GENESIS: Gamma Energy Neutron Energy Spectrometer for Inelastic Scattering

Improved neutron inelastic scattering cross section data are needed to inform integral benchmark studies and advance applications in a wide variety of areas including nuclear energy, stockpile stewardship, nonproliferation, and space exploration. Neutron inelastic scattering also serves as a non-selective probe of low-lying nuclear structure. To help meet these needs, the Gamma Energy Neutron Energy Spectrometer for Inelastic Scattering (GENESIS) was constructed at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. This array couples high-resolution γ-ray detectors and fast neutron detectors to achieve single and coincident n/γ detection over a broad energy range. The current configuration of the array includes 26 organic liquid scintillators and four high-purity germanium detectors (two single-crystal and two four-crystal CLOVER detectors with two-fold segmentation). The array was constructed with minimal supporting material and designed to cover a wide range of secondary particle angles and energies with limited inter-element scattering. Data acquisition is accomplished using Mesytec MDPP-16 multi-channel high-resolution digital pulse processing modules. The array characteristics, including γ-ray and neutron energy resolution, timing resolution, and detection efficiency were measured and used to validate a GEANT4 model of the array. The primary sources of neutron background and the uncertainties in the determination of incident and secondary neutron energy were assessed. GENESIS provides a new capability to address nuclear data needs and facilitates the advancement of a wide range of nuclear applications

A path to practical Solar Pumped Lasers via Radiative Energy Transfer

The optical conversion of incoherent solar radiation into a bright, coherent laser beam enables the application of nonlinear optics to solar energy conversion and storage. Here, we present an architecture for solar pumped lasers that uses a luminescent solar concentrator to decouple the conventional trade-off between solar absorption efficiency and the mode volume of the optical gain material. We report a 750-μm-thick Nd[superscript 3+]-doped YAG planar waveguide sensitized by a luminescent CdSe/CdZnS (core/shell) colloidal nanocrystal, yielding a peak cascade energy transfer of 14%, a broad spectral response in the visible portion of the solar spectrum, and an equivalent quasi-CW solar lasing threshold of 23 W-cm[superscript −2], or approximately 230 suns. The efficient coupling of incoherent, spectrally broad sunlight in small gain volumes should allow the generation of coherent laser light from intensities of less than 100 suns.United States. Dept. of DefenseUnited States. Air Force Office of Scientific ResearchUnited States. Dept. of Energy. Office of Basic Energy Sciences (DE-SC0001088)MIT Masdar Program (02/MI/MI/CP/11/07633/GEN/G/00)American Society for Engineering Education. National Defense Science and Engineering Graduate Fellowship (32 CFR 168a, FA9550-11-C-0028)Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (W911NF-13-D-0001

The generation of kidney organoids by differentiation of human pluripotent cells to ureteric bud progenitor-like cells

International audienceThis protocol presents recently developed methodologies for the differentiation of human pluripotent stem cells (hPSCs) into ureteric bud (UB) progenitor-like cells. Differentiation of human PSCs to UB progenitor-like cells allows for the generation of chimeric kidney cultures in which the human cells can self-assemble into chimeric 3D structures in combination with embryonic mouse kidney cells over a period of 18 d. UB progenitor-like cells are generated by a two-step process that combines in vitro commitment of human PSCs, whether embryonic stem cells (ESCs) or induced PSCs (iPSCs), under chemically defined culture conditions, with ex vivo cultures for the induction of 3D organogenesis. The models described here provide new opportunities for investigating human kidney development, modeling disease, evaluating regenerative medicine strategies, as well as for toxicology studies

Altered DNA methylation associated with an abnormal liver phenotype in a cattle model with a high incidence of perinatal pathologies

Cloning enables the generation of both clinically normal and pathological individuals from the same donor cells, and may therefore be a DNA sequence-independent driver of phenotypic variability. We took advantage of cattle clones with identical genotypes but different developmental abilities to investigate the role of epigenetic factors in perinatal mortality, a complex trait with increasing prevalence in dairy cattle. We studied livers from pathological clones dying during the perinatal period, clinically normal adult clones with the same genotypes as perinatal clones and conventional age-matched controls. The livers from deceased perinatal clones displayed histological lesions, modifications to quantitative histomorphometric and metabolic parameters such as glycogen storage and fatty acid composition, and an absence of birth-induced maturation. In a genome-wide epigenetic analysis, we identified DNA methylation patterns underlying these phenotypic alterations and targeting genes relevant to liver metabolism, including the type 2 diabetes gene TCF7L2. The adult clones were devoid of major phenotypic and epigenetic abnormalities in the liver, ruling out the effects of genotype on the phenotype observed. These results thus provide the first demonstration of a genome-wide association between DNA methylation and perinatal mortality in cattle, and highlight epigenetics as a driving force for phenotypic variability in farmed animals