look hard at the PCB layout, power supply decoupling, etc. It's also highly possible the isolated input and output grounds are degrading stability.
 - Update the PCB Layout: I saw indications the Mini3 is more susceptible to external fields than it should be. This is almost always because of poor PCB layout and/or ground problems. There are also signs of marginal high frequency stability and this may also be a PCB layout problem (see above). Ground fills, as used on the Mini3 are cut up into "islands". Ground currents are forced to take a much longer path around all the interruption compared to a real ground plane. So ground fills tend to work nothing like a real ground plane unless very careful attention is paid to all the ground current paths.
 - Remove PCB "Ground Strips": Enclosures should never be used to carry signal ground currents. They should be grounded only at a single point using a nut and washer for a consistent low resistance connection. The Mini3, however, has long ground strips the length of both sides of the PCB that make contact with the "rails" inside the aluminum case (see photo above right). This creates multiple problems. Anodized aluminum is an excellent insulator, and even raw aluminum quickly forms an insulating layer of aluminum oxide when exposed to air. So any connection between the case and the ground tracks that slip into the "rails" is likely to be intermittent and rather random. That's a recipe for intermittent noise and/or having ground paths change over the life of the amp. Having ground signal currents flowing through parts of the case may have contributed to the hum/EMI problem I observed. It's really poor design practice—especially here where it forms "loops" from one side of the board to the other through the top and bottom halves of the case.
 - Add an Input Coupling Capacitor For DC Protection: A high quality input capacitor would not change the sound but it would provide much needed DC protection and help to prevent expensive headphone damage. Such capacitors have been proven transparent with measurements, blind listening tests and audio differencing.
 - Add RFI Protection: It's considered good design practice to have an RFI filter on the input stage of audio op amp devices. RF (say from a cell phone) picked up by external cables can easily be demodulated at the AD8397's input creating dc offset, noise and/or distortion. A simple capacitor to ground in each channel and a ferrite bead would be a huge improvement. Again DC can damage headphones.
 - Revise The Specs & Claims: Especially with a DIY project people expect honest information to base their project decision on. AMB should not claim an active ground channel "results in lower output impedance, greater linearity and reduced stereo crosstalk" when the opposite is true of all three. And they should make proper measurements (or find someone who can) and avoid publishing misleading specifications.
FINE PRINT: The Mini3 PCB was version 2.01 and built to the standard AMB design minus D4 which has no effect when the battery is installed. It should be consistent with those available from MisterX (Marshall Wyant), YBM Audio, or Wilmer Workshop. Except as noted, the Mini 3 was run from a freshly charged 8.4 volt NiMh battery for all the tests (consistent with AMB's Specifications page). My instrumentation and methods are detailed here: Testing Methods
TECH SECTION SUMMARY: I wasn't expecting perfection from a simple single op amp Cmoy design, but I was still relatively disappointed in the AMB Mini3. It didn't come close to meeting many of its published specifications even when I tried to re-create AMB's test conditions. And it has some potentially significant design problems. AMB claims it can "drive low and high impedance headphones with authority" but, in reality, it doesn't much like low impedance loads even at typical levels of only 400 mV. With 80 ohm or greater headphones, it will likely work reasonably well as long as you're OK with the short battery life, DC risk, potential stability issues, and it has enough voltage swing for your cans. But I strongly suspect the AD8397 op amp would perform better in more of a classic "Cmoy" design running from 2 batteries. That eliminates the need for the third "virtual ground" channel that causes so many performance issues with the Mini3. Dual batteries, however, create other potential issues—see my Virtual Ground article.
REAL GROUND FOLLOW UP (added 5/27): See my test of a classic 2 battery Cmoy which, despite using a much cheaper op amp, performed better than the Mini3 in nearly every test. It's further evidence virtual grounds don't work as advertised.
O2 DIY AMP FOLLOW UP (added 8/7): I have since designed a similar amp using 2 batteries and a conventional ground. Despite using much less expensive op amps, the O2 DIY Amp outperforms the Mini3 in every measurement. It can also suitably drive most any headphones, has longer battery life, battery protection, RF protection, and costs less. The O2 is open source hardware and the design is available to anyone.
 1. Where did the 12volt zener go that was in the D4 spot?
 2. Measurements are always welcome with me. However, it appears your build has a missing diode and that is likely affecting all the results.
 Also, you may need to grind/sand away some of the anodizing from the black Hammond case's board slot. Otherwise it won't be able to provide proper RFI shielding.
 3. D4 (the zener) does nothing when running from the correct battery. And it's considered bad practice, as I explain in my review, to use anything besides a single ground point to an enclosure. Doing so can let ground signal currents pass through the case which is a bad idea for many reasons. The ground strips should be removed from the PCB--they're likely part of the problem, not the solution.
 4. D4 is in parallel with the battery according to the schematic. A 12V (breakdown voltage) Zener diode is pretty much an open circuit when the voltage across it is about 9V from the battery and not 12V or higher.
 Anyway, an issue with the supply voltage probably shouldn't cause the kinds of issues observed for the device.
 5. Very interesting article, thanks. Judging by their RMAA results*, I had expected the "high performance" variant to be overall "excellent". I must admit, though, that most of your tech section goes over my head.
 How did you define those measurement summary quality attributes (excellent, very good, etc.)? At what point do you think become the differences humanly audible under ideal conditions (i.e., could a human hear a difference between excellent and very good, good or fair attributes)?
 * _URL_
 There's a small error in one sentence:
 "and leading to possible to [sic] oscillations"
 (No need to publish this part.)
 6. Without D4 the ground opamp will become damaged when the wallwart is plugged in. And a damaged opamp would explain a lot of the suboptimal results.
 7. Good point Yoga Flame, but not the case here. You would have to remove the battery to get dangerous voltages and it's not removable with the Mini3 in its enclosure. So the battery is really part of the circuit.
 The OPA690 was working as well as can be expected for an op amp not designed for audio use. And, when op amps are damaged, 99.99% of the time they slam into a rail and stay there. I specifically verified the OPA690 wasn't doing anything weird because that was my first suspicion as to what might be wrong.
 The fact is, TI specs the OPA690 at 160 mA of peak current and it's progressively less happy the more current you ask it to source and sink. Driving both channels into 33 ohms at the 300 mW AMB claims on their website would require a peak current of 135 mA per channel forcing the OPA690 to source and sink 270 mA which is far beyond its ability.
 The OPA690's specified THD is relatively high as it's not designed for audio use. Between that and the peak current problem it's easy to see how it contributed to the measurements I obtained.
 8. Another great review. Keep them coming. Keep showing that "BIG price"


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Paleontology scientists have discovered the oldest root stem plant cells. They were found in an old fossil about 320million years old. The cells were found in a root tip of an ancient plant. The cells is gave rise to the ancient plant roots.
Trap jawed new ant species was discovered in piece of Burmese Amber which is about 99million years old. The new species is called Ceratomyrmex ellenbergeri. It belongs to the earliest ant linage of the Haidomyrmecin tribe. Ceratomyrmex ellenbergeri lived 99million year ago during the cretaceous period.
The discovery of over 6000 Antarctic marine fossils indicated the mass extinction scenario that had all dinosaurs killed at the Polar Regions is thought to be sudden and equally hazardous to life at the poles. Creatures at the poles were previously thought to be in less hazardous position at the southern pole during mass extinction event.
Mitochondrial genome of a fossil of about 3500years old was retrieved in Pestera Muierii in Romania. The fossil is part of the first population of the human species that inhabited Europe. The lineage she (the fossil) belongs to embarks the theory of back migration to Africa during the Paleolithic period.
Snail eating marsupial fossils have been discovered by paleontologists in Australia. The snails were previous known to have lived in Australia between 10 to 15million years ago. The new family has been named Malleodectidae and using its massive premolar tooth to break into marsupials, favorite meal.
Evidence has been found on the predation of the ancient microbial ecosystem. Electron microscope was used to view minute fossils, which dates up to 740millions years. Circular holes were found and thought to may have been formed by an ancient Vampyrellidae amoeba, which reach inside to consume the cell content of the microbial systems.