Magnetic field assisted fractionation of nonmagnetic colloids in ferrofluid

IEEE Transactions on Magnetics, 43(6): pp. 2692-2694.Flocculation of nonmagnetic colloidal particles in ferrofluid while in the presence of an external uniform magnetic field is investigated experimentally. Magnetic nanoparticles in ferrofluid create magnetic interactions between nonmagnetic colloidal particles. It is demonstrated that nonmagnetic particles can be fractionated by size much more efficiently in the presence of these magnetic interactions

Early and rapid prediction of patency of the infarct-related coronary artery by using left ventricular wall thickness as measured by two-dimensional echocardiography

AbstractObjectives. The aim of this study was to determine whether echocardiography can distinguish between persistent coronary occlusion and reperfusion.Background. There are no adequate clinical or noninvasive laboratory markers to accurately predict successful reperfusion in an acute myocardial infarction.Methods. In a closed chest swine model, the effect of reperfusion on myocardial wall thickness was studied by comparing a 150-min total coronary artery occlusion (group 1) with 120 min of occlusion followed by 30 min of reperfusion (group 2) in the area of risk as measured by echocardiography. Wall thickness was measured at baseline and at 90 and 150 min.Results. In group 1 (n = 4), there was no appreciable change in mean wall thickness from 90 min to 150 min of occlusion at either end-diastole or end-systole (0.54 ± 0.02 to 0.52 ± 0.03 cm, 0.55 ± 0.03 to 0.54 ± 0.03 cm, respectively; p = NS). In contrast, in group 2 (n = 6), an increase in mean wall thickness from 0.53 ± 0.02 to 0.97 ± 0.05 cm at end-diastole and from 0.56 ± 0.04 to 1.04 ± 0.07 cm at end-systole was found from 90 min of occlusion to 30 min of reperfusion (p < 0.001). Reperfusion resulted. in an increase in wall thickness of 83 ± 11% at end-diastole and 92 ± 17% at end-systole. In contrast, persistent coronary occlusion showed minimal changes of −3.0 ± 5% at end-diastole and −2.0 ± 6% at end-systole.Conclusions. This study confirms the hypothesis that an increase in wall thickness can accurately distinguish between reperfusion and permanent coronary occlusion

A Chiral N=1 Type I Vacuum in Four Dimensions and Its Heterotic Dual

In this paper we consider Type I string theory compactified on a Z_7 orbifold. The model has N=1 supersymmetry, a U(4) \otimes U(4) \otimes U(4) \otimes SO(8) gauge group, and chiral matter. There are only D9-branes (for which we discuss tadpole cancellation conditions) in this model corresponding to a perturbative heterotic description in a certain region of the moduli space. We construct the heterotic dual, match the perturbative type I and heterotic tree-level massless spectra via giving certain scalars appropriate vevs, and point out the crucial role of the perturbative superpotential (on the heterotic side) for this matching. The relevant couplings in this superpotential turn out to be non-renormalizable (unlike the Z-orbifold case discussed in Ref [1], where Yukawa couplings sufficed for duality matching). We also discuss the role of the anomalous U(1) gauge symmetry present in both type I and heterotic models. In the perturbative regime we match the (tree-level) moduli spaces of these models. We point out possible generalizations of the Z_3 and Z_7 cases to include D5-branes which would help in understanding non-perturbative five-brane dynamics on the heterotic side.Comment: Revtex 3.0, 23 pages, 1 eps figure (to appear in Phys. Rev. D

Point of View: What’s in a name?

Numerous concerns have been raised about the sustainability of the biomedical research enterprise in the United States. Improving the postdoctoral training experience is seen as a priority in addressing these concerns, but even identifying who the postdocs are is made difficult by the multitude of different job titles they can carry. Here, we summarize the detrimental effects that current employment structures have on training, compensation and benefits for postdocs, and argue that academic research institutions should standardize the categorization and treatment of postdocs. We also present brief case studies of two institutions that have addressed these challenges and can provide models for other institutions attempting to enhance their postdoctoral workforces and improve the sustainability of the biomedical research enterprise

tofacitinib treatment is associated with modest and reversible increases in serum lipids in patients with ulcerative colitis

Background & Aims Tofacitinib is an oral, small-molecule Janus kinase inhibitor for the treatment of ulcerative colitis (UC). We analyzed inflammation, lipid concentrations, and incidence rates of major adverse cardiovascular (CV) events (MACEs) in patients who received tofacitinib in worldwide studies. Methods We collected data from 1157 patients who participated in 3 8-week induction studies (1 phase-2 study and 2 phase-3 studies; patients received tofacitinib 10 mg twice daily or placebo), a 52-week phase-3 maintenance study of responders (patients received tofacitinib 5 or 10 mg twice daily or placebo), and an ongoing long-term extension study of patients who did and did not respond to induction or maintenance therapy (patients received tofacitinib 5 or 10 mg twice daily). Lipid concentrations were assessed from induction baseline to week 61 (week 52 of maintenance therapy). We calculated MACE incidence rates (patients with ≥1 event per 100 patient-years of exposure) and Reynolds risk score (RRS; a composite score used to determine CV risk) for patients given tofacitinib vs placebo. Results The mean RRS was P Conclusions In an analysis of data from 5 trials of patients with UC who received tofacitinib, we found reversible increases in lipids with treatment and inverse correlations with reduced levels of high-sensitivity C-reactive protein. We did not find clinically meaningful changes in lipid ratios or RRS. MACEs were infrequent and not dose-related. Clinical trial registration Clinicaltrials.gov : A3921063 ( NCT00787202 ); OCTAVE Induction 1 ( NCT01465763 ); OCTAVE Induction 2 ( NCT01458951 ); OCTAVE Sustain ( NCT01458574 ); OCTAVE Open ( NCT01470612

Arraying nonmagnetic colloids by magnetic nanoparticle assemblers

IEEE Transactions On Magnetics, 42(10): pp. 3548-3553.We review our recent work on the manipulation and assembly of nonmagnetic colloidal materials above magnetically programmable surface templates. The nonmagnetic materials are manipulated by a fluid dispersion of magnetic nanoparticles, known as ferrofluid. Particle motion is guided by a program of magnetic information stored in a substrate in the form of a lithographically patterned template of micromagnets. We show how dynamic control over the motion of nonmagnetic particles can be accomplished by applying rotating external magnetic field. This unexpectedly large degree of control over particle motion can be used to manipulate large ensembles of particles in parallel, potentially with local control over particle trajectory

Topology and Signature Changes in Braneworlds

It has been believed that topology and signature change of the universe can only happen accompanied by singularities, in classical, or instantons, in quantum, gravity. In this note, we point out however that in the braneworld context, such an event can be understood as a classical, smooth event. We supply some explicit examples of such cases, starting from the Dirac-Born-Infeld action. Topology change of the brane universe can be realised by allowing self-intersecting branes. Signature change in a braneworld is made possible in an everywhere Lorentzian bulk spacetime. In our examples, the boundary of the signature change is a curvature singularity from the brane point of view, but nevertheless that event can be described in a completely smooth manner from the bulk point of view.Comment: 26 pages, 8 figures, references and comments are added, minor revisions and a number of additional footnotes added, error corrected, minor corrections, to appear in Class. Quant. Gra

Nonthermal atmospheric pressure plasma enhances mouse limb bud survival, growth, and elongation.

The enhanced differentiation of mesenchymal cells into chondrocytes or osteoblasts is of paramount importance in tissue engineering and regenerative therapies. A newly emerging body of evidence demonstrates that appendage regeneration is dependent on reactive oxygen species (ROS) production and signaling. Thus, we hypothesized that mesenchymal cell stimulation by nonthermal (NT)-plasma, which produces and induces ROS, would (1) promote skeletal cell differentiation and (2) limb autopod development. Stimulation with a single treatment of NT-plasma enhanced survival, growth, and elongation of mouse limb autopods in an in vitro organ culture system. Noticeable changes included enhanced development of digit length and definition of digit separation. These changes were coordinated with enhanced Wnt signaling in the distal apical epidermal ridge (AER) and presumptive joint regions. Autopod development continued to advance for approximately 144 h in culture, seemingly overcoming the negative culture environment usually observed in this in vitro system. Real-time quantitative polymerase chain reaction analysis confirmed the up-regulation of chondrogenic transcripts. Mechanistically, NT-plasma increased the number of ROS positive cells in the dorsal epithelium, mesenchyme, and the distal tip of each phalange behind the AER, determined using dihydrorhodamine. The importance of ROS production/signaling during development was further demonstrated by the stunting of digital outgrowth when anti-oxidants were applied. Results of this study show NT-plasma initiated and amplified ROS intracellular signaling to enhance development of the autopod. Parallels between development and regeneration suggest that the potential use of NT-plasma could extend to both tissue engineering and clinical applications to enhance fracture healing, trauma repair, and bone fusion

Validation of high gradient magnetic field based drug delivery to magnetizable implants under flow

IEEE Transactions on Biomedical Engineering, 55(2): pp. 643-649.The drug-eluting stent’s increasingly frequent occurrence late stage thrombosis have created a need for new strategies for intervention in coronary artery disease. This paper demonstrates further development of our minimally invasive, targeted drug delivery system that uses induced magnetism to administer repeatable and patient specific dosages of therapeutic agents to specific sites in the human body. Our first aim is the use of magnetizable stents for the prevention and treatment of coronary restenosis; however, future applications include the targeting of tumors, vascular defects, and other localized pathologies. Future doses can be administered to the same site by intravenous injection. This implant-based drug delivery system functions by placement of a weakly magnetizable stent or implant at precise locations in the cardiovascular system, followed by the delivery of magnetically susceptible drug carriers. The stents are capable of applying high local magnetic field gradients within the body, while only exposing the body to a modest external field. The local gradients created within the blood vessel create the forces needed to attract and hold drug-containing magnetic nanoparticles at the implant site. Once these particles are captured, they are capable of delivering therapeutic agents such as antineoplastics, radioactivity, or biological cells