Dynamics of an inchworm nano-walker

An inchworm processive mechanism is proposed to explain the motion of dimeric molecular motors such as kinesin. We present here preliminary results for this mechanism focusing on observables like mean velocity, coupling ratio and efficiency versus ATP concentration and the external load F.Comment: 6 pages, 2 figure

Vortex Pull by an External Current

In the context of a dynamical Ginzburg-Landau model it is shown numerically that under the influence of a homogeneous external current J the vortex drifts against the current with velocity $V= -J$ in agreement to earlier analytical predictions. In the presence of dissipation the vortex undergoes skew deflection at an angle $90^{\circ} < \delta < 180^{\circ}$ with respect to the external current. It is shown analytically and verified numerically that the angle $\delta$ and the speed of the vortex are linked through a simple mathematical relation.Comment: 19 pages, LATEX, 6 Postscript figures included in separate compressed fil

Atomic scale engines: Cars and wheels

We introduce a new approach to build microscopic engines on the atomic scale that move translationally or rotationally and can perform useful functions such as pulling of a cargo. Characteristic of these engines is the possibility to determine dynamically the directionality of the motion. The approach is based on the transformation of the fed energy to directed motion through a dynamical competition between the intrinsic lengths of the moving object and the supporting carrier.Comment: 4 pages, 3 figures (2 in color), Phys. Rev. Lett. (in print

Quantum vortices in systems obeying a generalized exclusion principle

The paper deals with a planar particle system obeying a generalized exclusion principle (EP) and governed, in the mean field approximation, by a nonlinear Schroedinger equation. We show that the EP involves a mathematically simple and physically transparent mechanism, which allows the genesis of quantum vortices in the system. We obtain in a closed form the shape of the vortices and investigate its main physical properties. PACS numbers: 03.65.-w, 03.65.Ge, 05.45.YvComment: 7 pages, 4 figure

Mirror symmetry breaking through an internal degree of freedom leading to directional motion

We analyze here the minimal conditions for directional motion (net flow in phase space) of a molecular motor placed on a mirror-symmetric environment and driven by a center-symmetric and time-periodic force field. The complete characterization of the deterministic limit of the dissipative dynamics of several realizations of this minimal model, reveals a complex structure in the phase diagram in parameter space, with intertwined regions of pinning (closed orbits) and directional motion. This demonstrates that the mirror-symmetry breaking which is needed for directional motion to occur, can operate through an internal degree of freedom coupled to the translational one.Comment: Accepted for publication in Phys. Rev.

Novel genetic risk variants for pediatric celiac disease

Background: Celiac disease is a complex chronic immune-mediated disorder of the small intestine. Today, the pathobiology of the disease is unclear, perplexing differential diagnosis, patient stratification, and decision-making in the clinic. Methods: Herein, we adopted a next-generation sequencing approach in a celiac disease trio of Greek descent to identify all genomic variants with the potential of celiac disease predisposition. Results: Analysis revealed six genomic variants of prime interest: SLC9A4 c.1919G gt A, KIAA1109 c.2933T gt C and c. 4268_4269delCCinsTA, HoxB6 c.668C gt A, HoxD12 c.418G gt A, and NCK2 c.745_746delAAinsG, from which NCK2 c.745_746delAAinsG is novel. Data validation in pediatric celiac disease patients of Greek (n=109) and Serbian (n=73) descent and their healthy counterparts (n=111 and n=32, respectively) indicated that HoxD12 c.418G gt A is more prevalent in celiac disease patients in the Serbian population (P lt 0.01), while NCK2 c.745_746delAAinsG is less prevalent in celiac disease patients rather than healthy individuals of Greek descent (P = 0. 03). SLC9A4 c.1919G gt A and KIAA1109 c.2933T gt C and c.4268_4269delCCinsTA were more abundant in patients; nevertheless, they failed to show statistical significance. Conclusions: The next-generation sequencing-based family genomics approach described herein may serve as a paradigm towards the identification of novel functional variants with the aim of understanding complex disease pathobiology

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While previous research has focused on choosing between insourcing or outsourcing, no systematic attempt has been made to find a viable alternative for IT capable companies, which need to realize optimum value from their IT capabilities. This study reviews the IT outsourcing and strategic management literature and identifies outsourcing alliances as a strategic alternative to the traditional arms-length outsourcing for IT capable companies. By building an outsourcing alliance with complementary partners, an IT capable company can go beyond its internal market for IT services to provide similar and, even new, IT services to third parties. Grounded in transaction cost economics, relational theory, and the theory on reciprocal learning alliances, this study develops a model in which the IT capable company can earn collaboration-, transaction-, and firm-specific quasi rents through outsourcing alliance

Risk factors for delayed graft function defined as need for dialysis or failure of creatinine to fall by 10% in the first 24 hours after transplant.

OBJECTIVES: Delayed graft function after deceased-donor transplant remains a significant clinical problem. The conventional definition of delayed graft function is the requirement of dialysis within the first week after transplant, but this criterion has many problems that have led to many controversies including those of incidence and significance. Therefore, we sought to identify the possible risk factors of delayed graft function and to investigate their effect on short-term graft survival, according to a composite criterion. MATERIALS AND METHODS: We reviewed the records of 94 renal transplants obtained from heart-beating deceased donors done at our center during a 2-year period. Variables related to the donor, recipient, and graft were retrospectively collected. Follow-up was 12 months. Delayed graft function was defined as the need for dialysis or the failure of the creatinine level to fall by 10% during the first 24 hours after transplant. To confirm suspected rejection, protocol biopsies were done, irrespective of graft function, on the seventh and 28th days after transplant, or when indicated to confirm suspected rejection. RESULTS: The overall incidence of delayed graft function was 31.9%. Multivariate analysis showed donor age as a significant independent predictor of delayed graft function (OR=1.05, P = .03, 95% CI: 1.01-1.09), whereas donor hypotension was the only independent risk factor associated with a worse 1-year graft survival rate (OR=4.6, P = .021, 95% CI: 1.3-16.5). No association could be established between delayed graft function, acute rejection, and graft survival. CONCLUSIONS: Advanced donor age is a predictor of delayed graft function defined as the need for dialysis or the failure of creatinine to fall by 10% during the first 24 hours after transplant. Preventing hemodynamic instability should be an important aspect of donor care