Living trees can rot from the inside out, leaving only a hollowed trunk. Wood rot in living trees can cause overestimates of global carbon pools, […]

The post Measuring trees with the speed of sound appeared first on Smithsonian Insider.

The Smithsonian is celebrating Earth Day this month by hosting the first Earth Optimism Summit from April 21 to 23 in Washington, D.C. Its goal […]

The post The Smithsonian’s history is right in line with Earth Optimism appeared first on Smithsonian Insider.

This Earth Day weekend in Washington, D.C., the Smithsonian is convening the first Earth Optimism Summit. The three-day event, taking place April 21–23, will look […]

The post Earth Optimism: Smithsonian’s “Agua Salud” Project restores degraded land with forest appeared first on Smithsonian Insider.

For many Californians, last year’s wet winter triggered a case of whiplash. After five years of drought, rain from October 2016 to February 2017 broke […]

The post In San Francisco, one wet winter can switch up Bay’s invasive species appeared first on Smithsonian Insider.

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.

This work presents a technique for extracting the detailed shape of peaks with extended, overlapping tails in an X-ray powder diffraction pattern. The application discussed here concerns crystallite size broadening, though the technique can be applied to spectra of any origin and without regard to how the profiles are to be subsequently analyzed. Historically, the extraction of profile shapes has been difficult due to the complexity of determining the background under the peak, resulting in an offset of the low-frequency components of the Fourier transform of the peak known as the `hook' problem. The use of a carefully considered statistical weighting function in a non-linear least-squares fit, followed by summing the residuals from such a fit with the fit itself, allows one to extract the full shape of an isolated peak, without contributions from either the background or adjacent peaks. The extracted shape, consisting of the fit function recombined with the residuals, is not dependent on any specific shape model. The application of this to analysis of microstructure is performed independently of global parametric models, which would reduce the number of refined parameters; therefore the technique requires high-quality data to produce results of interest. The effectiveness of the technique is demonstrated by extraction of Fourier transforms of peaks from two sets of size-broadened materials with two differing pieces of equipment.

The development of antiviral strategies requires a clear understanding of the principles that control the protein arrangements in viral shells. Considered here are those capsids that violate the paradigmatic Caspar and Klug (CK) model, and it is shown that the important structural features of such anomalous shells from the Picobirnaviridae, Flaviviridae and Leviviridae families can be revealed by models in the form of spherical icosahedral packings of equivalent rhombic structural units (SUs). These SUs are composed of protein dimers forming the investigated capsids which, as shown here, are based on the rhombic triacontahedron (RT) geometry. How to modify the original CK approach in order to make it compatible with the considered rhombic tessellations of a sphere is also discussed. Analogies between capsids self-assembled from dimers and trimers are demonstrated. This analysis reveals the principles controlling the localization of receptor proteins (which recognize the host cell) on the capsid surface.

One of the essential components of molecular electronic circuits are switching elements that are stable in two different states and can ideally be switched on and off many times. Here, distinct buckminsterfullerenes within a self-assembled monolayer, forming a two-dimensional dodecagonal quasicrystal on a Pt-terminated Pt3Ti(111) surface, are identified to form well separated molecular rotational switching elements. Employing scanning tunneling microscopy, the molecular-orbital appearance of the fullerenes in the quasicrystalline monolayer is resolved. Thus, fullerenes adsorbed on the 36 vertex configuration are identified to exhibit a distinctly increased mobility. In addition, this finding is verified by differential conductance measurements. The rotation of these mobile fullerenes can be triggered frequently by applied voltage pulses, while keeping the neighboring molecules immobile. An extensive analysis reveals that crystallographic and energetic constraints at the molecule/metal interface induce an inequality of the local potentials for the 36 and 32.4.3.4 vertex sites and this accounts for the switching ability of fullerenes on the 36 vertex sites. Consequently, a local area of the 8/3 approximant in the two-dimensional fullerene quasicrystal consists of single rotational switching fullerenes embedded in a matrix of inert molecules. Furthermore, it is deduced that optimization of the intermolecular interactions between neighboring fullerenes hinders the realization of translational periodicity in the fullerene monolayer on the Pt-terminated Pt3Ti(111) surface.

To date X-ray protein crystallography is the most successful technique available for the determination of high-resolution 3D structures of biological molecules and their complexes. In X-ray protein crystallography the structure of a protein is refined against the set of observed Bragg reflections from a protein crystal. The resolution of the refined protein structure is limited by the highest angle at which Bragg reflections can be observed. In addition, the Bragg reflections alone are typically insufficient (by a factor of two) to determine the structure ab initio, and so prior information is required. Crystals formed from an imperfect packing of the protein molecules may also exhibit continuous diffraction between and beyond these Bragg reflections. When this is due to random displacements of the molecules from each crystal lattice site, the continuous diffraction provides the necessary information to determine the protein structure without prior knowledge, to a resolution that is not limited by the angular extent of the observed Bragg reflections but instead by that of the diffraction as a whole. This article presents an iterative projection algorithm that simultaneously uses the continuous diffraction as well as the Bragg reflections for the determination of protein structures. The viability of this method is demonstrated on simulated crystal diffraction.

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The cationic complex in the title compound, [Ir(C9H7N2)2(C12H8N2)]PF6, comprises two phenylpyrazole (ppz) cyclometallating ligands and one 1,10-phenanthroline (phen) ancillary ligand. The asymmetric unit consists of one [Ir(ppz)2(phen)]+ cation and one [PF6]− counter-ion. The central IrIII ion is six-coordinated by two N atoms and two C atoms from the two ppz ligands as well as by two N atoms from the phen ligand within a distorted octahedral C2N4 coordination set. In the crystal structure, the [Ir(ppz)2(phen)]+ cations and PF6− counter-ions are connected with each other through weak intermolecular C—H...F hydrogen bonds. Additional C—H...π interactions between the rings of neighbouring cations consolidate the three-dimensional network. Electron density associated with additional disordered solvent molecules inside cavities of the structure was removed with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9–18]. The given chemical formula and other crystal data do not take into account the unknown solvent molecule(s). The title compound has a different space-group symmetry (C2/c) from its solvatomorph (P21/c) comprising 1.5CH2Cl2 solvent molecules per ion pair.

The new copper(II) complex, namely, di-μ-chlorido-bis{chlorido[methyl(pyridin-2-ylmethylidene)amine-κ2N,N']copper(II)}, [Cu2Cl4(C7H8N2)2], (I), with the ligand 2-pyridylmethyl-N-methylimine (L, a product of Schiff base condensation between methylamine and 2-pyridinecarbaldehyde) is built of discrete centrosymmetric dimers. The coordination about the CuII ion can be described as distorted square pyramidal. The base of the pyramid consists of two nitrogen atoms from the bidentate chelate L [Cu—N = 2.0241 (9), 2.0374 (8) Å] and two chlorine atoms [Cu—Cl = 2.2500 (3), 2.2835 (3) Å]. The apical position is occupied by another Cl atom with the apical bond being significantly elongated at 2.6112 (3) Å. The trans angles of the base are 155.16 (3) and 173.79 (2)°. The Cu...Cu separation in the dimer is 3.4346 (3) Å. In the crystal structure, the loosely packed dimers are arranged in stacks propagating along the a axis. The X-band polycrystalline 77 K EPR spectrum of (I) demonstrates a typical axial pattern characteristic of mononuclear CuII complexes. Compound (I) is redox active and shows a cyclic voltammetric response with E1/2 = −0.037 V versus silver–silver chloride electrode (SSCE) assignable to the reduction peak of CuII/CuI in methanol as solvent.

The crystal structures of caesium di­hydrogen arsenate(V) bis­[tri­hydrogen arsen­ate(V)], Cs(H2AsO4)(H3AsO4)2, ammonium di­hydrogen arsenate(V) tri­hydrogen arsenate(V), NH4(H2AsO4)(H3AsO4), and dilithium bis­(di­hydrogen phosphate), Li2(H2PO4)2, were solved from single-crystal X-ray diffraction data. NH4(H2AsO4)(H3AsO4), which was hydro­thermally synthesized (T = 493 K), is homeotypic with Rb(H2AsO4)(H3AsO4), while Cs(H2AsO4)(H3AsO4)2 crystallizes in a novel structure type and Li2(H2PO4)2 represents a new polymorph of this composition. The Cs and Li compounds grew at room temperature from highly acidic aqueous solutions. Li2(H2PO4)2 forms a three-dimensional (3D) framework of PO4 tetra­hedra sharing corners with Li2O6 dimers built of edge-sharing LiO4 groups, which is reinforced by hydrogen bonds. The two arsenate compounds are characterized by a 3D network of AsO4 groups that are connected solely via multiple strong hydrogen bonds. A statistical evaluation of the As—O bond lengths in singly, doubly and triply protonated AsO4 groups gave average values of 1.70 (2) Å for 199 As—OH bonds, 1.728 (19) Å for As—OH bonds in HAsO4 groups, 1.714 (12) Å for As—OH bonds in H2AsO4 groups and 1.694 (16) Å for As—OH bonds in H3AsO4 groups, and a grand mean value of 1.667 (18) Å for As—O bonds to nonprotonated O atoms.

The enanti­opure monopyrrolidine derivative (2S)-methyl (Z)-5-(2-tert-but­oxy-1-cyano-2-oxo­ethyl­idene)pyrrolidine-2-carboxyl­ate, C13H18N2O4, (1), represents a potential ligand and an attractive inter­mediate for the synthesis of chiral metal com­plexes. At the mol­ecular level, the com­pound features an intra­molecular N—H⋯O hydrogen bond; neighbouring mol­ecules inter­act via N—H⋯N contacts to form chains along [100]. Due to its elemental com­position, resonant scattering of the target com­pound is entirely insignificant for diffraction experiments with Mo Kα and small even for Cu Kα radiation. A preliminary study with the harder radiation type confirmed the chiral space group and the suitability of the single crystal chosen; as expected, the results concerning the absolute structure remained com­pletely inconclusive. A second data collection with the longer wavelength gave satisfactory quality indicators for the correct handedness of the mol­ecule, albeit with high standard uncertainties. The absolute configuration has been assessed independently: CD spectra for both enanti­omers of the target mol­ecule were calculated and the spectrum for the S-configured stereoisomer was in agreement with the experiment. The Cotton effect of (1) may be ascribed to π–π* transitions from HOMO to LUMO and from HOMO to LUMO+1. As both independent techniques agree with respect to the handedness of the target mol­ecule, the absolute structure may be assigned with a high degree of confidence.

The com­pound poly[2-hy­droxy-N-methyl­ethan-1-aminium [μ3-cyanido-κ3C:C:N-di-μ-cyanido-κ4C:N-dicuprate(I)]], {(C3H10NO)[Cu2(CN)3]}n or [meoenH]Cu2(CN)3, crystallizes in the tetra­gonal space group P43. The structure consists of a three-dimensional (3D) anionic CuICN network with noncoordinated protonated N-methyl­ethano­lamine cations providing charge neutrality. Pairs of cuprophilic Cu atoms are bridged by the C atoms of μ3-cyanide ligands, which link these units into a 43 spiral along the c axis. The spirals are linked together into a 3D anionic network by the two other cyanide groups. The cationic moieties are linked into their own 43 spiral via N—H⋯O and O—H⋯O hydrogen bonds, and the cations inter­act with the 3D network via an unusual pair of N—H⋯N hydrogen bonds to one of the μ2-cyanide groups. Thermogravimetric analysis indicates an initial loss of the base cation and one cyanide as HCN at temperatures in the range 130–250 °C to form CuCN. We show how loss of a specific cyanide group from the 3D CuCN structure could form the linear CuCN structure. Further heating leaves a residue of elemental copper, isolated as the oxide.

The backdrop of the stage with the Oscar Award is seen onstage during the 84th Academy Awards announcement held at the Academy of Motion Picture Arts and Sciences Samuel Goldwyn Theater on Jan. 24, 2012 in Los Angeles.; Credit: Kevin Winter/Getty Images

The Academy Awards have made history with breakthroughs for minorities in the past — but with this year's nominations, observers are noting how white the Oscars are, with no actors of color nominated in any of this year's acting categories.

It marks the least diverse nominations since 1998. People have been speaking out about this disconnect, with films like "Selma" being shut out of the acting nominations (though it did pick up a Best Picture nomination).

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

File: (L-R) "The Sarah Silverman Program" writer Harris Wittels, comedian Sarah Silverman, executive producer/head writer Dan Sterling and actress Laura Silverman, arrive at Comedy Central's Emmy Awards party at the STK restaurant Sept. 21, 2008 in Los Angeles.; Credit: Ethan Miller/Getty Images

Harris Wittels, a comedy writer who worked on "Parks & Recreation," has died at 30, the Los Angeles Police Department's Jane Kim tells KPCC.

Wittels was discovered by his assistant around 12 p.m., Kim said, and was already dead. Kim said that Wittels' death was a possible overdose, but that the Coroner's Office would determine the cause of death. Wittels had attended drug rehab twice.

Comedy Central, where Wittels worked on "The Sarah Silverman Program" and "Secret Girlfriend," confirmed Wittels' death, as did the comedy show he appeared at Wednesday night.

Comedy Central tweet

Meltdown Show tweet

Wittels was also well known for his @Humblebrag Twitter account and later book, helping to popularize the idea online of the false modesty of bragging while trying not to look like you're bragging.

Wittels had spoken about his struggles with addiction in places including Pete Holmes's podcast "You Made It Weird" in a November episode.

"I just really stopped caring about my life," Wittels said on "You Made It Weird," explaining how he got into doing drugs. "I just really started to think, well, if I'm only here for 80 years, then who cares if I spend it high or not?"

Wittels received his first big break when Sarah Silverman saw him performing comedy and gave him a job writing for her Comedy Central show.

Wittels also wrote for HBO's "Eastbound & Down," several MTV awards shows and the American Music Awards. He had a recurring role on "Parks & Recreation" and was a regular guest on the "Comedy Bang Bang" podcast.

Comedians, actors and fans mourned Wittels' death online.

Harris Wittels Storify

See Wittels in a scene from "Parks & Recreation":

Wittels on Parks & Recreation

Listen to Wittels on "Comedy Bang Bang":

Wittels on Comedy Bang Bang

This story has been updated.

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

A method is adapted to generate a full rank realization of an abstract regular polyhedron with automorphism group H3.

The analytical solution of the problem of X-ray spherical-wave Laue diffraction in a single crystal with a linear change of thickness on the exit surface is derived. General equations are applied to a specific case of plane-wave Laue diffraction in a thick crystal under the conditions of the Borrmann effect.

Combining sodium hydride with some solvents can be a bad idea, as a group of researchers from Corteva Agriscience and Dow Chemical remind the chemistry community in Organic Process Research & Development ,(2019, DOI: 10.1021/acs.oprd.9b00276). Reports of explosions from combining NaH with a polar aprotic solvent such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide […]

The post Don’t mix sodium hydride with polar aprotic solvents appeared first on CENtral Science.

(The Paypers) Menlo Security, a global enterprise cloud security provider, has entered the Australian...

In this file photo, students warm up in a mariachi class at Hamilton High School.; Credit: Susanica Tam for KPCC

Los Angeles Unified's arts education leaders took steps to renew long-dormant community partnerships with arts organizations Wednesday, part of an effort to revitalize arts education in the nation’s second largest school district. 

At the Los Angeles Cathedral in downtown L.A., the district's new arts ed director, Rory Pullens, held his first meeting with community arts organizations. More than 100 people representing several dozen groups attended the event.

Pullens outlined the district's arts plans and how community partners can help boost the arts for students.

“Guess what," Pullens said, getting a round of applause with cheers of support from some of the attendees. "We're back." 

RELATED: LAUSD decision ushers in new source of funding for arts education

Pullens lauded the district's recent announcement clearing the way for arts funding for low-income students, and pointed to new allocations this year that helped some of the district's schools purchase items like art supplies.

He also said the district is working on a school survey to create an arts equity index that will change the way the district allocates arts funds. The index would measure how well schools are providing arts instruction and arts access to students. Originally planned for release last year, the index is now expected next month.

But Pullens also painted a grim picture of the district’s current arts offerings. He said about a third of the district's middle schools currently offer little or no exposure to the arts. Some of the district’s students can go through both elementary and middle school without taking a single arts class, he said. Because of gaps in arts instruction, students who start learning an instrument in elementary school, for example, might not have classes to continue music study in their middle or high schools.

Pullens further talked about widespread budget problems, but took district leaders to task for failing to restore arts funding to the budget as the recession eased.

He said the arts education branch is still facing a deficit. Superintendent Ramon Cortines told reporters recently that the district as a whole is looking at a $160 million shortfall heading into the 2015-2016 school  year.

Despite the mixed funding news, for many in attendance, the meeting marked a positive shift in the district's arts strategy. Some groups currently serve as partners with the district, but the gathering was the first major effort in several years to reach out to organizations with the aim of restoring arts in the schools.

Jay McAdams, the executive director of 24th Street Theatre, said he remembered a few years back when the district emailed a cease-and-desist letter calling for an end to all arts partnership programs. He saw Wednesday's meeting as a major turnaround. 

"This is just a real breath of fresh air. There’s hope, there’s hope for first time in a long time for arts," he said. 

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

Los Angeles Unified school board candidates, from left, Andrew Thomas, Ref Rodriguez and Bennett Kayser take a group photo after a debate at Eagle Rock High School on Feb. 5, 2015. ; Credit: Cheryl A. Guerrero for KPCC

Los Angeles Unified school board candidate Ref Rodriguez collected $21,000 in campaign donations from employees of his charter school network, Partnerships to Uplift Communities, in his bid to unseat incumbent Bennett Kayser in East Los Angeles’ District 5.

Most striking, a handful of his workers – a janitor, maintenance worker, tutor — are donating at or near the contribution limit, $1,100.

The contributions are a measure of supporters' high hopes to unseat Kayser in favor of Rodriguez, a candidate friendly to charter schools.

Rodriguez, an charter school administrator at Partnerships to Uplift Communities, received most of his financial support from the California Charter School Association Advocates, which received donations from such wealthy donors as former New York Mayor Michael Bloomberg and philanthropist Eli Broad.

Kayser, a former teacher elected as a board member in 2011, collected his largest donations from labor unions, particularly the United Teachers Los Angeles. 

Most of the money working toward Kayser and Rodriguez's reelection are not funneled into their individual campaigns, but to independent expenditure committees which are not subject to the $1,100 contribution limit.

In her first foray into political giving, Luz Maria Lopez, an office worker, donated $1,000 donation to the Rodriguez campaign, twice the amount of Partnerships to Uplift Communities' CEO, Jacqueline Elliot.

“I really believe in Ref. My kids go to PUC schools,” said Lopez, who has been employed by PUC since it opened 15 years ago.  

The employee contributions weren't coerced and will not be reimbursed, Rodriguez said. Many of them can be traced back to a holiday break fundraiser at Rodriguez’s sister’s home in La Puente.

“I know for many of them this is a tremendous sacrifice,” he said. “It’s just been sort of an outpouring of folks belief in me and what we are trying to do for the city.”

Charter school groups major funders

Direct campaign donations from individual contributors, such as Rodriguez’ employees, make up 18 percent of the money spent in the LAUSD’s District 5 school board race. 

The biggest donor is charter school advocacy groups, such as the California Charter School Association Advocates.

Donations have also come from self-described education reform groups that support charter school expansion and firing teachers deemed ineffective, among other issues.

All told, the advocacy groups contributed more than $700,000 to activities in support of Rodriguez and working against Kayser.

On the other side, UTLA funneled $330,000 of members’ contributions to activities supporting Kayser and working against Rodriguez.

While UTLA has turned up its political spending in the board race to stay competitive, it is routinely outspent, said Oraiu Amoni, the union’s political director.

“We never are going to be able to match [reformers] dollar for dollar,” Amoni said. “So our biggest thing is making sure our members are educated, are engaged, are aware — and vote.”

So far, campaigns and committees have spent more than $2 million on the 13 Los Angeles Unified school board candidates, according to filings with the L.A. City Ethics Commission. The contributions have paid for mailing of glossy ads, phone banks, billboards, robocalls and commercials on Spanish-language radio. 

Total contributions are expected to increase in the few days remaining before the primary and swell again in any May runoff. 

Even in major races, aggressive campaigns fueled by growing contributions from special interest groups make it difficult for candidates not affiliated with interest groups to stay competitive.

Limitless independent expenditures are "playing a major role in smaller and local elections,” said Ryan Brinkerhoff, campaign manager for Andrew Thomas, the unaffiliated candidate in the District 5 race.

Thomas, a professor at Walden University, donated $51,000 to his campaign, making him his own biggest contributor. He’s also attracted sizable local support: about 70 percent of his campaign donations come from residents who live in District 5.

Thomas has received no contributions from political action committees or advocacy groups.

Can he win?

“I think so, but it’s getting harder and harder,” Brinkerhoff said. “The results of this election are going to be very telling.”

Outside contributors, local concerns

When public schools were created in the United States, local communities were given control over their governance. Outside money “undermines the relationship between community members and their local public institutions,” according to John Rogers, an education professor at UCLA. 

“It undermines their sense that they own those institutions, and those institutions are theirs to be shaped,” he said.

Without the funds from Broad, Bloomberg and other large donors, Rodriguez’s employees’ contributions would have made up more than 30 percent of his campaign support. Instead, it’s 4 percent.

Kayser has also received support from outside the district, including donations from the American Federation of Teachers and the California Teachers Association.

"The voters have an interest in open and transparent elections in which outside dollars don't have too large an influence," Rogers said. 

To read more about the school board election and City Council races, visit the KPCC 2015 voter guide.

Clarification: This article has been updated to make clear that the California Charter Schools Association does not support or advocate for teacher firing policies. Support for incumbent Kayser from outside the district has also been noted.

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

Björn Eismann
Apr 15, 2020; 0:jcs.245043v1-jcs.245043
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Bridges make travel faster and more convenient, but, in an earthquake, these structures are subject to forces that can cause extensive damage and make them unsafe. Now civil and environmental engineer Petros Sideris of Texas A&M University is leading a National Science Foundation (NSF)-funded research project to investigate the performance of hybrid sliding-rocking (HSR) columns. HSR columns provide the same support as conventional bridge infrastructure columns but are more earthquake-resistant. HSR columns are a series of individual concrete segments held together by steel cables that allow for controlled sliding and rocking. This allows the columns to shift without damage, while post-tensioning strands ensure that at the end of an earthquake the columns are pushed back to their original position. Conventional bridges are cast-in-place monolithic concrete elements that are strong but inflexible. Structural damage in these bridge columns, typically caused by a natural disaster, often forces a bridge to close until repairs are completed. But bridges with HSR columns can withstand large earthquakes with minimal damage and require minor repairs, likely without bridge closures. Such infrastructure helps with post-disaster response and recovery and can save thousands in taxpayer dollars. In an earthquake, HSR columns provide "multiple advantages to the public," Sideris said. "By preventing bridge damage, we can maintain access to affected areas immediately after an event for response teams to be easily deployed, and help affected communities recover faster. In mitigating losses related to post-event bridge repairs and bridge closures, more funds can be potentially directed to supporting the recovery of the affected communities." According to Joy Pauschke, NSF program director for natural hazards engineering, "NSF invests in fundamental engineering research so that, in the future, the nation's infrastructure can be more resilient to earthquakes, hurricanes, and other forces of nature."

Image credit: Texas A&M University