81,538 research outputs found
Determinations of |V_ub| and |V_cb| from measurements of B -> X_u,c\ell\nu differential decay rates
Methods are described in the framework of light-cone expansion which allow
one to determine the Cabibbo-Kobayashi-Maskawa matrix elements |V_ub| and
|V_cb| from measurements of the differential decay rates as a function of the
scaling variables in the inclusive semileptonic decays of B mesons. By these
model-independent methods the dominant hadronic uncertainties can be avoided
and the B -> X_u\ell\nu decay can be very efficiently differentiated from the B
-> X_c\ell\nu decay, which may lead to precise determinations of |V_ub| and
|V_cb|.Comment: 11 pages, 2 figures, version as published in Mod. Phys. Lett. A, more
discussion, references added, title chang
Substantially Justified? The U.S. Governmentâs Use of Name-Check Technologies in Naturalization Procedures
The U.S. Citizenship and Immigration Services relies upon the Federal Bureau of Investigation to administer the National Name Check Program, which conducts background checks on applicants for naturalization. Backlogs have led to long delays for aspiring citizens and significant legal problems for the government.
This iBrief examines the First Circuitâs ruling in Aronov v. Napolitano that an eighteen-month delay in adjudicating a naturalization application was substantially justified. While the governmentâs inefficiency can be explained partly by an understaffed bureaucracy, overwhelming evidence suggests that these problems are exacerbated by a technological infrastructure that is ill-equipped to handle the scope of the backlog. This iBrief argues that the government should be held liable for its failures; and that long-overdue technological improvements should be implemented to prevent these issues from recurring in the future
Regioselective trans-Carboboration of Propargyl Alcohols
Proper choice of the base allowed trans-diboration of propargyl alcohols with B2(pin)2 to evolve into an exquisitely regioselective procedure for net trans-carboboration. The method is modular as to the newly introduced carbon substituent (aryl, methyl, allyl, benzyl, alkynyl), which is invariably placed distal to the âOH group
Feedback-stabilization of an arbitrary pure state of a two-level atom
Unit-efficiency homodyne detection of the resonance fluorescence of a
two-level atom collapses the quantum state of the atom to a stochastically
moving point on the Bloch sphere. Recently,Hofmann, Mahler, and Hess [Phys.
Rev. A {\bf 57}, 4877 (1998)] showed that by making part of the coherent
driving proportional to the homodyne photocurrent can stabilize the state to
any point on the bottom half of the sphere. Here we reanalyze their proposal
using the technique of stochastic master equations, allowing their results to
be generalized in two ways. First, we show that any point on the upper or lower
half, but not the equator, of the sphere may be stabilized. Second, we consider
non-unit-efficiency detection, and quantify the effectiveness of the feedback
by calculating the maximal purity obtainable in any particular direction in
Bloch space.Comment: 9 pages, 7 figures, Physical Review
Minimal Models for Axion and Neutrino
The PQ mechanism resolving the strong CP problem and the seesaw mechanism
explaining the smallness of neutrino masses may be related in a way that the PQ
symmetry breaking scale and the seesaw scale arise from a common origin.
Depending on how the PQ symmetry and the seesaw mechanism are realized, one has
different predictions on the color and electromagnetic anomalies which could be
tested in the future axion dark matter search experiments. Motivated by this,
we construct various PQ seesaw models which are minimally extended from the
(non-) supersymmetric Standard Model and thus set up different benchmark points
on the axion-photon-photon coupling in comparison with the standard KSVZ and
DFSZ models.Comment: 12 pages and 2 figures, references added, matched with the published
version in PL
A flexible mandatory access control policy for XML databases
A flexible mandatory access control policy (MAC) for XML
databases is presented in this paper. The label type and label
access policy can be defined according to the requirements of
applications. In order to preserve the integrity of data in XML
databases, a constraint between a read access rule and a write
access rule in label access policy is introduced. Rules for label
assignment and propagation are proposed to alleviate the
workload of label assignment. Also, a solution for resolving
conflicts of label assignments is proposed. At last, operations for
implementation of the MAC policy in a XML database are
illustrated
Recommended from our members
A practical mandatory access control model for XML databases
A practical mandatory access control (MAC) model for XML databases is presented in this paper. The
label type and label access policy can be defined according to the requirements of different applications. In order to
preserve the integrity of data in XML databases, a constraint between a read-access rule and a write-access rule in
label access policy is introduced. Rules for label assignment and propagation are presented to alleviate the workload
of label assignments. Furthermore, a solution for resolving conflicts in label assignments is proposed. Rules for
update-related operations, rules for exceptional privileges of ordinary users and the administrator are also proposed
to preserve the security of operations in XML databases. The MAC model, we proposed in this study, has been
implemented in an XML database. Test results demonstrated that our approach provides rational and scalable
performance
- âŠ