11,162 research outputs found
SNAP satellite focal plane development
The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics
Supersymmetric Benchmarks with Non-Universal Scalar Masses or Gravitino Dark Matter
We propose and examine a new set of benchmark supersymmetric scenarios, some
of which have non-universal Higgs scalar masses (NUHM) and others have
gravitino dark matter (GDM). The scalar masses in these models are either
considerably larger or smaller than the narrow range allowed for the same
gaugino mass m_{1/2} in the constrained MSSM (CMSSM) with universal scalar
masses m_0 and neutralino dark matter. The NUHM and GDM models with larger m_0
may have large branching ratios for Higgs and/or production in the cascade
decays of heavier sparticles, whose detection we discuss. The phenomenology of
the GDM models depends on the nature of the next-to-lightest supersymmetric
particle (NLSP), which has a lifetime exceeding 10^4 seconds in the proposed
benchmark scenarios. In one GDM scenario the NLSP is the lightest neutralino
\chi, and the supersymmetric collider signatures are similar to those in
previous CMSSM benchmarks, but with a distinctive spectrum. In the other GDM
scenarios based on minimal supergravity (mSUGRA), the NLSP is the lighter stau
slepton {\tilde \tau}_1, with a lifetime between ~ 10^4 and 3 X 10^6 seconds.
Every supersymmetric cascade would end in a {\tilde \tau}_1, which would have a
distinctive time-of-flight signature. Slow-moving {\tilde \tau}_1's might be
trapped in a collider detector or outside it, and the preferred detection
strategy would depend on the {\tilde \tau}_1 lifetime. We discuss the extent to
which these mSUGRA GDM scenarios could be distinguished from gauge-mediated
models.Comment: 52 pages LaTeX, 13 figure
POPULATION RECOVERY OF THE WHOOPING CRANE WITH EMPHASIS ON REINTRODUCTION EFFORTS: PAST AND FUTURE
The U.S. Fish and Wildlife Service (USFWS) began building a captive whooping crane (Grus americana) colony at Patuxent Wildlife Research Center (patuxent), Maryland, in 1966. From 1976 to 1984, 73 eggs from this colony and 216 eggs from Wood Buffalo National Park (Wood Buffalo), Canada, nests were placed in sandhill crane (G. canadensis) nests at Grays Lake National Wildlife Refuge (Grays Lake), Idaho, the site of the first whooping crane reintroduction attempt. Although 84 chicks fledged from the 289 eggs, the egg transfer program has been discontinued because of inordinately high mortality (only ca. 13 birds remain in the wild in 1991) and lack of breeding in survivors. In recent decades new methods have emerged for introducing captive-produced offspring to the wild. Surrogate studies with sandhill cranes, particularly the endangered Mississippi sandhill cranes (G. c. pulla), have shown that young cranes, raised either by captive, conspecific foster parents, or by costumed humans and in close association with live cranes and lifelike crane taxidermic dummies, have high post-release survival rates. These techniques will likely be used in future Whooping crane reintroduction programs. Current recovery objectives for the Whooping crane include expansion of the 2 captive colonies, establishment of a third captive colony in Canada, and reintroduction of 2 additional wild populations. The Kissimmee Prairie in central Florida has been selected for the next release experiment. Evaluation of this site began in 1984, and risk assessment is expected to begin in 1992 with the transfer and monitoring of a group of captivereared, juvenile whooping cranes. These tests of the environment will, if results are favorable, be followed by a full-scale reintroduction effort of at least 20 birds/year beginning in 1994 or 1995
Testing A (Stringy) Model of Quantum Gravity
I discuss a specific model of space-time foam, inspired by the modern
non-perturbative approach to string theory (D-branes). The model views our
world as a three brane, intersecting with D-particles that represent stringy
quantum gravity effects, which can be real or virtual. In this picture, matter
is represented generically by (closed or open) strings on the D3 brane
propagating in such a background. Scattering of the (matter) strings off the
D-particles causes recoil of the latter, which in turn results in a distortion
of the surrounding space-time fluid and the formation of (microscopic, i.e.
Planckian size) horizons around the defects. As a mean-field result, the
dispersion relation of the various particle excitations is modified, leading to
non-trivial optical properties of the space time, for instance a non-trivial
refractive index for the case of photons or other massless probes. Such models
make falsifiable predictions, that may be tested experimentally in the
foreseeable future. I describe a few such tests, ranging from observations of
light from distant gamma-ray-bursters and ultra high energy cosmic rays, to
tests using gravity-wave interferometric devices and terrestrial particle
physics experients involving, for instance, neutral kaons.Comment: 25 pages LATEX, four figures incorporated, uses special proceedings
style. Invited talk at the third international conference on Dark Matter in
Astro and Particle Physics, DARK2000, Heidelberg, Germany, July 10-15 200
First starlight spectrum captured using an integrated photonic micro-spectrograph
Photonic technologies have received growing consideration for incorporation
into next-generation astronomical instrumentation, owing to their miniature
footprint and inherent robustness. In this paper we present results from the
first on-telescope demonstration of a miniature photonic spectrograph for
astronomy, by obtaining spectra spanning the entire H-band from several stellar
targets. The prototype was tested on the 3.9 m Anglo-Australian telescope. In
particular, we present a spectrum of the variable star Pi 01 Gru, with observed
CO molecular absorption bands, at a resolving power R = 2500 at 1600 nm.
Furthermore, we successfully demonstrate the simultaneous acquisition of
multiple spectra with a single spectrograph chip by using multiple fibre
inputs.Comment: 5 Pages, 4 Figures; A&A, Volume 544 (2012
Intense physical activity is associated with cognitive performance in the elderly
Numerous studies have reported positive impacts of physical activity on cognitive function. However, the majority of these studies have utilised physical activity questionnaires or surveys, thus results may have been influenced by reporting biases. Through the objective measurement of routine levels of physical activity via actigraphy, we report a significant association between intensity, but not volume, of physical activity and cognitive functioning. A cohort of 217 participants (aged 60–89 years) wore an actigraphy unit for 7 consecutive days and underwent comprehensive neuropsychological assessment. The cohort was stratified into tertiles based on physical activity intensity. Compared with individuals in the lowest tertile of physical activity intensity, those in the highest tertile scored 9%, 9%, 6% and 21% higher on the digit span, digit symbol, Rey Complex Figure Test (RCFT) copy and Rey Figure Test 30-min recall test, respectively. Statistically, participants in the highest tertile of physical activity intensity performed significantly better on the following cognitive tasks: digit symbol, RCFT copy and verbal fluency test (all P<0.05). The results indicate that intensity rather than quantity of physical activity may be more important in the association between physical activity and cognitive function
Development of an inexpensive tire softening agent from readily available materials to improve traction in race car tires
Developing inexpensive tire softeners can prolong the life of tires and save people money that would be spent on new replacement tires. We have conducted two tests on the treated and untreated tires: the hardness test and the grip test. First, tire hardness was measured with a durometer on a tire that was treated with hot lap and a tire that was not. The tire that was treated with hot lap was slightly softer than the untreated tire substantiating the tire softener\u27s claim. Next, we will be cutting pieces out of the tire (also called omegas) and running them through an instron machine. This machine stretches the omegas at a certain frequency and reports back the hysteresis. The higher the hysteresis, the better the grip. Testing is ongoing, but initial results show that the tire softners did make the tires softer
Report of the QCD Tools Working Group
We report on the activities of the ``QCD Tools for heavy flavors and new
physics searches'' working group of the Run II Workshop on QCD and Weak Bosons.
The contributions cover the topics of improved parton showering and comparisons
of Monte Carlo programs and resummation calculations, recent developments in
Pythia, the methodology of measuring backgrounds to new physics searches,
variable flavor number schemes for heavy quark electro-production, the
underlying event in hard scattering processes, and the Monte Carlo MCFM for NLO
processes.Comment: LaTeX, 47 pages, 41 figures, 10 tables, uses run2col.sty, to appear
in the Proceedings of the Workshop on "QCD and Weak Boson Physics in Run II",
Fermilab, March - November 199
Managing clinical uncertainty in older people towards the end of life: a systematic review of person-centred tools.
BACKGROUND: Older people with multi-morbidities commonly experience an uncertain illness trajectory. Clinical uncertainty is challenging to manage, with risk of poor outcomes. Person-centred care is essential to align care and treatment with patient priorities and wishes. Use of evidence-based tools may support person-centred management of clinical uncertainty. We aimed to develop a logic model of person-centred evidence-based tools to manage clinical uncertainty in older people. METHODS: A systematic mixed-methods review with a results-based convergent synthesis design: a process-based iterative logic model was used, starting with a conceptual framework of clinical uncertainty in older people towards the end of life. This underpinned the methods. Medline, PsycINFO, CINAHL and ASSIA were searched from 2000 to December 2019, using a combination of terms: "uncertainty" AND "palliative care" AND "assessment" OR "care planning". Studies were included if they developed or evaluated a person-centred tool to manage clinical uncertainty in people aged ≥65 years approaching the end of life and quality appraised using QualSyst. Quantitative and qualitative data were narratively synthesised and thematically analysed respectively and integrated into the logic model. RESULTS: Of the 17,095 articles identified, 44 were included, involving 63 tools. There was strong evidence that tools used in clinical care could improve identification of patient priorities and needs (n = 14 studies); that tools support partnership working between patients and practitioners (n = 8) and that tools support integrated care within and across teams and with patients and families (n = 14), improving patient outcomes such as quality of death and dying and satisfaction with care. Communication of clinical uncertainty to patients and families had the least evidence and is challenging to do well. CONCLUSION: The identified logic model moves current knowledge from conceptualising clinical uncertainty to applying evidence-based tools to optimise person-centred management and improve patient outcomes. Key causal pathways are identification of individual priorities and needs, individual care and treatment and integrated care. Communication of clinical uncertainty to patients is challenging and requires training and skill and the use of tools to support practice
Higgs friends and counterfeits at hadron colliders
We consider the possibility of "Higgs counterfeits" - scalars that can be
produced with cross sections comparable to the SM Higgs, and which decay with
identical relative observable branching ratios, but which are nonetheless not
responsible for electroweak symmetry breaking. We also consider a related
scenario involving "Higgs friends," fields similarly produced through gg fusion
processes, which would be discovered through diboson channels WW, ZZ, gamma
gamma, or even gamma Z, potentially with larger cross sections times branching
ratios than for the Higgs. The discovery of either a Higgs friend or a Higgs
counterfeit, rather than directly pointing towards the origin of the weak
scale, would indicate the presence of new colored fields necessary for the
sizable production cross section (and possibly new colorless but electroweakly
charged states as well, in the case of the diboson decays of a Higgs friend).
These particles could easily be confused for an ordinary Higgs, perhaps with an
additional generation to explain the different cross section, and we emphasize
the importance of vector boson fusion as a channel to distinguish a Higgs
counterfeit from a true Higgs. Such fields would naturally be expected in
scenarios with "effective Z's," where heavy states charged under the SM produce
effective charges for SM fields under a new gauge force. We discuss the
prospects for discovery of Higgs counterfeits, Higgs friends, and associated
charged fields at the LHC.Comment: 27 pages, 5 figures. References added and typos fixe
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