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Craniosynostosis (CS) is a common congenital defect affecting more than 1/2000 infants. Infants with CS have a premature fusion of one or multiple cranial sutures resulting in restricted brain expansion. Single gene mutations account for 15-20% of cases, largely as part of a syndrome, but the majority are nonsyndromic with complex underlying genetics. Two noncoding genomic regions contributing to CS risk were previously identified by GWAS, one near BMP2 and one within BBS9. We hypothesized that the region within BBS9 contains distal regulatory elements controlling the neighboring gene encoding BMPER, a secreted modulator of BMP signaling. To identify regulatory sequences that might underlie disease risk, we surveyed conserved noncoding sequences from both risk loci identified from the GWAS for enhancer activity in transgenic Danio rerio. We identified enhancers from both regions that direct expression to skeletal tissues, consistent with the endogenous gene expression. Importantly, for each locus, we found a skeletal enhancer that also contains a sequence variant associated with CS risk. We examined the activity of each enhancer during craniofacial development and found that the BMPER-associated enhancer is active in the restricted region of cartilage closely associated with frontal bone initiation. We used an enhanced yeast one-hybrid assay to identify transcription factor interactions with several identified enhancers, implicating multiple signaling pathways in their regulation. In a targeted screen focused on risk-associated SNPs, we further identified differential binding to alternate and reference alleles. Additionally, we found that the risk allele of the BMPER enhancer directs significantly broader expression than the reference allele in transgenic zebrafish. Our findings support a specific genetic mechanism to explain the contribution of two risk loci to CS. More broadly, our combined in vivo approach is applicable to many complex genetic diseases to build a link between association studies and specific genetic mechanisms.Author SummaryGenome–wide association studies (GWASs) provide a wealth of information implicating regions of the genome in disease risk. The great challenge is linking those regions to specific genetic mechanisms. We used complementary approaches in zebrafish and yeast to evaluate the genetic risk of craniosynostosis (CS), a craniofacial birth defect affecting 1/2000 infants where two or more skull bones are fused prematurely. Using transgenic zebrafish, we identified sequences regulating expression of two genes in the BMP signaling pathway that had been previously implicated by GWAS. These included one from each region containing a sequence variant linked to disease risk. We used an assay in cultured yeast to detect proteins binding to identified DNA sequences that could alter expression of the target genes, including changes in protein binding caused by the sequence variants. Finally, we found that transgenic fish carrying one of the variant sequences showed broader and more sustained activity throughout the skeleton. Taken together, our results support a model where variant sequences lead to increased gene expression and BMP pathway activity, contributing to aberrant skull growth in CS. Importantly, our paradigm is broadly applicable to other complex genetic diseases, potentially illuminating many connections between genome variation and disease risk.

There is compelling evidence that stressing goals leads to stress and negatively affects the very objectives that educators are trying to achieve. Reaching testing goals matter, but if we're not careful, the goal of educating children for the 21st century becomes subsumed by the narrow measures meant to track progress. Performance measures become the goals. Stress overtakes inspiration. If it's true that what gets measured, gets done, then it's important that we measure the right things. Outputs like standardized test scores and graduation rates matter, but how we achieve outputs matters too. Process really is as important as product.

Ultrafast experiments using sub-picosecond pulses of light are poised to play an important role in the study and use of topological materials and, particularly, of the three-dimensional Dirac and Weyl semimetals. Many of these materials’ characteristic properties—their linear band dispersion, Berry curvature, near-vanishing density of states at the Fermi energy, and sensitivity to crystalline and time-reversal symmetries—are closely related to their sub- and few-picosecond response to light. Ultrafast measurements offer the opportunity to explore excitonic instabilities and transient photocurrents, the latter depending on the Berry curvature and possibly quantized by fundamental constants. Optical pulses may, through Floquet effects, controllably and reversibly move, split, merge, or gap the materials’ Dirac and Weyl nodes; coherent phonons launched by an ultrafast pulse offer alternate mechanisms for similar control of the nodal structure. This Perspective will briefly summarize the state of research on the ultrafast properties of Dirac and Weyl semimetals, emphasizing important open questions. It will describe the challenges confronting each of these experimental opportunities and suggest what research is needed for ultrafast pulses to achieve their potential of controlling and illuminating the physics of Dirac and Weyl semimetals.

Netzwerke spielen eine zentrale Rolle in der Transmission sozio-kultureller und fachspezifischer Normen in der Wissenschaft (vgl. Martensson 2014). Die Einfuhrung in die akademischen Netzwerke und das „Dazugehoren“ kann somit als ein zentraler Baustein einer erfolgreichen, wissenschaftlichen Karriere verstanden werden.

International audience; We investigate the diffusion of charge and spin at 15 K in p-type GaAs, combining transient-grating and energy-resolved microluminescence measurements to cover a broad range of photoelectron density. At very low optical power, in a unipolar nondegenerate regime, charge and spin diffuse at the same rate, implying that the spin-drag effects are negligible. Upon increasing the photoelectron concentration up to about 1016 cm–3, the charge diffusion constant decreases because of ambipolar electrostatic interactions with the slower-diffusing holes while the spin diffusion constant is reduced only weakly by the ambipolar interaction. A further increase in the excitation power causes increases in both the charge and spin diffusion constants as a consequence of the Pauli principle since the photoelectron gas becomes degenerate.

The authors developed a psychoeducational alcohol and drug program for Old Order Amish youth. Participants ranged in age from 16 to 20 years old. All were referred following arrest for a variety of predominantly alcohol-related offenses. The model was designed with input from the Old Order Amish community in response to concerns about existing programs that integrated Amish and non-Amish youth. Increased awareness of the effects of alcohol and drugs and the ability to resist social encouragement to use these substances were goals for the intervention. Preliminary results with 185 participants indicated that Amish youth increased factual knowledge about substances they considered culturally acceptable with moderate increases in comfort with choices. The article discusses the clinical and cultural implications of these findings.

Students in a junior high school serving a large Old Order Amish settlement completed a survey of attitudes, opinions, and intentions regarding substance use. A total of 1,031 students participated across a four-year span, approximately equally divided between Amish and non-Amish youths. Amish youths maintain attitudes that suggest perceived greater use of substances by their peers and greater concern about this use; however, they also express the intent to use alcohol and tobacco at a higher rate than non-Amish counterparts. The study addresses implications for interventions among Amish youths as they mature and enter an often culturally sanctioned period of alcohol use.

X-ray absorption spectroscopy (XAS) is a versatile technique for studying the electronic structure and/or the local geometry of matter, and time-resolved XAS has been developed into a powerful tool for studying the dynamics of materials [1, 2]. The temporal resolution of this technique is usually determined by the X-ray pulse duration in pump and probe geometries. Although this technique has been developed in the synchrotron environment and takes advantage of existing X-ray beamlines, the study of ultrafast dynamics on time scales on the order of a picosecond or faster is limited because typical pulse durations from third-generation light sources is on the order of tens of picoseconds. In addition, XAS typically requires the integration of a large number of X-ray pulses to get quality data. These features make it difficult to apply this technique to research areas in which samples undergo irreversible processes.

© 2018 Author(s). We report ultrafast optical measurements of the Dirac line-node semimetal ZrSiS and the Weyl semimetal NbAs, using mid-infrared pump photons from 86 meV to 500 meV to directly excite Dirac and Weyl fermions within the linearly dispersing bands. In NbAs, the photoexcited Weyl fermions initially form a non-thermal distribution, signified by a brief spike in the differential reflectivity whose sign is controlled by the relative energy of the pump and probe photons. In ZrSiS, electron-electron scattering rapidly thermalizes the electrons, and the spike is not observed. Subsequently, hot carriers in both materials cool within a few picoseconds. This cooling, as seen in the two materials' differential reflectivity, differs in sign, shape, and timescale. Nonetheless, we find that it may be described in a simple model of thermal electrons, without free parameters. The electronic cooling in ZrSiS is particularly fast, which may make the material useful for optoelectronic applications.

${\mathrm{SrMnSb}}_{2}$ is a candidate Dirac semimetal whose electrons near the $Y$ point have the linear dispersion and low mass of a Dirac cone. Here we demonstrate that ultrafast, 800-nm optical pulses can launch coherent phonon oscillations in ${\mathrm{Sr}}_{0.94}{\mathrm{Mn}}_{0.92}{\mathrm{Sb}}_{2}$, particularly an ${A}_{g}$ mode at 4.4 THz. Through first-principles calculations of the electronic and phononic structure of ${\mathrm{SrMnSb}}_{2}$, we show that high-amplitude oscillations of this mode would displace the atoms in a way that transiently opens and closes a gap at the node of the Dirac cone. The ability to control the nodal gap on a subpicosecond timescale could create opportunities for the design and manipulation of Dirac fermions.

Old Order Amish experience a theologically and culturally defined period of exploration in mid-adolescence that may include experimentation with alcohol and drugs. The trajectory into this period of identity exploration and its purpose are vastly different from those of non-Amish peers. As a result, interventions to address a behavior which appears superficially similar (substance abuse) must be tailored to their specific needs. This article describes a psychoeducational program designed to meet the unique challenges of a culturally respectful interface with this “peculiar people.” In particular, it describes a model that creates an interface between Amish and non-Amish culture, respects their spiritual beliefs, and maximizes learning and motivation to change behaviors.

According to Noethers theorem, for every symmetry in nature there is a corresponding conservation law. For example, invariance with respect to spatial translation corresponds to conservation of momentum. In another well-known example, invariance with respect to rotation of the electrons spin, or SU(2) symmetry, leads to conservation of spin polarization. For electrons in a solid, this symmetry is ordinarily broken by spin-orbit coupling, allowing spin angular momentum to flow to orbital angular momentum. However, it has recently been predicted that SU(2) can be achieved in a two-dimensional electron gas, despite the presence of spin-orbit coupling. The corresponding conserved quantities include the amplitude and phase of a helical spin density wave termed the persistent spin helix. SU(2) is realized, in principle, when the strength of two dominant spin-orbit interactions, the Rashba (strength parameterized by \alpha) and linear Dresselhaus (\beta_1), are equal. This symmetry is predicted to be robust against all forms of spin-independent scattering, including electron-electron interactions, but is broken by the cubic Dresselhaus term (\beta_3) and spin-dependent scattering. When these terms are negligible, the distance over which spin information can propagate is predicted to diverge as \alpha approaches \beta_1. Here we observe experimentally the emergence of the persistent spin helix in GaAs quantum wells by independently tuning \alpha and \beta_1. Using transient spin-grating spectroscopy, we find a spin-lifetime enhancement of two orders of magnitude near the symmetry point........., Comment: Will be published in Nature on April 2, 2009

We investigate nonlinear optical responses of black phosphorus in ambient conditions protected by exfoliating thin hexagonal-boron nitride on top. We observe sub-picosecond and polarization sensitive responses for few-layer black phosphorous.

We report ultrafast transient-grating measurements of crystals of the three-dimensional Dirac semimetal cadmium arsenide, Cd3As2, at both room temperature and 80 K. After photoexcitation with 1.5-eV photons, charge-carriers relax by two processes, one of duration 500 fs and the other of duration 3.1 ps. By measuring the complex phase of the change in reflectance, we determine that the faster signal corresponds to a decrease in absorption, and the slower signal to a decrease in the light's phase velocity, at the probe energy. We attribute these signals to electrons' filling of phase space, first near the photon energy and later at lower energy. We attribute their decay to cooling by rapid emission of optical phonons, then slower emission of acoustic phonons. We also present evidence that both the electrons and the lattice are strongly heated., 8 pages, 7 figures. Differs from the previous version in incorporating changes made during the review process and new appendices. Differs from the published version in including section headings and in omitting AIP copy-edits. No substantial differences in scientific conclusions from either version

The effects of people-first language usage and demographic variables on beliefs, attitudes and behavioral intentions toward people with disabilities were investigated. Participants included 351 undergraduate minors, masters, and doctoral level students in counseling psychology at a state university located in the Midwest. Study participants provided demographic information, produced a writing sample concerning a hypothetical client who has a disability, and completed the Attitudes Toward Disabled Persons Scale (ATOP) and the Beliefs and Behavioral Intentions Scale (BABI). The BABI examined beliefs and behavioral intentions across three dimensions; sexuality, quality of life potential, and professional personal social distance. Analysis of the writing samples indicated that only a minority of participants used people-first language consistently. A series of ANOVAs were conducted comparing people-first language usage and scores on both the ATOP and BABI scales. Although the results were mixed, language usage appears to affect the attitude and behavioral intentions towards persons with disabilities.

Recent years have seen the rapid discovery of solids whose low-energy electrons have a massless, linear dispersion, such as Weyl, line-node, and Dirac semimetals. The remarkable optical properties predicted in these materials show their versatile potential for optoelectronic uses. However, little is known of their response in the picoseconds after absorbing a photon. Here, we measure the ultrafast dynamics of four materials that share non-trivial band structure topology but that differ chemically, structurally, and in their low-energy band structures: ZrSiS, which hosts a Dirac line node and Dirac points; TaAs and NbP, which are Weyl semimetals; and Sr1–yMn1–zSb2, in which Dirac fermions coexist with broken time-reversal symmetry. After photoexcitation by a short pulse, all four relax in two stages, first sub-picosecond and then few-picosecond. Their rapid relaxation suggests that these and related materials may be suited for optical switches and fast infrared detectors. The complex change of refractive index shows that photoexcited carrier populations persist for a few picoseconds.

We demonstrate an intrinsically fast Seebeck-type metal–semimetal–metal infrared photodetector based on Cd3As2 crystals. The Seebeck voltage is induced under off-center illumination, leading to asymmetric temperature gradients and a net current flow. The room-temperature responsivity of the sensor is 0.27 mA/W. The photocurrent signal is readily registered at a modulation frequency of 6 kHz, and the intrinsic bandwidth of the sensor is predicted to approach the terahertz range. The photocurrent depends on the optical power and modulation frequency. Our study demonstrates that crystalline Cd3As2 is a promising material for high-bandwidth and spectrally broad photosensing, imaging, and communication.

We combine the results of terahertz time-domain spectroscopy with far-infrared transmission and reflectivity to obtain the conductivity of SrRuO{sub 3} over an unprecedented continuous range in frequency, allowing us to characterize the approach to zero frequency as a function of temperature. We show that the conductivity follows a simple phenomenological form, with an analytic structure fundamentally different from that predicted by the standard theory of metals.

We report on the testing of optical diagnostics developed for warm-dense-matter (WDM) experiments on the neutralized drift compression experiments (NDCX-1) at Lawrence Berkeley National Laboratory (LBNL). The diagnostics consists of a fast optical pyrometer, a streak camera spectrometer, and a Doppler-shift laser interferometer (VISAR). While the NDCX is in the last stage of commissioning for the target experiments, the diagnostics were tested elsewhere in an experiment where an intense laser pulse was used to generate the WDM state in metallic and carbon samples.

We report ultrafast transient-grating experiments on heavily p-type InP at 15 K. Our measurement reveals the dynamics and diffusion of photoexcited electrons and holes as a function of their density n in the range 2 × 1016 to 6 × 1017 cm−3. After the first few picoseconds, the grating decays primarily due to ambipolar diffusion. While, at low density, we observe a regime in which the ambipolar diffusion is electron-dominated and increases rapidly with n, it appears to saturate at 34 cm2/s at high n. We present a simple calculation that reproduces the main results of our measurements as well as of previously published measurements that had shown diffusion to be a flat or decreasing function of n. By accounting for effect of density on charge susceptibility, we show that, in p-type semiconductors, the regime we observe of increasing ambipolar diffusion is unique to heavy doping and low temperature, where both the holes and electrons are degenerate; in this regime, the electronic and ambipolar diffusion are nearly equal. The saturation is identified as a crossover to ambipolar diffusion dominated by the majority carriers, the holes. At short times, the transient-grating signal rises gradually. This rise reveals cooling of hot electrons and, at high photocarrier density, allows us to measure ambipolar diffusion of 110 cm2/s in the hot-carrier regime.

Integrated hohlraum/capsule post-shot simulation of the first full-scale cryogenic layered-DT experiment with top/bottom laser asymmetries of 8% is discussed. The imposed P1 Legendre mode drive on the capsule results in downward velocity of 85 ± 15 km/s as measured by neutron time of flight (NTOF) diagnostics and x-ray imagers, which is in excellent agreement with the calculated velocity of 87 km/s. The measured DT yield is approximately 30% less than the average of two comparable shots using the same 4 shock HiFoot pulse shape without drive asymmetry. The calculated DT yield of 5.0e15 is very close to the measured value of 4.86e15 for the shot with drive asymmetry, which implies that P1 effects dominate yield reduction. The neutron activation diagnostics (NADs) give clear indication of higher areal density in the direction of the north pole in excellent agreement with calculations. Integrated post-shot simulation of an earlier symcap (capsule with appropriate ablator thicknesses to act as a surrogate for an ignition capsule) experiment with laser asymmetries show that calculated neutron-wighted velocity is a strong function of capsule shape.

We use time-resolved x-ray absorption spectroscopy to investigate the unoccupied electronic density of states of warm dense copper that is produced isochorically through the absorption of an ultrafast optical pulse. The temperature of the superheated electron-hole plasma, which ranges from 4000 to 10 000 K, was determined by comparing the measured x-ray absorption spectrum with a simulation. The electronic structure of warm dense copper is adequately described with the high temperature electronic density of state calculated by the density functional theory. The dynamics of the electron temperature is consistent with a two-temperature model, while a temperature-dependent electron-phonon coupling parameter is necessary.

Evolution of superheated electron hole plasma in the warm dense copper is investigated using time resolved x-ray absorption technique. Experimental data indicate a strong electron-phonon non-equilibrium state and it is described with two-temperature model.

First-responders have a critical need to rapidly identify toxic chemicals during emergencies. However, current systems such as WISER require a large number of inputs before a chemical can be identified. Here we present a novel system which significantly reduces the number of inputs required to identify a toxic chemical.

We describe measurements of spin dynamics in the two-dimensional electron gas in GaAs/GaAlAs quantum wells. Optical techniques, including transient spin-grating spectroscopy, are used to probe the relaxation rates of spin polarization waves in the wavevector range from zero to $6\times 10^4$ cm$^{-1}$. We find that the spin polarization lifetime is maximal at nonzero wavevector, in contrast with expectation based on ordinary spin diffusion, but in quantitative agreement with recent theories that treat diffusion in the presence of spin-orbit coupling., 5 pages, 3 figures

Two separate data collections using Arete Associates' FLASH lidar are presented. The hardware and the experimental arrangements are discussed. An airborne data collection over military targets in clear and obscuring camouflage environments provided high-resolution three-dimensional images for combat identification purposes. In the second field test, the sensor was suspended from a crane above the ocean surface to acquire FLASH imagery of anti-landing mines and obstacles in the highly turbid surf zone environment over a wide range of surf zone conditions.

Lockheed Martin Aeronautics (LM Aero) Company has developed an advanced capability to streamline development of composite aircraft structures with reduced complexity. This process leverages the capabilities of commercially available software, FiberSIM™, MSC.Patran™, and MSC.Nastran™, integrated with LM Aero applications and customizations. This development includes creation of a finite-element-based COmposite Zone MOdeler (COZMO) that enables rapid definition of laminate designs from a sized finite element model (FEM) through use of zone modeling. This application provides seamless data exchange between the MSC.Patran database and the FiberSIM for CATIA®V4 model by using a composites data exchange file written in extensible markup language, or XML. This paper describes the features of COZMO, its use of XML as a composite data exchange medium, and demonstrates its ability to simplify laminate complexity.

We report ultrafast transient-grating measurements, above and below the Curie temperature, of the dilute ferromagnetic semiconductor (Ga,Mn)As containing 6% Mn. At 80 K (15 K), we observe that photoexcited electrons in the conduction band have a lifetime of 8 ps (5 ps) and diffuse at about 70 cm2/s (60 cm2/s). Such rapid diffusion requires either an electronic mobility exceeding 7,700 cm2/Vs or a conduction-band effective mass less than half the GaAs value. Our data suggest that neither the scattering rate nor the effective mass of the (Ga,Mn)As conduction band differs significantly from that of GaAs., Comment: 5 pages, 3 figures. Differs from the previous version in incorporating additional data and changes made during the review process. Differs from the published version in including section headings and in omitting AIP copy-edits. No substantial differences in scientific conclusions from either version

We use optical transient-grating spectroscopy to measure spin diffusion of optically oriented electrons in bulk, semi-insulating GaAs(100). Trapping and recombination do not quickly deplete the photoexcited population. The spin diffusion coefficient of 88 +/- 12 cm2/s is roughly constant at temperatures from 15 K to 150 K, and the spin diffusion length is at least 450 nm. We show that it is possible to use spin diffusion to estimate the electron diffusion coefficient. Due to electron-electron interactions, the electron diffusion is 1.4 times larger than the spin diffusion.

An ultrafast x-ray streak camera has been realized using a grazing incidence reflection photocathode. X-rays are incident on a gold photocathode at a grazing angle of 20 degree and photoemitted electrons are focused by a large aperture magnetic solenoid lens. The streak camera has high quantum efficiency, 600fs temporal resolution, and 6mm imaging length in the spectral direction. Its single shot capability eliminates temporal smearing due to sweep jitter, and allows recording of the ultrafast dynamics of samples that undergo non-reversible changes.

LOS ANGELES (AP) ” Tens of thousands of academic employees across the University of California™s 10 campuses walked off the job Monday, demanding better pay and benefits in what union leaders say could be the largest work stoppage the prestigious public university system has ever faced.The unions representing some 48,000 teaching assistants, researchers, postdoctoral scholars, tutors and graders say the vast majority of members turned out at picket lines starting at 8 a.m. They say they are seeking significant pay increases and child-care subsidies to afford the cost of living in cities such as Los Angeles, San Diego and Berkeley, where housing costs are soaring. [ABSTRACT FROM PUBLISHER]

LOS ANGELES (AP) ” The last man seen with Kristin Smart was convicted Tuesday of killing the college freshman, who vanished from a California campus 25 years ago.Jurors unanimously found Paul Flores guilty of first-degree murder, the San Luis Obispo Tribune reported. [ABSTRACT FROM PUBLISHER]