We present direct detection constraints on the absorption of hidden-photon dark matter with particle masses in the range 1.2-30 eV c^{-2} with the DAMIC experiment at SNOLAB. Under the assumption ...that the local dark matter is entirely constituted of hidden photons, the sensitivity to the kinetic mixing parameter κ is competitive with constraints from solar emission, reaching a minimum value of 2.2×10^{-14} at 17 eV c^{-2}. These results are the most stringent direct detection constraints on hidden-photon dark matter in the galactic halo with masses 3-12 eV c^{-2} and the first demonstration of direct experimental sensitivity to ionization signals <12 eV from dark matter interactions.
Contemporary epidemiological methods testing the associations between green space and psychological well-being treat all vegetation cover as equal. However, there is very good reason to expect that ...variations in ecological "quality" (number of species, integrity of ecological processes) may influence the link between access to green space and benefits to human health and well-being. We test the relationship between green space quality and restorative benefit in an inner city urban population in Bradford, United Kingdom. We selected 12 urban parks for study where we carried out botanical and faunal surveys to quantify biodiversity and assessed the site facilities of the green space (cleanliness, provision of amenities). We also conducted 128 surveys with park users to quantify psychological restoration based on four self-reported measure of general restoration, attention-grabbing distractions, being away from everyday life, and site preference. We present three key results. First, there is a positive association between site facilities and biodiversity. Second, restorative benefit is predicted by biodiversity, which explained 43% of the variance in restorative benefit across the parks, with minimal input from other variables. Third, the benefits accrued through access to green space were unrelated to age, gender, and ethnic background. The results add to a small but growing body of evidence that emphasize the role of nature in contributing to the well-being of urban populations and, hence, the need to consider biodiversity in the design of landscapes that enhance multiple ecosystem services.
We present results of a dark matter search performed with a 0.6 kg d exposure of the DAMIC experiment at the SNOLAB underground laboratory. We measure the energy spectrum of ionization events in the ...bulk silicon of charge-coupled devices down to a signal of 60 eV electron equivalent. The data are consistent with radiogenic backgrounds, and constraints on the spin-independent WIMP-nucleon elastic-scattering cross section are accordingly placed. A region of parameter space relevant to the potential signal from the CDMS-II Si experiment is excluded using the same target for the first time. This result obtained with a limited exposure demonstrates the potential to explore the low-mass WIMP region (<10 GeV c−2) with the upcoming DAMIC100, a 100 g detector currently being installed in SNOLAB.
Direct and inverse Auger scattering are amongst the primary processes that mediate the thermalization of hot carriers in semiconductors. These two processes involve the annihilation or generation of ...an electron-hole pair by exchanging energy with a third carrier, which is either accelerated or decelerated. Inverse Auger scattering is generally suppressed, as the decelerated carriers must have excess energies higher than the band gap itself. In graphene, which is gapless, inverse Auger scattering is, instead, predicted to be dominant at the earliest time delays. Here, <8 fs extreme-ultraviolet pulses are used to detect this imbalance, tracking both the number of excited electrons and their kinetic energy with time-and angle-resolved photoemission spectroscopy. Over a time window of approximately 25 fs after absorption of the pump pulse, we observe an increase in conduction band carrier density and a simultaneous decrease of the average carrier kinetic energy, revealing that relaxation is in fact dominated by inverse Auger scattering. Measurements of carrier scattering at extreme time scales by photoemission will serve as a guide to ultrafast control of electronic properties in solids for petahertz electronics.
The periodontal complex is essential for tooth attachment and function and includes the mineralized tissues, cementum and alveolar bone, separated by the unmineralized periodontal ligament (PDL). To ...gain insights into factors regulating cementum-PDL and bone-PDL borders and protecting against ectopic calcification within the PDL, we employed a proteomic approach to analyze PDL tissue from progressive ankylosis knock-out (Ank−/−) mice, featuring reduced PPi, rapid cementogenesis, and excessive acellular cementum. Using this approach, we identified the matrix protein osteopontin (Spp1/OPN) as an elevated factor of interest in Ank−/− mouse molar PDL. We studied the role of OPN in dental and periodontal development and function. During tooth development in wild-type (WT) mice, Spp1 mRNA was transiently expressed by cementoblasts and strongly by alveolar bone osteoblasts. Developmental analysis from 14 to 240days postnatal (dpn) indicated normal histological structures in Spp1−/− comparable to WT control mice. Microcomputed tomography (micro-CT) analysis at 30 and 90dpn revealed significantly increased volumes and tissue mineral densities of Spp1−/− mouse dentin and alveolar bone, while pulp and PDL volumes were decreased and tissue densities were increased. However, acellular cementum growth was unaltered in Spp1−/− mice. Quantitative PCR of periodontal-derived mRNA failed to identify potential local compensators influencing cementum in Spp1−/− vs. WT mice at 26dpn. We genetically deleted Spp1 on the Ank−/− mouse background to determine whether increased Spp1/OPN was regulating periodontal tissues when the PDL space is challenged by hypercementosis in Ank−/− mice. Ank−/−; Spp1−/− double deficient mice did not exhibit greater hypercementosis than that in Ank−/− mice. Based on these data, we conclude that OPN has a non-redundant role regulating formation and mineralization of dentin and bone, influences tissue properties of PDL and pulp, but does not control acellular cementum apposition. These findings may inform therapies targeted at controlling soft tissue calcification.
•Osteopontin (Spp1/OPN) was identified as increased in periodontal tissues of the Ank-/-mouse model of hypercementosis.•Spp1 is transiently expressed by cementoblasts and strongly expressed by alveolar bone osteoblasts during tooth development.•Spp1 knockout in mice causes increased volumes and densities of dentin and alveolar bone•Acellular cementum growth is unaltered in Spp1-/- mice.•Knock-out of Spp1/OPN on the Ank-/- mouse background does not exacerbate hypercementosis.
Greenspace is important for physical and mental health. Low-income, multi-ethnic populations in deprived urban areas experience several barriers to using greenspace. This may exacerbate health ...inequalities. The current study explored structural and individual determinants of greenspace use amongst parents of young children in an urban, deprived, multi-cultural area situated in the North of England, UK. Semi-structured in-depth interviews and focus group discussions were conducted with 30 parents of children aged 0–3 between December 2016 and May 2017 from a range of ethnic groups. Thematic analyses were informed by the Human Health Habitat Map and the Theoretical Domains Framework. The results show that whilst all families recognised the benefits of greenspaces, use was bounded by a variety of structural, community, and individual determinants. Individual determinants preventing use included lack of knowledge about where to go, or how to get there and confidence in managing young children whilst outdoors. Fear of crime, antisocial behaviour and accidents were the overriding barriers to use, even in high quality spaces. Social and community influences both positively encouraged use (for example, positive social interactions, and practical support by others) and prevented use (antisocial or inappropriate behaviours experienced in greenspace). The built environment was a key barrier to use. Problems related to unsuitable or unsafe playgrounds, no gardens or safe areas for children's play, poor accessibility, and lack of toilets were identified. However, the value that parents and children placed on natural blue and green features was an enabler to use. Contextual influences included external time pressures, difficulties of transporting and caring for young children and poor weather. Multi-sectoral efforts are needed to tackle the uneven playing field experienced by multi-ethnic, urban, deprived communities. Initiatives to increase use should tackle structural quality issues, addressing fears about safety, whilst simultaneously encouraging communities to reclaim their local greenspaces.
•Low income, multi-ethnic families with young children greatly value greenspace.•Greenspaces can become no-go areas for these groups due to fears about safety.•Social support is a key facilitator of use, reducing fears around using these spaces.•Improving quality of greenspace alone is unlikely to increase use.•Empowering communities and co-producing interventions are key to encourage use.
The CONNIE detector prototype is operating at a distance of 30 m from the core of a 3.8 GW sub(th) nuclear reactor with the goal of establishing Charge-Coupled Devices (CCD) as a new technology for ...the detection of coherent elastic neutrino-nucleus scattering. We report on the results of the engineering run with an active mass of 4 g of silicon. The CCD array is described, and the performance observed during the first year is discussed. A compact passive shield was deployed around the detector, producing an order of magnitude reduction in the background rate. The remaining background observed during the run was stable, and dominated by internal contamination in the detector packaging materials. The in-situ calibration of the detector using X-ray lines from fluorescence demonstrates good stability of the readout system. The event rates with the reactor ON and OFF are compared, and no excess is observed coming from nuclear fission at the power plant. The upper limit for the neutrino event rate is set two orders of magnitude above the expectations for the standard model. The results demonstrate the cryogenic CCD-based detector can be remotely operated at the reactor site with stable noise below 2 e super(-) RMS and stable background rates. The success of the engineering test provides a clear path for the upgraded 100 g detector to be deployed during 2016.
The CONNIE experiment Aguilar-Arevalo, A.; Bertou, X.; Bonifazi, C. ...
Journal of physics. Conference series,
10/2016, Letnik:
761, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The CONNIE experiment uses fully depleted, high resistivity CCDs as particle detectors in an attempt to measure for the first time the Coherent Neutrino-Nucleus Elastic Scattering of antineutrinos ...from a nuclear reactor with silicon nuclei. This talk, given at the XV Mexican Workshop on Particles and Fields (MWPF), discussed the potential of CONNIE to perform this measurement, the installation progress at the Angra dos Reis nuclear power plant, as well as the plans for future upgrades.
Mineralization of bones and teeth is tightly regulated by levels of extracellular inorganic phosphate (Pi) and pyrophosphate (PPi). Three regulators that control pericellular concentrations of Pi and ...PPi include tissue-nonspecific alkaline phosphatase (TNAP), progressive ankylosis protein (ANK), and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). Inactivation of these factors results in mineralization disorders affecting teeth and their supporting structures. This study for the first time analyzed the effect of decreased PPi on dental development in individuals with generalized arterial calcification of infancy (GACI) due to loss-of-function mutations in the ENPP1 gene. Four of the 5 subjects reported a history of infraocclusion, overretained primary teeth, ankylosis, and/or slow orthodontic tooth movement, suggesting altered mineral metabolism contributing to disrupted tooth movement and exfoliation. All subjects had radiographic evidence of unusually protruding cervical root morphology in primary and/or secondary dentitions. High-resolution micro–computed tomography (micro-CT) analyses of extracted primary teeth from 3 GACI subjects revealed 4-fold increased cervical cementum thickness (P = 0.00007) and a 23% increase in cementum density (P = 0.009) compared to age-matched healthy control teeth. There were no differences in enamel and dentin densities between GACI and control teeth. Histology revealed dramatically expanded cervical cementum in GACI teeth, including cementocyte-like cells and unusual patterns of cementum resorption and repair. Micro-CT analysis of Enpp1 mutant mouse molars revealed 4-fold increased acellular cementum thickness (P = 0.002) and 5-fold increased cementum volume (P = 0.002), with no changes in enamel or dentin. Immunohistochemistry identified elevated ENPP1 expression in cementoblasts of human and mouse control teeth. Collectively, these findings reveal a novel dental phenotype in GACI and identify ENPP1 genetic mutations associated with hypercementosis. The sensitivity of cementum to reduced PPi levels in both human and mouse teeth establishes this as a well-conserved and fundamental biological process directing cementogenesis across species (ClinicalTrials.gov NCT00369421).
This work presents the luminescent, structural and morphological properties of carbon dots (CDs) synthesized on ZnAl2O4 (ZAO) by a simple combustion method. The samples were annealed at different ...temperatures (600 °C, 700 °C, 800 °C, and 900 °C) in order to change the concentration and size of the CDs on ZAO. The XRD patterns indicated that the annealed samples present a cubic phase (spinel structure). According to the TEM analysis, the CDs on ZAO (CZAO) have a particle size in the range of 2.0-4.0 nm. The annealing treatment, allowed to tune their luminescence emission from green (517 nm) to red (650 nm) under excitation with blue light (455 nm). Yellow, orange, and red phosphorescence were observed for the first time from CDs. The green/yellow and orange/red phosphorescence lasted 5 min and 15 min, respectively, which are the longest phosphorescence times reported for CDs. It is proposed that CDs' luminescence originates from the deep levels formed after the annealing treatment. Due to the color tunability presented by the CDs in fluorescence and phosphorescence, the CZAO samples can be useful for applications in biolabeling, bioimaging, lighting, and signaling for buildings and roads.
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