4,034 research outputs found
Reconceptualizing Security Strategies For Courts: Developing A Typology For Safer Court Environments
There have been heightened concerns about security in courts in recent years, prompting a strong response that has largely been focused on perimeter security. This paper draws on recent research conducted in Australian on court users' safety needs, to propose a typology for designing safer courtroom environments that moves beyond the entry point to the court, and incorporates consideration of process and design elements
Molecular gyroscopes and biological effects of weak ELF magnetic fields
Extremely-low-frequency magnetic fields are known to affect biological
systems. In many cases, biological effects display `windows' in biologically
effective parameters of the magnetic fields: most dramatic is the fact that
relatively intense magnetic fields sometimes do not cause appreciable effect,
while smaller fields of the order of 10--100 T do. Linear resonant
physical processes do not explain frequency windows in this case. Amplitude
window phenomena suggest a nonlinear physical mechanism. Such a nonlinear
mechanism has been proposed recently to explain those `windows'. It considers
quantum-interference effects on protein-bound substrate ions. Magnetic fields
cause an interference of ion quantum states and change the probability of
ion-protein dissociation. This ion-interference mechanism predicts specific
magnetic-field frequency and amplitude windows within which biological effects
occur. It agrees with a lot of experiments. However, according to the
mechanism, the lifetime of ion quantum states within a protein
cavity should be of unrealistic value, more than 0.01 s for frequency band
10--100 Hz. In this paper, a biophysical mechanism has been proposed that (i)
retains the attractive features of the ion interference mechanism and (ii) uses
the principles of gyroscopic motion and removes the necessity to postulate
large lifetimes. The mechanism considers dynamics of the density matrix of the
molecular groups, which are attached to the walls of protein cavities by two
covalent bonds, i.e., molecular gyroscopes. Numerical computations have shown
almost free rotations of the molecular gyros. The relaxation time due to van
der Waals forces was about 0.01 s for the cavity size of 28 angstr\"{o}ms.Comment: 10 pages, 7 figure
Accretion Disks and Dynamos: Toward a Unified Mean Field Theory
Conversion of gravitational energy into radiation in accretion discs and the
origin of large scale magnetic fields in astrophysical rotators have often been
distinct topics of research. In semi-analytic work on both problems it has been
useful to presume large scale symmetries, necessarily resulting in mean field
theories. MHD turbulence makes the underlying systems locally asymmetric and
nonlinear. Synergy between theory and simulations should aim for the
development of practical mean field models that capture essential physics and
can be used for observational modeling. Mean field dynamo (MFD) theory and
alpha-viscosity accretion theory exemplify such ongoing pursuits. 21st century
MFD theory has more nonlinear predictive power compared to 20th century MFD
theory, whereas accretion theory is still in a 20th century state. In fact,
insights from MFD theory are applicable to accretion theory and the two are
artificially separated pieces of what should be a single theory. I discuss
pieces of progress that provide clues toward a unified theory. A key concept is
that large scale magnetic fields can be sustained via local or global magnetic
helicity fluxes or via relaxation of small scale magnetic fluctuations, without
the kinetic helicity driver of 20th century textbooks. These concepts may help
explain the formation of large scale fields that supply non-local angular
momentum transport via coronae and jets in a unified theory of accretion and
dynamos. In diagnosing the role of helicities and helicity fluxes in disk
simulations, each disk hemisphere should be studied separately to avoid being
misled by cancelation that occurs as a result of reflection asymmetry. The
fraction of helical field energy in disks is expected to be small compared to
the total field in each hemisphere as a result of shear, but can still be
essential for large scale dynamo action.Comment: For the Proceedings of the Third International Conference and
Advanced School "Turbulent Mixing and Beyond," TMB-2011 held on 21 - 28
August 2011 at the Abdus Salam International Centre for Theoretical Physics,
Trieste, http://users.ictp.it/~tmb/index2011.html Italy, To Appear in Physica
Scripta (corrected small items to match version in print
Efficiency at optimal work from finite reservoirs: a probabilistic perspective
We revisit the classic thermodynamic problem of maximum work extraction from
two arbitrary sized hot and cold reservoirs, modelled as perfect gases.
Assuming ignorance about the extent to which the process has advanced, which
implies an ignorance about the final temperatures, we quantify the prior
information about the process and assign a prior distribution to the unknown
temperature(s). This requires that we also take into account the temperature
values which are regarded to be unphysical in the standard theory, as they lead
to a contradiction with the physical laws. Instead in our formulation, such
values appear to be consistent with the given prior information and hence are
included in the inference. We derive estimates of the efficiency at optimal
work from the expected values of the final temperatures, and show that these
values match with the exact expressions in the limit when any one of the
reservoirs is very large compared to the other. For other relative sizes of the
reservoirs, we suggest a weighting procedure over the estimates from two valid
inference procedures, that generalizes the procedure suggested earlier in [J.
Phys. A: Math. Theor. {\bf 46}, 365002 (2013)]. Thus a mean estimate for
efficiency is obtained which agrees with the optimal performance to a high
accuracy.Comment: 14 pages, 6 figure
Mean magnetic field generation in sheared rotators
A generalized mean magnetic field induction equation for differential
rotators is derived, including a compressibility, and the anisotropy induced on
the turbulent quantities from the mean magnetic field itself and a mean
velocity shear. Derivations of the mean field equations often do not emphasize
that there must be anisotropy and inhomogeneity in the turbulence for mean
field growth. The anisotropy from shear is the source of a term involving the
product of the mean velocity gradient and the cross-helicity correlation of the
isotropic parts of the fluctuating velocity and magnetic field,
\lb{\bfv}\cdot{\bfb}\rb^{(0)}. The full mean field equations are derived to
linear order in mean fields, but it is also shown that the cross-helicity term
survives to all orders in the velocity shear. This cross-helicity term can
obviate the need for a pre-existing seed mean magnetic field for mean field
growth: though a fluctuating seed field is necessary for a non-vanishing
cross-helicity, the term can produce linear (in time) mean field growth of the
toroidal field from zero mean field. After one vertical diffusion time, the
cross-helicity term becomes sub-dominant and dynamo exponential
amplification/sustenance of the mean field can subsequently ensue. The
cross-helicity term should produce odd symmetry in the mean magnetic field, in
contrast to the usually favored even modes of the dynamo amplification in
sheared discs. This may be important for the observed mean field geometries of
spiral galaxies. The strength of the mean seed field provided by the cross-
helicity depends linearly on the magnitude of the cross-helicity.Comment: 15 pages, LaTeX, matches version accepted to ApJ, minor revision
Jet Deflection via Cross winds: Laboratory Astrophysical Studies
We present new data from High Energy Density (HED) laboratory experiments
designed to explore the interaction of a heavy hypersonic radiative jet with a
cross wind. The jets are generated with the MAGPIE pulsed power machine where
converging conical plasma flows are produced from a cylindrically symmetric
array of inclined wires. Radiative hypersonic jets emerge from the convergence
point. The cross wind is generated by ablation of a plastic foil via
soft-X-rays from the plasma convergence region. Our experiments show that the
jets are deflected by the action of the cross wind with the angle of deflection
dependent on the proximity of the foil. Shocks within the jet beam are apparent
in the data. Analysis of the data shows that the interaction of the jet and
cross wind is collisional and therefore in the hydro-dynamic regime. MHD plasma
code simulations of the experiments are able to recover the deflection
behaviour seen in the experiments. We consider the astrophysical relevance of
these experiments applying published models of jet deflection developed for AGN
and YSOs. Fitting the observed jet deflections to quadratic trajectories
predicted by these models allows us to recover a set of plasma parameters
consistent with the data. We also present results of 3-D numerical simulations
of jet deflection using a new astrophysical Adaptive Mesh Refinement code.
These simulations show highly structured shocks occurring within the beam
similar to what was observed in the experimentsComment: Submitted to ApJ. For a version with figures go to
http://web.pas.rochester.edu/~afrank/labastro/CW/Jet-Wind-Frank.pd
A randomized, phase II study of afatinib versus cetuximab in metastatic or recurrent squamous cell carcinoma of the head and neck.
BackgroundAfatinib is an oral, irreversible ErbB family blocker that has shown activity in epidermal growth factor receptor (EGFR)-mutated lung cancer. We hypothesized that the agent would have greater antitumor activity compared with cetuximab in recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) patients, whose disease has progressed after platinum-containing therapy.Patients and methodsAn open-label, randomized, phase II trial was conducted in 43 centers; 124 patients were randomized (1 : 1) to either afatinib (50 mg/day) or cetuximab (250 mg/m(2)/week) until disease progression or intolerable adverse events (AEs) (stage I), with optional crossover (stage II). The primary end point was tumor shrinkage before crossover assessed by investigator (IR) and independent central review (ICR).ResultsA total of 121 patients were treated (61 afatinib, 60 cetuximab) and 68 crossed over to stage II (32 and 36 respectively). In stage I, mean tumor shrinkage by IR/ICR was 10.4%/16.6% with afatinib and 5.4%/10.1% with cetuximab (P = 0.46/0.30). Objective response rate was 16.1%/8.1% with afatinib and 6.5%/9.7% with cetuximab (IR/ICR). Comparable disease control rates were observed with afatinib (50%) and cetuximab (56.5%) by IR; similar results were seen by ICR. Most common grade â„3 drug-related AEs (DRAEs) were rash/acne (18% versus 8.3%), diarrhea (14.8% versus 0%), and stomatitis/mucositis (11.5% versus 0%) with afatinib and cetuximab, respectively. Patients with DRAEs leading to treatment discontinuation were 23% with afatinib and 5% with cetuximab. In stage II, disease control rate (IR/ICR) was 38.9%/33.3% with afatinib and 18.8%/18.8% with cetuximab.ConclusionAfatinib showed antitumor activity comparable to cetuximab in R/M HNSCC in this exploratory phase II trial, although more patients on afatinib discontinued treatment due to AEs. Sequential EGFR/ErbB treatment with afatinib and cetuximab provided sustained clinical benefit in patients after crossover, suggesting a lack of cross-resistance
- âŠ