Prenatal Neurogenesis in Autism Spectrum Disorders.

An ever-increasing body of literature describes compelling evidence that a subset of young children on the autism spectrum show abnormal cerebral growth trajectories. In these cases, normal cerebral size at birth is followed by a period of abnormal growth and starting in late childhood often by regression compared to unaffected controls. Recent work has demonstrated an abnormal increase in the number of neurons of the prefrontal cortex suggesting that cerebral size increase in autism is driven by excess neuronal production. In addition, some affected children display patches of abnormal laminar positioning of cortical projection neurons. As both cortical projection neuron numbers and their correct layering within the developing cortex requires the undisturbed proliferation of neural progenitors, it appears that neural progenitors lie in the center of the autism pathology associated with early brain overgrowth. Consequently, autism spectrum disorders associated with cerebral enlargement should be viewed as birth defects of an early embryonic origin with profound implications for their early diagnosis, preventive strategies, and therapeutic intervention

Labor Retrenchment Laws and Their Effect on Wages and Employment: A Theoretical Investigation

Many countries have legislation which make it costly for firms to dismiss or retrench workers. In the case of India, the Industrial Disputes Act, 1947, requires firms that employ 50 or more workers to pay compensation to any worker who is to be retrenched. This paper builds a theoretical model to analyze the effects of such anti-retrenchment laws. Our model reveals that an anti-retrenchment law can cause wages and employment to rise or fall, depending on the parametric conditions prevailing in the market. We then use this simple model to isolate conditions under which an anti-retrenchment law raises wages and employment. In a subsequent section we assume that the law specifies exogenously the amount of compensation, s, a firm has to pay each worker who is being dismissed. It is then shown that as s rises, starting from zero, equilibrium wages fall. However beyond a certain point, further rises in s cause wages to rise. In other words, the relation between the exogenously specified cost to the firm of dismissing a worker and the equilibrium wage is V-shaped

Polymorphous low grade adenocarcinoma-an unusual presentation

Polymorphous low-grade adenocarcinoma (PLGA) is a neoplasm that occurs frequently in the mucosa of the soft and hard palates, in the buccal mucosa and in the upper lip and is very rare within the nasopharynx. We present a case of PLGA, which presented as a nasal polyp

Evidence for two spin-glass transitions with magnetoelastic and magnetoelectric couplings in the multiferroic (Bi1−x_{1-x}Bax_x)(Fe1−x_{1-x}Tix_x)O3_3 system

For disordered Heisenberg systems with small single ion anisotropy, two spin glass transitions below the long range ordered phase transition temperature has been predicted theoretically for compositions close to the percolation threshold. Experimental verification of these predictions is still controversial for conventional spin glasses. We show that multiferroic spin glass systems can provide a unique platform for verifying these theoretical predictions via a study of change in magnetoelastic and magnetoelectric couplings, obtained from an analysis of diffraction data, at the spin glass transition temperatures. Results of macroscopic and microscopic (x-ray and neutron scattering) measurements are presented on disordered BiFeO3, a canonical Heisenberg system with small single ion anisotropy, which reveal appearance of two spin glass phases SG1 and SG2 in coexistence with the LRO phase below the A-T and G-T lines. It is shown that the temperature dependence of the integrated intensity of the antiferromagnetic peak shows dips with respect to the Brillouin function behaviour around the SG1 and SG2 transition temperatures. The ferroelectric polarisation changes significantly at the two spin glass transition temperatures. These results, obtained using microscopic techniques, clearly demonstrate that the SG1 and SG2 transitions occur on the same magnetic sublattice and are intrinsic to the system. We also construct a phase diagram showing all the magnetic phases in BF-xBT system. While our results on the two spin glass transitions support the theoretical predictions, it also raises several open questions which need to be addressed by revisiting the existing theories of spin glass transitions by taking into account the effect of magnetoelastic and magnetoelectric couplings as well as electromagnons.Comment: 59 pages 21 figure

Alternative Labor Retrenchment Laws and Their Effect on Wages and Employment: A Theoretical Investigation with Special Reference to Developing Countries

Many countries have legislation which make it costly for firms to dismiss or retrench workers. In the case of India, the Industrial Disputes Act, 1947, requires firms that employ 50 or more workers to pay a compensation to any worker who is to be retrenched. This paper builds a theoretical model to analyze the effects of such antiretrenchment laws. Our model reveals that an anti-retrenchment law can cause wages and employment to rise or fall, depending on the parametric conditions prevailing in the market. We then use this simple model to isolate conditions under which an antiretrenchment law raises wages and employment. In a subsequent section we assume that the law specifies exogenously the amount of compensation, s, that a firm has to pay each worker who is being dismissed. It is then shown that as s rises, starting from zero, equilibrium wages fall. However beyond a certain point, further rises in s cause wages to rise. In other words, the relation between the exogenously specified cost to the firm of dismissing a worker and the equilibrium wage is V-shaped.