499 research outputs found
Continued development of doped-germanium photoconductors for astronomical observations at wavelengths from 30 to 120 micrometers
The development of doped-germanium detectors which have optimized performance in the 30- to 120-mu m wavelength range and are capable of achieving the objectives of the infrared astronomical satellite (IRAS) space mission is discussed. Topics covered include the growth and evaluation of Ge:Ga and Ge:Be crystals, procedures for the fabrication and testing of detectors, irradiance calculations, detector responsivity, and resistance measurements through MOSFET. Test data are presented in graphs and charts
Design-for-test structure to facilitate test vector application with low performance loss in non-test mode.
A switching based circuit is described which allows application of voltage test vectors to internal nodes of a chip without the problem of backdriving. The new circuit has low impact on the performance of an analogue circuit in terms of loss of bandwidth and allows simple application of analogue test voltages into internal nodes. The circuit described facilitates implementation of the forthcoming IEEE 1149.4 DfT philosophy [1]
On Gauge-Invariant Decomposition of Nucleon Spin
We investigate the relation between the known decompositions of the nucleon
spin into its constituents, thereby clarifying in what respect they are common
and in what respect they are different essentially. The decomposition recently
proposed by Chen et al. can be thought of as a nontrivial generalization of the
gauge-variant Jaffe-Manohar decomposition so as to meet the gauge-invariance
requirement of each term of the decomposition. We however point out that there
is another gauge-invariant decomposition of the nucleon spin, which is closer
to the Ji decomposition, while allowing the decomposition of the gluon total
angular momentum into the spin and orbital parts. After clarifying the reason
why the gauge-invariant decomposition of the nucleon spin is not unique, we
discuss which decomposition is more preferable from the experimental viewpoint.Comment: The version to appear in Phys. Rev.
Molecular-beam epitaxial growth of a far-infrared transparent electrode for extrinsic Germanium photoconductors
We have evaluated the optical and electrical properties of a far-infrared
(IR) transparent electrode for extrinsic germanium (Ge) photoconductors at 4 K,
which was fabricated by molecular beam epitaxy (MBE). As a far-IR transparent
electrode, an aluminum (Al)-doped Ge layer is formed at well-optimized doping
concentration and layer thickness in terms of the three requirements: high
far-IR transmittance, low resistivity, and excellent ohmic contact. The
Al-doped Ge layer has the far-IR transmittance of >95 % within the wavelength
range of 40--200 microns, while low resistivity (~5 ohm-cm) and ohmic contact
are ensured at 4 K. We demonstrate the applicability of the MBE technology in
fabricating the far-IR transparent electrode satisfying the above requirements.Comment: 18 pages, 7 figures, accepted for publication in the PAS
Brane universes tested by supernovae
We discuss observational constrains coming from supernovae Ia
\cite{Perlmutter99} imposed on the behaviour of the Randall-Sundrum models. In
the case of dust matter on the brane, the difference between the best-fit
general relativistic model with a -term \cite{Perlmutter99} and the
best-fit brane models becomes detectable for redshifts . It is
interesting that brane models predict brighter galaxies for such redshifts
which is in agreement with the measurement of the supernova
\cite{Riess01} and with the New Data from the High Z Supernovae Search Team
\cite{schmit02}. We also demonstrate that the fit to supernovae data can also
be obtained, if we admit the "super-negative" dark energy
on the brane, where the dark energy in a way mimics the influence of the
cosmological constant. It also appears that the dark energy enlarges the age of
the universe which is demanded in cosmology. Finally, we propose to check for
dark radiation and brane tension by the application of the angular diameter of
galaxies minimum value test.Comment: 4 pages, 5 figures, REVTEX4, amended versio
Risk, commercialism and social purpose: Repositioning the English housing association sector
Originally seen as the âthird armâ of UK housing policy, the independent, not-for-profit housing association sector had long been seen as effective in âfilling the gapâ where the state or market were unable to provide for households in need. Since the 1980s in particular, successive governments had viewed housing associations in favourable terms as efficient, semi-autonomous social businesses, capable of leveraging significant private funding. By 2015, in contrast, central government had come to perceive the sector as inefficient, bureaucratic and wasteful of public subsidy. Making use of institutional theory, this paper considers this paradigm shift and examines the organisational responses to an increasingly challenging operating environment. By focusing, in particular, on large London housing associations, the paper analyses their strategic decision-making to address the opportunities and threats presented. The paper argues that in facing an era of minimal subsidy, low security and high risk, the 2015 reforms represent a critical juncture for the sector. Housing organisations face a stark dilemma about whether to continue a strategy of âprofit for purposeâ or to embrace an unambiguously commercial ethos. The article contends that the trajectory of decision-making (although not unidirectional) leads ultimately towards an increased exposure to risk and vulnerability to changes in the housing market. More fundamentally, the attempt to reconcile social and commercial logics is likely to have wider consequences for the legitimacy of the sector
Delaunay graph mapping based mesh deformation for simulation of a spanwise rigid and flexible flapping NACA0012 wing using DES with parallel implementation
A flapping NACA0012 wing with spanwise rigid and flexible configurations is simulated using the Delaunay graph mapping based mesh deformation technique. This mesh deformation scheme is quite efficient and gives a good alternate to the spring analogy due to its non-iterative nature and simple implementation. It is also well suited for the parallel implementation due to its preservation of the original mesh topology. The preliminary simulated case is spanwise rigid at Garrick frequency of 1.82 and Reynolds number 30,000, corresponding to the experimental data by Heathcote et. al [AIAA- 2006-2870]. The results obtained for this case are in a good agreement with the experimental data for the instantaneous thrust. The simulation also predicts the lag in flapping motion cycle and generated thrust due to the dynamic effects of the flapping cycle and a corresponding phase lag is depicted in the thrust during the flapping cycle. The detailed paper will also include the implementation and results of the spanwise flexible flapping NACA0012 wing
CAG repeat length in the androgen receptor gene is related to age at diagnosis of prostate cancer and response to endocrine therapy, but not to prostate cancer risk
The length of the polymorphic CAG repeat in the N-terminal of the androgen receptor (AR) gene is inversely correlated with the transactivation function of the AR. Some studies have indicated that short CAG repeats are related to higher risk of prostate cancer. We performed a caseâcontrol study to investigate relations between CAG repeat length and prostate cancer risk, tumour grade, tumour stage, age at diagnosis and response to endocrine therapy. The study included 190 AR alleles from prostate cancer patients and 186 AR alleles from female control subjects. All were whites from southern Sweden. The frequency distribution of CAG repeat length was strikingly similar for cases and controls, and no significant correlation between CAG repeat length and prostate cancer risk was detected. However, for men with non-hereditary prostate cancer (n = 160), shorter CAG repeats correlated with younger age at diagnosis (P = 0.03). There were also trends toward associations between short CAG repeats and high grade (P = 0.07) and high stage (P = 0.07) disease. Furthermore, we found that patients with long CAG repeats responded better to endocrine therapy, even after adjusting for pretreatment level of prostate-specific antigen and tumour grade and stage (P = 0.05). We conclude that short CAG repeats in the AR gene correlate with young age at diagnosis of prostate cancer, but not with higher risk of the disease. Selection of patients with early onset prostate cancer in caseâcontrol studies could therefore lead to an over-estimation of the risk of prostate cancer for men with short CAG repeats. An association between long CAG repeats and good response to endocrine therapy was also found, but the mechanism and clinical relevance are unclear. © 1999 Cancer Research Campaig
Finite volume corrections to the electromagnetic current of the nucleon
We compute corrections to both the isovector anomalous magnetic moment and
the isovector electromagnetic current of the nucleon to in the
framework of covariant two-flavor Baryon Chiral Perturbation Theory. We then
apply these corrections to lattice data for the anomalous magnetic moment from
the LHPC, RBC & UKQCD and QCDSF collaborations
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