Stress relaxation above and below the jamming transition

We numerically investigate stress relaxation in soft athermal disks to reveal critical slowing down when the system approaches the jamming point. The exponents describing the divergence of the relaxation time differ dramatically depending on whether the transition is approached from the jammed or unjammed phase. This contrasts sharply with conventional dynamic critical scaling scenarios, where a single exponent characterizes both sides. We explain this surprising difference in terms of the vibrational density of states (vDOS), which is a key ingredient of linear viscoelastic theory. The vDOS exhibits an extra slow mode that emerges below jamming, which we utilize to demonstrate the anomalous exponent below jamming.Comment: 5 pages, 4 figure

Evolution of the Quasar Luminosity Function Over 3 < z < 5 in the COSMOS Survey Field

We investigate the high-redshift quasar luminosity function (QLF) down to an apparent magnitude of I(AB) = 25 in the Cosmic Evolution Survey (COSMOS). Careful analysis of the extensive COSMOS photometry and imaging data allows us to identify and remove stellar and low-redshift contaminants, enabling a selection that is nearly complete for type-1 quasars at the redshifts of interest. We find 155 likely quasars at z > 3.1, 39 of which have prior spectroscopic confirmation. We present our sample in detail and use these confirmed and likely quasars to compute the rest-frame UV QLF in the redshift bins 3.1 < z < 3.5 and 3.5 < z < 5. The space density of faint quasars decreases by roughly a factor of four from z \sim 3.2 to z \sim 4, with faint-end slopes of {\beta} \sim -1.7 at both redshifts. The decline in space density of faint optical quasars at z > 3 is similar to what has been found for more luminous optical and X-ray quasars. We compare the rest-frame UV luminosity functions found here with the X-ray luminosity function at z > 3, and find that they evolve similarly between z \sim 3.2 and z \sim 4; however, the different normalizations imply that roughly 75% of X-ray bright active galactic nuclei (AGN) at z \sim 3 - 4 are optically obscured. This fraction is higher than found at lower redshift and may imply that the obscured, type-2 fraction continues to increase with redshift at least to z \sim 4. Finally, the implications of the results derived here for the contribution of quasars to cosmic reionization are discussed.Comment: Accepted for publication in ApJ. 17 pages, 14 figure

Magnetic-Field-Independent Ultrasonic Dispersions in the Magnetically Robust Heavy Fermion System SmOs4Sb12

Elastic properties of the filled skutterudite compound SmOs$_4$Sb$_{12}$ have been investigated by ultrasonic measurements. The elastic constant $C_{11}(\omega)$ shows two ultrasonic dispersions at $\sim$15 K and $\sim$53 K for frequencies $\omega$ between 33 and 316 MHz, which follow a Debye-type formula with Arrhenius-type temperature-dependent relaxation times, and remain unchanged even with applied magnetic fields up to 10 T. The corresponding activation energies were estimated to be $E_2$ = 105 K and $E_1$ = 409 K, respectively. The latter, $E_1$, is the highest value reported so far in the Sb-based filled skutterudites. The presence of magnetically robust ultrasonic dispersions in SmOs$_4$Sb$_{12}$ implies a possibility that an emergence of a magnetically insensitive heavy fermion state in this system is associated with a novel local charge degree of freedom which causes the ultrasonic dispersion.Comment: 5 pages, 4 figure

Residual Attention Guidance in Blindsight Monkeys Watching Complex Natural Scenes

SummaryPatients with damage to primary visual cortex (V1) demonstrate residual performance on laboratory visual tasks despite denial of conscious seeing (blindsight) [1]. After a period of recovery, which suggests a role for plasticity [2], visual sensitivity higher than chance is observed in humans and monkeys for simple luminance-defined stimuli, grating stimuli, moving gratings, and other stimuli [3–7]. Some residual cognitive processes including bottom-up attention and spatial memory have also been demonstrated [8–10]. To date, little is known about blindsight with natural stimuli and spontaneous visual behavior. In particular, is orienting attention toward salient stimuli during free viewing still possible? We used a computational saliency map model to analyze spontaneous eye movements of monkeys with blindsight from unilateral ablation of V1. Despite general deficits in gaze allocation, monkeys were significantly attracted to salient stimuli. The contribution of orientation features to salience was nearly abolished, whereas contributions of motion, intensity, and color features were preserved. Control experiments employing laboratory stimuli confirmed the free-viewing finding that lesioned monkeys retained color sensitivity. Our results show that attention guidance over complex natural scenes is preserved in the absence of V1, thereby directly challenging theories and models that crucially depend on V1 to compute the low-level visual features that guide attention

Pro–B-Type Natriuretic Peptide1–108 Circulates in the General Community Plasma Determinants and Detection of Left Ventricular Dysfunction

ObjectivesThe purpose of this study was to investigate circulating pro–B-type natriuretic peptide (proBNP1–108) in the general community and evaluate its ability to detect left ventricular (LV) dysfunction.BackgroundThe current concept for cardiac endocrine function is that, in response to cardiac stress, the heart secretes B-type natriuretic peptide (BNP1–32) and amino-terminal pro–B-type natriuretic peptide (NT-proBNP1–76) after intracardiac cleavage of their molecular precursor, proBNP1–108. We hypothesized that proBNP1–108 circulates in normal human subjects and that it is a useful biomarker for LV dysfunction.MethodsOur population-based study included a cohort of 1,939 adults (age ≥45 years) from Olmsted County, Minnesota, with 672 participants defined as healthy. Subjects underwent in-depth clinical characterization, detailed echocardiography, and measurement of proBNP1–108. Independent factors associated with proBNP1–108 and test characteristics for the detection of LV dysfunction were determined.ResultsProBNP1–108 in normal humans was strongly influenced by sex, age, heart rate, and body mass index. The median concentration was 20 ng/l with a mean proBNP1–108 to NT-proBNP1–76 ratio of 0.366, which decreased with heart failure stage. ProBNP1–108 was a sensitive (78.8%) and specific (86.1%) biomarker for detecting LV systolic dysfunction, which was comparable to BNP1–32, but less than NT-proBNP1–76, in several subsets of the population.ConclusionsProBNP1–108 circulates in the majority of healthy humans in the general population and is a sensitive and specific biomarker for the detection of systolic dysfunction. The proBNP1–108 to NT-proBNP1–76 ratio may provide insights into altered proBNP1–108 processing during heart failure progression. Thus, this highly specific assay for proBNP1–108 provides important new insights into the biology of the BNP system

A long-forgotten ‘dinosaur’ bone from a museum cabinet, uncovered to be a Japan\u27s iconic extinct mammal, Paleoparadoxia (Desmostylia, Mammalia)

Here, we report a new ‘discovery’ of a desmostylian fossil in the geological collection at a national university in Japan. This fossil was unearthed over 60 years ago and donated to the university. Owing to the original hand-written note kept with the fossil in combination with interview investigation, we were able to reach two equally possible fossil sites in the town of Tsuchiyu Onsen, Fukushima. Through the interviews, we learned that the fossil was discovered during construction of a debris flow barrier and that it was recognized as a ‘dinosaur’ bone among the locals and displayed in the Village Hall before/until the town experienced a fire disaster in 1954. As scientific findings, the fossil was identified to be a right femur of Paleoparadoxia (Desmostylia), which shows well-preserved muscle scars on the surface. The age was estimated to be 15.9 Ma or younger in zircon-dating. This study shows an excellent case that historical and scientific significances could be extracted from long-forgotten uncatalogued specimens as long as the original information is retained with the specimens

Non-Locality and Strong Coupling in the Heavy Fermion Superconductor CeCoIn5_{5}: A Penetration Depth Study

We report measurements of the magnetic penetration depth $\lambda$ in single crystals of CeCoIn$_{5}$ down to $\sim$0.14 K using a tunnel-diode based, self-inductive technique at 28 MHz. While the in-plane penetration depth tends to follow a power law, $\lambda_{//} \sim {\it T}^{3/2}$, the data are better described as a crossover between linear ({\it T} $\gg$ ${\it T}^\ast$) and quadratic ({\it T} $\ll {\it T}^\ast$) behavior, with ${\it T}^\ast$ the crossover temperature in the strong-coupling limit. The {\it c}-axis penetration depth $\lambda_{\perp}$ is linear in {\it T}, providing evidence that CeCoIn$_{5}$ is a {\it d}-wave superconductor with line nodes along the {\it c}-axis. The different temperature dependences of $\lambda_{//}$ and $\lambda_{\perp}$ rule out impurity effects as the source of ${\it T}^{\ast}$.Comment: 4 pages, 3 figure

A comparison of surgical outcomes between endoscopic and robotically assisted thyroidectomy: the authors’ initial experience

Background: The gasless, transaxillary endoscopic thyroidectomy (GTET) offers a distinct advantage over the conventional open operation by leaving no visible neck scar, and in an attempt to improve its ergonomics and surgical outcomes, the robotically assisted thyroidectomy (RAT) was introduced. The RAT uses the same endoscopic route as the GTET but with the assistance of the da Vinci S robotic system. Excellent results for RAT have been reported, but it remains unclear whether RAT offers any potential benefits over GTET. Methods: From June to December 2009, 46 patients underwent endoscopic thyroidectomy. Of these patients, 39 had surgery without the robot (GTET) and 7 had surgery with the robot (RAT). Demographics, surgical indications, operative findings, and postoperative outcomes were compared between the two groups. All the patients were followed up for at least 6 months after surgery. Results: Patient demographics, surgical indications, and extent of resection were similar between the two groups. The median total procedure time was significantly longer for RAT (149 min) than for GTET (100 min; p = 0.018), but the contralateral recurrent laryngeal nerve was more likely to identified in RAT (100%) than in GTET (42.9%; p = 0.070). On the average, GTET needed one more surgical assistant than RAT (1 vs. 0; ppublished_or_final_versionSpringer Open Choice, 21 Feb 201

The role of the chemokine receptor CXCR4 in infection with feline immunodeficiency virus

Infection with feline immunodeficiency virus (FIV) leads to the development of a disease state similar to AIDS in man. Recent studies have identified the chemokine receptor CXCR4 as the major receptor for cell culture-adapted strains of FIV, suggesting that FIV and human immunodeficiency virus (HIV) share a common mechanism of infection involving an interaction between the virus and a member of the seven transmembrane domain superfamily of molecules. This article reviews the evidence for the involvement of chemokine receptors in FIV infection and contrasts these findings with similar studies on the primate lentiviruses HIV and SIV (simian immunodeficiency virus)

An Infrared Census of Star Formation in the Horsehead Nebula

At ~ 400 pc, the Horsehead Nebula (B33) is the closest radiatively-sculpted pillar to the Sun, but the state and extent of star formation in this structure is not well understood. We present deep near-infrared (IRSF/SIRIUS JHKs) and mid-infrared (Spitzer/IRAC) observations of the Horsehead Nebula in order to characterize the star forming properties of this region and to assess the likelihood of triggered star formation. Infrared color-color and color-magnitude diagrams are used to identify young stars based on infrared excess emission and positions to the right of the Zero-Age Main Sequence, respectively. Of the 45 sources detected at both near- and mid-infrared wavelengths, three bona fide and five candidate young stars are identified in this 7' by 7' region. Two bona fide young stars have flat infrared SEDs and are located at the western irradiated tip of the pillar. The spatial coincidence of the protostars at the leading edge of this elephant trunk is consistent with the Radiation-Driven Implosion (RDI) model of triggered star formation. There is no evidence, however, for sequential star formation within the immediate ~ 1.5' (0.17 pc) region from the cloud/H II region interface.Comment: 30 pages, 11 figures; accepted for publication in The Astronomical Journa