Demonstration of an ultra-short polarization converter in InGaAsP/InP membrane

An ultra-short (<10 µm length) polarization converter is demonstrated in an indium phosphide based membrane. Measurements show very high polarization conversion efficiency (97 %) with low excess losses (~ 1 dB)

Remote Identification of Polar Bear Maternal Den Habitat in Northern Alaska

Polar bears (Ursus maritimus) give birth in dens of ice and snow to protect their altricial young. During the snow-free season, we visited 25 den sites located previously by radiotelemetry and characterized the den site physiognomy. Seven dens occurred in habitats with minimal relief. Eighteen dens (72%) were in coastal and river banks. These "banks" were identifiable on aerial photographs. We then searched high-resolution aerial photographs (n=3000) for habitats similar to those of the 18 dens. On aerial photos, we mapped 1782 km of bank habitats suitable for denning. Bank habitats comprised 0.18% of our study area between the Colville River and the Tamayariak River in northern Alaska. The final map, which correctly identified 88% of bank denning habitat in this region, will help minimize the potential for disruptions of maternal dens by winter petroleum exploration activities.Les ourses polaires (Ursus maritimus) donnent naissance dans des tanières de glace et de neige afin de protéger leurs petits qui sont nidicoles. Durant la saison libre de neige, on a visité 25 lieux de mise bas repérés précédemment par télémesure et on a caractérisé la structure physionomique de ces lieux. Sept tanières étaient localisées au sein d'habitats au relief très peu prononcé. Dix-huit tanières, soit 72 p. cent, se trouvaient sur des berges côtières ou fluviales. Ces «berges» étaient identifiables sur des clichés aériens. On a ensuite cherché sur des clichés aériens (n=3000) pris à haute résolution des habitats semblables à ceux des 18 tanières. Sur ces clichés, on a cartographié 1782 km d'habitats de berges appropriés à l'établissement de tanières. Les habitats de berges constituaient 0,18 p. cent de notre zone d'étude entre la rivière Colville et la Tamayariak dans l'Alaska septentrional. La carte finalisée, qui identifiait correctement 88 p. cent de l'habitat contenant des berges propres à l'établissement de tanières dans la région, aidera à minimiser le potentiel de perturbation des tanières d' ourses due aux activités de prospection pétrolière hivernales

Polar Bear Maternal Den Habitat in the Arctic National Wildlife Refuge, Alaska

Polar bears (Ursus maritimus) give birth during mid-winter in dens of ice and snow. Denning polar bears subjected to human disturbances may abandon dens before their altricial young can survive the rigors of the Arctic winter. Because the Arctic coastal plain of Alaska is an area of high petroleum potential and contains existing and planned oil field developments, the distribution of polar bear dens on the plain is of interest to land managers. Therefore, as part of a study of denning habitats along the entire Arctic coast of Alaska, we examined high-resolution aerial photographs (n = 1655) of the 7994 km2 coastal plain included in the Arctic National Wildlife Refuge (ANWR) and mapped 3621 km of bank habitat suitable for denning by polar bears. Such habitats were distributed uniformly and comprised 0.29% (23.2 km2) of the coastal plain between the Canning River and the Canadian border. Ground-truth sampling suggested that we had correctly identified 91.5% of bank denning habitats on the ANWR coastal plain. Knowledge of the distribution of these habitats will help facilitate informed management of human activities and minimize disruption of polar bears in maternal dens.Les ours polaires (Ursus maritimus) mettent bas au beau milieu de l’hiver dans des tanières de glace et de neige. Les ours polaires des tanières qui sont la cible de dérangements occasionnés par l’être humain peuvent abandonner leur tanière avant que leurs petits ne soient prêts à survivre les rigueurs de l’hiver de l’Arctique. Puisque la plaine côtière arctique de l’Alaska renferme de grandes possibilités sur le plan pétrolier et comprend des champs pétrolifères mis en valeur ou dont la mise en valeur est planifiée, la répartition des tanières d’ours polaires sur la plaine revêt de l’intérêt chez les gestionnaires des terres. Par conséquent, dans le cadre d’une étude portant sur les habitats des tanières tout le long de la côte arctique de l’Alaska, on a examiné des photographies aériennes de haute résolution (n = 1655) portant sur une superficie de 7994 km2 de la plaine côtière faisant partie de la Réserve faunique nationale de l’Arctique (la Réserve), puis on a cartographié 3621 km d’habitats de berges propices à l’établissement de tanières. Ces habitats étaient répartis de manière uniforme et représentaient 0,29 % (23,2 km2) de la plaine côtière entre la rivière Canning et la frontière canadienne. L’échantillonnage des données de terrain suggérait qu’on avait correctement repéré 91,5 % des habitats de tanières de berges sur la plaine côtière de la Réserve. Le fait de connaître la répartition de ces habitats favorisera une bonne gestion de l’activité humaine et permettra de déranger les ours polaires le moins possible dans leurs tanières maternelles

Design of a new ultra-small polarization converter in InGaAsP/InP membrane

The design of an ultra-small (4.1 µm length) polarization converter in Indium phosphide (InP) membrane is presented. The device is modelled using a vectorial 2D mode solver. Simulations show strong conversion (> 94%) and low-loss operation (<0.5 dB) over a wavelength range of 200 nm. A description of a possible fabrication scheme for the device using standard InP technology is also given

Substantia nigra hyperechogenicity in Polish patients with Parkinson’s disease

Background: Hyperechogenicity of the substantia nigra (SN) measured by transcranial sonography (TCS) is a characteristic feature observed in patients with Parkinson’s disease (PD). To our knowledge, no SN hyperechogenicity data are available for Polish population. Moreover most of studies come from few centres, which used the one type of ultrasound device. The main aim of the study was to investigate the association between PD and SN hyperechogenicity measured by sonographic machine, not assessed so far.Materials and methods: In this study cross-sectional study SN hyperechogenicity was evaluated in 102 PD patients and 95 control subjects. Midbrain was visualised by Aloka Prosound 7 ultrasound device. SN area measurement, the relation to the clinical features of PD, inter- and intra-observer reliability were evaluated.Results: We confirmed that SN echogenicity is significantly increased in PD patients compared to control subjects (p < 0.001). The area under curve for PD patients vs. controls was 0.93. Receiver operating characteristic analysis indicated a cut-offs for SN echogenicity at 0.19 cm2 with accuracy equal to 90%, specificity — 86% and sensitivity — 93.7%. The SN hyperechogenicity was not related to PD clinical findings. Reliability was good if an experienced sonographer performed the SN measurements.Conclusions: This study shows that the SN abnormality observed by TCS isa specific feature, which can be helpful in the process of PD diagnosing

Low-loss passive waveguides in a generic InP foundry process via local diffusion of zinc

Generic InP foundry processes allow monolithic integration of active and passive elements into a common p-n doped layerstack. The passive loss can be greatly reduced by restricting the p-dopant to active regions. We report on a localized Zn-diffusion process based on MOVPE, which allows to reduce waveguide loss from 2 dB/cm to below 0.4 dB/cm. We confirm this value by fabrication of a 73 mm long spiral ring resonator, with a record quality factor of 1.2 million and an extinction ratio of 9.7 dB.</p

A malaria parasite subtilisin propeptide-like protein is a potent inhibitor of the egress protease SUB1.

Subtilisin-like serine peptidases (subtilases) play important roles in the life cycle of many organisms, including the protozoan parasites that are the causative agent of malaria, Plasmodium spp. As with other peptidases, subtilase proteolytic activity has to be tightly regulated in order to prevent potentially deleterious uncontrolled protein degradation. Maturation of most subtilases requires the presence of an N-terminal propeptide that facilitates folding of the catalytic domain. Following its proteolytic cleavage, the propeptide acts as a transient, tightly bound inhibitor until its eventual complete removal to generate active protease. Here we report the identification of a stand-alone malaria parasite propeptide-like protein, called SUB1-ProM, encoded by a conserved gene that lies in a highly syntenic locus adjacent to three of the four subtilisin-like genes in the Plasmodium genome. Template-based modelling and ab initio structure prediction showed that the SUB1-ProM core structure is most similar to the X-ray crystal structure of the propeptide of SUB1, an essential parasite subtilase that is discharged into the parasitophorous vacuole (PV) to trigger parasite release (egress) from infected host cells. Recombinant Plasmodium falciparum SUB1-ProM was found to be a fast-binding, potent inhibitor of P. falciparum SUB1, but not of the only other essential blood-stage parasite subtilase, SUB2, or of other proteases examined. Mass-spectrometry and immunofluorescence showed that SUB1-ProM is expressed in the PV of blood stage P. falciparum, where it may act as an endogenous inhibitor to regulate SUB1 activity in the parasite

The 243 steps of making photonic integrated circuits in InP

The fabrication ofInP-based Photonic Integrated Circuits (PICs) is a complex process. The process used in the COBRA cleanroom in Eindhoven consists of 13 deposition, 10 lithography, 14 dry- and 7 wet-etching steps. Together with the intermediate cleaning, preparation and inspection procedures, the total process flow consists of 243 steps. In this paper we show how we created a robust modular process flow that can be usedfor a large variety of active- and passive circuits. These circuits can be fabricated together in multi-project wafer runs, allowing a drastic reduction of the fabrication costs making even small-volume production economicallyfeasible