493 research outputs found
Condensate fragmentation as a sensitive measure of the quantum many-body behavior of bosons with long-range interactions
The occupation of more than one single-particle state and hence the emergence
of fragmentation is a many-body phenomenon universal to systems of spatially
confined interacting bosons. In the present study, we investigate the effect of
the range of the interparticle interactions on the fragmentation degree of one-
and two-dimensional systems. We solve the full many-body Schr\"odinger equation
of the system using the recursive implementation of the multiconfigurational
time-dependent Hartree for bosons method, R-MCTDHB. The dependence of the
degree of fragmentation on dimensionality, particle number, areal or line
density and interaction strength is assessed. It is found that for contact
interactions, the fragmentation is essentially density independent in two
dimensions. However, fragmentation increasingly depends on density the more
long-ranged the interactions become. The degree of fragmentation is increasing,
keeping the particle number fixed, when the density is decreasing as
expected in one spatial dimension. We demonstrate that this remains,
nontrivially, true also for long-range interactions in two spatial dimensions.
We, finally, find that within our fully self-consistent approach, the
fragmentation degree, to a good approximation, decreases universally as
when only is varied.Comment: 8 pages of RevTex4-1, 5 figure
Superfluid-insulator transition in strongly disordered one-dimensional systems
We present an asymptotically exact renormalization-group theory of the superfluid-insulator transition in one-dimensional (1D) disordered systems, with emphasis on an accurate description of the interplay between the Giamarchi-Schulz (instanton-anti-instanton) and weak-link (scratched-XY) criticalities. Combining the theory with extensive quantum Monte Carlo simulations allows us to shed new light on the ground-state phase diagram of the 1D disordered Bose-Hubbard model at unit filling
Strategien zur Immuntherapie beim Neuroblastom
Das Neuroblastom ist ein vom sympathischen Nervensystem ausgehender neuroektodermaler maligner Tumor des Kleinkindesalters. Bei über 50% der Neuroblastom-Ersterkrankungen liegt bereits das disseminierte Stadium 4 vor, das eine infauste Prognose hat. Eine wirksame Behandlung des Stadium 4 Neuroblastoms stellt deshalb nach wie vor eine der größten Herausforderungen der pädiatrischen Onkologie dar: Die Gesamtüberlebensrate von 20-25% der Kinder, die an dieser bösartigen Krankheit leiden, konnte während der letzten zwei Jahrzehnte trotz neuer Chemotherapie-Protokolle nicht wesentlich verbessert werden. Aus diesem Grund gibt es zunehmend Bestrebungen sich um Therapiealternativen zu bemühen. In dieser Arbeit werden die derzeit möglichen immunologischen Strategien zur Behandlung des Neuroblastoms abgehandelt.Neuroblastoma is a neuroectodermal malignancy of early childhood derived from sympathetic nervous tissue. At initial diagnosis over 50% of patients present with disseminated stage 4 disease which has a dismal prognosis. Effective treatment of patients with stage 4 neuroblastoma remains a major challenge in pediatric oncology. Despite novel therapeutic approaches including chemotherapy and autologous stem cell transplantation the overall survival rate of only 20-25% did not improve over the last two decades. Therefore, a lot of effort has been made to develop novel alternative therapies. This thesis summarizes possible immunotherapeutic strategies for the treatment of neuroblastoma
Decay modes of two repulsively interacting bosons
We study the decay of two repulsively interacting bosons tunneling through a
delta potential barrier by direct numerical solution of the time-dependent
Schr\"odinger equation. The solutions are analyzed according to the regions of
particle presence: both particles inside the trap (in-in), one particle in and
one particle out (in-out), and both particles outside (out-out). It is shown
that the in-in probability is dominated by exponential decay, and its decay
rate is predicted very well from outgoing boundary conditions.
Up to a certain range of interaction strength the decay of in-out probability
is dominated by the single particle decay mode.
The decay mechanisms are adequately described by simple models.Comment: 18 pages, 13 figure
Rotating solenoidal perfect fluids of Petrov type D
We prove that aligned Petrov type D perfect fluids for which the vorticity
vector is not orthogonal to the plane of repeated principal null directions and
for which the magnetic part of the Weyl tensor with respect to the fluid
velocity has vanishing divergence, are necessarily purely electric or locally
rotationally symmetric. The LRS metrics are presented explicitly.Comment: 6 pages, no figure
Maximally inhomogeneous G\"{o}del-Farnsworth-Kerr generalizations
It is pointed out that physically meaningful aligned Petrov type D perfect
fluid space-times with constant zero-order Riemann invariants are either the
homogeneous solutions found by G\"{o}del (isotropic case) and Farnsworth and
Kerr (anisotropic case), or new inhomogeneous generalizations of these with
non-constant rotation. The construction of the line element and the local
geometric properties for the latter are presented.Comment: 4 pages, conference proceeding of Spanish Relativity Meeting (ERE
2009, Bilbao
DNA Vaccination: Using the Patient's Immune System to Overcome Cancer
Cancer is one of the most challenging diseases of today. Optimization of standard treatment protocols consisting of the main columns of chemo- and radiotherapy followed or preceded by surgical intervention is often limited by toxic side effects and induction of concomitant malignancies and/or development of resistant mechanisms. This requires the development of therapeutic strategies which are as effective as standard therapies but permit the patients a life without severe negative side effects. Along this line, the development of immunotherapy in general and the innovative concept of DNA vaccination in particular may provide a venue to achieve this goal. Using the patient's own immune system by activation of humoral and cellular immune responses to target the cancer cells has shown first promising results in clinical trials and may allow reduced toxicity standard therapy regimen in the future. The main challenge of this concept is to transfer the plethora of convincing preclinical and early clinical results to an effective treatment of patients
Immunogenity of the pneumococcal polysaccharide vaccine in COPD patients. The effect of systemic steroids
AbstractRationale: To investigate if systemic steroids influence the antibody response to the 23-valent pneumococcal polysaccaride vaccine (23-PPV) in COPD patients.Patients and methods: COPD patients on: (a)⩾10mg of prednisolone/day (SS, n=30); (b) inhalative steroids (IS, n=30); (c) controls without COPD (CG, n=29) were vaccinated with 23-PPV. The concentration (μg/ml) of capsular specific anti-pneumococcal IgG antibodies (AB) for the serotypes (PNC) 4,6B,9V,14,18C,19F,23F were measured by Elisa technique before, 3 and 12 months (m) after vaccination. Non-responders were defined when AB-concentrations did neither doubled nor reach ⩾1μg/ml.Results: N=24 (CG), n=29 (IS), n=18 (SS) patients completed the study (mean age 64yrs.). Serious adverse events were not observed. Geometric mean (GM) AB-concentration of all serotypes increased significantly (CG, IS, SS) 3 and 12m after vaccination (P<0.05). The percentage of non-responders ranged between 16% (PNC 19F, IS) and 65% (PNC 4, SS) after 3m and 21% (PNC 19F, IS) and 82% (PNC 4, CG) after 12m. Neither post-vaccine AB-concentrations (3 and 12m) nor the rate of non-responders differed significantly between patients on systemic steroids and the other groups (IS, CG).Conclusions: Systemic steroids did not influence the AB-response. In all groups mean AB-concentration increased significantly after vaccination but an important percentage of subjects of all three groups were non-responders
Tumor-targeted IL-2 amplifies T cell-mediated immune response induced by gene therapy with single-chain IL-12
Expanding perfect fluid generalizations of the C-metric
We reexamine Petrov type D gravitational fields generated by a perfect fluid
with spatially homogeneous energy density and in which the flow lines form a
timelike non-shearing and non-rotating congruence. It is shown that the
anisotropic such spacetimes, which comprise the vacuum C-metric as a limit
case, can have \emph{non-zero} expansion, contrary to the conclusion in the
original investigation by Barnes (Gen. Rel. Grav. 4, 105 (1973)). This class
consists of cosmological models with generically one and at most two Killing
vectors. We construct their line element and discuss some important properties.
The methods used in this investigation incite to deduce testable criteria
regarding shearfree normality and staticity op Petrov type spacetimes in
general, which we add in an appendix.Comment: 16 pages, extended and amended versio
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