Free swimming organisms: Microgravity as an investigative tool

On earth, micro-organisms are in the grip of gravitational and viscous forces. These forces, in combination with sensory stimuli, determine the average orientation of the organisms' swimming trajectories relative to the fluid environment. Microgravity provides the opportunity to study the rules which govern the summation or orienting influences and to develop quantitative physical measurements of sensory responses, e.g. the measurement of phototactic orientation tendency in torque units. Also, by reducing or eliminating density anisotropy-driven buoyant convection, it will be possible to study illumination, temperature gradient and concentration gradient-mediated collective dynamics

The Global Employer: The Labor Relations and Collective Agreements Issue

[Excerpt] Baker & McKenzie’s Global Employment Practice Group is pleased to present its 56th issue of The Global Employer™ entitled “The Labor Relations and Collective Agreements Issue.” In this issue you will find the first report from our Future of Work Series. Labor Relations Report - Brand Attack: How to avoid becoming the target of a corporate campaign and what actions to take if you do. The Future of Work is a series of client reports based on panel discussions at our Global Employer Forum, a two-day thought leadership conference. During the forum, nearly 70 clients, academics and consultants gathered with our employment partners to discuss pressing workplace topics like talent shortages, data privacy, global mobility assignments, globalization of unions and managing the employment aspects of M&A deals. Rather than the traditional “how to” legal format of most law firm conferences, the Global Employer Forum features panel discussions of in-house counsel and senior-level executives from some of the world’s largest multinational organizations who discussed their personal experiences addressing these challenges and the solutions they have found to overcome them. Following the Labor Relations Report, you will also find information pertaining to the current state of labor relations and union negotiations in Argentina and a general overview of the current state of collective bargaining in Brazil. In Germany, we take a look at some of the numbers behind collective bargaining agreements; and a review of the impacts on labor benefits of the January 2014, Income Tax Law reform in Mexico. From Spain we bring you articles that discuss negotiating with representatives bodies in collective lay-offs and the new role of company level collective bargaining agreements; and from the US, recent efforts by the NLRB as it Targets Successor Issues in US Mergers and Acquisitions

The Global Employer: The Employment Law Review and Reform Issue

[Excerpt] Although the economies of many jurisdictions are improving, there is still some lingering global economic uncertainty. It is no surprise that governments the world over continue to revisit their employment laws to see what else, if anything, can be done to further stimulate their economies. 2013 was another busy year for employment law reform. Baker & McKenzie’s Global Employment Practice Group is pleased to present its 55th issue of The Global Employer™ entitled “The Employment Law Review and Reform Issue.” In this issue, we review changes to the law in 2013 and a look at pending changes for 2014. Included, you will find information pertaining to the leasing of employees in Germany; new measures in Spain intended to promote employment among young people under 30 and employee privacy rights over employers\u27 controls; challenges to the applicable interest rate to worker\u27s claims in Argentina; how employment law reforms will significantly impact employers in Mexico and in some specific cases, may considerably elevate increase the cost of formal employment; and controversy around making the Colombian Social Security System more progressive. We also review several significant legal developments in China during 2013 that impact employers operating there; legislative changes that were expected in Hong Kong in 2013 that may be implemented in 2014 including a focus on discrimination in the coming years; and welcome changes to TUPE and automatic pension plan enrollment in the United Kingdom

Taylor dispersion of gyrotactic swimming micro-organisms in a linear flow

The theory of generalized Taylor dispersion for suspensions of Brownian particles is developed to study the dispersion of gyrotactic swimming micro-organisms in a linear shear flow. Such creatures are bottom-heavy and experience a gravitational torque which acts to right them when they are tipped away from the vertical. They also suffer a net viscous torque in the presence of a local vorticity field. The orientation of the cells is intrinsically random but the balance of the two torques results in a bias toward a preferred swimming direction. The micro-organisms are sufficiently large that Brownian motion is negligible but their random swimming across streamlines results in a mean velocity together with diffusion. As an example, we consider the case of vertical shear flow and calculate the diffusion coefficients for a suspension of the alga <i>Chlamydomonas nivalis</i>. This rational derivation is compared with earlier approximations for the diffusivity

Nonlinear lattice model of viscoelastic Mode III fracture

We study the effect of general nonlinear force laws in viscoelastic lattice models of fracture, focusing on the existence and stability of steady-state Mode III cracks. We show that the hysteretic behavior at small driving is very sensitive to the smoothness of the force law. At large driving, we find a Hopf bifurcation to a straight crack whose velocity is periodic in time. The frequency of the unstable bifurcating mode depends on the smoothness of the potential, but is very close to an exact period-doubling instability. Slightly above the onset of the instability, the system settles into a exactly period-doubled state, presumably connected to the aforementioned bifurcation structure. We explicitly solve for this new state and map out its velocity-driving relation

Does the continuum theory of dynamic fracture work?

We investigate the validity of the Linear Elastic Fracture Mechanics approach to dynamic fracture. We first test the predictions in a lattice simulation, using a formula of Eshelby for the time-dependent Stress Intensity Factor. Excellent agreement with the theory is found. We then use the same method to analyze the experiment of Sharon and Fineberg. The data here is not consistent with the theoretical expectation.Comment: 4 page

Mott scattering of polarized electrons in a strong laser field

We present analytical and numerical results of the relativistic calculation of the transition matrix element $S_{fi}$ and differential cross section for Mott scattering of initially polarized Dirac particles (electrons) in the presence of strong laser field with linear polarization. We use exact Dirac-Volkov wave functions to describe the dressed electrons and the collision process is treated in the first Born approximation. The influence of the laser field on the degree of polarization of the scattered electron is reported.Comment: 12 pages, 11 figures, Revte