Strained silicon as a new electro-optic material

For decades, silicon has been the material of choice for mass fabrication of electronics. This is in contrast to photonics, where passive optical components in silicon have only recently been realized. The slow progress within silicon optoelectronics, where electronic and optical functionalities can be integrated into monolithic components based on the versatile silicon platform, is due to the limited active optical properties of silicon. Recently, however, a continuous-wave Raman silicon laser was demonstrated; if an effective modulator could also be realized in silicon, data processing and transmission could potentially be performed by all-silicon electronic and optical components. Here we have discovered that a significant linear electro-optic effect is induced in silicon by breaking the crystal symmetry. The symmetry is broken by depositing a straining layer on top of a silicon waveguide, and the induced nonlinear coefficient, chi(2) approximately 15 pm V(-1), makes it possible to realize a silicon electro-optic modulator. The strain-induced linear electro-optic effect may be used to remove a bottleneck in modern computers by replacing the electronic bus with a much faster optical alternative.     

Analysis of Plasmodium falciparum diversity in natural infections by deep sequencing

Malaria elimination strategies require surveillance of the parasite population for genetic changes that demand a public health response, such as new forms of drug resistance. Here we describe methods for the large-scale analysis of genetic variation in Plasmodium falciparum by deep sequencing of parasite DNA obtained from the blood of patients with malaria, either directly or after short-term culture. Analysis of 86,158 exonic single nucleotide polymorphisms that passed genotyping quality control in 227 samples from Africa, Asia and Oceania provides genome-wide estimates of allele frequency distribution, population structure and linkage disequilibrium. By comparing the genetic diversity of individual infections with that of the local parasite population, we derive a metric of within-host diversity that is related to the level of inbreeding in the population. An open-access web application has been established for the exploration of regional differences in allele frequency and of highly differentiated loci in the P.?falciparum genome.     

Reinterpretation of the ultrastructure of cartilage matrix.

The epiphyseal cartilage from new-born mouse was treated with collagenase in two ways: either before fixation or after glutaraldehyde fixation. The electron dense granules of the matrix were not seen in the micrographs of cartilage treated with collagenase before fixation. It is concluded that collagen plays a definite role in the formation of the granules at the time of tissue fixation and that the granules are fixation artifacts.     

Action du succinate de soude sur la respiration

Summary Intravenous injection of sodium succinate in dogs anesthetized with chloralosane produces a prolonged stimulation of respiration and decreases the duration of the apnea following pulmonary hyperventilation.     

Observations expérimentales sur l'apnée acapnique chez le Chien

Summary Suppression of the chemo-receptors of the carotid sinus and aorta æreas prolongs the acapnic apnea markedly. Animals deprived of their chemo-receptors may even die in apnea.During hyperventilation, the expiratory position of the thorax increases. During the acapnic apnea the inspiratory position returns progressively to normal. During hyperventilation and acapnic apnea, rhythmic changes occur in the tonus of the respiratory muscles. These changes in tonus occur in normal animals as well as in animals deprived of their chemo-receptors and vagi nerves.In normal dogs, hyperventilation and acapnea do not induce a fall in arterial blood pressure. Arterial hypotension occurs, however, during hyperventilation in dogs deprived of their carotid sinus and aortic innervation. During acapnic apnea, the arterial blood pressure rises in animals deprived of their carotid sinus and aortic nerves. A secondary fall of arterial pressure occurs during prolonged acapnic apnea in these animals.