A digital data acquisition system (DDAS) has been implemented for the Low Energy Neutron Detector Array (LENDA). LENDA is an array of 24 BC-408 plastic-scintillator bars designed to measure ...low-energy neutrons with kinetic energies in the range of 100keV–10MeV from (p,n)-type charge-exchange reactions. Compared to the previous data acquisition (DAQ) system for LENDA, DDAS offers the possibility to lower the neutron detection threshold, increase the overall neutron-detection efficiency, decrease the dead time of the system, and allow for easy expansion of the array. The system utilized in this work was XIA׳s Digital Gamma Finder Pixie-16 250MHz digitizers. A detector-limited timing resolution of 400ps was achieved for a single LENDA bar. Using DDAS, the neutron detection threshold of the system was reduced compared to the previous analog system, now reaching below 100keV. The new DAQ system was successfully used in a recent charge-exchange experiment using the 16C(p,n) reaction at the National Superconducting Cyclotron Laboratory (NSCL).
To evaluate whether medical students who have expressed a strong desire to pursue ophthalmology as a career perform simulated ophthalmic surgical tasks to a higher level than medical students whose ...interests lie elsewhere.
All participants were fourth or fifth year students at University College London (UCL) Medical School, London, UK. One cohort was recruited from the Moorfields Academy, an ophthalmic forum designed to enhance collaboration and innovation within the specialty. These students were therefore seen as highly motivated, expressing a desire to pursue a career in ophthalmology. The other cohort of students was invited to participate during their fourth year UCL Ophthalmology attachment, but expressed interest in non-ophthalmic disciplines. Participants carried out a single attempt of three modules on the Eyesi Surgical Simulator, and total and mean scores were calculated out of 100.
13 academy and 15 non-academy students were enrolled. The overall mean scores were 51/100 for the academy group, range 0-97, and 45.5/100 for the non-academy group, range 0-90 (p=0.49). Scores for precision testing, forceps training and capsulorrhexis training for academy versus non-academy were 45.8 versus 37.8 (p=0.61), 57.1 versus 52.3 (p=0.8) and 50.2 versus 46.4 (p=0.55), respectively.
This study is the first to suggest that medical students with a strong career interest in ophthalmology do not perform microsurgical tasks to a higher level than medical students who have no goal in this area. This also indicates variation in scores between novices, which may serve as a pitfall in the use of simulators as a tool for entry into training.
This Letter reports results from a haloscope search for dark matter axions with masses between 18 2.66 and 2.81 eV. The search excludes the range of axion-photon couplings predicted by plausible 19 ...models of the invisible axion. This unprecedented sensitivity is achieved by operating a large-volume 20 haloscope at sub-Kelvin temperatures, thereby reducing thermal noise as well as the excess noise 21 from the ultra-low-noise SQUID amplier used for the signal power readout. Ongoing searches will 22 provide nearly denitive tests of the invisible axion model over a wide range of axion masses.
We discuss the analysis of the experimental values of the nuclear spin-lattice and spin-spin relaxation times for the tunneling of \( reversible reaction \)He as isotopic impurities in solid \( pound ...sterling \)He. These two relaxation times cannot be described quantitatively using a unique correlation time although it is often presented as such in the literature. In this paper, we discuss how to distinguish the high-frequency portion of the spectral densities that determine the spin-lattice relaxation rates from the low-frequency components which determine the spin-spin relaxation rates.
The investigation presented in this paper illustrates a technique for growing in-situ polymerized networks, forming scaffold-like structures usually formed by means of electrospinning. The technique ...of jet atomization employing electrohydrodynamics is a manifestation of electrospinning. However, we show for the first time that using this technique where individual droplets are generated, a continuous self-supporting submicrometer web-like structure can be grown whereby fragments of the structure are delivered in the droplets and polymerize on the surface of the growing structure via polycondensation. The development of these growing fibers into web structures is a direct result of the processing route together with the excellent tailor-made cross-linking nature of the resin. An operational map is generated to identify a parametric space in which the stable cone-jet mode of electrohydrodynamic atomization prevails for generating the finest droplets. A statistical analysis on the formed fibers for a given time and electrospray condition is presented together with optical micrographs of the structure, which concludes the discussion in this paper.
New antibiotics are urgently needed to counter the emergence of antimicrobial-resistant pathogenic bacteria. A major challenge in antibiotic drug discovery is to turn potent biochemical inhibitors of ...essential bacterial components into effective antimicrobials. This difficulty is underpinned by a lack of methods to investigate the physicochemical properties needed for candidate antibiotics to permeate the bacterial cell envelope and avoid clearance by the action of bacterial efflux pumps. To address these issues, here we used a target engagement assay to measure the equilibrium and kinetic binding parameters of antibiotics targeting dihydrofolate reductase (DHFR) in live bacteria. We also used this assay to identify novel DHFR ligands having antimicrobial activity. We validated this approach using the Gram-negative bacteria Escherichia coli and the emerging human pathogen Mycobacterium abscessus. We expect the use of target engagement assays in bacteria to expedite the discovery and progression of novel, cell-permeable antibiotics with on-target activity.
Positional cloning of hereditary deafness genes is a direct approach to identify molecules and mechanisms underlying auditory function. Here we report a locus for dominant deafness, DFNA36, which ...maps to human chromosome 9q13-21 in a region overlapping the DFNB7/B11 locus for recessive deafness. We identified eight mutations in a new gene, transmembrane cochlear-expressed gene 1 (TMC1), in a DFNA36 family and eleven DFNB7/B11 families. We detected a 1.6-kb genomic deletion encompassing exon 14 of Tmc1 in the recessive deafness (dn) mouse mutant, which lacks auditory responses and has hair-cell degeneration. TMC1 and TMC2 on chromosome 20p13 are members of a gene family predicted to encode transmembrane proteins. Tmc1 mRNA is expressed in hair cells of the postnatal mouse cochlea and vestibular end organs and is required for normal function of cochlear hair cells.
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