1,902 research outputs found
Transitions Induced by the Discreteness of Molecules in a Small Autocatalytic System
Autocatalytic reaction system with a small number of molecules is studied
numerically by stochastic particle simulations. A novel state due to
fluctuation and discreteness in molecular numbers is found, characterized as
extinction of molecule species alternately in the autocatalytic reaction loop.
Phase transition to this state with the change of the system size and flow is
studied, while a single-molecule switch of the molecule distributions is
reported. Relevance of the results to intracellular processes are briefly
discussed.Comment: 5 pages, 4 figure
Bypassing the structural bottleneck in the ultrafast melting of electronic order
The emergent properties of quantum materials, such as symmetry-broken phases
and associated spectral gaps, can be effectively manipulated by ultrashort
photon pulses. Impulsive optical excitation generally results in a complex
non-equilibrium electron and lattice dynamics that involves multiple processes
on distinct timescales, and a common conception is that for times shorter than
about 100 fs the gap in the electronic spectrum is not seriously affected by
lattice vibrations. Here, we directly monitor the photo-induced collapse of the
spectral gap in a canonical charge-density-wave material, blue bronze
Rb0.3MoO3. We find that ultra-fast (about 60 fs) vibrational disordering due to
efficient hot-electron energy dissipation quenches the gap significantly faster
than the typical structural bottleneck time corresponding to one half-cycle
oscillation (about 315 fs) of the coherent charge-density-wave amplitude mode.
This result not only demonstrates the importance of incoherent lattice motion
in the photo-induced quenching of electronic order, but also resolves the
perennial debate about the nature of the spectral gap in a coupled
electron-lattice system
Standard Model Higgs Physics at a 4 TeV Upgraded Tevatron
We compute an array of Standard Model Higgs boson (\hsm) signals and
backgrounds for a possible upgrade of the Tevatron to E_{\rm cm}=4\tev.
Taking \mt\geq 140\gev, and assuming a total accumulated luminosity of
L=30\fbi, we find that a Standard Model Higgs boson with \mhsm\lsim 110\gev
could almost certainly be detected using the \wpm\hsm\rta l\nu b\anti b mode.
A Higgs boson with mass between \sim 120\gev and \sim 140\gev or above
\sim 230-250\gev almost certainly would not be seen. A Higgs boson with
\mhsm\sim 150\gev or 200\lsim\mhsm\lsim 230-250\gev has a decent chance of
being detected in the ZZ\rta 4l mode. There would also be some possibility of
discovering the \hsm in the WW\rta l\nu jj mode for 150\lsim\mhsm\lsim
200\gev. Finally, hints of an event excess in the WW\rta ll \nu\nu mode due
to the \hsm might emerge for 140\lsim\mhsm\lsim 180\gev. Given the
difficult nature of the Higgs boson signals for \mhsm values beyond the reach
of LEP-200, and the discontinuous \mhsm range that could potentially be
probed, justification of an upgrade of the Tevatron to 4\tev on the basis of
its potential for Standard Model Higgs boson discovery would seem
inappropriate.Comment: 21 pages; requires phyzzx.tex and tables.tex; full postscript file
including embedded figures available via anonymous ftp at ucdhep.ucdavis.edu
as [anonymous.gunion]4tev.ps, preprint UCD-94-1
Anomalous Higgs Couplings
We review the effects of new effective interactions on the Higgs boson
phenomenology. New physics in the electroweak bosonic sector is expected to
induce additional interactions between the Higgs doublet field and the
electroweak gauge bosons leading to anomalous Higgs couplings as well as to
anomalous gauge-boson self-interactions. Using a linearly realized invariant effective Lagrangian to describe the bosonic sector of
the Standard Model, we review the effects of the new effective interactions on
the Higgs boson production rates and decay modes. We summarize the results from
searches for the new Higgs signatures induced by the anomalous interactions in
order to constrain the scale of new physics in particular at CERN LEP and
Fermilab Te vatron colliders.Comment: 35 pages, latex using epsfig.sty psfig.sty and axodraw.sty, 16
postscript figure
QCD and Yukawa corrections to single-top-quark production via q qbar -> t bbar
We calculate the O(alpha_s) and O(alpha_W m_t^2/M_W^2) corrections to the
production of a single top quark via the weak process q qbar -> t bbar at the
Fermilab Tevatron and the CERN Large Hadron Collider. An accurate calculation
of the cross section is necessary in order to extract |V_tb| from experiment.Comment: LaTeX, 13 pages, replaced with version to appear in Phys. Rev.
Training scholars in dissemination and implementation research for cancer prevention and control: A mentored approach
Abstract Background As the field of D&I (dissemination and implementation) science grows to meet the need for more effective and timely applications of research findings in routine practice, the demand for formalized training programs has increased concurrently. The Mentored Training for Dissemination and Implementation Research in Cancer (MT-DIRC) Program aims to build capacity in the cancer control D&I research workforce, especially among early career researchers. This paper outlines the various components of the program and reports results of systematic evaluations to ascertain its effectiveness. Methods Essential features of the program include selection of early career fellows or more experienced investigators with a focus relevant to cancer control transitioning to a D&I research focus, a 5-day intensive training institute, ongoing peer and senior mentoring, mentored planning and work on a D&I research proposal or project, limited pilot funding, and training and ongoing improvement activities for mentors. The core faculty and staff members of the MT-DIRC program gathered baseline and ongoing evaluation data regarding D&I skill acquisition and mentoring competency through participant surveys and analyzed it by iterative collective reflection. Results A majority (79%) of fellows are female, assistant professors (55%); 59% are in allied health disciplines, and 48% focus on cancer prevention research. Forty-three D&I research competencies were assessed; all improved from baseline to 6 and 18 months. These effects were apparent across beginner, intermediate, and advanced initial D&I competency levels and across the competency domains. Mentoring competency was rated very highly by the fellows––higher than rated by the mentors themselves. The importance of different mentoring activities, as rated by the fellows, was generally congruent with their satisfaction with the activities, with the exception of relatively greater satisfaction with the degree of emotional support and relatively lower satisfaction for skill building and opportunity initially. Conclusions These first years of MT-DIRC demonstrated the program’s ability to attract, engage, and improve fellows’ competencies and skills and implement a multicomponent mentoring program that was well received. This account of the program can serve as a basis for potential replication and evolution of this model in training future D&I science researchers
Detecting the intermediate-mass Higgs boson through the associate production channel pp --> t + anti-t + H + X
We examine the detection of the intermediate-mass Higgs boson (IMH) at LHC
through the associate production channel pp-->t+(anti-t)+H+X-->l+photon+
photon+X'. It is shown that by applying kinematic cuts or b-tagging on the
final state jets, the main backgrounds of W(-->l+nu)+photon+photon+(n-jet) can
be reduced substantially without significant loss of signals. It is possible to
detect the Higgs boson at LHC through the pp-->t+(anti-t)+H+X channel using a
modest photon detector with mass resolution of about 3% of the photon pair
invariant mass.Comment: 10 pages, standard LaTex fil
Compact Frontend-Electronics and Bidirectional 3.3 Gbps Optical Datalink for Fast Proportional Chamber Readout
The 9600 channels of the multi-wire proportional chamber of the H1 experiment
at HERA have to be read out within 96 ns and made available to the trigger
system. The tight spatial conditions at the rear end flange require a compact
bidirectional readout electronics with minimal power consumption and dead
material.
A solution using 40 identical optical link modules, each transferring the
trigger information with a physical rate of 4 x 832 Mbps via optical fibers,
has been developed and commisioned. The analog pulses from the chamber can be
monitored and the synchronization to the global HERA clock signal is ensured.Comment: 13 pages, 10 figure
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