We report direct-detection constraints on light dark matter particles interacting with electrons. The results are based on a method that exploits the extremely low levels of leakage current of the ...DAMIC detector at SNOLAB of 2–6×10−22 A cm−2. We evaluate the charge distribution of pixels that collect <10e− for contributions beyond the leakage current that may be attributed to dark matter interactions. Constraints are placed on so-far unexplored parameter space for dark matter masses between 0.6 and 100 MeV c−2. We also present new constraints on hidden-photon dark matter with masses in the range 1.2–30 eV c−2.
Essentials Hypodysfibrinogenemia is rarely reported among the congenital fibrinogen disorders. This first systematic literature review led to identification of 51 hypodysfibrinogenemic cases. ...Diagnosis based only on functional/antigenic fibrinogen ratio may be insufficient. Family studies show an incomplete segregation of mutation with the clinical phenotypes.
Background Hypodysfibrinogenemia is a rare disease characterized by decreased levels of a dysfunctional fibrinogen. It shares features with both hypo- and dysfibrinogenemia, although with specific molecular patterns and clinical phenotypes. Objectives To better define the genetics, the diagnosis and the clinical features of hypodysfibrinogenemia. Patients/Methods A systematic literature search led to 167 records. After removal of duplicates, abstract screening and full-text reviewing, 56 molecular and/or clinical studies were analyzed, including a novel FGB missense mutation in a woman with a mild bleeding phenotype. Results A total of 32 single causative mutations were reported, mainly in the COOH-terminal region of the γ or Aα chains at heterozygous or homozygous state. Seven additional hypodysfibrinogenemias were due to compound heterozygosity. The hypofibrinogenemic phenotypes were a result of an impaired assembly or secretion or an increased clearance of the fibrinogen variant, whereas the dysfibrinogenemic phenotype was mainly a result of a defective fibrin polymerization and an abnormal calcium or tPA binding. Among 51 identified index cases, a functional/antigenic fibrinogen ratio < 0.7 had a sensitivity of 86% for the diagnosis of hypodysfibrinogenemia. Eleven patients (22%) were asymptomatic at time of diagnosis, 23 (45%) had a mild bleeding phenotype with mainly obstetrical or gynecologic-related hemorrhage and 22 (43%) had experienced at least one thrombotic event, including 23 venous and eight arterial thromboses. Conclusions This first systematic review on hypodysfibrinogenemia shows the heterogeneity of causative mutations and that misdiagnosis could occur in relation to the functional and antigenic fibrinogen levels. Family studies reveal an incomplete segregation of the mutation with the clinical phenotype.
We present constraints on the existence of weakly interacting massive particles (WIMPs) from an 11 kg d target exposure of the DAMIC experiment at the SNOLAB underground laboratory. The observed ...energy spectrum and spatial distribution of ionization events with electron-equivalent energies >200 eV_{ee} in the DAMIC CCDs are consistent with backgrounds from natural radioactivity. An excess of ionization events is observed above the analysis threshold of 50 eV_{ee}. While the origin of this low-energy excess requires further investigation, our data exclude spin-independent WIMP-nucleon scattering cross sections σ_{χ-n} as low as 3×10^{-41} cm^{2} for WIMPs with masses m_{χ} from 7 to 10 GeV c^{-2}. These results are the strongest constraints from a silicon target on the existence of WIMPs with m_{χ}<9 GeV c^{-2} and are directly relevant to any dark matter interpretation of the excess of nuclear-recoil events observed by the CDMS silicon experiment in 2013.
In this paper the surface topography of titanium samples irradiated by femtosecond laser pulses is described. When the fluence is about 0.5
J/cm
2 periodic ripples with a period of about 700
nm are ...formed. For fluences between 0.5 and 2
J/cm
2, a microcolumnar surface texture develops in the center of the irradiated spots and ripples are formed in the periphery of the spots. When experiments are performed with a non-stationary sample, the microcolumns exhibit ripples similar to those observed when the radiation fluence is about 0.5
J/cm
2 and in the outer regions of the irradiated areas for fluences between 0.5 and 2
J/cm
2. Since the energy distribution in the transverse cross-section of the laser beam is Gaussian, we conclude that the ripples form when the microcolumns are subjected to fluences near the melting threshold of the material at the trailing edge of the moving laser beam.
The aim of this study was to investigate the effect of surrounding medium on the laser ablation characteristics of aluminum (Al). Al specimens were subjected to tightly focused laser beam in three ...dissimilar media; air, water and ionic liquid. For processing, the laser beam was tightly focused using a converging lens and the laser pulse energy was varied from 1–5 µJ. The produced laser tracks and areas were examined by field emission scanning electron microscope (FESEM) for their microstructural characterization. Laser induced periodic surface structure (LIPSS) were observed in air whereas no LIPSS were witnessed in the case of water and ionic liquid media for the same laser pulse energy. The laser ablated surface was cleaner for liquid media as compared to air due to change in laser-matter interactions and hampered settling down of the ablated debris on the surface. In addition to LIPSS three different structures; protrusions, pits and complex conical spikes were observed in different media. The average periodicity of the produced LIPSS was calculated to be 710 ± 10 nm while average diameter of protrusions and pits was found to be 115 ± 30 nm and 93 ± 35 nm, respectively. The ablation mechanism in air and liquid has been discussed in detail.
Relatively poor adhesion of carbon fibers with matrix leads to various serious concerns in high performance composites. Interface debonding during loading is the most vulnerable among them ...particularly when polymer matrix is used. This paper presents the results of electron microscopy investigation of four different techniques that are beneficial for improving interfacial bonding. These techniques were based on modifying the fiber surface by way of both; coating a film on the fiber and ablating a layer from it. The former employed growth of nanostructures of carbon and zinc oxide by thermal catalytic chemical vapor deposition and magnetron sputtering respectively and depositing a layer of pyrolytic carbon by CVD while the latter involved ablation of an outer layer of fiber using femtosecond laser treatment. Both the approaches relied on introducing mechanical anchoring on the fiber surface by micro roughening anticipating an improved fiber- matrix interfacial bonding. Carbon fiber surface prior and post treatment was investigated microscopically using FESEM and TEM. CNTs growth formed network like structure around the fiber, while PyC coating showed continuous layer around the fiber. HRTEM images of ZnO nanostructures; both nanowires and nanowalls possessed crystalline structure revealed by the presence of Moiré fringes formed due to overlapping of two crystals with different orientation. Laser treated fiber surface showed formation of LIPSS with average periodicity of 147 ± 10 nm.
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•Surface modification of carbon fiber at nano-scale for interface strengthening in composites by; (i) PyC coating, (ii) MWCNTs growth, (iv) ZnO nanowires, nanowalls growth and (v) Femtosecond laser machining•FESEM imaging revealing uniform growth•HRTEM shows crystalline structure of grown nanostructures
In the present work single and multiple layer NiCrAlY coatings were produced by laser cladding on (100) single-crystalline substrates of SRR99 Ni-based superalloy. Detailed structural ...characterisation and texture analysis by optical microscopy, scanning electron microscopy, X-ray diffraction and Rutherford backscattering showed that the NiCrAlY coatings consisted essentially of
γ phase with yttrium oxide (Y
2O
3) and a small proportion of yttrium–aluminum garnet (Al
5Y
3O
12) precipitated in the interdendritic regions. The coatings presented a columnar dendritic structure grown by epitaxial solidification on the substrate and inherited the single-crystalline nature and the orientation of the substrate. The coating material also showed a mosaicity and a defect density similar to those of the substrate. It can be expected that the protective effect of these coatings against oxidation is greatly enhanced compared with polycrystalline coatings because high diffusivity paths, such as grain boundaries, are eliminated in single-crystalline coatings, thus reducing mass transport through the coating.
Weakly supervised semantic segmentation (WSSS) methods have received significant attention in recent years, since they can dramatically reduce the annotation costs of fully supervised alternatives. ...While most previous studies focused on leveraging classification labels, we explore instead the use of image captions, which can be obtained easily from the web and contain richer visual information. Existing methods for this task assigned text snippets to relevant semantic labels by simply matching class names, and then employed a model trained to localize arbitrary text in images to generate pseudo-ground truth segmentation masks. Instead, we propose a dedicated caption processing module to extract structured supervision from captions, consisting of improved relevant object labels, their visual attributes, and additional background categories, all of which are useful for improving segmentation quality. This module uses syntactic structures learned from text data, and semantic relations retrieved from a knowledge database, without requiring additional annotations on the specific image domain, and consequently can be extended immediately to new object categories. We then present a novel localization network, which is trained to localize only these structured labels. This strategy simplifies model design, while focusing training signals on relevant visual information. Finally, we describe a method for leveraging all types of localization maps to obtain high-quality segmentation masks, which are used to train a supervised model. On the challenging MS-COCO dataset, our method moves the state-of-the-art forward significantly for WSSS with image-level supervision by a margin of 7.6% absolute (26.7% relative) mean Intersection-over-Union, achieving 54.5% precision and 50.9% recall.
The brain reward system is key to understanding adolescent obesity in the current obesogenic environment, rich in highly appetising stimuli, to which adolescents are particularly sensitive. We aimed ...to examine the association between body fat levels and brain reward system responsivity to general (monetary) rewards in male and female adolescents.
Sixty-eight adolescents (34 females; mean age (s.d.)= 16.56 (1.35)) were measured for body fat levels with bioelectric impedance, and underwent a functional magnetic resonance imaging (fMRI) scan during the Monetary Incentive Delay (MID) task. The MID task reliably elicits brain activations associated with two fundamental aspects of reward processing: anticipation and feedback. We conducted regression analyses to examine the association between body fat and brain reward system responsivity during reward anticipation and feedback, while controlling for sex, age and socioeconomic status. We also analysed the moderating impact of sex on the relationship between fat levels and brain responsivity measures. Brain imaging analyses were corrected for multiple comparisons, with a cluster-defining threshold of P<0.001, and minimum cluster size of 38 contiguous voxels.
Higher body fat levels were associated with lower activation of the primary somatosensory cortex (S1) and the supramarginal gyrus during reward feedback after controlling for key sociodemographic variables. Although we did not find significant associations between body fat and brain activations during reward anticipation, S1/supramarginal gyrus activation during feedback was linked to increased negative prediction error, that is, less reward than expected, in illustrative post hoc analyses. Sex did not significantly moderate the association between body fat and brain activation in the MID task.
In adolescents, higher adiposity is linked to hypo-responsivity of somatosensory regions during general (monetary) reward feedback. Findings suggest that adolescents with excess weight have blunted activation in somatosensory regions involved in reward feedback learning.
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