265 research outputs found
Sailing New Seas
This Newport paper presents the ideas of one of the Navy\u27s most senior leaders. Admiral Reason\u27s topic is the course the United States Navy should steer in the typhoon of change characterizing today\u27s and tomorrow\u27s world. Admiral Reason proposes a new way to think about the fleet as a whole, one that discards the industrial age model in favor of the flight deck paradigm of a high-performance organization operating at the edge of chaos.https://digital-commons.usnwc.edu/usnwc-newport-papers/1013/thumbnail.jp
Identifying perinatal risk factors for infant maltreatment: an ecological approach
BACKGROUND: Child maltreatment and its consequences are a persistent problem throughout the world. Public health workers, human services officials, and others are interested in new and efficient ways to determine which geographic areas to target for intervention programs and resources. To improve assessment efforts, selected perinatal factors were examined, both individually and in various combinations, to determine if they are associated with increased risk of infant maltreatment. State of Georgia birth records and abuse and neglect data were analyzed using an area-based, ecological approach with the census tract as a surrogate for the community. Cartographic visualization suggested some correlation exists between risk factors and child maltreatment, so bivariate and multivariate regression were performed. The presence of spatial autocorrelation precluded the use of traditional ordinary least squares regression, therefore a spatial regression model coupled with maximum likelihood estimation was employed. RESULTS: Results indicate that all individual factors or their combinations are significantly associated with increased risk of infant maltreatment. The set of perinatal risk factors that best predicts infant maltreatment rates are: mother smoked during pregnancy, families with three or more siblings, maternal age less than 20 years, births to unmarried mothers, Medicaid beneficiaries, and inadequate prenatal care. CONCLUSION: This model enables public health to take a proactive stance, to reasonably predict areas where poor outcomes are likely to occur, and to therefore more efficiently allocate resources. U.S. states that routinely collect the variables the National Center for Health Statistics (NCHS) defines for birth certificates can easily identify areas that are at high risk for infant maltreatment. The authors recommend that agencies charged with reducing child maltreatment target communities that demonstrate the perinatal risks identified in this study
Nucleotide-binding flexibility in ultrahigh-resolution structures of the SRP GTPase Ffh
Crystal structures of the Ffh NG GTPase domain at < 1.24 Å resolution reveal multiple overlapping nucleotide binding modes
Confinement of Bose-Einstein magnon condensates in adjustable complex magnetization landscapes
Coherent wave states such as Bose-Einstein condensates (BECs), which
spontaneously form in an overpopulated magnon gas even at room temperature,
have considerable potential for wave-based computing and information processing
at microwave frequencies. The ability to control the transport properties of
magnon BECs plays an essential role for their practical use. Here, we
demonstrate spatio-temporal control of the BEC density distribution through the
excitation of magnon supercurrents in an inhomogeneously magnetized yttrium
iron garnet film. The BEC is created by microwave parametric pumping and probed
by Brillouin light scattering spectroscopy. The desired magnetization profile
is prepared by heating the film with optical patterns projected onto its
surface using a phase-based wavefront modulation technique. Specifically, we
observe a pronounced spatially localized magnon accumulation caused by magnon
supercurrents flowing toward each other originating in two heated regions. This
accumulation effect increases the BEC lifetime due to the constant influx of
condensed magnons into the confinement region. The shown approach to manipulate
coherent waves provides an opportunity to extend the lifetime of freely
evolving magnon BECs, create dynamic magnon textures, and study the interaction
of magnon condensates formed in different regions of the sample.Comment: 8 pages, 4 figure
Experimental observation of Aharonov-Bohm caging using orbital angular momentum modes in optical waveguides
The discovery of artificial gauge fields, controlling the dynamics of
uncharged particles that otherwise elude the influence of standard electric or
magnetic fields, has revolutionized the field of quantum simulation. Hence,
developing new techniques to induce those fields is essential to boost quantum
simulation in photonic structures. Here, we experimentally demonstrate in a
photonic lattice the generation of an artificial gauge field by modifying the
input state, overcoming the need to modify the geometry along the evolution or
imposing the presence of external fields. In particular, we show that an
effective magnetic flux naturally appears when light beams carrying orbital
angular momentum are injected into waveguide lattices with certain
configurations. To demonstrate the existence of that flux, we measure the
resulting Aharonov-Bohm caging effect. Therefore, we prove the possibility of
switching on and off artificial gauge fields by changing the topological charge
of the input state, paving the way to access different topological regimes in
one single structure, which represents an important step forward for optical
quantum simulation
Model for eukaryotic tail-anchored protein binding based on the structure of Get3
The Get3 ATPase directs the delivery of tail-anchored (TA) proteins to the endoplasmic reticulum (ER). TA-proteins are characterized by having a single transmembrane helix (TM) at their extreme C terminus and include many essential proteins, such as SNAREs, apoptosis factors, and protein translocation components. These proteins cannot follow the SRP-dependent co-translational pathway that typifies most integral membrane proteins; instead, post-translationally, these proteins are recognized and bound by Get3 then delivered to the ER in the ATP dependent Get pathway. To elucidate a molecular mechanism for TA protein binding by Get3 we have determined three crystal structures in apo and ADP forms from Saccharomyces cerevisae (ScGet3-apo) and Aspergillus fumigatus (AfGet3-apo and AfGet3-ADP). Using structural information, we generated mutants to confirm important interfaces and essential residues. These results point to a model of how Get3 couples ATP hydrolysis to the binding and release of TA-proteins
Directional wetting in anisotropic inverse opals
Porous materials display interesting transport phenomena due to the restricted motion of fluids within the nano- to micro-scale voids. Here, we investigate how liquid wetting in highly ordered inverse opals is affected by anisotropy in pore geometry. We compare samples with different degrees of pore asphericity and find different wetting patterns depending on the pore shape. Highly anisotropic structures are infiltrated more easily than their isotropic counterparts. Further, the wetting of anisotropic inverse opals is directional, with liquids filling from the side more easily. This effect is supported by percolation simulations as well as direct observations of wetting using time-resolved optical microscopy
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