1,217 research outputs found
Has the incidence of empyema in Scottish children continued to increase beyond 2005?
Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.Peer reviewedPostprin
SUSY GUTs with Yukawa unification: a go/no-go study using FCNC processes
We address the viability of exact Yukawa unification in the context of
general SUSY GUTs with universal soft-breaking sfermion and gaugino mass terms
at the GUT scale. We find that this possibility is challenged, unless the
squark spectrum is pushed well above the limits allowed by naturalness. This
conclusion is assessed through a global fit using electroweak observables and
quark flavour-changing neutral current (FCNC) processes. The problem is mostly
the impossibility of accommodating simultaneously the bottom mass and the BR(B
--> Xs gamma), after the stringent CDF upper bound on the decay Bs --> mu^+
mu^- is taken into account, and under the basic assumption that the b --> s
gamma amplitude have like sign with respect to the Standard Model one, as
indicated by the B --> Xs l^+ l^- data.
With the same strategy, we also consider the possibility of relaxing Yukawa
unification to b - tau Yukawa unification. We find that with small departures
from the condition tan beta ~= 50, holding when Yukawa unification is exact,
the mentioned tension is substantially relieved. We emphasize that in the
region where fits are successful the lightest part of the SUSY spectrum is
basically fixed by the requirements of b - tau unification and the applied FCNC
constraints. As such, it is easily falsifiable once the LHC turns on.Comment: 10 pages, 1 figure, 5 tables. v3: A few textual modifications.
Conclusions unchanged. Matches journal versio
Properdin Levels in Individuals with Chemotherapy-Induced Neutropenia
BACKGROUND: Neutrophils produce and carry key components of the alternative pathway (AP) of complement, including properdin (P). The effect of chemotherapy-induced absolute neutropenia on circulating P levels and AP function has not been previously established.
METHODS: We prospectively measured free P levels in serum from 27 individuals expected to develop neutropenia after administration of chemotherapy for hematological malignancies in preparation for hematopoietic stem cell transplantation and here describe the relationship between serum P levels and the neutrophil count over time.
RESULTS: When the absolute neutrophil count (ANC) was \u3e 500 cells/mm3 pre-chemotherapy, P levels were significantly higher than P levels associated with an ANC â€500 cells/mm3 (median values 8392 ng/mL and 6355 ng/mL, respectively; P = .001). Pairwise comparison between pre-chemotherapy P levels and P levels at initial or last documented neutropenia before recovery showed a significant decline (P \u3c .0001). No correlation was observed between P levels during neutropenia and after recovery of neutropenia in 20 subjects for which postneutropenia samples were obtained. A small but significant (P = .02) decrease in AP hemolytic activity was noted between baseline (preneutropenia) and samples obtained at the onset of neutropenia, but only with low (6.25%) and not higher (12.5 or 25%) serum concentrations.
CONCLUSIONS: A decline in P levels and AP activity could contribute to the increased risk of infection in neutropenic patients and warrants further study
Bone marrow recovery by morphometry during induction chemotherapy for acute lymphoblastic leukemia in children
Bone marrow architecture is grossly distorted at the diagnosis of ALL and details of the morphological changes that accompany response to Induction chemotherapy have not been reported before. While marrow aspirates are widely used to assess initial response to ALL therapy and provide some indications, we have enumerated marrow components using morphometric analysis of trephine samples with the aim of achieving a greater understanding of changes in bone marrow niches. Morphometric analyses were carried out in the bone marrow trephine samples of 44 children with ALL, using a NanoZoomer HT digital scanner. Diagnostic samples were compared to those of 32 control patients with solid tumors but without marrow involvement. Samples from patients with ALL had significantly increased fibrosis and the area occupied by bony trabeculae was lower than in controls. Cellularity was higher in ALL samples due to leukemic infiltration while the percentage of normal elements such as megakaryocytes, adipocytes, osteoblasts and osteoclasts were all significantly lower. During the course of Induction therapy, there was a decrease in the cellularity of ALL samples at day 15 of therapy with a further decrease at the end of Induction and an increase in the area occupied by adipocytes and the width of sinusoids. Reticulin fibrosis decreased throughout Induction. Megakaryocytes increased, osteoblasts and osteoclasts remained unchanged. No correlation was found between clinical presentation, early response to treatment and morphological changes. Our results provide a morphological background to further studies of bone marrow stroma in ALL
Magnetic dipole moment of the (1232) from the reaction
The reaction in the -resonance
region is investigated as a method to access the magnetic
dipole moment. The calculations are performed within the context of an
effective Lagrangian model containing both the -resonant mechanism and
a background of non-resonant contributions to the
reaction. Results are shown both for existing and forthcoming experiments. In particular, the sensitivity of unpolarized
cross sections and photon asymmetries to the magnetic dipole moment
is displayed for those forthcoming data.Comment: 25 pages, 11 figure
An analysis of a Heavy Gluino LSP at CDF : The Heavy Gluino Window
In this paper we consider a heavy gluino to be the lightest supersymmetric
particle [LSP]. We investigate the limits on the mass of a heavy gluino LSP,
using the searches for excess events in the jets plus missing momentum channel
in Run I. The neutral and charged R-hadrons, containing a heavy gluino LSP,
have distinct signatures at the Fermilab Tevatron. The range of excluded gluino
masses depends on whether the R-hadron is charged or neutral and the amount of
energy deposited in the hadronic calorimeter. The latter depends on the energy
loss per collision in the calorimeter and the number of collisions; where both
quantities require a model for R-hadron- Nucleon scattering. We show how the
excluded range of gluino mass depends on these parameters. We find that gluinos
with mass in the range between GeV and GeV are excluded by
CDF Run I data. Combined with previous results of Baer et al., which use LEP
data to exclude the range 3 - 2225 GeV, our result demonstrates that an
allowed window for a heavy gluino with mass between 25 and 35 GeV is quite
robust. Finally we discuss the relevant differences of our analysis of Tevatron
data to that of Baer et al.Comment: 36 pages, 11 figures, added an acknowledgemen
The Phenomenology of SUSY models with a Gluino LSP
In this paper we study the experimental consequences of a theory which
naturally has a heavy, stable (or almost stable) gluino. We define the boundary
conditions at a messenger scale GeV which lead to this
alternative phenomenologically acceptable version of the minimal supersymmetric
standard model.
In this theory, either the gluino or the gravitino is the lightest
supersymmetric particle [LSP]. If the gravitino is the LSP, then the gluino is
the next-to-LSP with a lifetime on the order of 100 years. In either case, the
gluino is (for all practical purposes) a stable particle with respect to
experiments at high energy accelerators. Thus the standard missing energy
signature for SUSY fails. A stable gluino forms a color singlet hadron, the
lightest of which is assumed to be an isoscalar gluino-gluon bound state
(). The has strong interactions and will interact in a hadronic
calorimeter; depositing some fraction of its kinetic energy. Finally, in the
case the gravitino is the LSP, bounds from searches for stable heavy isotopes
of hydrogen or oxygen do not apply to the metastable .Comment: 34 pages, 16 figures color code
Study of Constrained Minimal Supersymmetry
Taking seriously phenomenological indications for supersymmetry, we have made
a detailed study of unified minimal SUSY, including effects at the few percent
level in a consistent fashion. We report here a general analysis without
choosing a particular unification gauge group. We find that the encouraging
SUSY unification results of recent years do survive the challenge of a more
complete and accurate analysis. Taking into account effects at the 5-10% level
leads to several improvements of previous results, and allows us to sharpen our
predictions for SUSY in the light of unification. We perform a thorough study
of the parameter space. The results form a well-defined basis for comparing the
physics potential of different facilities. Very little of the acceptable
parameter space has been excluded by LEP or FNAL so far, but a significant
fraction can be covered when these accelerators are upgraded. A number of
initial applications to the understanding of the SUSY spectrum, detectability
of SUSY at LEP II or FNAL, BR(), Width(), dark
matter, etc, are included in a separate section. We formulate an approach to
extracting SUSY parameters from data when superpartners are detected. For small
tan(beta) or large both and are entirely bounded from
above at O(1 tev) without having to use a fine-tuning constraint.Comment: Michigan preprint UM-TH-93-24, LaTeX, 60 pages without figures.
Complete paper with inline figures available by anonymous ftp to
williams.physics.lsa.umich.edu in /pub/preprints/UM-TH-93-24.ps.Z
(uncompresses to 10MB / 77 pages), or by e-mailing reques
Are Nanoparticles Spherical or Quasi-Spherical?
The geometry of quasi-spherical nanoparticles is investigated. The combination of SEM imaging and electrochemical nano-impact experiments is demonstrated to allow sizing and characterization of the geometry of single silver nanoparticles
Nonrandom processes maintain diversity in tropical forests
An ecological community\u27s species diversity tends to erode through time as a result of stochastic extinction, competitive exclusion, and unstable host-enemy dynamics. This erosion of diversity can be prevented over the short term if recruits are highly diverse as a result of preferential recruitment of rare species or, alternatively, if rare species survive preferentially, which increases diversity as the ages of the individuals increase. Here, we present census data from seven New and Old World tropical forest dynamics plots that all show the latter pattern. Within local areas, the trees that survived were as a group more diverse than those that were recruited or those that died. The larger (and therefore on average older) survivors were more diverse within local areas than the smaller survivors. When species were rare in a local area, they had a higher survival rate than when they were common, resulting in enrichment for rare species and increasing diversity with age and size class in these complex ecosystems
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