A WDM-PON Employing Fabry–PÉrot Laser Diodes Without a Seed Light Injection

We propose and demonstrate a wavelength-division-multiplexed passive optical network by employing double-contact Fabry-Perot laser diodes (F-P LDs) without a seed light injection. To avoid the high mode partition noise at low frequency, we use a binary phase-shift keying as a modulation format at a low relative intensity noise window. An error-free transmission is achieved by compensating a lasing envelope shift due to temperature variation with the double-contact F-P LD.     

袁泉：活力天然的一泓清泉

明眸晧齿，笑容爽朗，脸部轮廓分明。看到袁泉，马上会有清冽甘甜的感觉，一如她的名字，仿佛夏日里活力天然的一泓清泉。从《春天的狂想》到娃哈哈广告中的美丽少女，袁泉给人的印象一直是青春、健康而甜美的，举手投足，一颦一笑，洋溢着独有的耀眼活力。不久前，这位活力闰女更是担任了“中国女性健康白皮书系列活动”的形象大使。作为宣传女性健康的代言人，袁泉呼吁，要让更多的女性认识到：健康的身体才是美丽人生的根基。[编者按]     

Drug release from heat-treated polyvinyl alcohol films

Polyvinyl alcohol (PVA) films containing 10% w/w of a model drug, sulphathiazole, were cast from aqueous solutions and subjected to heat treatment at specific temperatures for known periods of time. Heat treatment at temperatures above the T_g of the PVA films slowed down the rate of drug release from the films. Increasing the temperature of heat treatment from 120°C to 160°C further decreased the rate of drug release. On the other hand, if the heat treatment were conducted at a temperature below the T_g e.g. at 80°C, there were insignificant differences between the release profile of sulphathiazole from heat-treated films and that from untreated films. The duration of heat treatment affected the rate of drug release to a smaller extent compared to the temperature of heat treatment. These results correlated with the heat induced changes in the morphology of, and in the extent of water uptake by the PVA films.     

A 3.3-V single power supply 16-Mb nonvolatile virtual DRAM using aNAND flash memory technology

A 3.3-V 16-Mb nonvolatile memory having operation virtually identical to DRAM with package pin compatibility has been developed. Read and write operations are fully DRAM compatible except for a longer RAS precharge time after write. Fast random access time of 63 ns with the NAND flash memory cell is achieved by using a hierarchical row decoder scheme and a unique folded bit-line architecture which also allows bit-by-bit program verify and inhibit operation. Fast page mode with a column address access time of 21 ns is achieved by sensing and latching 4 k cells simultaneously. To allow byte alterability, nonvolatile restore operation with self-contained erase is developed. Self-contained erase is word-line based, and increased cell disturb due to the word-line based erase is relaxed by adding a boosted bit-line scheme to a conventional self-boosting technique. The device is fabricated in a 0.5-μm triple-well, p-substrate CMOS process using two-metal and three-poly interconnect layers. A resulting die size is 86.6 mm², and the effective cell size including the overhead of string select transistors is 2.0 μm²     

Correlates of osteopenia in patients with cystic fibrosis

The responses to heat shock in Tritrichomonas mobilensis, a squirrel monkey parasite and Tritrichomonas augusta, an amphibian trichomonad, were evaluated by means of metabolic labeling with [35S]methionine. Electrophoretically separated trichomonad proteins synthesized at different temperatures were visualized by autoradiography and the label incorporation quantitated by a trichloroacetic acid precipitation procedure. A considerable difference in thermotolerance between the two species was found as the protein synthesis reached a maximum at 41 C in T. mobilensis and 37 C in T. augusta. The latter tolerated temperature increases 13 C above normal cultivation temperatures as compared to only 4 C thermotolerance range above normal in T. mobilensis. Major heat shock proteins (Hsps) were expressed in both T. mobilensis (with apparent Mr 94, 72, and 58 kDa) and T. augusta (Mr 94, 70, and 56 kDa) as revealed by autoradiography. Western blot analysis with polyclonal antibody against DnaK of Escherichia coli showed the presence of antigenic Hsp70 homologs in both trichomonads. Similarly, a polyclonal antibody against Hsp60 with broad interspecies cross-reactivity detected Hsp60 homologs in both T. mobilensis and T. augusta. The anti-DnaK antibody cross-reacted with a T. mobilensis protein localized in Golgi apparatus as demonstrated by immunoelectron microscopy. Immunocytochemistry on trichomonad frozen sections revealed the presence of the Hsp60 homolog in light-microscopic granules corresponding to hydrogenosomes.     

Rapid Prototyping and Tooling of Custom-Made Tracheobronchial Stents

Rapid prototyping (RP) and rapid tooling (RT) techniques can be applied to the field of medicine primarily because of their ability to produce customised profiles and geometries in relatively short lead times. In this paper, the process by which these techniques can be applied for the production of customised tracheobronchial stents for the purpose of maintaining patency in an occluded respiratory tract is described. A comparison of RP systems was carried out to establish the preferred RP method to produce the master model. The vacuum casting RT process was then used to produce the stent.     

Bacteroides fragilis enterotoxin cleaves the zonula adherens protein, E-cadherin

Strains of Bacteroides fragilis associated with diarrheal disease (enterotoxigenic B. fragilis) produce a 20-kDa zinc-dependent metalloprotease toxin (B. fragilis enterotoxin; BFT) that reversibly stimulates chloride secretion and alters tight junctional function in polarized intestinal epithelial cells. BFT alters cellular morphology and physiology most potently and rapidly when placed on the basolateral membrane of epithelial cells, suggesting that the cellular substrate for BFT may be present on this membrane. Herein, we demonstrate that BFT specifically cleaves within 1 min the extracellular domain of the zonula adherens protein, E-cadherin. Cleavage of E-cadherin by BFT is ATP-independent and essential to the morphologic and physiologic activity of BFT. However, the morphologic changes occurring in response to BFT are dependent on target-cell ATP. E-cadherin is shown here to be a cellular substrate for a bacterial toxin and represents the identification of a mechanism of action, cell-surface proteolytic activity, for a bacterial toxin.     

Protein fluctuations are sensed by stimulated infrared echoes of the vibrations of carbon monoxide and azide probes

The correlation functions of the fluctuations of vibrational frequencies of azide ions and carbon monoxide in proteins are determined directly from stimulated photon echoes generated with femtosecond infrared pulses. The asymmetric stretching vibration of azide bound to carbonic anhydrase II exhibits a pronounced evolution of its vibrational frequency distribution on the time scale of a few picoseconds, which is attributed to modifications of the ligand structure through interactions with the nearby Thr-199. When azide is bound in hemoglobin, a more complex evolution of the protein structure is required to interchange the different ligand configurations, as evidenced by the much slower relaxation of the frequency distribution in this case. The time evolution of the distribution of frequencies of carbon monoxide bound in hemoglobin occurs on the approximately 10-ps time scale and is very nonexponential. The correlation functions of the frequency fluctuations determine the evolution of the protein structure local to the probe and the extent to which the probe can navigate those parts of the energy landscape where the structural configurations are able to modify the local potential energy function of the probe.