1,375 research outputs found
Infrared constraints on the dark mass concentration observed in the cluster Abell 1942
We present a deep H-band image of the region in the vicinity of the cluster
Abell 1942 containing the puzzling dark matter concentration detected in an
optical weak lensing study by Erben et al. (2000). We demonstrate that our
limiting magnitude, H=22, would be sufficient to detect clusters of appropriate
mass out to redshifts comparable with the mean redshift of the background
sources. Despite this, our infrared image reveals no obvious overdensity of
sources at the location of the lensing mass peak, nor an excess of sources in
the I-H vs. H colour-magnitude diagram. We use this to further constrain the
luminosity and mass-to-light ratio of the putative dark clump as a function of
its redshift. We find that for spatially-flat cosmologies, background lensing
clusters with reasonable mass-to-light ratios lying in the redshift range 0<z<1
are strongly excluded, leaving open the possibility that the mass concentration
is a new type of truly dark object.Comment: 8 pages, 7 figures. MNRAS submitted (after referee revision
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Saving Water Saves Energy
Hot water use in households, for showers and baths as wellas for washing clothes and dishes, is a major driver of household energyconsumption. Other household uses of water (such as irrigatinglandscaping) require additional energy in other sectors to transport andtreat the water before use, and to treat wastewater. In California, 19percent of total electricity for all sectors combined and 32 percent ofnatural gas consumption is related to water. There is a criticalinterdependence between energy and water systems: thermal power plantsrequire cooling water, and water pumping and treatment require energy.Energy efficiency can be increased by a number of means, includingmore-efficient appliances (e.g., clothes washers or dishwashers that useless total water and less heated water), water-conserving plumbingfixtures and fittings (e.g., showerheads, faucets, toilets) and changesin consumer behavior (e.g., lower temperature set points for storagewater heaters, shorter showers). Water- and energy-conserving activitiescan help offset the stress imposed on limited water (and energy) suppliesfrom increasing population in some areas, particularly in drought years,or increased consumption (e.g., some new shower systems) as a result ofincreased wealth. This paper explores the connections between householdwater use and energy, and suggests options for increased efficiencies inboth individual technologies and systems. Studies indicate that urbanwater use can be reduced cost-effectively by up to 30 percent withcommercially available products. The energy savings associated with watersavings may represent a large additional and largely untappedcost-effective opportunity
Concurrent MEK targeted therapy prevents MAPK pathway reactivation during BRAFV600E targeted inhibition in a novel syngeneic murine glioma model.
Inhibitors of BRAFV600E kinase are currently under investigations in preclinical and clinical studies involving BRAFV600E glioma. Studies demonstrated clinical response to such individualized therapy in the majority of patients whereas in some patients tumors continue to grow despite treatment. To study resistance mechanisms, which include feedback activation of mitogen-activated protein kinase (MAPK) signaling in melanoma, we developed a luciferase-modified cell line (2341luc) from a BrafV600E mutant and Cdkn2a- deficient murine high-grade glioma, and analyzed its molecular responses to BRAFV600E- and MAPK kinase (MEK)-targeted inhibition. Immunocompetent, syngeneic FVB/N mice with intracranial grafts of 2341luc were tested for effects of BRAFV600E and MEK inhibitor treatments, with bioluminescence imaging up to 14-days after start of treatment and survival analysis as primary indicators of inhibitor activity. Intracranial injected tumor cells consistently generated high-grade glioma-like tumors in syngeneic mice. Intraperitoneal daily delivery of BRAFV600E inhibitor dabrafenib only transiently suppressed MAPK signaling, and rather increased Akt signaling and failed to extend survival for mice with intracranial 2341luc tumor. MEK inhibitor trametinib delivered by oral gavage daily suppressed MAPK pathway more effectively and had a more durable anti-growth effect than dabrafenib as well as a significant survival benefit. Compared with either agent alone, combined BRAFV600E and MEK inhibitor treatment was more effective in reducing tumor growth and extending animal subject survival, as corresponding to sustained MAPK pathway inhibition. Results derived from the 2341luc engraftment model application have clinical implications for the management of BRAFV600E glioma
HIV Drug Resistance Early Warning Indicators in Cohorts of Individuals Starting Antiretroviral Therapy Between 2004 and 2009: World Health Organization Global Report From 50 Countries
The World Health Organization developed a set of human immunodeficiency virus drug resistance (HIVDR) early warning indicators (EWIs) to assess antiretroviral therapy clinic and program factors associated with HIVDR. EWIs are monitored by abstracting data routinely recorded in clinical records, and the results enable clinics and program managers to identify problems that should be addressed to minimize preventable emergence of HIVDR in clinic populations. As of June 2011, 50 countries monitored EWIs, covering 131 686 patients initiating antiretroviral treatment between 2004 and 2009 at 2107 clinics. HIVDR prevention is associated with patient care (appropriate prescribing and patient monitoring), patient behavior (adherence), and clinic/program management efforts to reduce treatment interruptions (follow up, retention on first-line ART, procurement and supply management of antiretroviral drugs). EWIs measure these factors and the results have been used to optimize patient and population treatment outcome
Shaping electron wave functions in a carbon nanotube with a parallel magnetic field
A magnetic field, through its vector potential, usually causes measurable
changes in the electron wave function only in the direction transverse to the
field. Here we demonstrate experimentally and theoretically that in carbon
nanotube quantum dots, combining cylindrical topology and bipartite hexagonal
lattice, a magnetic field along the nanotube axis impacts also the longitudinal
profile of the electronic states. With the high (up to 17T) magnetic fields in
our experiment the wave functions can be tuned all the way from "half-wave
resonator" shape, with nodes at both ends, to "quarter-wave resonator" shape,
with an antinode at one end. This in turn causes a distinct dependence of the
conductance on the magnetic field. Our results demonstrate a new strategy for
the control of wave functions using magnetic fields in quantum systems with
nontrivial lattice and topology.Comment: 5 figure
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Economics of residential gas furnaces and water heaters in United States new construction market
New single-family home construction represents a significant and important market for the introduction of energy-efficient gas-fired space heating and water-heating equipment. In the new construction market, the choice of furnace and water-heater type is primarily driven by first cost considerations and the availability of power vent and condensing water heaters. Few analysis have been performed to assess the economic impacts of the different combinations of space and water-heating equipment. Thus, equipment is often installed without taking into consideration the potential economic and energy savings of installing space and water-heating equipment combinations. In this study, we use a life-cycle cost analysis that accounts for uncertainty and variability of the analysis inputs to assess the economic benefits of gas furnace and water-heater design combinations. This study accounts not only for the equipment cost but also for the cost of installing, maintaining, repairing, and operating the equipment over its lifetime. Overall, this study, which is focused on US single-family new construction households that install gas furnaces and storage water heaters, finds that installing a condensing or power-vent water heater together with condensing furnace is the most cost-effective option for the majority of these houses. Furthermore, the findings suggest that the new construction residential market could be a target market for the large-scale introduction of a combination of condensing or power-vent water heaters with condensing furnaces
Small intestinal injuries in mice caused by a new toxin, Azaspiracid, isolated from Irish mussels
Pathological changes of the small intestine caused by a new toxin, azaspiracid, from Irish mussels were studied. Human poisoning cases included both diarrhetic shellfish and paralitic shellfish poisoning symptoms. The present paper focused on the former. Injuries were observed in the Upper part of the small intestine, where lamina propria in the villi became atrophied at the initial stage, followed by desquamation of epithelial cells and shortening of villi. The injuries were different from the DSP toxin okadaic acid; 1) they developed very slowly after a lag time of about 3 hr, 2) recovery was very late, 3) initial target and process were different
Business Case for Energy Efficiency in Support of Climate Change Mitigation, Economic and Societal Benefits in India
This study seeks to provide policymakers and other stakeholders with actionable information towards a road map for reducing energy consumption cost-effectively. We focus on individual end use equipment types (hereafter referred to as appliance groups) that might be the subject of policies - such as labels, energy performance standards, and incentives - to affect market transformation in the short term, and on high-efficiency technology options that are available today. the high efficiency or Business Case scenario is constructed around a model of cost-effective efficiency improvement. Our analysis demonstrates that a significant reduction in energy consumption and emissions is achievable at net negative cost, that is, as a profitable investment for consumers. Net savings are calculated assuming no additional costs to energy consumption such as carbon taxes. Savings relative to the base case as calculated in this way is often referred to as “economic savings potential”. So far, the Indian market has responded favorably to government efficiency initiatives, with Indian manufacturers producing a higher fraction of high-efficiency equipment than before program implementation. This study highlights both the financial benefit and the scope of potential impact for adopting this equipment, all of which is already readily available on the market. The approach of the study is to assess the impact of short-term actions on long-term impacts. “Short-term” market transformation is assumed to occur by 2015, while “long-term” energy demand reduction impacts are assessed in 2030. In the intervening years, most but not all of the equipment studied will turn over completely. The Business Case concentrates on technologies for which cost-effectiveness can be clearly demonstrated
FIRBACK IV: Towards the nature of the 170microns source population
We present a detailed study of the brighter ( detections) sources
in the 170m FIRBACK northern N1 ISO survey, with the help of complementary
data in the optical, radio, and mid-IR domain. For 82% of them, an optical
galaxy counterpart is identified, either as the unique source of the IR
emission, or as part of a multiple identification. With less than 15% of AGNs,
these sources are essentially local, moderate starbursters with a dominating
cold dust component. and represent a population of cold galaxies rather
neglected up to now. Their colours do not match those of the far-IR Cosmic IR
Background (CIB), to which they contribute less than 5%. The bulk of the
sources contributing to the CIB is thus to be searched for in more distant
galaxies, possibly counterparts of the fainter FIRBACK sources still under
study. These bright, local, galaxies however play an important role in the
evolution of IR galaxies: they dominate the number counts at high 170 m
fluxes, and represent half of the contribution at 250 mJy. Although not
particularly massive (typically M*), they form more stars than a typical spiral
galaxy and many are bulge dominated, that could represent the remnant of a
former merger. The fainter part of this population may represent the missing
link with the higher-z sources found in sub-mm observations.Comment: 40 pages, 10 figures, accepted for publication in Astronomy &
Astrophysic
The Primordial Inflation Polarization Explorer (PIPER)
The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne
cosmic microwave background (CMB) polarimeter designed to search for evidence
of inflation by measuring the large-angular scale CMB polarization signal.
BICEP2 recently reported a detection of B-mode power corresponding to the
tensor-to-scalar ratio r = 0.2 on ~2 degree scales. If the BICEP2 signal is
caused by inflationary gravitational waves (IGWs), then there should be a
corresponding increase in B-mode power on angular scales larger than 18
degrees. PIPER is currently the only suborbital instrument capable of fully
testing and extending the BICEP2 results by measuring the B-mode power spectrum
on angular scales = ~0.6 deg to 90 deg, covering both the reionization
bump and recombination peak, with sensitivity to measure the tensor-to-scalar
ratio down to r = 0.007, and four frequency bands to distinguish foregrounds.
PIPER will accomplish this by mapping 85% of the sky in four frequency bands
(200, 270, 350, 600 GHz) over a series of 8 conventional balloon flights from
the northern and southern hemispheres. The instrument has background-limited
sensitivity provided by fully cryogenic (1.5 K) optics focusing the sky signal
onto four 32x40-pixel arrays of time-domain multiplexed Transition-Edge Sensor
(TES) bolometers held at 140 mK. Polarization sensitivity and systematic
control are provided by front-end Variable-delay Polarization Modulators
(VPMs), which rapidly modulate only the polarized sky signal at 3 Hz and allow
PIPER to instantaneously measure the full Stokes vector (I, Q, U, V) for each
pointing. We describe the PIPER instrument and progress towards its first
flight.Comment: 11 pages, 7 figures. To be published in Proceedings of SPIE Volume
9153. Presented at SPIE Astronomical Telescopes + Instrumentation 2014,
conference 915
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