Seven corrections are made and several supplementary equations are added to the article by Yoshimura [Acta Cryst. (2015), A71, 368–381].

Entangled embedded periodic nets and crystal frameworks are defined, along with their dimension type, homogeneity type, adjacency depth and periodic isotopy type. Periodic isotopy classifications are obtained for various families of embedded nets with small quotient graphs. The 25 periodic isotopy classes of depth-1 embedded nets with a single-vertex quotient graph are enumerated. Additionally, a classification is given of embeddings of n-fold copies of pcu with all connected components in a parallel orientation and n vertices in a repeat unit, as well as demonstrations of their maximal symmetry periodic isotopes. The methodology of linear graph knots on the flat 3-torus [0,1)3 is introduced. These graph knots, with linear edges, are spatial embeddings of the labelled quotient graphs of an embedded net which are associated with its periodicity bases.

"The Antarctic Treaty Summit: Science-Policy Interactions in International Governance" will be convened at the Smithsonian Institution, National Museum of Natural History in Washington, DC from Nov. 30 to Dec. 3 2009. More information on this event can be found at the Web site: www.atsummit50.aq/

To assess legacy lessons about managing nearly 10% of the Earth "for peaceful purposes only"

Find out how you can be involved:

www.atsummit50.aq

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One of Italy’s greatest treasures, Leonardo da Vinci’s Codex on the Flight of Birds, will be exhibited at the National Air and Space Museum from […]

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Click photo to take a tour of the 1903 Wright Flyer with Smithsonian X 3D Explorer. The Smithsonian X 3D Collection features objects from the […]

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How 3D technology is used at the Smithsonian to create world class exhibits!

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The Smithsonian has launched an ambitious project to scan millions of items and make them available to the world on a searchable database. CBS reporter […]

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Vince Rossi and Jon Blundell from the Smithsonian’s Digitization Program Office (http://3d.si.edu) apply various 3-D capture methods on the pointed plaster model for the “Greek […]

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To mark the 47th anniversary of the Apollo 11 moon-landing mission, the Smithsonian has made available a high-resolution 3-D scan of the command module “Columbia,” […]

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When it comes time to eat, Abyssinian ground hornbills pick up prey with their beak, toss it into the air and swallow it whole. But […]

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Yesterday, we heard about the hyper-loop, a system that could get you from L.A. to San Francisco in about 30 minutes without losing your eyeballs.

Steve Julian: Business analyst Mark Lacter, that might come in handy given how crowded California's air corridor has become...

Mark Lacter: We'll talk about the hyper-loop in a moment, Steve, but yes, the L.A.-to-San Francisco air route is the busiest in the U.S., and it's already the most competitive.  We're talking about more than 50 flights a day, which - if you spread them out between six in the morning and 10:30 at night - there'd be one flight every 20 minutes.  But, Delta obviously thinks there's room for more because it's announced an hourly shuttle between the two cities.  That's another 14 daily flights beginning September 3.  The airline will be using a somewhat smaller jet, and it sounds as if the focus will be on the business traveler, with free newspapers, wine, and beer.

Julian: How much will it cost, do we know?

Lacter: As usual, it's a lot cheaper if you make an advance purchase, but if you're buying your tickets at the last minute - which is what a lot of business travelers do - roundtrip runs a hefty $430.  Actually, this Bay Area shuttle is just the latest effort by Delta to expand out of LAX, which is different from other major airports in that it doesn't have any one airline that dominates (United has a slight edge in market share over American, with Delta about three percentage points behind).  American also has been adding flights out of LAX.

Julian: Sounds like the airline business is improving...

Lacter: That's what happens when you pack planes to the absolute max, which is bad news for travelers being crammed into coach seats.  But it's good news for LAX, which continues to be the airport of choice among airlines looking to add service - matter of fact, domestic passenger traffic was up almost 8 percent in June compared with a year earlier.  Some of those gains might be at the expense of service elsewhere - most especially Ontario Airport, which has seen a big exodus among airlines and passengers.  Ontario city officials have been trying to regain control of the airport, which has been operated by the city of Los Angeles.

Julian: Back to the hyper-loop - is this kind of transport possible?

Lacter: Well, it's the brainchild of billionaire Elon Musk, and you never say never with this guy.  He started the electric car company Tesla and the private space company Space X.  The hyper-loop is a high-speed system of passenger pods that would travel on a cushion of air (think of air hockey table).  The pods would travel at more than 700 miles per hour, but they wouldn't result in sonic booms that severely restricted the Concorde aircraft.  Of course, anything that promises super-speed travel is bound to get people talking - and, from what the physics professors are saying, the Musk idea seems feasible.

Julian: How would its cost compare to the bullet train?

Lacter: He says a lot cheaper.  The price tag on the train is $70 billion at last check; Musk says he can do his for $6 billion.  But, the issue isn't so much the cost or even the technology, but the politics.  As a rule, governments do not think outside the box, and that's what a project like this is all about.  Already, you have bullet train supporters saying that the hyper-loop is impossible, but what they're really saying is we have a lot riding on the train, and we don't want this guy to mess it up.

Julian: But, how much demand is there for high-speed transport?

Lacter: You'd think there would be a lot, but when Boeing came up with a nifty idea for a souped-up plane that would shave almost an hour from L.A. to New York, the airlines said no because it would require more fuel - and that would mean raising fares.  Musk says his system would be a lot cheaper than traveling by plane, which could be a game changer in the attitudes about going places.  But, those attitudes won't change until the thing is actually built, and that can't realistically happen until attitudes change.  That's the ultimate problem.

Julian: Hence, why we're content to squeeze into coach.

Lacter: Yep.

Mark Lacter is a contributing writer for Los Angeles Magazine and writes the business blog at LA Observed.com.

This content is from Southern California Public Radio. View the original story at SCPR.org.

When talk turns to the economy, it's clear that LA brings out the best and the worst.

Steve Julian: Business analyst Mark Lacter, where do you see the best of it here?

Mark Lacter: You see the best of the economy, Steve, with all kinds of startup activity - much of it tech-related - and you also see the large number of auto sales, the improved housing market, and the record number of people visiting Southern California - all indications of a growing economy.  But then, you have the other L.A. economy, with large numbers of families struggling to make ends meet, and seeing very little sign of recovery.  You know, the government has been releasing income data covering the last few years, and what you see is that the disparity between the richest 1 percent and the other 99 percent is at its widest point since the 1920s.  You especially see that kind of bifurcated economy in Southern California, which has some of the wealthiest people in the country, and also some of the poorest.

Julian: Now, the split between rich and poor has been happening for a good long time, hasn't it?

Lacter: Yes, but L.A. is in a special class because there are so many immigrants with limited job skills - in fact, a new study by the UCLA Anderson Forecast says it's a much higher percentage than immigrants living in Miami, San Francisco, and New York.  What's interesting is that 20 years ago the job skills among immigrants were significantly higher in L.A.  Limited job skills mean there's very little opportunity to move up the income ladder.  That factors into buying homes, sending your kids to college - really becoming part of the middle class.

Julian: I imagine that's particularly true for factory work…

Lacter: Yes, some of the same jobs that newly-arrived immigrants in previous generations would gravitate to.  Today, many of those jobs are gone, and they're being replaced by positions that require greater skill that's borne out of greater education.  And that, of course, is another problem: a sizable percentage of recently-arrived immigrants never finished high school, much less college, and that makes it even less likely that they'll be able to move up.

Julian: Related, or unrelated, to the recession?

Lacter: Actually, L.A. had serious income inequality in December of 2006, before the recession, when the county's unemployment rate was just 4.3 percent - a stunningly low rate when you consider that as of July, the jobless rate was almost 10 percent.  This points out that the division of haves and have-nots can happen even when the economy is doing well.

Julian: And it seems the last C-17 to be built for Air Force is a reminder of wage gap.

Lacter: That's right - it'll be up to foreign customers to keep the program in Long Beach alive.  Boeing currently has an order from India for 10 of the cargo planes, which will keep the line moving through the third quarter of next year.  Frankly, the only reason the C-17 has lasted this long is heavy political pressure by congressional lawmakers whose districts have an economic stake in the program.  At one time, as many as 16,000 people may have worked on the C-17 in Long Beach, but that number has fallen sharply over the years.

Julian: Still, this is the last airplane manufacturing plant in Southern California.

Lacter: And that, of course, speaks volumes about the state of the aerospace business, which had been one of the main economic drivers back in the days leading up to World War II.  Aerospace continued to be very important until the end of the Cold War, when you had a huge industry consolidation that resulted in the loss of tens of thousands of local jobs throughout the 1990s.  There's still quite a bit of aerospace activity locally that involves missiles, satellites, and electronics - both for the major defense contractors like Boeing and Northrop, and for smaller contractors and sub-subcontractors that still get a piece of the military pie.

Julian: But most of them require high skill levels…

Lacter: Yes, and that gets us back to the folks who are stuck in low-paying jobs with little prospect for moving up.  This is what the L.A. economy is all about, the good and the bad.

Mark Lacter writes for Los Angeles Magazine and pens the business blog at LA Observed.com.

This content is from Southern California Public Radio. View the original story at SCPR.org.

Sign ups for the Affordable Care Act start in a week, and the program is leading to changes in the way employers handle health coverage.

Steve Julian: Business analyst Mark Lacter, what's the most noticeable adjustment?

Mark Lacter: Steve, once you get beyond the squabbling over efforts to defund the new law, what's happening is quite remarkable: businesses are finding new ways to administer and pay for coverage - and some would say it's long overdue.  One interesting example: the grocery chain Trader Joe's, which is based in Monrovia, employs over 20,000 people, and shells out millions of dollars a year in helping provide its people with health insurance.  Well, Trader Joe's has decided to end coverage for part-timers working fewer than 30 hours a week - under the new law businesses are not obligated to provide benefits to employees who work less than that amount.  However, the company is giving those people $500 to go towards the purchase of premiums at the new public exchanges.  And that, along with the tax credits available, could make the new arrangement cost about the same or even cheaper than the current health care package.

Julian: How did TJ's explain this to its employees?

Lacter: The company cited the example of an employee with one child who makes $18 an hour and works 25 hours a week.  Under the old system, she pays $166 a month for coverage; under the new system, she can get a nearly identical plan for $70 a month.  Now, there are cases in which workers will end up paying more - usually it involves having a family member who makes more money, but who doesn't have access to coverage (good example would be an independent contractor or freelancer).  By the way, other companies - including the drug store chain Walgreen's - are also moving part-timers to the public market, and offering some sort of a subsidy.

Julian: I imagine not all companies are being as conscientious...

Lacter: No.  We've seen a number of corporations cut worker hours and not offer a supplemental payment.  Steve, it's worth remembering that administering health insurance is something that businesses fell into quite by accident 60 years or so ago - premiums cost next to nothing at the time, and it was seen as way of attracting workers without having to jack up wages.  The arrangement became more attractive over the years because of certain tax benefits.  But, it's far from ideal - workers move from job to job more often than they used to, and not all businesses are capable of handling the extra costs, especially small businesses.

Julian: Doesn't L.A. have a higher percentage of uninsured than elsewhere?

Lacter: Considerably higher - the Census Bureau show that 21 percent did not have coverage in 2012, which is higher than the overall national number.  Now, there are a bunch of reasons for this: L.A. has a large percentage of households that simply can't afford health insurance or don't have access to government programs, among them undocumented immigrants.  You also have big numbers of people who are self-employed and don't get covered - we're talking about freelancers or consultants of some sort.

Julian: …Or, they work for small businesses whose owners either can't afford, or don't want to provide coverage…

Lacter: That's right - the new law only requires businesses with more than 50 full-time workers to offer health insurance, and a lot of small businesses don't meet that threshold.  The Census Bureau says that in the L.A. area, one in four people with jobs do not have health insurance - and, by the way, there's been a drop-off both in the percentage of businesses in California that offer coverage.

Julian: Sounds dire.  Who picks up the cost?

Lacter: Well, we all do in one way or another - and that, of course, is the problem.  What the Affordable Care Act offers is a start in getting some of the uninsured onto the rolls.  Clearly, it's an imperfect solution that will require all sorts of adjustments, and even though everyone and their uncle seems to have formed a definitive opinion about the new law, it's going to be years before there's any real sense of how it's going.  And, let's remember, signing up for these programs is not some political act.  It's just a way for people to get health insurance for themselves and their families.

Mark Lacter writes for Los Angeles Magazine and pens the business blog at LA Observed.com.

This content is from Southern California Public Radio. View the original story at SCPR.org.

What can you do to bring some of the Smithsonian’s 137 million objects to life? Put them in 3-D! This is a full-time job for […]

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Corn, known also as maize, is a vital crop in the U.S. and throughout the Americas. First domesticated in Mexico some 9,000 years ago, scientists […]

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This article aims to encourage practitioners, young and seasoned, by enhancing their structure-determination toolboxes with a selection of tips and tricks on recognizing and handling aspects of data collection, structure modelling and refinement, and the interpretation of results.

In the first reported crystal structure involving the potential ligand N,N',N''-tris­(2-pyridin­yl)-1,3,5-benzene­tricarboxamide, inter­molecular N—H⋯O hydrogen bonds link the mol­ecules via their amide groups into slanted ladder-like chains. Only two of the three amide groups in the mol­ecule are involved in hydrogen bonding, which influences the degree of out-of-plane twisting at each amide group.

In the structure of the title salt, second-order Jahn–Teller distortion of the coordination octa­hedra around V ions is reflected by coexistence of short V—O bonds and trans-positioned long V—F bonds, with four equatorial V—F distances being inter­mediate in magnitude. Hydrogen bonding of the anions is restricted to F-atom acceptors only, with particularly strong N–H⋯F inter­actions [N⋯F = 2.5072 (15) Å] established by axial and cis-positioned equatorial F atoms.

The cationic cyclo­metallated iridium(III) complex [Ir(C9H7N2)2(C12H8N2)](PF6) has been synthesized and crystallized by the inter-diffusion method. It contains an unknown number of solvent mol­ecules and has a different space-group symmetry (C2/c) structure than its solvatomorph (P21/c).

The new copper(II) complex [CuLCl2]2, where L is a product of Schiff base condensation between methyl­amine and 2-pyridine­carbaldehyde, is built of discrete centrosymmetric dimers.

The asymmetric unit of the title compound contains two independent mol­ecules, consisting of perimidine and phenol units, which are linked through an N—H⋯O hydrogen bond. Intra­molecular O—H⋯N hydrogen bonds are observed in both independent mol­ecules.

The title compound, 1-(2,5-di­meth­oxy­phen­yl)-2,2,6,6-tetra­methyl­piperidine, was synthesized as a side-product during the synthesis of the inter­mediate, methyl 3,6-dimeth­oxy-2-(2-meth­oxy-2-oxoeth­yl)benzoate, necessary for the total synthesis of the isocoumarin 5,8-dimeth­oxy-3-methyl-1H-isochromen-1-one.

The title compound exhibits exceptionally weak inter­molecular C—H⋯π hydrogen bonding of the ethynyl groups, with the corresponding H⋯π separations [2.91 (2) and 3.12 (2) Å] exceeding normal vdW distances. This bonding compliments distal contacts of the CH (aliphatic)⋯π type [H⋯π = 3.12 (2)–3.14 (2) Å] to sustain supra­molecular layers.

The dihedral angle between the two aromatic rings of the title compound is 64.12 (14)°. The crystal structure is stabilized by a short Cl⋯H contact, C—Cl⋯π and van der Waals inter­actions.

The title complex, Cu(L)2 or [Cu(C15HF10O2)2], comprising one copper ion and two fully fluorinated ligands (L−), was crystallized with 3,4-ethyl­ene­dioxy­thio­phene (EDOT, C6H6O2S) as a guest mol­ecule to give in a di­chloro­methane solution a unique co-crystal, Cu(L)2·3C6H6O2S.