Critical Behavior of Light

Light is shown to exhibit critical and tricritical behavior in passive mode-locked lasers with externally injected pulses. It is a first and unique example of critical phenomena in a one-dimensional many body light-mode system. The phase diagrams consist of regimes with continuous wave, driven para-pulses, spontaneous pulses via mode condensation, and heterogeneous pulses, separated by phase transition lines which terminate with critical or tricritical points. Enhanced nongaussian fluctuations and collective dynamics are observed at the critical and tricritical points, showing a mode system analog of the critical opalescence phenomenon. The critical exponents are calculated and shown to comply with the mean field theory, which is rigorous in the light system.Comment: RevTex, 5 pages, 3 figure

Metamagnetism in the 2D Hubbard Model with easy axis

Although the Hubbard model is widely investigated, there are surprisingly few attempts to study the behavior of such a model in an external magnetic field. Using the Projector Quantum Monte Carlo technique, we show that the Hubbard model with an easy axis exhibits metamagnetic behavior if an external field is turned on. For the case of intermediate correlations strength $U$, we observe a smooth transition from an antiferromagnetic regime to a paramagnetic phase. While the staggered magnetization will decrease linearly up to a critical field $B_c$, uniform magnetization develops only for fields higher than $B_c$.Comment: RevTeX 5 pages + 2 postscript figures (included), accepted for PRB Rapid Communication

Assessment of Minimum Inhibitory Concentrations of Telavancin by Revised Broth Microdilution Method in Phase 3 Hospital-Acquired Pneumonia/Ventilator-Associated Pneumonia Clinical Isolates

INTRODUCTION: The broth microdilution method (BMD) for testing telavancin minimum inhibitory concentrations (MICs) was revised (rBMD) in 2014 to improve the accuracy, precision, and reproducibility of the testing method. The aim of this study was to determine the effect of the revised method on telavancin MIC values for Staphylococcus aureus (S. aureus) clinical isolates obtained from hospital-acquired pneumonia (HAP) patients. METHODS: Isolates from patients who participated in the phase 3 Assessment of Telavancin for Treatment of HAP Studies were retested using the rBMD method. RESULTS: Retesting of 647 isolates produced a range of telavancin MIC values from 0.015 µg/mL to 0.12 µg/mL with MIC(50/90) values of 0.06/0.06 µg/mL for the total pool of samples. For methicillin-resistant S. aureus (MRSA), MIC(50/90) values were 0.06/0.12 µg/mL. These values are up to 4-fold lower than MIC(50/90) values obtained using the original method. These results were used in part to justify lowering the telavancin breakpoints. All tested isolates remained susceptible to telavancin at the revised susceptibility breakpoint of ≤0.12 µg/mL. Overall, the clinical cure rate for microbiologically evaluable telavancin-treated patients was 78% for S. aureus, 76% for patients with MRSA, and 79% for patients with isolates with reduced susceptibility to vancomycin (MIC ≥1 µg/mL). CONCLUSION: Results from the rBMD method support the in vitro potency of telavancin against S. aureus. TRIAL REGISTRATION: ATTAIN (NCT00107952 and NCT00124020). FUNDING: Theravance Biopharma Antibiotics, Inc

Large Orbital Magnetic Moment and Coulomb Correlation effects in FeBr2

We have performed an all-electron fully relativistic density functional calculation to study the magnetic properties of FeBr2. We show for the first time that the correlation effect enhances the contribution from orbital degrees of freedom of $d$ electrons to the total magnetic moment on Fe$^{2+}$ as opposed to common notion of nearly total quenching of the orbital moment on Fe$^{2+}$ site. The insulating nature of the system is correctly predicted when the Hubbard parameter U is included. Energy bands around the gap are very narrow in width and originate from the localized Fe-3$d$ orbitals, which indicates that FeBr2 is a typical example of the Mott insulator.Comment: 4 pages, 3 figures, revtex4, PRB accepte

Telavancin for hospital-acquired pneumonia: Clinical response and 28-day survival

U.S. Food and Drug Administration draft guidance for future antibiotic clinical trials of bacterial nosocomial pneumonia recommends the use of diagnostic criteria according to American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) guidelines and the use of a primary endpoint of 28-day all-cause mortality. The effect of applying these guidelines on outcomes of phase III nosocomial pneumonia studies of telavancin was evaluated in a post hoc analysis. ATS/IDSA criteria were applied in a blind fashion to the original all-treated (AT) group. Clinical cure rates at final follow-up were determined in the refined AT and clinically evaluable (CE) groups (ATS/IDSA-AT and ATS/IDSA-CE, respectively). The exploratory endpoint of 28-day survival was evaluated for the ATS/IDSA-AT group. Noninferiority of telavancin versus vancomycin was demonstrated, with similar cure rates in the ATS/IDSA-AT (59% versus 59%) and ATS/IDSA-CE (83% versus 80%) groups. Cure rates favored telavancin in ATS/IDSA-CE patients where Staphylococcus aureus was the sole pathogen (86% versus 75%). Overall, 28-day survival rates were similar in the telavancin (76%) and vancomycin (77%) groups but lower in telavancin-treated patients with preexisting moderate-to-severe renal impairment (creatinine clearance [CL(CR)] of <50 ml/min). Telavancin should be administered to patients with moderate-to-severe renal impairment only if treatment benefit outweighs the risk or if no suitable alternatives are available

Vision Engineering

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Metamagnetism and critical fluctuations in high quality single crystals of the bilayer ruthenate Sr3Ru2O7

We report the results of low temperature transport, specific heat and magnetisation measurements on high quality single crystals of the bilayer perovskite Sr3Ru2O7, which is a close relative of the unconventional superconductor Sr2RuO4. Metamagnetism is observed, and transport and thermodynamic evidence for associated critical fluctuations is presented. These relatively unusual fluctuations might be pictured as variations in the Fermi surface topography itself. No equivalent behaviour has been observed in the metallic state of Sr2RuO4.Comment: 4 pages, 4 figures, Revtex 3.

Speciation genomics and morphological evolution in an extraordinary avian radation, the Lonchura munias of New Guinea and Australia

Speciation, the evolution of morphologically, behaviorally and/or ecologically distinct lineages from a common ancestor, is the fundamental process generating biodiversity. The rapidly developing field of speciation genomics is challenging traditional views of speciation as a gradual, genome-wide process, and highlighting the role of divergent natural selection in the speciation process. This study investigates morphological evolution and the genomic architecture of speciation in a clade of 12 "munias" in the genus Lonchura, one of the most extraordinary cases of recent and rapid diversification in birds. With a diversity of plumage patterns and replicate examples of closely related species living in sympatry, this group is ideally suited for addressing fundamental questions about the genomics of speciation. In this study, I (1) test for evidence of character displacement between sympatric species using quantitative measurements of plumage coloration and morphology; (2) examine the structure of genome-wide variation using ddRAD-seq (double-digest Restriction Site Associated DNA sequencing); and (3) investigate the genomic structure of divergence using whole-genome sequencing. I find some evidence for character displacement, particularly in morphometrics and crown coloration. There is also a trend, however, for sympatric species to be more similar in coloration than allopatric species, particularly those that have come into contact more recently. Analysis of 7,043 ddRAD-seq loci reveals evidence of introgression among sympatric populations, with overall genomic variation corresponding more closely to geography than species identity. There is also substantial heterogeneity in genetic structure among mitochondrial, autosomal, and Z-linked markers. Finally, whole-genome sequencing reveals low overall genomic divergence while pinpointing "islands of differentiation" that exhibit elevated divergence between species. Two of these islands overlap genes known to be associated with coloration—Agouti signaling protein (ASIP) and Kit ligand (KITLG)—and allelic variation at these genes is associated with phenotypic traits. I also find evidence of a ~26 million base pair inversion on the Z chromosome, which groups the focal species differently than genome-wide variation. A strongly mosaic pattern of population structure among genomic regions supports a genic view of speciation, in which a small fraction of the genome is involved in the initial divergence of species

Prospective Multicenter Study of Community-Associated Skin and Skin Structure Infections due to Methicillin-Resistant Staphylococcus aureus in Buenos Aires, Argentina

Background. Community-associated methicillin-resistant Staphylococcus aureus(CAMRSA) is now the most common cause of skin and skin structure infections (SSSI) in several world regions. In Argentina prospective, multicenter clinical studies have only been conducted in pediatric populations. Objective. Primary: describe the prevalence, clinical and demographic characteristics of adult patients with community acquired SSSI due to MRSA; secondary: molecular evaluation of CA-MRSA strains. Patients with MRSA were compared to those without MRSA. Material and Methods. Prospective, observational, multicenter, epidemiologic study, with molecular analysis, conducted at 19 sites in Argentina (18 in Buenos Aires)between March 2010 and October 2011. Patients were included if they were ≥ 14 years, were diagnosed with SSSI, a culture was obtained, and there had no significant healthcare contact identified. A logistic regression model was used to identify factors associated with CA-MRSA. Pulse field types, SCCmec, and PVL status were also determined. Results. A total of 311 patients were included. CA-MRSA was isolated in 70% (218/311) of patients. Clinical variables independently associated with CA-MRSA were: presence of purulent lesion (OR 3.29; 95%CI 1.67, 6.49) and age <50 years (OR 2.39; 95%CI 1.22, 4.70). The vast majority of CA-MRSA strains causing SSSI carried PVL genes (95%) and were SCCmec type IV. The sequence type CA-MRSA ST30 spa t019 was the predominant clone. Conclusions. CA-MRSA is now the most common cause of SSSI in our adult patients without healthcare contact. ST30, SCCmec IV, PVL+, spa t019 is the predominant clone in Buenos Aires, Argentina.Fil: Lopez Furst, Maria Jose. Sanatorio Municipal Dr. Julio Méndez, Ciudad Autónoma de Buenos Aires; Argentina;Fil: de Vedia, Lautaro. Gobierno de la Ciudad de Buenos Aires. Htal.de Infecciosas F.j. Muñiz; Argentina;Fil: Fernandez, Silvina. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Quimica Biologica. Cat.de Microbiologia; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina;Fil: Gardella, Noella Mariel. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Quimica Biologica. Cat.de Microbiologia; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina;Fil: Ganaha, Cristina. Pcia. de Buenos Aires. Hospital Vicente López y Planes, Gral. Rodríguez; Argentina;Fil: Prieto, Sergio. Provincia de Buenos Aires. Hospital Nuestra Señora de Luján; Argentina;Fil: Carbone, Edith. Hospital Aeronautico Central; Argentina;Fil: Lista, Nicolás. Gobierno de la Ciudad de Buenos Aires. Htal.de Infecciosas F.j. Muñiz; Argentina;Fil: Rotryng, Flavio. Universidad Abierta Interamericana; Argentina;Fil: Morera, Graciana I.. Hospital Dr. Jose Cullen; Argentina;Fil: Mollerach, Marta Eugenia. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Quimica Biologica. Cat.de Microbiologia; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina;Fil: Stryjewski, Martin E.. Centro de Educaciones Medicas E Investig.Clinica "Norberto Quirno"; Argentina

Paper Session III-B - Characterization of Potential ISS/Space Shuttle Environmental Conditions on Growth and Development of R. Sativus: Ground Studies for the Rasta Space Flight Experiment

Using radish as a model system, the RASTA project (Radish Assimilation in Spaceflight Testbed Atmospheres) will be investigating carbon partitioning of salad crops in microgravity. Before this goal can be accomplished, the effects of the unique environment of orbiting spacecraft on growth and development of radish must be characterized so they can be separated from those of microgravity. The environmental conditions on ISS and the space shuttle most likely to effect carbon partitioning in radish are air temperature, CO2 concentration and atmospheric contaminants. Several radish cultivars were grown in temperatures ranging from 18-30°C at ambient (400 part per million [ppm]) or elevated (1,500, 3,000 and 10,000 ppm) CO2. The effects of temperature and CO2 on growth and development of these cultivars were characterized and a high temperature cultivar was identified. In a separate series of experiments, radishes were exposed to different levels of ethylene, a biologically active volatile organic compound, to characterize its impact on radish growth and development over a range of concentrations. With these environmental characterizations, the effect of microgravity on carbon partitioning can be more readily separated from environmental factors coincidental to the spacecraft environment