The affine preservers of non-singular matrices

When K is an arbitrary field, we study the affine automorphisms of M_n(K) that stabilize GL_n(K). Using a theorem of Dieudonn\'e on maximal affine subspaces of singular matrices, this is easily reduced to the known case of linear preservers when n>2 or #K>2. We include a short new proof of the more general Flanders' theorem for affine subspaces of M_{p,q}(K) with bounded rank. We also find that the group of affine transformations of M_2(F_2) that stabilize GL_2(F_2) does not consist solely of linear maps. Using the theory of quadratic forms over F_2, we construct explicit isomorphisms between it, the symplectic group Sp_4(F_2) and the symmetric group S_6.Comment: 13 pages, very minor corrections from the first versio

Clostridium difficile infection in the United States: A national study assessing preventive practices used and perceptions of practice evidence

We surveyed 571 US hospitals about practices used to prevent Clostridium difficile infection (CDI). Most hospitals reported regularly using key CDI prevention practices, and perceived their strength of evidence as high. The largest discrepancy between regular use and perceived evidence strength occurred with antimicrobial stewardship programs.Infect. Control Hosp. Epidemiol. 2015;36(8):969–971</jats:p

Quantifying Electrophoretic Deposition of Nanocrystal Superlattices Using Quartz Crystal Microbalance

Please click Additional Files below to see the full abstract

Generalized Geologic Map for Land-Use Planning: Rowan County, Kentucky

This map is not intended to be used for selecting individual sites. Its purpose is to inform land-use planners, government officials, and the public in a general way about geologic bedrock conditions that affect the selection of sites for various purposes. The properties of thick soils may supercede those of the underlying bedrock and should be considered on a site-to-site basis. At any site, it is important to understand the characteristics of both the soils and the underlying rock

Photon deflection and precession of the periastron in terms of spatial gravitational fields

We show that a Maxwell-like system of equations for spatial gravitational fields $\bf g$ and $\bf B$ (latter being the analogy of a magnetic field), modified to include an extra term for the $\bf B$ field in the expression for force, leads to the correct values for the photon deflection angle and for the precession of the periastron

Unveiling the Impact of Human Influence on Species Distributions in Vietnam: A Case Study Using Babblers (Aves: Timaliidae)

As developing countries give priority to economic growth, the effects of development threaten natural habitats and species distributions. Over the course of two decades, Vietnam has rapidly developed, especially in the expansion of agricultural production. However, no study has quantitatively measured the effects of recent human impact on the effects of past species distributions in Vietnam. We use locality data collected from multiple natural history collections, including several in Vietnam, to infer past species distributions. We assess habitat availability of five common babbler species (Aves: Timaliidae) using distribution models with data prior to rapid development that followed political reform. Overlaying the Global Human Influence Index with predicted distributions highlights the human impact on these distributions. Three important patterns emerge: (1) human impact influences common Timaliidae distributions similarly, (2) widespread species distributions show higher fragmentation due to human influence compared to narrowly distributed species in Vietnam, and (3) less than 20% of distributions overlap with nationally declared protected areas. We emphasize that conservation efforts should not only prioritize individual species, but also focus efforts on a regional scale, and that the use of museum data can be highly informative in conservation analyses. There are current obstacles to enforcing conservation of Vietnam’s already fragmented habitats, but our results suggest there is still time to reevaluate conservation approaches

Investigation of an advanced fault tolerant integrated avionics system

Presented is an advanced, fault-tolerant multiprocessor avionics architecture as could be employed in an advanced rotorcraft such as LHX. The processor structure is designed to interface with existing digital avionics systems and concepts including the Army Digital Avionics System (ADAS) cockpit/display system, navaid and communications suites, integrated sensing suite, and the Advanced Digital Optical Control System (ADOCS). The report defines mission, maintenance and safety-of-flight reliability goals as might be expected for an operational LHX aircraft. Based on use of a modular, compact (16-bit) microprocessor card family, results of a preliminary study examining simplex, dual and standby-sparing architectures is presented. Given the stated constraints, it is shown that the dual architecture is best suited to meet reliability goals with minimum hardware and software overhead. The report presents hardware and software design considerations for realizing the architecture including redundancy management requirements and techniques as well as verification and validation needs and methods

Variations in the quality of care of patients with acute myocardial infarction among Swiss university hospitals

Objectives. The objective of our study was to assess hospital variations in the quality of care delivered to acute myocardial infarction (AMI) patients among three Swiss academic medical centres. Design. Cross-sectional study. Setting. Three Swiss university hospitals. Study participants. We selected 1129 eligible patients discharged from these hospitals from 1 January to 31 December 1999, with a primary or secondary diagnosis code [International Classification of Diseases, 10th revision (ICD-10)] of AMI. We abstracted medical records for information on demographic characteristics, risk factors, symptoms, and findings at admission. We also recorded the main ECG and laboratory findings, as well as hospital and discharge management and treatment. We excluded patients transferred to another hospital and who did not meet the clinical definition of AMI. Main outcome measures. Percentage of patients receiving appropriate intervention as defined by six quality of care indicators derived from clinical practical guidelines. Results. Among 577 eligible patients with AMI in this study, the mean (SD) age was 68.2 (13.9), and 65% were male. In the assessment of the quality indicators we excluded patients who were not eligible for the procedure. Among cohorts of ‘ideal candidates' for specific interventions, 64% in hospital A and 73% in hospital C had reperfusion within 12 hours either with thrombolytics or percutaneous transluminal coronary angioplasty (P = 0.367). Further, in hospitals A, B, and C, respectively 97, 94, and 84% were prescribed aspirin during the initial hospitalization (P = 0.0002), and respectively 68, 91, and 75% received angiotensin converting enzyme inhibitors at discharge in the case of left ventricular systolic dysfunction (P = 0.003). Conclusions. Our results showed important hospital-to-hospital variations in the quality of care provided to patients with AMI between these three university hospital

Controlled electrochemical growth of ultra-long gold nanoribbons

Citation: Basnet, G., Panta, K. R., Thapa, P. S., & Flanders, B. N. (2017). Controlled electrochemical growth of ultra-long gold nanoribbons. Applied Physics Letters, 110(7), 5. doi:10.1063/1.4976027This paper describes the electrochemical growth of branchless gold nanoribbons with similar to 40 nm x similar to 300 nm cross sections and >100 mu m lengths (giving length-to-thickness aspect ratios of > 10(3)). These structures are useful for opto-electronic studies and as nanoscale electrodes. The 0.75-1.0V voltage amplitude range is optimal for branchless ribbon growth. Reduced amplitudes induce no growth, possibly due to reversible redox chemistry of gold at reduced amplitudes, whereas elevated amplitudes, or excess electrical noise, induce significant side-branching. The inter-relatedness of voltage-amplitude, noise, and side-branching in electrochemical nanoribbon growth is demonstrated. Published by AIP Publishing

Laser-Induced Electron Emission from Au Nanowires: A Probe for Orthogonal Polarizations

Photoelectron field emission, induced by femtosecond laser pulses focused on metallic nanotips, provides spatially coherent and temporally short electron pulses. The properties of the photoelectron yield give insight into both the material properties of the nanostructure and the exciting laser focus. Ultralong nanoribbons, grown as a single crystal attached to a metallic taper, are sources of electron field emission that have not yet been characterized. In this report, photoemission from gold nanoribbon samples is studied and compared to emission from tungsten and gold tips. We observe that the emission from sharp tips generally depends on one transverse component of the exciting laser field, while the emission of a blunted nanoribbon is found to be sensitive to both components. We propose that this property makes photoemission from nanoribbons a candidate for position-sensitive detection of the longitudinal field component in a tightly focused beam