Partial synchronisation of stochastic oscillators through hydrodynamic coupling

Holographic optical tweezers are used to construct a static bistable optical potential energy landscape where a Brownian particle experiences restoring forces from two nearby optical traps and undergoes thermally activated transitions between the two energy minima. Hydrodynamic coupling between two such systems results in their partial synchronisation. This is interpreted as an emergence of higher mobility pathways, along which it is easier to overcome barriers to structural rearrangement.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let

Endocrine-Immune Interactions in Pregnant Non-Human Primates With Intrauterine Infection

Preterm birth remains the most common cause of perinatal mortality. Although the causes of preterm labor are multifactorial and vary according to gestational age, preterm labor and term labor share common cellular and molecular mechanisms, including stimulation of the fetal hypothalamic-pituitary-adrenal (HPA) axis and endocrine/immune system interactions. We have developed a non-human primate experimental model for intrauterine infection and preterm labor using chronically instrumented rhesus monkeys (Macaca mulatta) with timed gestations. We have documented the temporal and quantitative relationships among intrauterine infection, the synthesis and release of proinflammatory cytokines, prostaglandins, and fetal-placental steroid biosynthesis in this model. Infection-induced preterm parturition is characterized by significant elevations in amniotic fluid proinflammatory cytokines and by increases in fetal adrenal steroid biosynthesis, but not by corresponding increases in placental estrogen biosynthesis characteristic of spontaneous parturition. This suggests that activation of the fetal HPA axis by the stress of infection is accompanied by placental dysfunction and also that infection-induced preterm parturition is not dependent upon the increased estrogen biosynthesis observed in spontaneous parturition. These different endocrine and immune responses have important diagnostic and therapeutic implications in the management of preterm labor

Trypanosoma cruzi IIc: phylogenetic and phylogeographic insights from sequence and microsatellite analysis and potential impact on emergent Chagas disease.

Trypanosoma cruzi, the etiological agent of Chagas disease, is highly genetically diverse. Numerous lines of evidence point to the existence of six stable genetic lineages or DTUs: TcI, TcIIa, TcIIb, TcIIc, TcIId, and TcIIe. Molecular dating suggests that T. cruzi is likely to have been an endemic infection of neotropical mammalian fauna for many millions of years. Here we have applied a panel of 49 polymorphic microsatellite markers developed from the online T. cruzi genome to document genetic diversity among 53 isolates belonging to TcIIc, a lineage so far recorded almost exclusively in silvatic transmission cycles but increasingly a potential source of human infection. These data are complemented by parallel analysis of sequence variation in a fragment of the glucose-6-phosphate isomerase gene. New isolates confirm that TcIIc is associated with terrestrial transmission cycles and armadillo reservoir hosts, and demonstrate that TcIIc is far more widespread than previously thought, with a distribution at least from Western Venezuela to the Argentine Chaco. We show that TcIIc is truly a discrete T. cruzi lineage, that it could have an ancient origin and that diversity occurs within the terrestrial niche independently of the host species. We also show that spatial structure among TcIIc isolates from its principal host, the armadillo Dasypus novemcinctus, is greater than that among TcI from Didelphis spp. opossums and link this observation to differences in ecology of their respective niches. Homozygosity in TcIIc populations and some linkage indices indicate the possibility of recombination but cannot yet be effectively discriminated from a high genome-wide frequency of gene conversion. Finally, we suggest that the derived TcIIc population genetic data have a vital role in determining the origin of the epidemiologically important hybrid lineages TcIId and TcIIe

Development of a 3D printer using scanning projection stereolithography

We have developed a system for the rapid fabrication of low cost 3D devices and systems in the laboratory with micro-scale features yet cm-scale objects. Our system is inspired by maskless lithography, where a digital micromirror device (DMD) is used to project patterns with resolution up to 10 µm onto a layer of photoresist. Large area objects can be fabricated by stitching projected images over a 5cm2 area. The addition of a z-stage allows multiple layers to be stacked to create 3D objects, removing the need for any developing or etching steps but at the same time leading to true 3D devices which are robust, configurable and scalable. We demonstrate the applications of the system by printing a range of micro-scale objects as well as a fully functioning microfluidic droplet device and test its integrity by pumping dye through the channels

Linking Project-Based Interdisciplinary Learning And Recommended Professional Competencies With Business Management, Digital Media, Distance Learning, Engineering Technology, And English

This paper encourages the investigation of real world problems by students and faculty and links recommended student competencies with project based learning. In addition to the traditional course objectives, project-based learning (PBL) uses real world problems for classroom instruction and fieldwork to connect students, instructors, and industry mentors from several disciplines with the recommended professional competencies required of students entering a profession or career. The purpose and focus of this paper is to inform and enlighten, to instruct and educate, and to evoke industry and community interest by combining educational service value with an educational enterprising activity. The paper demonstrates how project-based learning objectives in the classroom integrate with industry recommended professional competencies in solving real world problems. Utilizing the extraordinary intellectual capital of students and faculty in a learning environment on college campuses allows projects to be arranged and managed in a manner that may also provide funding and grant opportunities. Project-based learning linked to recommended professional competencies is a contributing educational force that addresses the needs in communities, student life, and career choices

Experimental Study of Parametric Autoresonance in Faraday Waves

The excitation of large amplitude nonlinear waves is achieved via parametric autoresonance of Faraday waves. We experimentally demonstrate that phase locking to low amplitude driving can generate persistent high-amplitude growth of nonlinear waves in a dissipative system. The experiments presented are in excellent agreement with theory.Comment: 4 pages, 4 eps figures, to appear in Phys. Rev. Let

The Trypanosoma cruzi enzyme TcGPXI is a glycosomal peroxidase and can be linked to trypanothione reduction by glutathione or tryparedoxin.

Trypanosoma cruzi glutathione-dependent peroxidase I (TcGPXI) can reduce fatty acid, phospholipid, and short chain organic hydroperoxides utilizing a novel redox cycle in which enzyme activity is linked to the reduction of trypanothione, a parasite-specific thiol, by glutathione. Here we show that TcGPXI activity can also be linked to trypanothione reduction by an alternative pathway involving the thioredoxin-like protein tryparedoxin. The presence of this new pathway was first detected using dialyzed soluble fractions of parasite extract. Tryparedoxin was identified as the intermediate molecule following purification, sequence analysis, antibody studies, and reconstitution of the redox cycle in vitro. The system can be readily saturated by trypanothione, the rate-limiting step being the interaction of trypanothione with the tryparedoxin. Both tryparedoxin and TcGPXI operate by a ping-pong mechanism. Overexpression of TcGPXI in transfected parasites confers increased resistance to exogenous hydroperoxides. TcGPXI contains a carboxyl-terminal tripeptide (ARI) that could act as a targeting signal for the glycosome, a kinetoplastid-specific organelle. Using immunofluorescence, tagged fluorescent proteins, and biochemical fractionation, we have demonstrated that TcGPXI is localized to both the glycosome and the cytosol. The ability of TcGPXI to use alternative electron donors may reflect their availability at the corresponding subcellular sites

Empirical validation of the S-Score algorithm in the analysis of gene expression data

BACKGROUND: Current methods of analyzing Affymetrix GeneChip(® )microarray data require the estimation of probe set expression summaries, followed by application of statistical tests to determine which genes are differentially expressed. The S-Score algorithm described by Zhang and colleagues is an alternative method that allows tests of hypotheses directly from probe level data. It is based on an error model in which the detected signal is proportional to the probe pair signal for highly expressed genes, but approaches a background level (rather than 0) for genes with low levels of expression. This model is used to calculate relative change in probe pair intensities that converts probe signals into multiple measurements with equalized errors, which are summed over a probe set to form the S-Score. Assuming no expression differences between chips, the S-Score follows a standard normal distribution, allowing direct tests of hypotheses to be made. Using spike-in and dilution datasets, we validated the S-Score method against comparisons of gene expression utilizing the more recently developed methods RMA, dChip, and MAS5. RESULTS: The S-score showed excellent sensitivity and specificity in detecting low-level gene expression changes. Rank ordering of S-Score values more accurately reflected known fold-change values compared to other algorithms. CONCLUSION: The S-score method, utilizing probe level data directly, offers significant advantages over comparisons using only probe set expression summaries