866 research outputs found
Modelling the variability of 1ES1218+30.4
The blazar 1ES1218+30.4 has been previously detected by the VERITAS and MAGIC
telescopes in the very high energies. The new detection of VERITAS from
December 2008 to April 2009 proves that 1ES1218+30.4 is not static, but shows
short-time variability. We show that the time variability may be explained in
the context of a self-consistent synchrotron-self Compton model, while the long
time observation do not necessarily require a time-resolved treatment. The
kinetic equations for electrons and photons in a plasma blob are solved
numerically including Fermi acceleration for electrons as well as synchrotron
radiation and Compton scattering. The light curve observed by VERITAS can be
reproduced in our model by assuming a changing level of electron injection
compared to the constant state of 1ES1218+30.4. The multiwavelength behaviour
during an outburst becomes comprehensible by the model. The long time
measurements of VERITAS are still explainable via a constant emission in the
SSC context, but the short outbursts each require a time-resolved treatment.Comment: 4 pages, 3 figures; accepted in A&A; AA/2010/1429
Adipokines and Their Role in Intestinal Inflammation
Fat tissue was initially described for its endocrine and metabolic function. Over the last two decades increasing evidence indicated a close interaction with the immune system. Partly responsible for this immune modulatory function are soluble factors released by the fat tissue, most prominently the so-called adipokines. These discoveries led to the question how adipokines influence inflammatory diseases. Linking inflammation and adipose tissue, Crohn's disease, a chronic inflammatory bowel disease, is of particular interest for studying the immune modulatory properties of adipokines since it is characterized by a hyperplasia of the mesenteric fat that subsequently is creeping around the inflamed segments of the small intestine. Thus, the role of several adipokines in the creeping fat as well as in intestinal inflammation was recently explored. The present review selected the four adipokines adiponectin, apelin, chemerin, and leptin and provides a working model based on the available literature how these factors participate in the maintenance of intestinal immune homeostasis
A Granulysin-Derived Peptide with Potent Activity against Intracellular Mycobacterium tuberculosis
Granulysin is an antimicrobial peptide (AMP) expressed by human T-lymphocytes and natural killer cells. Despite a remarkably broad antimicrobial spectrum, its implementation into clinical practice has been hampered by its large size and off-target effects. To circumvent these limitations, we synthesized a 29 amino acid fragment within the putative cytolytic site of Granulysin (termed “Gran1”). We evaluated the antimicrobial activity of Gran1 against the major human pathogen Mycobacterium tuberculosis (Mtb) and a panel of clinically relevant non-tuberculous mycobacteria which are notoriously difficult to treat. Gran1 efficiently inhibited the mycobacterial proliferation in the low micro molar range. Super-resolution fluorescence microscopy and scanning electron microscopy indicated that Gran1 interacts with the surface of Mtb, causing lethal distortions of the cell wall. Importantly, Gran1 showed no off-target effects (cytokine release, chemotaxis, cell death) in primary human cells or zebrafish embryos (cytotoxicity, developmental toxicity, neurotoxicity, cardiotoxicity). Gran1 was selectively internalized by macrophages, the major host cell of Mtb, and restricted the proliferation of the pathogen. Our results demonstrate that the hypothesis-driven design of AMPs is a powerful approach for the identification of small bioactive compounds with specific antimicrobial activity. Gran1 is a promising component for the design of AMP-containing nanoparticles with selective activity and favorable pharmacokinetics to be pushed forward into experimental in vivo models of infectious diseases, most notably tuberculosis
Extended Lyman alpha emission around bright quasars
Quasars trace the most massive structures at high redshifts and their
presence may influence the evolution of the massive host galaxies. We study the
extended Lyman alpha emission line regions (EELRs) around seven bright, mostly
radio-quiet quasars (QSOs) at 2.7<z<4.5, and compare luminosities with EELRs
around radio-loud QSOs reported in the literature. Using integral field
spectroscopy, we analyse the morphology and kinematics of the quiescent Lya
EELRs around the QSOs. We find evidence for the presence of EELRs around four
radio-quiet and one radio-loud QSO. All EELRs appear asymmetric and the
optically brightest QSOs also have the brightest Lya nebulae. For the two
brightest nebulae we find velocities between ~600 km s^-1 at the QSO position
to ~200 km s^-1 at a distance of 3-4 arcsec from the QSO and surface flux
densities up to 2-3*10^{-16} erg cm^-2 s^-1 arcsec^-2. The five EELRs have
total Lya luminosities which correspond to ~0.5% of the luminosities from the
QSOs broad Lya emission lines. This fraction is an order of magnitude smaller
than found for EELRs around radio-loud, steep spectrum QSOs reported in the
literature. While the nebulae luminosities are correlated with the QSO Lya
luminosities, we find that nebulae luminosities are not correlated with the
central QSO ionising fluxes. The presence of gas in the EELRs can be
interpreted based on two competing scenarios: either from quasar feedback
mechanisms, or from infalling matter. Apart from these two effects, the Lya
flux around radio-loud objects can be enhanced due to interactions with the
radio jets. The relatively fainter nebulae around radio-quiet QSOs compared to
lobe-dominated radio-loud QSOs can be ascribed to this effect, or to
significant differences in the environments between the two classes.Comment: 15 pages, A&A accepted. Section 4 revise
Solvable model of a strongly-driven micromaser
We study the dynamics of a micromaser where the pumping atoms are strongly
driven by a resonant classical field during their transit through the cavity
mode. We derive a master equation for this strongly-driven micromaser,
involving the contributions of the unitary atom-field interactions and the
dissipative effects of a thermal bath. We find analytical solutions for the
temporal evolution and the steady-state of this system by means of phase-space
techniques, providing an unusual solvable model of an open quantum system,
including pumping and decoherence. We derive closed expressions for all
relevant expectation values, describing the statistics of the cavity field and
the detected atomic levels. The transient regime shows the build-up of mixtures
of mesoscopic fields evolving towards a superpoissonian steady-state field
that, nevertheless, yields atomic correlations that exhibit stronger
nonclassical features than the conventional micromaser.Comment: 9 pages, 16 figures. Submitted for publicatio
Factors predisposing to humoral autoimmunity against brain-antigens in health and disease Analysis of 49 autoantibodies in over 7000 subjects
Background:Circulating autoantibodies (AB) against brain-antigens, often deemed pathological, receive increasing attention. We assessed predispositions and seroprevalence/characteristics of 49 AB in >7000 individuals.Methods:Exploratory cross-sectional cohort study, investigating deeply phenotyped neuropsychiatric patients and healthy individuals of GRAS Data Collection for presence/characteristics of 49 brain-directed serum-AB. Predispositions were evaluated through GWAS of NMDAR1-AB carriers, analyses of immune check-point genotypes, APOE4 status, neurotrauma. Chi-square, Fisher’s exact tests and logistic regression analyses were used.Results:Study of N=7025 subjects (55.8% male; 41±16 years) revealed N=1133 (16.13%) carriers of any AB against 49 defined brain-antigens. Overall, age dependence of seroprevalence (OR=1.018/year; 95% CI [1.015-1.022]) emerged, but no disease association, neither general nor with neuropsychiatric subgroups. Males had higher AB seroprevalence (OR=1.303; 95% CI [1.144-1.486]). Immunoglobulin class (N for IgM:462; IgA:487; IgG:477) and titers were similar. Abundant were NMDAR1-AB (7.7%). Low seroprevalence (1.25%-0.02%) was seen for most AB (e.g. amphiphysin, KCNA2, ARHGAP26, GFAP, CASPR2, MOG, Homer-3, KCNA1, GLRA1b, GAD65). Non-detectable were others. GWAS of NMDAR1-AB carriers revealed three genome-wide significant SNPs, two intergenic, one in TENM3, previously autoimmune disease-associated. Targeted analysis of immune check-point genotypes (CTLA4, PD1, PD-L1) uncovered effects on humoral anti-brain autoimmunity (OR=1.55; 95% CI [1.058-2.271]) and disease likelihood (OR=1.43; 95% CI [1.032-1.985]). APOE4 carriers (∼19%) had lower seropositivity (OR=0.766; 95% CI [0.625-0.933]). Neurotrauma predisposed to NMDAR1-AB seroprevalence (IgM: OR=1.599; 95% CI [1.022-2.468]).Conclusions:Humoral autoimmunity against brain-antigens, frequent across health and disease, is predicted by age, gender, genetic predisposition, and brain injury. Seroprevalence, immunoglobulin class, or titers do not predict disease
Weak lensing analysis of RXC J2248.7-4431
We present a weak lensing analysis of the cluster of galaxies RXC
J2248.7-4431, a massive system at z=0.3475 with prominent strong lensing
features covered by the HST/CLASH survey (Postman et al. 2012). Based on UBVRIZ
imaging from the WFI camera at the MPG/ESO-2.2m telescope, we measure
photometric redshifts and shapes of background galaxies. The cluster is
detected as a mass peak at 5sigma significance. Its density can be parametrised
as an NFW profile (Navarro et al. 1996) with two free parameters, the mass
M_200m=(33.1+9.6-6.8)x10^14Msol and concentration c_200m=2.6+1.5-1.0. We
discover a second cluster inside the field of view at a photometric redshift of
z~0.6, with an NFW mass of M_200m=(4.0+3.7-2.6)x10^14Msol.Comment: 15 pages, 17 figures; matching published versio
Preparation of decoherence-free, subradiant states in a cavity
The cause of decoherence in a quantum system can be traced back to the
interaction with the environment. As it has been pointed out first by Dicke, in
a system of N two-level atoms where each of the atoms is individually dipole
coupled to the environment, there are collective, subradiant states, that have
no dipole coupling to photon modes, and therefore they are expected to decay
slower. This property also implies that these type of states, which form an N-1
dimensional subspace of the atomic subsytem, also decohere slower. We propose a
scheme which will create such states. First the two-level atoms are placed in a
strongly detuned cavity and one of the atoms, called the control atom is
excited. The time evolution of the coupled atom-cavity system leads to an
appropriately entangled state of the atoms. By applying subsequent laser pulses
at a well defined time instant, it is possible to drive the atomic state into
the subradiant, i. e., decoherence free subspace. Up to a certain average
number of the photons, the result is independent of the state of the cavity.
The analysis of the conditions shows that this scheme is feasible with present
day techniques achieved in atom cavity interaction experiments.Comment: 5 page
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