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por Robin Marks, M.A., Anthony Carpi, Ph.D.
What does it mean to dissolve?
Dissolving polar solutes in a polar solvent
Dissolving ionic solutes in a polar solvent
Dissolving nonpolar solutes in a nonpolar solvent
Dissolving involves energy
Molarity: How much solute is in the solution?
Solubility: A balance of forces
Solubility rules
Colligative properties: concentration matters
Freezing point depression
Vapor pressure lowering and boiling point elevation
Términos que usted debe saber
dissolve : process of a solid mixing into a liquid and creating a solution
polar : carrying an electrical charge
solubility : the extent to which a solid dissolves in a particular solvent
Términos de Glosario
Ancient Romans are still admired today for their ingenious water system, engineered with a series of aqueducts and underground lead pipes. The upper classes enjoyed water delivered to their homes, just as we have today. What Romans didn't realize about their water, however, was that little by little the lead pipes were dissolving into it. And, consequently, the lead was ending up inside the Romans who drank the water. In this module, we'll look at what actually happens when a compound dissolves, why some things dissolve more easily than others, and how the Romans might have been able to use knowledge of solubility to remove the lead from their water.
Figure 1: The Roman aqueduct in Segovia, Spain.image © David Corral Gadea
While researchers debate whether Rome's lead levels were high enough to cause widespread poisoning, one thing is certain: the Romans drinking that water couldn't see the lead in it. That's because the lead was dissolved as ions, much the same way that the sodium and chloride ions disappear into water when you stir table salt into it.
Still, the Romans' plumbing (from the Latin word for lead, plumbum, that gives rise to lead's symbol, Pb) was so clever that the system was adopted around the world. In the United States, many homes were built with lead pipes until the 1960s, and lead is present in some form in the plumbing of many modern buildings. In fact, lead is one of the chemicals most home water purifiers are designed to remove from our drinking water.
Some Romans questioned the use of lead pipes, noting that people who made the pipes and other lead items seemed to have a pale, unhealthy appearance. But even those concerned that lead was a toxin didn't have a precise way of measuring how much lead was in their water. Our ability to understand how much of a substance is dissolved into a given amount of water requires knowledge that grew over the centuries.
For starters, we need to consider what a solution actually is. The Properties of Liquids module describes a solution as a liquid with another substance dissolved in it. We use the term solvent for the liquid something is dissolved in, and the dissolved substance the solute. A solute can be either solid, liquid, or gas.
Many things that we drink are solutions containing substances dissolved in them, and sometimes we even mix those solutions ourselves. Electrolyte (or "energy") drink powders, for example, often contain the sugar called glucose and a variety of salts. Many athletes (and weekend warriors) will use these powders to make energy drinks when they are working out. When you add the drink powder to your water, the sugar and salts disappear. Both were solids, but they become dissolved in the liquid water and aren't visible anymore. The solids have separated into particles at the molecular level.
Punto de Comprensión
A solvent is _____.
a.a substance that is dissolved into a liquid
b.the liquid into which a substance is dissolved
Sugar and salt dissolve into water in different ways. Glucose, like all types of sugar, is a covalently bonded polar molecule, meaning that some parts of it have a slight positive charge and other parts a slight negative charge. Water is also a polar molecule.
In liquid water, areas of opposite charge on nearby water molecules are attracted to each other, creating what are called hydrogen bonds. Hydrogen bonds are strong attractions between charged atoms on separate molecules. They are strong enough to affect the properties of the liquid and its ability to dissolve certain types of solutes.
Glucose is a good example. When glucose and water interact, the positive areas of the glucose molecule are attracted to the negative areas of the water molecules, forming hydrogen bonds with the water molecules.
Figure 2: The structure of glucose. (From: Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014." WikiJournal of Medicine, 1(2). DOI:10.15347/wjm/2014.010)image © BruceBlaus
Similarly, the negative ends of the glucose molecule are attracted to the positive areas of the water molecules. In this way, the interaction allows the water molecules to surround each glucose molecule, separating them from their neighbors and dissolving them. If the solvent did not overcome the attraction between individual glucose molecules, they would clump together and remain undissolved. This is, in fact, what would happen if you tried to dissolve the drink powder in a non-polar solvent such as olive oil, rather than water.
Hydrogen bonds are formed by strong attractions between _____.
a.atoms in different molecules
b.atoms within a single molecule
Electrolyte drinks also contain NaCl and other salts, which provide ions your body uses when contracting muscles. These salt molecules have ionic bonds rather than covalent bonds and dissolve somewhat differently. Unlike covalent compounds, many ionic compounds break into their constituent ions in water. When the NaCl in the drink mix interacts with water, for example, the ionic bonds between the Na+ and Cl- ions are broken and the ions separate. They become distributed randomly and evenly throughout the solution. The surrounding water molecules form hydrogen bonds with the ions, which keeps the ions separated from each other.
Figure 3: NaCl in water - the ionic bonds between the Na+ and Cl- ions are broken and the ions separate. The surrounding water molecules form hydrogen bonds with the ions.image © Ahazard.sciencewriter
For all covalent and ionic compounds, the arrangement of water molecules around the solute particles keeps the solute from coming together again to form a solid—in other words, it's what keeps the solute dissolved. Therefore, the ability for these compounds to dissolve in water relies on charge and polarity.
When NaCl dissolves in water, _____.
a.the salt molecule separates into component ions
b.the salt molecule stays intact
Nonpolar solutes also dissolve in nonpolar solutions without breaking any bonds within the molecule. For example, if you're cooking, you can add some walnut oil to your olive oil for extra flavor. The molecules of walnut oil will mix in and become dispersed among the molecules of olive oil. As with polar solutions, the solvent molecules surround the solute molecules, but the attraction behind it is London dispersion forces (LDFs), rather than hydrogen bonding or ion-dipole interactions. LDFs are temporary forces formed when the electrons across two nearby atoms are unevenly distributed, resulting in a fleeting dipole-to-dipole attraction between the nearby atoms. These temporary attractive forces account for the dissolution of non-polar solutes in non-polar solvents. (See our Properties of Liquids module for more on intermolecular forces.)
Because LDFs are much weaker and temporary compared to hydrogen bonds, a non-polar solute will be much less likely to dissolve in water (or another polar substance). The LDFs between the non-polar solute and the polar solvent molecules are not strong enough to break the hydrogen bonds between water molecules (or other polar solvents). Thus, nonpolar solutes generally dissolve very little, if at all in polar solvents, and the opposite is also true.
This difference in solubility is often characterized by the phrase "like dissolves like." You can see this principle at work when you make salad dressing. Imagine you take your olive oil solution and mix it with a polar vinegar solution. You need to shake the dressing to mix it, and after a few minutes, the polar and nonpolar parts separate. That's because vinegar is a solution of water and polar acetic acid. The polar acetic acid and water molecules create hydrogen bonds with each other, but not with the nonpolar oil molecules. The oil particles are, in a sense, left out by the fact that they're not charged, and coalesce on their own, separate from the vinegar.
Figure 4: The difference in solubility of oil and water, separating into polar and nonpolar parts.image © Victor Blacus
Nonpolar solutes dissolve more readily in _____ solutions.
a.polar
b.nonpolar
The process of dissolving always involves a change in energy because of the bonds and intermolecular forces that are being broken and formed. This might mean that the solution needs to absorb energy from its environment, or it can also give off energy. Take, for example, a couple of common household items: baking soda, otherwise known as sodium bicarbonate, or NaHO3, and sodium carbonate, Na2CO3, a common ingredient in dishwashing powder. You can add a bit of either of these to a glass of water, and it will disappear. What might not be obvious is that when you dissolve the sodium bicarbonate, the water warms up slightly. And when you add the sodium carbonate, the water cools slightly. This is because dissolution of the baking soda results in a net release of energy, this energy flows into the system and warms the water. Dissolving sodium carbonate requires energy – thus cooling off the solution by absorbing energy from it.
Knowing what a solution is on a molecular level still doesn't tell us how many ions or molecules are dissolved in it. For that, we need to know the concentration, or number, of solute particles in a given volume of the solution.
Let's return to the example of electrolyte drink mix, but this time, let's say you want to make your own (much cheaper!). You're going to use glucose for energy and table salt, or NaCl for some of the electrolytes. The ideal flavor would be a sort of equal balance between sweet and salty. So, you weigh out 100g of glucose and 100g of NaCl, add them to your pitcher, and fill it up till you've got a liter. You give it a taste and discover it's terribly salty. How did that happen when you added the same amount of each?
The answer is that, while you added the same weight of each solute, you didn't add the same number of particles. To know the number of particles, we need to convert to moles.
As described in the The Mole and Atomic Mass module, a mole is a specific number of particles of a substance — 6.022 x 1023 particles, to be exact. The mole is a good unit for describing how many particles are in a solution, regardless of how much each particle weighs. Usually, when we are measuring quantities of a chemical, we just need to know the fraction of a mole we are using, rather than the exact number of particles.
Let's see how this works out with our electrolyte drink. One mole of glucose (C6H12O6) weighs 180 g. So to find the fraction of a mole we have, recall from the Moles unit:
Equation 1a
Sample mass (g) Sample's molar mass ( g m o l ) = Moles in sample (mol)
Doing the calculation:
Equation 1b
100 g glucose 180 ( g glucose mol ) = 0.55 mol glucose
Doing the same for NaCl, which has a molar mass of 58 g/mol:
Equation 1c
100 g NaCl 58 ( g NaCl mol ) = 1.7 mol NaCl
As you can see, you've added over three times more salt than glucose. No wonder it doesn't taste so good!
Measuring concentration using moles per liter (moles/L) is more useful in chemistry than using grams per liter because it tells you how many particles of a substance you're dealing with. We call the measure of moles per liter of solution the molarity. A solution with 0.5 moles of glucose per liter of water is a 0.5 M (M is for "molar") glucose solution. Your solution is also a 1.7 M NaCl solution.
Let's say you try to get rid of some excess NaCl by pouring out half of the solution. Well, you'll be disappointed. You may have gotten rid of half of your NaCl ions, but you've also got only have the volume of water. The ratio of ions to water remains the same, therefore your concentration of NaCl remains the same.
Equation 2
1.7 mol 1 L = 0.85 mol 0.5 L
This would be true for the glucose as well:
To add equal amounts of glucose and NaCl, you'd need to add the same fraction of moles to the liter of water. Let's say you want to add a half a mole of each:
0.5 mol glucose x 180 g 1 mol = 90 g glucose
0.5 mol NaCl x 58 g 1 mol = 29 g glucose
There is a big difference in weight, but if you added 90g of glucose and 29g of salt you would have an equal number of particles. This example gives you an idea of why chemists use molarity, mol/L, to describe the concentration of solutions.
It's worth noting that, while you add 0.5 mole of NaCl, once the salt dissolves and the Na+ and Cl- ions have separated from each other, you will have 0.5 mole of each of them in the solution. In other words, you will have 1.0 mol of solute particles, half of them being Na+ and the other half being Cl-. This can be important when you're calculating the total molarity of a solution you create.
Molarity is measured in _____ per liter.
a.grams
b.moles
Some compounds, such as NaCl dissolve easily in water—pour a teaspoon in a glass of water, stir, and it's dissolved. The ability of a compound to dissolve in water is called solubility. Some substances are much more soluble in water than others. The solubility of a compound arises from the forces at work when adding solute to water.
The fact that sodium chloride dissolves so readily in water makes it great for our ion-detecting taste buds. Other types of salts (salts generally are compounds made of a metal and a nonmetal) wouldn't be nearly as good on your French fries. In silver chloride, AgCl, for example, the bonds between the two ions are much stronger. Pour a teaspoon of AgCl into a glass of water, and it will just sit there.
To understand why, we can compare what's happening on the molecular level. In the case of table salt, the ionic bonds holding the Na+ and Cl- ions together are weak enough to be easily broken by attraction to the dipoles of the water molecules, and the ions separate. Because they are oppositely charged, there is still attraction between them, but they are surrounded by water molecules. The attraction is not enough to draw many of them together in that situation.
The bond between Ag+ and Cl- ions is stronger, however. So when the silver chloride is in water, few of the ionic bonds will be broken. Even when they are, and when the ions become surrounded by water molecules, the pull of Ag+ and Cl- ions toward one another will be great enough to overcome the attraction of the polar water molecules.
In this way, the solubility of a compound is a balance of the two forces: the attraction between the molecules or ions of the solute (which hold the solute together) and the dipole-ion interactions between the solute and water molecules (which keep particles of solute apart from each other). In the case of AgCl, the interactions between the ions are stronger than the forces that might keep them apart. Most of the AgCl remains ionically bonded as a solid. In NaCl, the opposite is true: the attraction between the ions and the surrounding water molecules is stronger than the attractive force between the Na+ and Cl- ions. Most of the NaCl will dissolve into its respective ions.
Figure 5: A traditional way of making salt is to harvest it by allowing the water to evaporate, like these mounds in Salar de Uyuni, Bolivia.image © Luca Galuzzi
This is true up to a point—the saturation point. As you continue to add more and more NaCl to a solution, the ion concentrations increase and they are packed in closer and closer to each other. Eventually, there will be so many Na+ and Cl- ions, that some of them will be close enough to each other that the attractive forces between them will outdo the forces keeping them apart. The Na+ and Cl- will be drawn back together and reform as a solid, leaving undissolved grains of salt at the bottom of the vessel. (This is, in fact, what happens if you allow the water to evaporate, and the Na+ and Cl- ions become solid NaCl crystals again.) At this point, we say the solution is saturated, meaning that it can't absorb any more solute.
When adding walnut oil to olive oil, as discussed above, the two simply mix together. Once the solution is more than 50% walnut oil, the olive oil becomes the solute and the walnut oil the solvent. We say something is miscible when it forms a homogeneous mixture with another substance.
When a solution cannot absorb any more of a solute, it has reached its _____ point.
a.concentration
b.saturation
As described earlier, the solubility of a compound is really the result of the balance of forces within and between molecules. But how do we know the result of that balance for a particular compound? Over the years, many different scientists have experimented with solubility, and some predictable patterns have emerged from their work. These patterns have been collected in a set of solubility guidelines (also called solubility rules) that are used to predict whether a compound will dissolve in water.
Table 1: Solubility rules for soluble ionic compounds in water
Compounds containing:
NO3- n/a
C2H3O2- n/a
CL- Ag+, Hg22+, & Pb2+ compounds
Br- Ag+, Hg22+, & Pb2+ compounds
I- Ag+, Hg22+, & Pb2+ compounds
SO42- Sr2+, Ba2+, Hg22+, & Pb2+ compounds
Table 2: Solubility rules for insoluble ionic compounds in water
S2- NH4+ compounds, alkali metal cations, Ca2+, Sr2+, & Ba2+
CO32- NH4+ compounds & alkali metal cations
PO43- NH4+ compounds & alkali metal cations
OH- Alkali metal cations compounds, NH4+, Ca2+, Sr2+, & Ba2+
These guidelines are very useful for chemical engineers, who are often devising products like fertilizer, drugs, and household goods. Such items are often most efficiently shipped as powders or solids but must be able to dissolve in water to be used. Consider powered laundry soap, for example. If it were simply powdered soap, it would get clumpy with changes in humidity. So manufacturers combine it with a naturally dry, flaky substance to prevent clumps and allow it to flow freely. That flaky substance also has to be soluble in water and not leave behind ions that might react and damage clothing, pipes, or the washer. The most common laundry detergent additive is sodium sulfate (Na2SO4). You can see from the chart above that all sulfates are soluble in water with the exceptions of those that form one of four different metal ions.
The solubility rules are useful in the other "direction" as well: in other words, let's say you have two solutions, each with different ions dissolved in them. The guidelines can help you predict whether mixing those two solutions will cause a reaction that produces an insoluble solid.
This could have been useful for the Romans if they'd wanted to get rid of the lead in their water. They would have been able to look at the chart and see that several ions will combine with lead to form insoluble compounds. An insoluble compound produced in reactions involving aqueous solutions is called a precipitate.
Here again, sodium sulfate can come in handy. The compound is found in many common rocks, and so the Romans probably had access to it. As you saw above, the solubility guidelines show that sodium sulfate is soluble in water. They also show that lead sulfate is not. Therefore, adding Na2SO4 to water that contains lead will produce a precipitate according to the reaction: Pb2+ (aq) + SO42- (aq) → PbSO4 (s)
And indeed, that reaction forms a cloudy white precipitate of lead sulfate that can be filtered out of the solution.
If a Roman chemist wanted to be sure they got rid of all the lead, they would need to know the molarity of lead in the water, and use an appropriate amount of sodium sulfate. Too little would leave dissolved lead behind, and too much would leave a lot of excess Na+ and SO42- ions, which could cause corrosion.
Precipitates are _____.
a.highly soluble
b.insoluble
Another reason that knowing the molarity of a solution is important is that it determines some of the solution's properties. For example, if you live in a snowy climate, you've seen trucks out spreading salt on icy roads. A little bit of the salt dissolves into the surface of the ice and creates a salt solution. This water with salt in it actually has a lower freezing point than water. Over time (and with cars driving over it), the salt dissolves into more and more of the ice, lowering its freezing point and allowing it to melt, creating safer driving conditions.
Figure 6: Phase diagrams of solutions of sodium chloride (NaCl) and calcium chloride (CaCl2) solutions. The calcium chloride-water remains a solution as low as -51°C (-60°F), whereas the sodium chloride-water freezes at about -21°C (-6°F).image © Federal Highway Administration
If you said that having more salt molecules dissolved in the water is what caused this change in freezing point, you'd be correct, but not exactly correct. It's not actually the concentration of solute that matters, but the concentration of solvent. And as more salt dissolves in the water, the concentration of salt goes up and the concentration of water goes down. IIt's this shift in the concentration of water that changes the properties of the solution. A less concentrated solvent will have a lower freezing point, and higher boiling point, and a lower vapor pressure. We call these properties that are affected by concentration colligative properties, (from the Latin words co – "together" – and ligare – "bind"). Colligative properties often relate to a state change, either from liquid to solid or liquid to gas. (See the States of Matter module for more on state change.)
Because these properties actually depend on the concentration of solvent, it doesn't matter what solute is added. If you find that a bit confusing, you're in good company. It took some very bright chemists about five decades to explain it.
In the early 1700s, the Swiss physicist chemist Daniel Bernoulli noted that concentrated salt and sugar solutions seemed to freeze at lower temperatures than pure water. He postulated that the solute particles in water somehow reduced the attractive forces between the water molecules, keeping the water from freezing until it had reached a lower temperature. He was curious about the phenomenon, but busy with other experiments and didn't pursue it further.
Some years later the English chemist Richard Watson, a follower of Bernoulli, also became curious about this phenomenon and wanted to quantify it. Does the freezing point shift in relation to which solute you add and how much of it? This wasn't a simple question to answer given that there was no refrigeration in the 18th century. Scientists at the time depended on the cold, snowy conditions of European winter.
Watson got a lucky break on February 12, 1771, when the temperature in his hometown of Cambridge plummeted to -14C. The resourceful chemist took advantage of this rare opportunity, and, no doubt shivering, tested the freezing points of 18 different salt solutions. His observations showed that the freezing point of a solution shifts downward in a way that varies with the concentration, regardless of the solute involved. This was a big step toward understanding freezing point depression, but Watson wasn't able to definitively quantify the relationship.
One of his contemporaries, Charles Blagden, carried out similar experiments on samples of water mixed with varying amounts of NaCl. Blagden, however, did not have the advantage of a particularly cold day, so he relied on snow and ice to chill his solutions. Blagden confirmed that the relationship between concentration and freezing point was inversely proportional. In other words, the higher the concentration of salt, the lower the freezing point. Because Blagden was making observations on only one salt (as opposed to many, as Watson had done), he was able to come up with a precise determination of how concentration affects the lowering of the freezing point. His discovery, which can be described mathematically using several different equations, is known as Blagden's Law. Blagden's Law quantifies what scientists before him had suspected—the presence of solute particles makes it harder for a solvent to coalesce and form a solid, and that forming a solid becomes harder in a way that's regular and predictable.
While it's easier to express this variation in terms of how many solute particles there are, it's important to remember that the number of solute particles, in turn, determines the number of solvent particles and that it's actually the concentration of solvent we're concerned about. We can explain this phenomenon at the molecular level by considering that when liquid water freezes, its particles come together in a regular, lattice-like arrangement. If all the particles are the same, it's relatively easy for a regular lattice to form. But when there are solute particles dissolved in the water, the water molecules are bumping into them, and therefore less likely to interact with each other. As the temperature cools, particles slow down and the attraction between water molecules becomes greater than the disruptive force of the solute.
Early American colonists cleverly used colligative properties to their advantage when making fermented apple cider (provided they had a cold winter day). They could ferment apple juice until they had a dilute alcohol solution. If they then set the fermented juice outside in the cold, pure water would freeze out of the solution. The fermented juice, with all that water removed, had a higher concentration of alcohol. Pour the solution out from the ice, and they had a drink called "apple jack," so named because the freezing process "jacked" up the concentration of alcohol.
A higher concentration of solute molecules makes it _____ for a solution to freeze into a solid.
a.easier
b.harder
Solute concentration affects not only freezing point of a solution but also its boiling point and vapor pressure. Vapor pressure is a measure of the pressure created at the surface of a liquid as molecules of liquid evaporate. In any liquid in an open container, a small number of the molecules on the surface gain enough kinetic energy to escape the liquid and become gas. The more particles that escape, the higher the vapor pressure. For example, rubbing alcohol evaporates more quickly than water, and therefore has a higher vapor pressure.
In a container of pure water, the entire surface of the liquid is made up of water molecules, some of which are evaporating. When solute particles are mixed in to create a solution, however, those particles take up "real estate," and leave less room for water molecules on the surface. Fewer water molecules on the surface means fewer water molecules evaporating, which reduces the vapor pressure.
Vapor pressure is related to temperature, in that the warmer the liquid, the more molecules have enough kinetic energy to leave the liquid phase and become gas. As mentioned above, more molecules evaporating translates to a higher vapor pressure. As heat is added, eventually a solution reaches its boiling point. At the boiling point, there are so many molecules with enough kinetic energy to become gas that the vapor pressure is equal to the surrounding atmospheric pressure.
Therefore, it makes sense that because solute concentration affects vapor pressure, it also affects boiling point. If the vapor pressure of a liquid is lower in the presence of solute, then getting to the boiling point will require more energy or a higher temperature. This phenomenon is known as boiling point elevation.
Antifreeze in cars takes advantage of colligative properties to keep your engine at the right temperature. True to its name, solutes in the antifreeze solution lower the freezing point and keep the antifreeze (and your engine) from freezing up on very cold days. Those same solutes raise the boiling point, keeping your car from overheating on a hot drive through the desert.
Aqueous solutions are found throughout our world, and their chemistry depends in part on how much of a dissolved substance is in them. This module explores how substances dissolve, why some substances don't dissolve, and how we express the concentration of a solution. The module describes the forces that hold particles together and interactions that keep dissolved particles apart. It also examines how concentration affects freezing point, boiling point, and vapor pressure.
Conceptos Clave
A solution is formed when solute particles are randomly distributed and dissolved in a solvent.
Molarity is a measure of the solute concentration in a solution, and remains consistent when a fraction of the solution is poured off.
In polar solutions, the charges on both the solute and solvent particles keep the solute dissolved, as the polar solvent molecules surround the solute particles and keep them apart.
The relative solubility of a salt or polar compound in water is a balance of two forces: the attraction between atoms of the salt molecule, and the attraction between the ions and the water molecules.
Solutions of non-polar solutes in non-polar solvent are driven by London dispersion forces, another type of attraction between molecules.
Colligative properties of solutions—freezing point depression, boiling point elevation, and vapor pressure lowering—are related to the concentration of solute molecules but independent of the specific solute type.
Lectura Adicional
El Mol
Robin Marks, M.A., Anthony Carpi, Ph.D. "Solutions, Solubility, and Colligative Properties" Visionlearning Vol. CHE-4 (5), 2017.
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Helen Lundeberg
Helen Lundeberg was raised in Southern California and decided to pursue a career as an artist after taking a course at the Stickney Memorial School of Art in Pasadena taught by artist Lorser Feitelson, whom she later married. Lundeberg was a founder—along with Feitelson—of Subjective Classicism, also known as Post-Surrealism. In 1934, the two wrote a manifesto distinguishing their movement from European Surrealism, which focused on the unconscious mind, whereas Post-Surrealism intended to guide viewers through imagery towards deeper meaning.
In the 1950s, Lundeberg began to explore geometric abstraction, creating works that hover between abstraction and figuration, using restricted colors and palettes. In the 1960s and 1970s, her work focused on landscapes, interiors, still lifes, and planetary forms, and her last body of work in the 1980s featured landscapes and architectural elements.
Planet Rising was a gift of the artist to Palm Springs Art Museum and is one of seven paintings by Lundeberg in the collection. Here, she returns to planet imagery—a subject which had interested her since her early Post-Surrealist work. She deploys rationality rather than emotion in this piece, applying her fascination with order and structure through the cosmos and planetary movements, as well as the otherworldly desert-like landscape below.
Helen Lundeberg (American, 1908-1999), Planet Rising, 1967, acrylic on canvas, 59 3/4 × 39 7/8 inches. Gift of the artist, 28-1969.
Tam Van Tran
Since the early 1990s, Tam Van Tran has been producing a multi-faceted body of work comprising abstract paintings, mixed-media collages, ceramic tiles, and sculpture. By mixing traditional art materials such as linen and acrylic with unconventionally applied organic substances (including spirulina, chlorophyll, wood), staples, and aluminum foil, Tran creates colorful and highly textured works that formally and thematically unite Eastern and Western influences.
In this piece, the artist paints with spirulina algae mixed with acrylic on torn and hole-punched layers of paper, fastened with staples that delineate and punctuate the curves of the artwork. The textured surface seems at once lacy and armored, resonating with animal skins, plant leaves, and industrial materials. This fusion of elements reflects the artist's ongoing interest in how natural and human-made phenomena coexist in the world. The undulating structure of parabolic curves combines mathematical symmetry with organic forms, suggesting a synthesis of technology and nature.
Tam Van Tran (American, born Vietnam, 1966), Nonceptual Space, 2009, acrylic, spirulina and staples on paper and museum board, 87 x 106 x 16 inches. Museum purchase with funds provided by Gladys Rubinstein, Angie and Harvey Gerber, Helene Galen, David Kaplan and Glenn Ostergaard, Lynn and Robert Zimmer, and Myrna Kaplan, 2-2010.

redpajama_set_name: RedPajamaCommonCrawl


Cosmoquest Forum > Science and Space > Astronomical Observing, Equipment and Accessories > Newbie wants a telescope!
View Full Version : Newbie wants a telescope!
I've decided that I want to get involved in astronomy in a bigger way. This means I need to purchase my first telescope. I've read and read, but all the advice seems to be so noncommittal as to what type to buy as to almost be useless. So, I'm looking for biased views on what I should get.
Let's assume a few things. I've three young children who may catch the bug too. Money is not an issue. I'm a newbie (well that's obvious), so I don't know if planet hopping or deep sky objects are my eventual interests, but I want a half decent chance viewing both with my first scope. I'm in a city, so I've got to deal with a fair bit of background light pollution.
First, what is your astronomy experience so far? Have you exhausted everything you could do with binocular and naked eye observation?
In light polluted areas, deep sky objects aren't as easy to find. You're probably better starting off with planetary observation. For that, you'll want a refractor. Without a secondary obstruction, you don't get diffraction that reduces the detail on the image.
If you're in a populated area there's a good chance that there's an astonomy club nearby. If there is it's really helpful to visit, talk to other amateurs, and get a first hand idea of what type of scope you'd like.
Another thread with some good advice is this one (http://www.badastronomy.com/phpBB/viewtopic.php?t=4197&highlight=telescope).
I've mentioned this before on other sites but I'll say it again: at least think about building your own first scope. ESPECIALLY if there are kids involved.
Grind the mirror, build the mount (both require relatively little money, space or tools. Granted it can get a bit messy).
Well, I'm still stargazing, and its been about 35 years.
I agree that building your own is a good thing to do, but grinding mirrors is becoming less common. Decent quality mirrors can be had for relatively small amounts of money.
I agree. But as Russel Porter and Albert Ingalls pointed out, once you get rouge under your nails and pitch in your hair you will know what's really going on in that scope. Then by all means buy a super-dooper job (which I recently did). I enjoy my new Meade enormously. I love my old scope.
I'm going to put in my two cents worth here.
Second, I assume that you are more interested in looking at things than looking for them.
1) Get a computerized goto telescope. Looking at things is much more rewarding than looking for them. And it is much less frustrating than looking for and not finding them.
2) Get the biggest scope you can afford to lose interest in. After all, you may grow tired of astronomy (it happens) and the scope may wind up under a tarp in the garage.
3) Someone mentioned a refractor for planetary observation. While it is true that refractors work better for planets, that is on an aperture for aperture basis. On a bang-for-buck basis, aperture rules. A 10" Schmidt-Cassegrain will beat a 4" refractor in showing planetary details.
4) Do not expect deep-sky objects to look like photographs you see in magazines or on line. We don't call them faint fuzzies for nothing.
5) As was mentioned, find a local astronomy club. They love to show off their scopes and can give you firsthand advice and hands-on experience. Sky & Telescope has a list of astronomy club on their website.


Our beloved 3D printer, an Ultimater Original, was the very first equipment the lab acquired. It came as a kit of parts, and the amazing Engineering summer interns Jason and Sohrab assembled it in the record speed (1 day by 2 people - 2 people days!).
A service which provides access to information about plants and gardens within a given locality. The service currently covers the Scottish Borders, as indicated on the map. It was created as part of a Smart Tourism research project.


1898-O VAM-4/A/B. Date set center normal at 2.50 denticles. Mint mark set High - left, high, and tilted left.
Obverse: Attributes - Description. Markers - Description.
Reverse: Attributes - Description. Markers - Description.
Tip of upper serif of s clashed on field near horizontal bar of t at hair V. Comment.


Solar energy | Alternate Energy Holdings Inc.
Posted by cleanidahoenergy in AEHI, Electric cars, electric vehicles, Energy Neutral, housing, renewable energy, Solar energy, Transportation.
An Eagle company is constructing its first "Energy Neutral" home, designed from the ground-up to produce more energy than it consumes.
"This first home will establish that an efficiently built home equipped with renewable technologies will achieve energy neutrality" said Micah Gosney, Executive Director of Energy Neutral.
The idea of using renewable energy to augment residential power has been around for years. However, Energy Neutral is using established methods of energy production – such as solar panels – and combining them with energy-saving construction practices to provide an affordable home that achieves energy neutrality. The home may draw energy from the grid as needed, such as during evening hours, but send energy back into the grid on sunny days. In all, the home is expected to be a net producer of electricity and carry a zero energy bill over its life.
Energy Neutral is a holding of Eagle-based Alternate Energy Holdings Inc., which is seeking to build a nuclear plant in Idaho and other states and is working with Chinese companies on related energy ventures. AEHI CEO Don Gillispie said he has had the idea for several years to make an energy neutral home and is funding its construction with a personal loan to the company.
Biltmore Company of Meridian was chosen to construct the home and construction started on November 3, 2009 and will be completed in the spring of 2010. The home's address is 12963 W. Scotfield Court in Boise in the Monet Meadows subdivision, located in west Boise, near Centennial High School.
A computerized system that monitors energy use in the house and looks for waste and potential savings.
The home will feature standard amenities such as a full basement; five bedrooms; home office; three bathrooms; covered front and rear patio; three car garage; large master suite with sitting area and spacious master bathroom; large kitchen with solid surface counter tops and large dining area; 10' ceilings in living area; 14' ceiling in office; 9' ceilings for all other area; hardwood floors; expansive windows and 8' entry and interior doors; fully landscaped front and rear yard with sod, trees, planter bed with bushes and underground sprinklers; and finished and painted garage.
The home will participate in Idaho Power's net metering program, drawing and supplying energy to and from the grid. Energy Neutral Inc. seeks to assist homeowners and businesses to reduce their dependence on traditional power by implementing alternative renewable power sources.
Energy forecasters predict more and more people will charge their hybrid vehicles at home, making further demands on the energy grid. Gillispie said energy neutral homes will be able to soak up some of that demand, allowing people to power their cars, in part, with free energy from their homes.
Energy Neutral is able to add more energy production features in future houses, such as photovoltaic panels that resemble shingles and small wind turbines for windy areas. While Energy Neutral is showcasing its abilities with the model home, it can also apply these technologies to farms and businesses and is hoping to break into those markets as well. Gillispie said he hopes to eventually develop an Energy Neutral subdivision in Idaho and the model home is the first step.
"We think this will become more common over time in all kinds of development, especially if someone builds an example to show that energy neutrality is attainable, affordable and can be done with traditional construction methods. It is a green house that saves your green backs." Gillispie said.
Posted by cleanidahoenergy in AEHI, Agriculture, approval process, economic benefits, Elmore County, nuclear industry, rural nuclear, Snake River Alliance, Solar energy, Wind energy.
The Elmore County Commission said some surprising things Monday. Since they can't hear any more testimony, it is likely my words won't make it to them. But it would be helpful, whether or not this project succeeds, to clarify a few things.
The Commissioners correctly pointed out on several occasions the comprehensive plan appears to conflict with itself. That is to be expected in a complex effort like land use planning, but it doesn't have to be that way. As I will talk about, our rezone proposal actually does conform to the comprehensive plan because our development would provide steady, well-paying jobs; will greatly improve the local tax base; won't threaten the rural way of life so important to Elmore County residents; and we have addressed concerns about possible future misuse of the land.
The Commission asked their attorney for an opinion as to whether or not they can restrict future uses of the land. The Commissioners are concerned that if they rezone the land for industrial use and the nuclear plant isn't developed, the landowner could apply to build some undesirable use and the commission would have little ability to stop it.
This is a reasonable concern. However, we addressed it early on in the process. Along with our application, we submitted a development agreement. The agreement makes clear that if we do not build a nuclear power plant on the land, then it must revert to agricultural zoning.
Elected officials are understandably reluctant to deviate from their comprehensive plans. However, they also know there will come times to make reasonable exceptions. We believe this is such a time. The current comprehensive plan, however well-intentioned, did not foresee the possibility of an ambitious and economically significant proposal such as ours, the most expensive single piece of private infrastructure ever proposed for Idaho.
The designated industrial location, Simco Road, has very little water; a 20-mile-long pipe would need to be constructed, presenting insurmountable safety and right-of-way concerns. The site has geologic issues that also make it difficult to site a nuclear plant there. Interestingly, much more intrusive uses, such as industrial wind farms and natural gas plants, may be located anywhere in the county without a heavy industrial designation. This is especially puzzling, as a nuclear plant emits no smoke, noise, dust or odors and takes up very little space.
Another commissioner said the people of Hammett have spoken overwhelmingly against the rezone. While many Hammett-area farmers spoke as individuals (and included their feelings again as members of a group), that is by no means representative of Hammett the town, where many of the workers on these farms actually live.
Of the 1,600 signatures we gathered in favor of the rezone (half from Elmore County), we estimate at least 50 came from in and around Hammett, where our community organizing efforts found people, many of them agricultural workers, desperate for stable, well-paying jobs. These figures suggest national polls about nuclear power, which routinely show 70%-plus support.
One of the commissioners' least enviable jobs is to balance competing interests, each of them important. Should they (as our opponents say) approve an industry that would destroy the rural way of life? Or should they adopt a clean, stable source of energy and the jobs that go with it? Unfortunately, our opponents have presented this as an either-or choice when, in fact, it is not. In terms of being an industrial use, we will no more impose upon Elmore County's rural way of life than a cheese plant or an air force base (which we whole heartedly support as a veteran run organization).
Indeed, Elmore County farms have for decades abutted extremely intensive heavy-industrial uses with no problems. I'm speaking of Mountain Home Air Force Base, Despite the general mistrust of government in our society, the Air Force Base has been a good neighbor and is a pillar of the region's economy. Safe to say, MHAFB would have a hard time fitting in the Simco Road location.
One commissioner also expressed concern about how construction would affect local services. Any sort of significant project will certainly impose some burdens and we have suggested ways to address them. Ideas include paying money directly to the county to reduce the bill for all taxpayers as compensation for disruption; job training; a community center; scholarships; direct infrastructure funding; and a committee to oversee service needs (for details, see my open letter to the people of Hammett on my blog at www.cleanidahoenergy.wordpress.com). Not to mention, these burdens would pale in comparison to the benefits specified in the next paragraph.
Current farms in Elmore County produce 2.86 jobs (some seasonal) per acre, or about 4 jobs at the current location. Our plant would produce 500-year round jobs at the site and 5,000 peak jobs per year during construction; $558 million in local payroll and labor income; and $205 million in local ripple payroll income. The plant would also create an additional 1,754 full-time support jobs and massive improvements in schools, police, fire and other infrastructure funding.
The irony isn't lost on me that the commission these days is also holding meetings on how to deal with a pressing budget crisis. Our proposal would start putting people to work immediately and increase the economic security for the all residents of Elmore County.
One of the Commissioners made another important statement. If Elmore County residents – and presumably the Snake River Alliance – wish to see farmland kept undeveloped, they should probably consider forming a land trust or other legal vehicle to accomplish it. To restrict private property rights for that reason is not a wise use of power.
Things are going well for AEHI. Last week, we signed an agreement with Source Capital Group Inc. to raise money for the project. The funds will cover land, water rights and engineering services to obtain Nuclear Regulatory Commission approval to construct and operate an advanced nuclear plant in Elmore County, Idaho, estimated to total some $70 million. Every company that has undertaken the NRC application process has successfully completed it and received a construction/operation license.
We see a bright future for Elmore County, one that many communities in America share. It is a future of economic security and low-cost energy, with a nuclear plant quietly, cleanly and dependably powering its farms, homes and businesses. We hope the Elmore County Commission votes for this future and approves our rezone.
Posted by cleanidahoenergy in AEHI, anti-renewable energy, balanced approach, Energy policy, environmentalists, renewable energy, Snake River Alliance, Solar energy, Wind energy.
Normally, the media are very starry-eyed when reporting on renewable energy. When it comes to coverage of nuclear power, the media are extremely skeptical and ask the tough questions (as all good journalists should), but renewable get a pass and questions about reliability, viability, environmental impact and public support are rarely raised.
Among other projects, Barker looked at "the most controversial wind farm in the state," the proposed China Mountain project, a 185-turbine farm in Twin Falls County. The project, on 30,000 acres of public land, would produce more than 400 megawatts of electricity (by comparison, our plant would produce four times that amount of energy on four percent of the area, and at 95 percent reliability, compared to around 20 for wind). Environmentalists have opposed wind farms nationwide, not just Idaho.
As Barker reports, in July, a regional Fish and Game supervisor voiced concerns about the effects the wind farm could have on wildlife, including the endangered sage grouse. Neighbors complained about the effect the wind farm would have on the views from their cabins and Advocates of the West, a group that provides lawyers for environmental groups, is preparing to challenge several wind projects planned in sagebrush habitat.
July 1, 2008, was a good example of where the priorities of some environmentalist lie. The embattled China Mountain wind farm was facing a crucial public hearing, but it was the same night as a meeting to organize opposition to our nuclear plant. When push came to shove, "We were not present at the China Mountain scoping meeting because it occurred the same night as our public meeting about the AEHI plant." Liz Woodruff, SRA energy policy analyst, said the SRA "submitted comments regarding the proposal" but tellingly doesn't say if they actually supported China Mountain or urged officials to approve it. The Snake River Alliance's own mission statement declares that it can oppose specific facilities, but advocating for specific facilities isn't part of the mission (at least give the SRA credit for sticking to its real game plan).
I think the radical environmentalist veneer is starting to fall. Something tells me the SRA didn't try to "educate and inform" residents opposed to China Mountain, as they have done to rally opposition to our plant. Personally, I think the SRA lacks the stomach to face an angry group of neighbors and declare that a wind farm should be approved because it's in the broader public interest. If the Snake River Alliance is out there directly supporting specific renewable facilities in public hearings, they're doing a good job keeping it quiet.
Some environmentalists take opposition to renewable a step further. Laird Lucas, lead attorney for Advocates of the West, says he's "skeptical that wind, solar and geothermal plants spread out across the wide open spaces of the West and linked to populated areas through vast transmissions systems are the answer to increasing carbon-free energy supplies," according to Barker's story.
I think some environmentalists are really aiming for a larger target and their ultimate goal is to "power down" and de-industrialize our society. I'm not making any of this up – see it at http://www.postcarbon.org and similar sites, where discussion of "societal collapse" and hopeless peak oil scenarios are enough to make you end it all today. An industrial society needs industrial energy sources and combating those sources is one way to "power down" our civilization.
In the meantime, out-of-the-mainstream environmentalists will have to content themselves with paying lip service to renewable energy, by opposing it or failing to speak up for it every chance they get. I hope the media educate the public about this more.


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Fontainemelon is een plaats en voormalige gemeente in het Zwitserse kanton Neuchâtel. In 2013 is de gemeente gefuseerd naar de nieuwe gemeente Val-de-Ruz.
Fontainemelon telt 1619 inwoners.

Plaats in Neuchâtel (kanton)
Val-de-Ruz
Voormalige gemeente in Zwitserland

redpajama_set_name: RedPajamaWikipedia


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Christopher Kehoe
Whoa, hoss! You got to back up there: Only registered users can do that.
But fortunately, registering for Playlist is free.
Stage manager
Christopher Kehoe is a performer, playwright, and director from Minneapolis, Minnesota. His work has been called "brilliant" by the Minneapolis Star Tribune and "genius" by Minnesota Playlist, for both developing original plays (I Will Show You Fear in a Handful of Dust, Joe Dowling's William Shakespeare's "Romeo & Juliet" on the Moon..., Reykjavík, St. Christopher of Financial Aid) and performing onstage with The Jungle Theater (Hamlet), Frank Theatre (Ajax in Iraq, The Metamorphosis, By the Bog of Cats, Vinegar Tom), Sandbox Theatre (.faust), Skylark Opera (Mlle. Modiste), The Strange Capers (Comedy of Errors, Twelfth Night), the Minnesota Centennial Showboat (The Count of Monte Cristo, Sherlock's Last Case, Forty-Five Minutes from Broadway), and more. He studied with many artists from the former Theatre de la Jeune Lune at the Unversity of Minnesota, and has an MFA in Ensemble-Based Physical Theatre from Dell'Arte International School of Physical Theatre in California.
The Brothers Todd
Video of The Brothers Todd
Notable credits:
Ella Enchanted (Sir Peter/Squire), Oregon Children's Theatre
All My Sons (Chris), Ferndale Repertory Theatre
The Threepenny Opera (Macheath), Ferndale Repertory Theatre
The Rocky Horror Show (Frank), Ferndale Repertory Theatre
.faust (Wagner), Sandbox Theatre
The Metamorphoses (Chief Clerk/Charwoman), Frank Theatre
Ajax in Iraq (Ensemble), Frank Theatre
Vinegar Tom (Packer), Frank Theatre
Hamlet (Osric), The Jungle Theater
Dido, Queen of Carthage (Aeneas), Theatre Pro Rata
Download a more complete résumé below!
Download Christopher's résumé


Sparse recovery algorithms have shown great potential to reconstruct images with limited view datasets in optoacoustic tomography, with a disadvantage of being computational expensive. In this paper, we improve the fast convergent Split Augmented Lagrangian Shrinkage Algorithm (SALSA) method based on least square QR (LSQR) formulation for performing accelerated reconstructions. Further, coherence factor is calculated to weight the final reconstruction result, which can further reduce artifacts arising in limited-view scenarios and acoustically heterogeneous mediums. Several phantom and biological experiments indicate that the accelerated SALSA method with coherence factor (ASALSA-CF) can provide improved reconstructions and much faster convergence compared to existing sparse recovery methods.


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Touré eyes Afcon glory
Yaya Touré is suffering from tall-poppy syndrome. Best not call him a poppy to his face, though. The towering Ivorian midfielder is in no mood for nonsense this month: he has an Africa Cup of Nations to win, a potentially costly leave of absence from Manchester City to justify and an African Footballer of the Year title to own.
Not that anyone seriously disputes Touré's claim to the honour bestowed on him in Accra. There were no credible rivals: he is now the most influential player in the most powerful side in the world's richest league. Even so, there were begrudging murmurs. The announcement got a less than rapturous reception outside his homeland and the blue chunk of Manchester.
That is partly because Touré is not a rapturous player. He does score designer goals on occasion and his forward charges can be spectacular, but most of his excellence is in unflashy virtues: organisational ability, box-to-box endurance and unanswerable physical power. He is the on-pitch chief executive officer of City, the boss man and not the ideas man, and the African football public tends not to idolise players who fit that niche. He is the first recipient of the prize, in 19 editions to date, who is not a striker or creative midfielder.
His image also shed a bit of gloss when he skedaddled from Barcelona to Eastlands, motivated by what seemed at the time to be simple avarice. What self-respecting footballer leaves the Camp Nou willingly, people asked, even for the carrot of £200 000 a week?
Now, with City finally coalescing into a team with brio, identity and finesse under Roberto Mancini, the career wisdom of his move is clear. Touré has much more responsibility and space to dominate than he would ever have enjoyed in Xavi's orbit. A league title this season would end that line of criticism.
But first he must help guide his fellow Elephants out of the jungle of underachievement this month in Equatorial Guinea and Gabon. In the absence of serial champions Egypt, the Nations Cup trophy is beckoning both the Ivorians and the Ghanaians, who are joint favourites, but Touré's men have an edge in personnel.
Touré's brother Kolo is back and in form and skipper Didier Drogba is peeved — always disturbing news for his opponents. Some exciting younger components will complete the Ivorian machine: the fearsome Newcastle defensive midfielder Cheik Tiote, the quicksilver Arsenal winger Gervinho, CSKA Moscow striker Seydou Doumbia — the Russian league's player of the season — and fast-rising St Etienne winger Max Gradel, who shone in a recent friendly against Bafana Bafana.
Prowling the technical area is Francois Zahoui, a 49-year-old former Ivorian international who has little prior coaching experience: a stint in charge of the national under-20 side and another in charge of Abidjan club Africa Sports.
Zahoui's obscurity did not hinder a smooth qualification campaign — and his Ivorianness may have helped him harmonise the jostling egos in his squad. A friendly win over Italy when he was serving as caretaker helped Zahoui clinch the job — but the crest on his passport did not hurt either. Many of his compatriots are keenly aware that the Elephants' last and only Nations Cup triumph, in 1992, was overseen by an Ivorian — Martial Yeo.
The faith in Zahoui is part of a sudden and growing zeitgeist: a conviction that Africa's national dugouts are due for some decolonisation. At the 2008 finals, 12 of the 16 coaches were foreigners, but the ratio has fallen to nine for this tournament. Significantly, three of the six homegrown coaches are in charge of three of the four serious contenders: Zahoui, Amara Traore of Senegal and Sami Trabelsi of Tunisia.
It is a safe bet that unless the Serb Goran Stevanovic triumphs with the Black Stars, the winning coach will be African.
Outside the heavyweights, Stanley Tshosane of Botswana and Niger's Harouna Doula Gabde both excelled to qualify for their sides and Sudan's Mohamed Abdallah Ahmed and Angola's Lito Vidigal complete the African brain gain.
Had Samson Siasia of Nigeria and Bafana's Pitso Mosimane guided their sides to the finals, the homegrown contingent would have exceeded 50%.
The unprecedented success of Egypt's Hassan Shehata must have helped spark this new belief in the intellectual capital of African football, but the cult of the "white witchdoctor" was always destined to collapse. As Ian Hawkey explains in his book The Feet of the Chameleon, African administrators have long hired European or South American coaches on the assumption they were better informed, less prone to selection bias and commanded greater respect from rich, bolshy stars than local coaches.
Results did not support those assumptions. A linen-suited, floppy-haired clique of gallivanting "white witchdoctors" — including some competent coaches, but consisting mainly of charlatans or undiagnosed lunatics — were sacked with dizzying frequency, only to hop straight into another plum job in another balmy capital.
Men like Claude le Roy, Patrice Neveu, Henryk Kasperczak, Otto Pfister and Philippe Troussier can be credited at least with some passion for the African game. Not so Henri Michel, formerly of Mamelodi Sundowns, a terminally suave carpetbagger who likes his severance cheques paid upfront. He recently quit his Equatorial Guinea job.
If anyone can testify to the reality and intensity of tall-poppy syndrome as it affects African coaches, it is Mosimane. Bafana's inept failure to qualify for these finals has triggered inevitable abuse and he has endured it all with dignity. It would have been politically fatal to blame his players for slacking off at home against Niger, though as international footballers they should never have done so.
Even the mightiest coach is inescapably at the mercy of his players. Zahoui needs Touré much more than vice versa. But if Africa's coaching revolution is to continue, the tall poppies must stick together.
Television time: Ivory Coast vs Sudan: Group A, Sunday January 22 at 5pm on SuperSport 4
Francois Zahoui
Kolo Toure


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CID-42 (también conocido como CXOC J100043.1+020637) es un cuásar galáctico situado a unos 3.900 millones de años luz en la constelación de Sextans. Se cree que tiene un agujero negro supermasivo en su centro.

Descripción
Se cree que CID-42 es el resultado de la colisión de dos galaxias más pequeñas. Tiene una estela distintiva de estrellas que se extiende muchos años luz.

Agujero negro
El descubrimiento de un posible agujero negro se realizó tras combinar los datos e imágenes tomados por varios telescopios, como el Observatorio de rayos X Chandra de la NASA, el telescopio Hubble, el telescopio Canadá-Francia-Hawaii y los telescopios terrestres Magallanes y Very Large Telescope de Chile.

Cuando las dos galaxias chocaron, los agujeros negros de sus centros colisionaron, formando un único agujero negro supermasivo. El agujero negro retrocedió entonces por las ondas gravitacionales producidas por la fusión y está siendo expulsado fuera de la galaxia a varios millones de millas por hora (~2000 km s⁻¹).

Una vez expulsado se espera que brille como un cuásar desplazado durante 10 millones a 10.000 millones de años hasta que agote su combustible y deje de ser reconocible como cuásar.

Referencias

Enlaces externos

 CID-42: Simulacro de Agujero Negro Ejection Simulación de colisión y expulsión

Constelación de Sextans
Cuásares
Agujeros negros supermasivos


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redpajama_set_name: RedPajamaGithub


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Moab Celebrates 100% Renewable Electricity Resolution and Solar Project Completion
Moab, Utah – On Tuesday, February 14, 2017, the City of Moab, Utah, became the latest in a series of communities across the US to commit to 100 percent renewable electricity. Today, city officials, business owners, and other stakeholders joined together at City Hall to celebrate the Moab City Council's passing of a resolution committing the city to 100 percent renewable electricity by 2032, during a ribbon-cutting ceremony for the building's new solar array.
"Moab's commitment for 100 percent renewable electricity is driven by our community's passion for our natural environment and a sustainable future," said Mayor Dave Sakrison. "Moab City is excited to do our part with our move to make City Hall go solar. This makes sense from not only an environmental perspective, but fiscally as well."
The City Hall solar energy project, made possible by a Rocky Mountain Power Blue Sky Grant, will double the capacity of the building's solar generation capability to 63 kilowatts.
"Moab is known for its spectacular scenery, but the community should also be recognized for its early commitment to renewable energy," said Rocky Mountain Power spokesman Paul Murphy. "This new solar installation at Moab City Hall is one more opportunity for Rocky Mountain Blue Sky customers to acknowledge the city's efforts to go green."
Moab's commitment follows on the heels of a similar pledge from Salt Lake City and Park City, Utah, to transition to 100 percent renewable electricity, showing that mountain and outdoor sports communities are leading the way to a clean energy future.
"For Moab, one of the world's great outdoor sports destinations, the implications of climate change could not be more troubling," said City Councilmember Kalen Jones. "With rising temperatures, reduced water supplies, economic instability and other impacts threatening to greatly limit activity for months at a time and quell the steady stream of mountain bikers, hikers, and other adventurers making the pilgrimage and fueling the city's economy."
The good news is that the mountain and recreation-based communities feeling the impacts of a changing climate are recognizing the power of clean energy to solve it and taking the lead in a growing movement.
"Our mountain and outdoor recreation communities worldwide are recognizing that we are at the forefront of the fight against the climate crisis," said Kim Stevens, senior field organizer with The Climate Reality Project's I AM PRO SNOW program. "Today, Moab joins the growing movement of communities with the I AM PRO SNOW 100% Committed campaign, committing to clean electricity and sending a message to the rest of the world that we are in charge of our electricity future." For more information about The Climate Reality Project go to www.theclimaterealityproject.org.


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Q: mysql: organize search in a big tree I have a question about organizing my web application (php + mysql). I have many tables. I must search in it by different parameters. for example: country: 2 and category1: 33 and language: 3.
select distinct s.id from tbl_item s
left join tbl_item_act ep on s.id = ep.item_id
left join tbl_item_act_category cl3 on cl3.id = ep.category_id
left join tbl_item_act_category cl2 on cl2.id = cl3.parent_id
left join tbl_item_act_category cl1 on cl1.id = cl2.parent_id
left join tbl_city ci on ci.id = s.city_id
left join tbl_country co on co.id = ci.country_id
left join tbl_language la on la.id = cl2.language_id
left join tbl_item_subject sbb on sbb.item_id = s.id
left join tbl_subject sb on sb.id = sbb.subject_id and sb.subject_type = 'subject'
left join tbl_subject ev on ev.id = sbb.subject_id and ev.subject_type = 'event'
left join tbl_season se on se.id = cl1.season_id or se.id = cl2.season_id
left join tbl_education_type et on et.id = s.education_type_id
left join tbl_item_tag_binding stagb on stagb.item_id = s.id
left join tbl_item_tag stag on stag.id = stagb.tag_id
left join tbl_item_type_binding stb on stb.item_id = s.id
left join tbl_item_type st on st.id = stb.item_type_id
where s.original_id is null and cl1.id = 33 and la.id = 2 and se.id = 2

I must execute 9-10 queries on one page.
I takes about 50ms each query. I tried to generate one table (such as view) and store joined data here (as cache table) but it stores millions rows and searching takes about 500ms each query. I tried nosql (mongodb) search (big data tree) and it takes small time. about 20-30 ms but it is much for me.
What the best practices to create fast search by many parameters in my data structure?
sorry for my english.

A: Its big challenge but you need apache's Solr or Lucene here

redpajama_set_name: RedPajamaStackExchange


Millions of Miles: MOM'S RETREAT 2010!!!!
Oh my goodness! Can you feel my excitement through your screen????? I have been thinking about hosting a mom's retreat for a looooong time. I mentioned it on here a couple of weeks ago and so many of you said that you wanted to come. So I spent 2 weeks scouring the country in search of the perfect place where all us moms could converge for a couple of days of peace and quiet. Some places were fabulous but cost a fortune. Some places were cheap, but were complete dumps. But finally, I found the perfect place!
It just screams peacefulness and serenity! Harbourwood sleeps up to 14 people. There are 5 bedrooms with 6 beds, 4 inflatable mattresses and several couches. Even though that means that every person won't have their own private bedroom, if you're like me you'd sleep on asphalt just to get a night's sleep away from the kiddos. There are 4 bathrooms, a hot tub, hiking trails, a barn with farm animals, a gorgeous lake..
I don't know about you, but I HATE to cook when I'm on vacation. And since I have designed this whole weekend to give you a break- I will not allow you to cook, either. We've gotten a fabulous deal on catering, so all of our yummy meals will be brought right to us. We are also having some local professionals come in to give spa treatments for your weary bones and muscles. The only thing you have to do is show up and eat and sleep and get pampered. Sounds like my kind of weekend!
And the very best part is that I created this trip with your wallet in mind. I know that so many of you stressed out moms are paying buckets of money for therapies for your kids. You or your spouse have been laid off. You feel guilty about spending money, blah, blah, blah. I know that. I want you to be able to go. So I am giving you 4 whole months to start collecting your pennies and line out some childcare.
The only other costs associated with this trip are your transportation costs. Cincinnatti is very centrally located so hopefully lots of you will be able to drive. Once we know who is coming and where you live, we can arrange some carpooling if you'd like. Or better yet, convince your BFF to come with you and split the costs of gas! If you are coming from far away, check priceline and Expedia for airline tickets.
If you are a bit nervous about getting together with a group of women you don't know at all, don't be! I'll put together a contact list of everyone before hand, so we can all email back and forth and get to know each other a little before we join together for our giant slumber party.
I already had to put down a deposit, so if you'd like to go, I need half of your trip costs ASAP to hold your spot. ($62) Spots are on a first come- first served basis. The other half will be due 30 days before the trip. Email me at meganterry01@aol.com and let me know if you want to come along. If you have any questions (because I am sure that I am leaving out some really important info) leave a comment and I'll keep adding new info and answers there!
Hope that you can come! I can't wait to meet so many of you in person! And remember-YOU deserve a break! See you in Cincy!!!!!


Mojoy: Random Ellie pics AND a RETREAT UPDATE.
Random Ellie pics AND a RETREAT UPDATE.
And this is just a random photo of my girls. Gabbi in the cute matching outfit, and precoius little girl sandals. Ellie in Toms, a Justice tee, and likely a well placed off the shoulder tank. Oh, and blue streak in hair. Lawdy.
One of my patient's mamas just started designing tanks and onesies and sent a sample for each of my girls. This was Ellie's first week of school. She chose that tank, a cut off denim mini skirt and pink glitter Toms.
And then she posed with her outfit for the next day. I decided not to argue, rather just added a little jacket to try and offset all the skin on display for all the kindergarteners.
And have I mentioned Moonshell? This is the crab Emma Lou brought Ellie from Gulf Shores. And see Moonshell in the bottom right corner? That is what a dead crab looks like when it leaves it's shell for the last time.
The girls wanted to take a final picture with good ol' Moonshell!
Ellie before school. And by the way, she has decided she really doesn't like school. That's bad, because she has another 12 years of it!
"BUT, you should see the cute little jacket that Avery had on." And every day it is the same.
All I know so far about kindergarten is what all the girls in her class wear!
Avery wore a maxi dress. Jansen wore a "ballet tutu". Isabella wore a cute skirt. Blah, blah, blah. It's pretty humorous how much she is into fashion!
In fact, I asked her today if she'd like me to find her someone to teach her to sew. She was in the bathtub yesterday and had two wet rags tied in a knot on each side, with a rubberband, on her sister to make a "red and blue skirt". It seriously reminded me of Project Runway when the designers are fitting their models.
We're not doing soccer and we skipped tee ball. We have dancing and are adding gymnastics this year. She'll also do the art class with the big kids starting next week. But, I think we could work in a sewing class if I could find one. It'd be right up her alley!
It DOES look like Justin Bieber!
OK. I have ideas a-flowin for the art retreat in a couple of weeks. I just need a final head count. It'll be Friday, the 21st at noon through Sunday, the 23rd. If you need to come in on Thursday night, no sweat. I have plenty of beds, so I can hook you up. I have a lot of new things for us to do, vs only painting. I need those of you who are going to partake to send me your email and cellphone info so I can send you the details! Riley and Jennifer, if y'all are bringing friends/ kin, I need their numbers/ email info too! Send to mojoy@att.net.
I have Courtney C, Anne O in Colorado, Kerrie BP, Riley and mom and maybe friend, Jennifer and friend, Kaye C, Sandy P and maybe sister and mama, Rebecca C as my prelim participants. You all still in? We'll be in contact in the next couple of days.
I just love Ellie! She will keep you young Mo! I think she would love sewing.
I wish I was coming to your retreat. No go this time, as I got my hand crushed last week, and am NO good as a lefty!
As always, love seeing/reading about your girls.
Okay, something happened when I tried to post last time - try again - Ellie would love a sewing class - even from an individual who would love to teach her some basics - she is a visionary.
That girl knows what she likes. Too funny.


Learn more about the Department of Sustainable Development.
Planning is a highly interactive process in our City. DSD works closely with Transportation & Mobility on issues like traffic calming and safe cycling. They work with Public Works on water management, with Police on safe streets, with Parks & Recreation on green space expansion, and with our Sustainability Division on everything from recycling to to long-range sea level issues.
These principles include limiting urban sprawl, creating civic spaces which support living and working in the same area, connecting these spaces to each other, and increasing walkability. Key goals are to limit the amount of time that people need to be in their cars, to facilitate local purchasing, and to maximize the value to the community of each individual building. Achieving these goals allows us to reduce GHG emissions, cool our city, and keep our water and green spaces clean and healthy.
The City of Fort Lauderdale is proud to be a leader in this type of city planning. Our Department of Sustainable Development (DSD) has sustainability right in its name! DSD's urban design team is tasked with shaping our City's physical realm in a way that allows buildings, streets and public places to function better so that the way people interact with their environment promotes resiliency and green living.
Read on to learn more about these four important design principles, and how they come together to influence plans and design guidelines, and to create policy.
It is one thing to subscribe to certain design principles, and quite another to put them to work. Design Guidelines are the planners tool for doing just that.
Guidelines address building form, height and density, parking standards, vehicular and pedestrian circulation, building frontage standards, streetscape, landscaping, historic preservation, and so on. Design guidelines allow a city to implement certain standards for development that create a certain character or look as well as improve functionality of the built environment. They also help us to build in sustainability.
Master plans are tools to visualize a new development or the redevelopment of an area. The formation of a master plan is guided by experts and stakeholders who have a vested interest in the community's future. Scopes of study for these plans can be in the form of a corridor such as the City's Davie Boulevard Corridor Master Plan or a city district such as the Central Beach Master Plan. Master plans are comprehensive in nature and usually take into consideration the existing conditions of the project site including the population, housing, transportation network, land use, economic conditions, and so on with the purpose of making recommendations for strategies for future growth and development. Therefore, the Master Plan is the perfect place to incorporate long-term resilience issues and implementation of changes to support sustainable living. Visit Planning Initiatives to see descriptions and get online access to the Fort Lauderdale''s master plans.
When the four principles of sustainable development come together, they produce policies with the power-- power to significantly lower GHGs. An example of this is Transit Oriented Development (TOD).
TOD is the integration of land use and transit by creating compact, walkable, mixed-use communities within a short distance of a transit stop or station. It brings together people, jobs, housing and services and is designed in a way that makes it efficient, safe, and convenient to travel on foot or by bicycle, by transit, or partially by car.
TOD promotes density and mixed use by advocating multi-modal transit centers and making living in the city a logical choice. It creates spaces of value by co-locating ammenities and gathering spaces with the transit centers or stops or even in parking areas. TOD connects places with a variety of mass transit that connects to cycling paths and safe walkways, and in this way it also invites pedestrians.


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Daily Security Breif
Geeska Afrika Online
Home Daily Security Briefing The Eritrea-Ethiopia peace deal is yet to show dividends
Daily Security Briefing
The Eritrea-Ethiopia peace deal is yet to show dividends
Addis Ababa (HAN) September 11. 2020. Monitoring Regional Issues. BY:Selam Tadesse Demissie. It's been over two years since the much-heralded rapprochement between Eritrea and Ethiopia culminated in a peace and friendship agreement in July 2018.
The settlement was internationally praised for its potential to stabilise the region beyond improving the two countries' affairs. Abiy even received the 2019 Nobel Peace Prize for his efforts to build bridges with Eritrea.
Two years later, positive steps have been taken in some areas, but not in others due to tensions between Ethiopia's federal government and Tigray regional state, and unresolved animosity between Tigray and Eritrean leaders.
The dispute over the small border town of Badme, which both Eritrea and Ethiopia claimed as their own, is often cited as the reason for the outbreak of the 1998-2000 border conflict. However the root causes go deeper.
They include historical rivalry, political and economic differences and hegemonic competition between the ruling elites of both countries. These were the Eritrean leadership, and the ruling party in Ethiopia's Tigray State – the Tigray People's Liberation Front (TPLF) – Ethiopia's dominant political party until Abiy came to power.
The Eritrea-Ethiopia Boundary Commission (EEBC), established to resolve the border issue, decided in 2002 that Badme should belong to Eritrea. A failure to implement the EEBC's decision led to the stand-off between the two countries.
In the 2018 peace deal, the leaders agreed to begin political, economic, social, cultural and security cooperation. They decided to resume diplomatic, transport, trade and communication ties that had been frozen for two decades. The leaders resolved to implement the EEBC decision and jointly ensure regional peace, development and cooperation.
Since then, progress in reconnecting the two countries has been made in key areas. Numerous high-level leadership visits took place, diplomatic relations were normalised and embassies reopened. Daily flights between Addis Ababa and Asmara were established and phone connections resumed. Four border posts were opened, although they were closed after a short period.
Talks about infrastructure and transport linkages, such as Ethiopia's use of Eritrean ports (including a feasibility study for a railway between Massawa and Addis Ababa) and rebuilding of roads, dominated discussions. Other symbolic soft power and people-to-people interactions took place. United Nations sanctions on Eritrea were lifted.
The high-profile start of the rapprochement raised expectations, both at home and internationally, that 20 years of tension and mistrust could be eroded. Two years later, this potential has waned, paralysing anticipated socio-economic gains for people in both countries. And the cause is mostly tensions between Ethiopia's federal and Tigray officials, and ongoing conflict between the TPLF and Eritrean leadership – just like old times.
Ethiopia's Tigray regional state and Eritrea share the border that was contested. Badme is also under Tigray administration, and so the region's TPLF leaders share responsibility for implementing the EEBC's decision. But the peace process was initiated from Addis Ababa, and there wasn't adequate consultation and consensus building among stakeholders like the TPLF.
This exclusion – together with other political differences relating to ideology, foreign policy, governance and elections – have worsened the division between Abiy's government and the TPLF's rule in Tigray. One point of contention involves how to engage with Eritrea.
Abiy, in his April 2018 inaugural speech, announced his administration's unconditional acceptance of the stalled Algiers agreement signed in 2000 and aimed at ending the border war. In February 2020, Debretsion Gebremichael – the TPLF's highest official – said a structured peace process was needed that included all relevant sides, not just the two national leaders.
Implementation of the 2018 deal cannot occur without buy-in from all relevant government actors in Tigray. Consensus is also needed within the respective agencies of both Ethiopia and Eritrea and all other relevant stakeholders.
The four border posts that were opened and quickly closed symbolise the lack of consensus among federal and state agencies on both sides around regulating movement and trade across national boundaries. Proper consultations would have allowed time to develop harmonised positions and enact new regulations.
Unresolved hostility between Eritrea's and the Tigray region's ruling elites also hampers progress. Isaias accused the TPLF of complicating implementation of the EEBC's decision, which the TPLF denied. Isaias also claims the TPLF created division among Eritreans, organising ethnic-based opposition and spreading misinformation to spoil relations between Eritreans and Ethiopians. The TPLF in turn accuses Eritrea of interfering in Ethiopia's internal affairs and threatening regional security.
Twenty years after the bloody border war, and despite the new peace deal, the conflict's main protagonists – the TPLF and the Eritrean leadership – are still fighting.
Given the increasingly serious confrontation between Mekele and Addis Ababa and the unresolved animosity between Mekele and Asmara, the TPLF feels unfairly targeted from both sides. Without political will and confidence building between the TPLF, Abiy and Isaias, the peace deal may not bear fruit.
Resolution of the conflict between Ethiopia and Eritrea is imperative for advancing economic and development prospects in the Horn. Sustainable peace and the benefits that it will bring can only be achieved if the 2018 agreement is implemented.
The priority is to de-escalate tensions between the Federal Government of Ethiopia and the Tigray region. Consultation and confidence building is equally important between Eritrea and Tigray's leadership and people. Only then will the new peace deal stand a chance of bringing much-needed stability to the people of both countries and the region.
Selam Tadesse Demissie, Research Officer, Horn of Africa Security Analysis, ISS Addis Ababa
SOURCEissafrica
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In 1982 Mike joined his Dad (Peter) and brother (Jim) behind the dispensary at Ealing Pharmacy in London. As a pharmacist, he split his time between Ealing Pharmacy and a large chain drug store. With his dad's help and advice, he opened Greenhills Pharmacy in Lambeth in 1985. Mike has a wealth of pharmaceutical experience with interests in Diabetes and Older Adult Care.
Heather's been a Pharmacist with Greenhill Pharmacy since 2014, and is a graduate of the Memorial University Pharmacy program in Newfoundland.
She's a tremendous supporter of the wholistic approach that Greenhills Pharmacy takes for the wellbeing of each customer. This includes a team approach to overall wellness, by providing and bringing in Diabetes Educators to Nutritional Counselling, Weightloss Counselling and more... "The whole patient needs to be considered," she says, "not just part."
Outside of Greenhill Pharmacy, Heather also works at a Plastic Surgeons Office supporting patients through their procedures, and loves all aspects of health including practicing yoga and mindfulness.
Lillian has been a Pharmacist with Greenhills PharmaChoice since 2007. She's is a local Lambeth resident and takes pride in being able to help people in the community where she lives. Each day brings new challenges that keep her excited and engaged in her work. Come by and let Lillian help you with your pharmacy and health-related needs today.
When Lillian isn't in the pharmacy she enjoys dinning out, and finding new restaurants to visit with her husband.