Resolving the M2-brane

We construct deformed, T^2 wrapped, rotating M2-branes on a resolved cone over Q^{1,1,1} and Q^{1,1,1}/Z_2, as well as on a product of two Eguchi-Hanson instantons. All worldvolume directions of these supersymmetric and regular solutions are fibred over the transverse space. These constitute gravity duals of D=3, N=2 gauge theories. In particular, the deformed M2-brane on a resolved cone over Q^{1,1,1} and the S^1 wrapped M2-brane on a resolved cone over Q^{1,1,1}/Z_2 provide explicit realizations of holographic renormalization group flows in M-theory for which both conformal and Lorentz symmetries are broken in the IR region and restored in the UV limit. These solutions can be dualized to supersymmetric type IIB pp-waves, which are rendered non-singular either by additional flux or a twisted time-like direction.Comment: Latex, 23 pages, references adde

Wrapped branes with fluxes in 8d gauged supergravity

We study the gravity dual of several wrapped D-brane configurations in presence of 4-form RR fluxes partially piercing the unwrapped directions. We present a systematic approach to obtain these solutions from those without fluxes. We use D=8 gauged supergravity as a starting point to build up these solutions. The configurations include (smeared) M2-branes at the tip of a G_2 cone on S^3 x S^3, D2-D6 branes with the latter wrapping a special Lagrangian 3-cycle of the complex deformed conifold and an holomorphic sphere in its cotangent bundle T^*S^2, D3-branes at the tip of the generalized resolved conifold, and others obtained by means of T duality and KK reduction. We elaborate on the corresponding N=1 and N=2 field theories in 2+1 dimensions.Comment: 32 pages, LateX, v2: minor changes, reference added, v3: section 3.5.2 improve

Near-flat space limit and Einstein manifolds

We study the near-flat space limit for strings on AdS(5)xM(5), where the internal manifold M(5) is equipped with a generic metric with U(1)xU(1)xU(1) isometry. In the bosonic sector, the limiting sigma model is similar to the one found for AdS(5)xS(5), as the global symmetries are reduced in the most general case. When M(5) is a Sasaki-Einstein space like T(1,1), Y(p,q) and L(p,q,r), whose dual CFT's have N=1 supersymmetry, the near-flat space limit gives the same bosonic sector of the sigma model found for AdS(5)xS(5). This indicates the generic presence of integrable subsectors in AdS/CFT.Comment: 30 pages, 1 figur

A New Fractional D2-brane, G_2 Holonomy and T-duality

Recently, a new example of a complete non-compact Ricci-flat metric of G_2 holonomy was constructed, which has an asymptotically locally conical structure at infinity with a circular direction whose radius stabilises. In this paper we find a regular harmonic 3-form in this metric, which we then use in order to obtain an explicit solution for a fractional D2-brane configuration. By performing a T-duality transformation on the stabilised circle, we obtain the type IIB description of the fractional brane, which now corresponds to D3-brane with one of its world-volume directions wrapped around the circle.Comment: Latex, 13 page

Semiclassical strings in Sasaki-Einstein manifolds and long operators in N=1 gauge theories

We study the AdS/CFT relation between an infinite class of 5-d Ypq Sasaki-Einstein metrics and the corresponding quiver theories. The long BPS operators of the field theories are matched to massless geodesics in the geometries, providing a test of AdS/CFT for these cases. Certain small fluctuations (in the BMN sense) can also be successfully compared. We then go further and find, using an appropriate limit, a reduced action, first order in time derivatives, which describes strings with large R-charge. In the field theory we consider holomorphic operators with large winding numbers around the quiver and find, interestingly, that, after certain simplifying assumptions, they can be described effectively as strings moving in a particular metric. Although not equal, the metric is similar to the one in the bulk. We find it encouraging that a string picture emerges directly from the field theory and discuss possible ways to improve the agreement.Comment: 44 pages, LaTeX, 9 figures. v2: References adde

The Prevalence of Latent Mycobacterium Tuberculosis Infection Based on an Interferon-γ Release Assay: A Cross-Sectional Survey Among Urban Adults in Mwanza, Tanzania.

One third of the world's population is estimated to be latently infected with Mycobacterium tuberculosis (LTBI). Surveys of LTBI are rarely performed in resource poor TB high endemic countries like Tanzania although low-income countries harbor the largest burden of the worlds LTBI. The primary objective was to estimate the prevalence of LTBI in household contacts of pulmonary TB cases and a group of apparently healthy neighborhood controls in an urban setting of such a country. Secondly we assessed potential impact of LTBI on inflammation by quantitating circulating levels of an acute phase reactant: alpha-1-acid glycoprotein (AGP) in neighborhood controls. The study was nested within the framework of two nutrition studies among TB patients in Mwanza, Tanzania. Household contacts- and neighborhood controls were invited to participate. The study involved a questionnaire, BMI determination and blood samples to measure AGP, HIV testing and a Quantiferon Gold In tube (QFN-IT) test to detect signs of LTBI. 245 household contacts and 192 neighborhood controls had available QFN-IT data. Among household contacts, the proportion of QFT-IT positive was 59% compared to 41% in the neighborhood controls (p = 0.001). In a linear regression model adjusted for sex, age, CD4 and HIV, a QFT-IT positive test was associated with a 10% higher level of alpha-1-acid glycoprotein(AGP) (10(B) 1.10, 95% CI 1.01; 1.20, p = 0.03), compared to individuals with a QFT-IT negative test. LTBI is highly prevalent among apparently healthy urban Tanzanians even without known exposure to TB in the household. LTBI was found to be associated with elevated levels of AGP. The implications of this observation merit further studies

Evidence for waning of latency in a cohort study of tuberculosis

<p>Abstract</p> <p>Background</p> <p>To investigate how the risk of active tuberculosis disease is influenced by time since original infection and to determine whether the risk of reactivation of tuberculosis increases or decreases with age.</p> <p>Methods</p> <p>Cohort analysis of data for the separate ten year birth cohorts of 1876-1885 to 1959-1968 obtained from Statistics Norway and the National Tuberculosis Registry. These data were used to calculate the rates and the changes in the rates of bacillary (or active) tuberculosis. Data on bacillary tuberculosis for adult (20+) age groups were obtained from the National Tuberculosis Registry and Statistics Norway from 1946 to 1974. Most cases during this period arose due to reactivation of remote infection. Participants in this part of the analysis were all reported active tuberculosis cases in Norway from 1946 to 1974 as recorded in the National Tuberculosis Registry.</p> <p>Results</p> <p>Tuberculosis decreased at a relatively steady rate when following individual birth cohorts, but with a tendency of slower decline as time passed since infection. A mean estimate of this rate of decline was 57% in a 10 year period.</p> <p>Conclusions</p> <p>The risk of reactivation of latent tuberculosis decreases with age. This decline may reflect the rate at which latent tuberculosis is eliminated from a population with minimal transmission of tubercle bacilli. A model for risk of developing active tuberculosis as a function of time since infection shows that the rate at which tuberculosis can be eliminated from a society can be quite substantial if new infections are effectively prevented. The findings clearly indicate that preventative measures against transmission of tuberculosis will be the most effective. These results also suggest that the total population harbouring live tubercle bacilli and consequently the future projection for increased incidence of tuberculosis in the world is probably overestimated.</p

Is Adipose Tissue a Place for Mycobacterium tuberculosis Persistence?

BACKGROUND: Mycobacterium tuberculosis, the etiological agent of tuberculosis (TB), has the ability to persist in its human host for exceptionally long periods of time. However, little is known about the location of the bacilli in latently infected individuals. Long-term mycobacterial persistence in the lungs has been reported, but this may not sufficiently account for strictly extra-pulmonary TB, which represents 10–15% of the reactivation cases. METHODOLOGY/PRINCIPAL FINDINGS: We applied in situ and conventional PCR to sections of adipose tissue samples of various anatomical origins from 19 individuals from Mexico and 20 from France who had died from causes other than TB. M. tuberculosis DNA could be detected by either or both techniques in fat tissue surrounding the kidneys, the stomach, the lymph nodes, the heart and the skin in 9/57 Mexican samples (6/19 individuals), and in 8/26 French samples (6/20 individuals). In addition, mycobacteria could be immuno-detected in perinodal adipose tissue of 1 out of 3 biopsy samples from individuals with active TB. In vitro, using a combination of adipose cell models, including the widely used murine adipose cell line 3T3-L1, as well as primary human adipocytes, we show that after binding to scavenger receptors, M. tuberculosis can enter within adipocytes, where it accumulates intracytoplasmic lipid inclusions and survives in a non-replicating state that is insensitive to the major anti-mycobacterial drug isoniazid. CONCLUSIONS/SIGNIFICANCE: Given the abundance and the wide distribution of the adipose tissue throughout the body, our results suggest that this tissue, among others, might constitute a vast reservoir where the tubercle bacillus could persist for long periods of time, and avoid both killing by antimicrobials and recognition by the host immune system. In addition, M. tuberculosis-infected adipocytes might provide a new model to investigate dormancy and to evaluate new drugs for the treatment of persistent infection

Reduced Transmissibility of East African Indian Strains of Mycobacterium tuberculosis

BACKGROUND: Mycobacterium tuberculosis (MTB) has been classified into 4 main lineages. Some reports have associated certain lineages with particular clinical phenotypes, but there is still insufficient information regarding the clinical and epidemiologic implications of MTB lineage variation. METHODS: Using large sequence polymorphisms we classified MTB isolates from a population-based study in Montreal, Canada into the 4 major lineages, and identified the associated clinical and epidemiologic features. In addition, IS6110-RFLP and spoligotyping were used as indicators of recent TB transmission. The study population was divided into a derivation cohort, diagnosed between 2001 and 2007, and a separate validation cohort, diagnosed between 1996 and 2000. RESULTS: In the derivation cohort, when compared to the other MTB lineages, the East African-Indian (EAI) lineage was associated with lower rates of TB transmission, as measured by: positive TST among close contacts of pulmonary TB cases (adjusted odds ratio 0.6: [95% confidence interval 0.4-0.9]), and clustered TB cases (0.3: [<0.001-0.6]). Severe forms of TB were also less likely among the EAI group (0.4: [<0.001-0.8]). There were no significant differences when comparing patients with the other MTB lineages. In the validation cohort, the EAI lineage was associated with lower rates of positive TST among contacts (0.5: [0.3-0.9]) and a trend towards less clustered TB cases (0.5: [0.1-1.8]) when compared to the other lineages. Disease severity among the different groups was not significantly different in the validation cohort. CONCLUSIONS: We conclude that in Montreal, EAI strains were associated with reduced transmission compared to other MTB lineages