5,410 research outputs found
The Simplest Dark-Matter Model, CDMS II Results, and Higgs Detection at LHC
The direct-search experiment for dark matter performed by the CDMS II
Collaboration has observed two candidate events. Although these events cannot
be interpreted as significant evidence for the presence of weakly interacting
massive particle (WIMP) dark matter (DM), the total CDMS II data have led to an
improved upper-limit on the WIMP-nucleon spin-independent cross-section. We
study some implications of these results for the simplest WIMP DM model, the
SM+D, which extends the standard model (SM) by the addition of a real
SM-singlet scalar field dubbed darkon to play the role of the DM. We find that,
although the CDMS II data rule out a sizable portion of parameter space of the
model, a large part of the parameter space is still allowed. We obtain strong
correlations among the darkon mass, darkon-nucleon cross-section, mass of the
Higgs boson, and branching ratio of its invisible decay. We point out that
measurements of the Higgs invisible branching-ratio at the LHC can lift some
possible ambiguities in determining the darkon mass from direct DM searches.Comment: 10 pages, 5 figures; results updated with WMAP7 input, references
added, conclusions unchanged, to match published versio
CDMS stands for Constrained Dark Matter Singlet
Motivated by the two candidate Dark Matter events observed by the CDMS
experiment, we consider a Constrained Dark Matter Singlet (CDMS) model that,
with no free parameters, predicts the DM mass and the DM direct cross section
to be in the range weakly favored by CDMS.Comment: 6 pages, 2 figure
Gauging U(1) symmetries and the number of right-handed neutrinos
In this letter we consider that assuming: a) that the only left-handed
neutral fermions are the active neutrinos, b) that is a gauge symmetry,
and c) that the assignment is restricted to the integer numbers, the
anomaly cancellation imply that at least three right-handed neutrinos must be
added to the minimal representation content of the electroweak standard model.
However, two types of models arise: i) the usual one where each of the three
identical right-handed neutrinos has total lepton number L=1; ii) and the other
one in which two of them carry L=4 while the third one carries .Comment: Published version in PLB forma
Testing Higgs portal dark matter via fusion at a linear collider
We investigate the possibility of detecting dark matter at TeV scale linear
colliders in the scenario where the dark matter is a massive particle weakly
interacting only with the Higgs boson in the low energy effective theory
(the Higgs portal dark matter scenario). The dark matter in this scenario would
be difficult to be tested at the CERN Large Hadron Collider when the decay of
the Higgs boson into a dark matter pair is not kinematically allowed. We study
whether even in such a case the dark matter can be explored or not via the
boson fusion process at the International Linear Collider and also at a
multi TeV lepton collider. It is found that for the collision energy
TeV with the integrated luminosity 1 ab, the signal
() can be seen after
appropriate kinematic cuts. In particular, when the dark matter is a fermion or
a vector, which is supposed to be singlet under the standard gauge symmetry,
the signal with the mass up to 100 GeV can be tested for the Higgs boson mass
to be 120 GeV.Comment: 13 pages, 11 figures and 1 tabl
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Genome-Scale Promoter Engineering by Coselection MAGE
Multiplex Automated Genome Engineering (MAGE) employs short oligonucleotides to scarlessly modify genomes. However, insertions of >10 bases are still inefficient, but can be improved substantially by selection of highly modified chromosomes. Here, we describe Co-Selection MAGE (CoS-MAGE) to optimize biosynthesis of aromatic amino acid derivatives by combinatorially inserting multiple T7 promoters simultaneously into 12 genomic operons. Promoter libraries can be quickly generated to study gain-of-function epistatic interactions in gene networks
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Improving Lambda Red Genome Engineering in Escherichia coli via Rational Removal of Endogenous Nucleases
Lambda Red recombineering is a powerful technique for making targeted genetic changes in bacteria. However, many applications are limited by the frequency of recombination. Previous studies have suggested that endogenous nucleases may hinder recombination by degrading the exogenous DNA used for recombineering. In this work, we identify ExoVII as a nuclease which degrades the ends of single-stranded DNA (ssDNA) oligonucleotides and double-stranded DNA (dsDNA) cassettes. Removing this nuclease improves both recombination frequency and the inheritance of mutations at the 3′ ends of ssDNA and dsDNA. Extending this approach, we show that removing a set of five exonucleases (RecJ, ExoI, ExoVII, ExoX, and Lambda Exo) substantially improves the performance of co-selection multiplex automatable genome engineering (CoS-MAGE). In a given round of CoS-MAGE with ten ssDNA oligonucleotides, the five nuclease knockout strain has on average 46% more alleles converted per clone, 200% more clones with five or more allele conversions, and 35% fewer clones without any allele conversions. Finally, we use these nuclease knockout strains to investigate and clarify the effects of oligonucleotide phosphorothioation on recombination frequency. The results described in this work provide further mechanistic insight into recombineering, and substantially improve recombineering performance
Staat van infectieziekten in Nederland, 2013
In dit rapport wordt gelinked naar een bijlage: appendix150205001.De uitbraak van mazelen in 2013 was de meest in het oog springende infectieziekte van dat jaar. Dit blijkt uit de Staat van Infectieziekten in Nederland 2013, die inzicht geeft in ontwikkelingen van infectieziekten bij de Nederlandse bevolking. Daarnaast worden de ontwikkelingen in het buitenland beschreven die voor Nederland relevant zijn. Met deze jaarlijkse uitgave informeert het RIVM beleidsmakers van het ministerie van Volksgezondheid, Welzijn en Sport (VWS). Elk jaar komt in de Staat van Infectieziekten een thema aan bod; dit jaar is dat de hoeveelheid jaren in goede gezondheid die verloren gaan (ziektelast) door infectieziekten. Sommige infectieziekten, zoals maag-darminfecties, komen erg vaak voor maar veroorzaken over het algemeen geen ernstige klachten. Andere daarentegen, bijvoorbeeld tetanus, komen slechts zelden voor maar veroorzaken relatief veel sterfgevallen. Een gezondheidsmaat die deze aspecten van ziekten combineert is de Disability Adjusted Life Year (DALY). Voor 32 infectieziekten is de ziektelast in Nederland tussen 2007 en 2011 geschat. De gemiddelde jaarlijkse ziektelast voor de totale Nederlandse bevolking was het hoogst voor ernstige pneumokokkenziekte (9444 DALY's per jaar) en griep (8670 DALY's per jaar), die respectievelijk 16 en 15 procent van de totale ziektelast van alle 32 infectieziekten vertegenwoordigen. Na polio en difterie (0 gevallen in de onderzochte periode), werd de laagste ziektelast geschat voor rodehond op 0,14 DALY's per jaar. De ziektelast voor deze ziekten is zo laag dankzij het Rijksvaccinatieprogramma. De ziektelast per individu varieerde van 0,2 DALY's per honderd infecties voor giardiasis (diarree die wordt veroorzaakt door een parasiet), tot 5081 en 3581 DALY's per honderd infecties voor respectievelijk hondsdolheid en een variant van de ziekte van Creutzfeldt-Jakob. Voor alle ziektelaststudies geldt dat de resultaten afhankelijk zijn van de modelparameters en aannames, en van de beschikbaarheid van accurate gegevens over de mate waarin de ziekten voorkomen. Toch kunnen deze schattingen informatief zijn voor beleidsmakers binnen de gezondheidszorg om prioriteiten te kunnen aanbrengen in preventieve en andere maatregelen.The measles outbreak in 2013 was the most striking infectious disease of that year. This is demonstrated in the State of Infectious Diseases in the Netherlands 2013, which provides insight into infectious disease trends in the Dutch population. Developments in other countries that are relevant for the Netherlands are also described. This annual RIVM publication informs policy-makers from the Ministry of Health, Welfare and Sport (VWS). Every year the State of Infectious Diseases in the Netherlands publishes reports on a particular theme. This year's topic concerns the estimation of disease burden: how many years of health life are lost due to infectious diseases? Some infectious diseases, such as gastrointestinal infections, occur frequently in the population, but do not generally give rise to serious complaints. In contrast, other diseases, for example tetanus, occur rarely but may lead to a high risk of death. A summary measure of population health that combines the morbidity and premature mortality attributable to a disease in a single quantity is the Disability Adjusted Life Year (DALY). For 32 infectious diseases, we estimated the disease burden in the Netherlands between 2007 and2011. The highest average annual burden for the total Netherlands population was estimated for invasive pneumococcal disease (9444 DALYs per year) and influenza (8670 DALYs per year), which represent 16 and 15 percent, respectively, of the total burden of all 32 diseases considered. After poliomyelitis and diphtheria (no cases in the period investigated), the lowest burden was estimated for rubella, at 0.14 DALYs per year. The extremely low burden for these diseases is due to the National Immunization Programme. The disease burden per individual varied from 0.2 DALYs per 100 infections for giardiasis (diarrhea that is caused by a parasite), to 5081 and 3581 DALYs per 100 infections for rabies and variant Creutzfeldt-Jakob disease, respectively. As with all burden of disease studies, results depend on disease model parameters and assumptions and on the availability of accurate data on the incidence of infection. Nevertheless, estimates of disease burden can be informative for public health policy-makers regarding the prioritization of preventive and other measures.Ministerie van VW
Topological Phase Transition in the Quantum Hall Effect
The double layer fractional quantum Hall system is studied using
the edge state formalism and finite-size diagonalization subject to periodic
boundary conditions. Transitions between three different ground states are
observed as the separation as well as the tunneling between the two layers is
varied. Experimental consequences are discussed.Comment: 11 pages, REVTEX v3.0, 7 figure
Vacuum Stability, Perturbativity, and Scalar Singlet Dark Matter
We analyze the one-loop vacuum stability and perturbativity bounds on a
singlet extension of the Standard Model (SM) scalar sector containing a scalar
dark matter candidate. We show that the presence of the singlet-doublet quartic
interaction relaxes the vacuum stability lower bound on the SM Higgs mass as a
function of the cutoff and lowers the corresponding upper bound based on
perturbativity considerations. We also find that vacuum stability requirements
may place a lower bound on the singlet dark matter mass for given singlet
quartic self coupling, leading to restrictions on the parameter space
consistent with the observed relic density. We argue that discovery of a light
singlet scalar dark matter particle could provide indirect information on the
singlet quartic self-coupling.Comment: 25 pages, 10 figures; v2 - fixed minor typos; v3 - added to text
discussions of other references, changed coloring of figures for easier black
and white viewin
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