bluuebunny/crossref_metadata_2025 huggingface dataset:
The Expression of the t-SNARE AtSNAP33 Is Induced by Pathogens and Mechanical Stimulation
Authors: Wick Peter , Gansel Xavier , Oulevey Catherine , Page Valérie , Studer Ingrid , Dürst Michael , Sticher Liliane
Published: May 2003

The fusion of vesicles in the secretory pathway involves the interaction of t-soluble N-ethylmaleimide-sensitive factor attachment protein receptors (t-SNAREs) on the target membrane and v-SNAREs on the vesicle membrane. AtSNAP33 is an Arabidopsis homolog of the neuronal t-SNARE SNAP-25 involved in exocytosis and is localized at the cell plate and at the plasma membrane. In this paper, the expression of AtSNAP33 was analyzed after different biotic and abiotic stresses. The expression of AtSNAP33increased after inoculation with the pathogens Plectosporium tabacinum and virulent and avirulent forms ofPeronospora parasitica and Pseudomonas syringae pv tomato. The expression ofPR1 transcripts encoding the secreted pathogenesis-related protein 1 also increased after inoculation with these pathogens and the expression of AtSNAP33 preceded or occurred at the same time as the expression of PR1. AtSNAP33 was also expressed in npr1 plants that do not express PR1 after pathogen inoculation as well as incpr1 plants that overexpress PR1 in the absence of a pathogen. The level of AtSNAP33 decreased slightly in leaves inoculated with P. parasitica in theNahG plants, and eds5 andsid2 mutants that are unable to accumulate salicylic acid (SA) after pathogen inoculation, indicating a partial dependence on SA. AtSNAP33 was also expressed in systemic noninoculated leaves of plants inoculated with P. syringae. In contrast to the situation in infected leaves, the expression of AtSNAP33 in systemic leaves was fully SA dependent. Thus, the expression of AtSNAP33 after pathogen attack is regulated by SA-dependent and SA-independent pathways. Mechanical stimulation also led to an increase ofAtSNAP33 transcripts.
CACTA Transposons in Triticeae. A Diverse Family of High-Copy Repetitive Elements
Authors: Wicker Thomas , Guyot Romain , Yahiaoui Nabila , Keller Beat
Published: May 2003

In comparison with retrotransposons, which comprise the majority of the Triticeae genomes, very few class 2 transposons have been described in these genomes. Based on the recent discovery of a local accumulation of CACTA elements at theGlu-A3 loci in the two wheat species Triticum monococcum and Triticum durum, we performed a database search for additional such elements in Triticeae spp. A combination of BLAST search and dot-plot analysis of publicly available Triticeae sequences led to the identification of 41 CACTA elements. Only seven of them encode a protein similar to known transposases, whereas the other 34 are considered to be deletion derivatives. A detailed characterization of the identified elements allowed a further classification into seven subgroups. The major subgroup, designated the “Caspar ” family, was shown by hybridization to be present in at least 3,000 copies in theT. monococcum genome. The close association of numerous CACTA elements with genes and the identification of several similar elements in sorghum (Sorghum bicolor) and rice (Oryza sativa) led to the conclusion that CACTA elements contribute significantly to genome size and to organization and evolution of grass genomes.
STA11, a Chlamydomonas reinhardtii Locus Required for Normal Starch Granule Biogenesis, Encodes Disproportionating Enzyme. Further Evidence for a Function of α-1,4 Glucanotransferases during Starch Granule Biosynthesis in Green Algae
Authors: Wattebled Fabrice , Ral Jean-Philippe , Dauvillée David , Myers Alan M. , James Martha G. , Schlichting Ralf , Giersch Christoph , Ball Steven G. , D'Hulst Christophe
Published: May 2003

In Chlamydomonas reinhardtii, the presence of a defective STA11 locus results in significantly reduced granular starch deposition displaying major modifications in shape and structure. This defect simultaneously leads to the accumulation of linear malto-oligosaccharides (MOS). The mutants ofSTA11 were showed to lack d-enzyme, a plant α-1,4 glucanotransferase analogous to the Escherichia coli amylomaltase. We have cloned and characterized both the cDNA and gDNA corresponding to the C.reinhardtii  d-enzyme. We now report allele-specific modifications of the d-enzyme gene in the mutants of STA11. These allele-specific modifications cosegregate with the corresponding sta11 mutations, thereby demonstrating that STA11 encodesd-enzyme. MOS production and starch accumulation were investigated during day and night cycles in wild-type and mutantC. reinhardtii cells. We demonstrate that in the algae MOS are produced during starch biosynthesis and degraded during the phases of net polysaccharide catabolism.
Expression of the Plastid-Located Glutamine Synthetase ofMedicago truncatula. Accumulation of the Precursor in Root Nodules Reveals an in Vivo Control at the Level of Protein Import into Plastids
Authors: Melo Paula M. , Lima Lı́gia M. , Santos Isabel M. , Carvalho Helena G. , Cullimore Julie V.
Published: May 2003

In this paper, we report the cloning and characterization of the plastid-located glutamine synthetase (GS) of Medicago truncatula Gaertn (MtGS2). A cDNA was isolated encoding a GS2 precursor polypeptide of 428 amino acids composing an N-terminal transit peptide of 49 amino acids. Expression analysis, by Westerns and by northern hybridization, revealed thatMtGS2 is expressed in both photosynthetic and non-photosynthetic organs. Both transcripts and proteins ofMtGS2 were detected in substantial amounts in root nodules, suggesting that the enzyme might be performing some important role in this organ. Surprisingly, about 40% of the plastid GS in nodules occurred in the non-processed precursor form (preGS2). This precursor was not detected in any other organ studied and moreover was not observed in non-fixing nodules. Cellular fractionation of nodule extracts revealed that preGS2 is associated with the plastids and that it is catalytically inactive. Immunogold electron microscopy revealed a frequent coincidence of GS with the plastid envelope. Taken together, these results suggest a nodule-specific accumulation of the GS2 precursor at the surface of the plastids in nitrogen-fixing nodules. These results may reflect a regulation of GS2 activity in relation to nitrogen fixation at the level of protein import into nodule plastids.
Salicylic Acid Alleviates the Cadmium Toxicity in Barley Seedlings
Authors: Metwally Ashraf , Finkemeier Iris , Georgi Manfred , Dietz Karl-Josef
Published: May 2003

Salicylic acid (SA) plays a key role in plant disease resistance and hypersensitive cell death but is also implicated in hardening responses to abiotic stressors. Cadmium (Cd) exposure increased the free SA contents of barley (Hordeum vulgare) roots by a factor of about 2. Cultivation of dry barley caryopses presoaked in SA-containing solution for only 6 h or single transient addition of SA at a 0.5 mmconcentration to the hydroponics solution partially protected the seedlings from Cd toxicity during the following growth period. Both SA treatments had little effect on growth in the absence of Cd, but increased root and shoot length and fresh and dry weight and inhibited lipid peroxidation in roots, as indicated by malondialdehyde contents, in the presence of Cd. To test whether this protection was due to up-regulation of antioxidant enzymes, activities and transcript levels of the H2O2-metabolizing enzymes such as catalase and ascorbate peroxidase were measured in control and SA-treated seedlings in the presence or absence of 25 μmCd. Cd stress increased the activity of these enzymes by variable extent. SA treatments strongly or completely suppressed the Cd-induced up-regulation of the antioxidant enzyme activities. Slices from leaves treated with SA for 24 h also showed an increased level of tolerance toward high Cd concentrations as indicated by chlorophyll a fluorescence parameters. The results support the conclusion that SA alleviates Cd toxicity not at the level of antioxidant defense but by affecting other mechanisms of Cd detoxification.
Mining for Single Nucleotide Polymorphisms and Insertions/Deletions in Maize Expressed Sequence Tag Data
Authors: Batley Jacqueline , Barker Gary , O'Sullivan Helen , Edwards Keith J. , Edwards David
Published: May 2003

We have developed a computer based method to identify candidate single nucleotide polymorphisms (SNPs) and small insertions/deletions from expressed sequence tag data. Using a redundancy-based approach, valid SNPs are distinguished from erroneous sequence by their representation multiple times in an alignment of sequence reads. A second measure of validity was also calculated based on the cosegregation of the SNP pattern between multiple SNP loci in an alignment. The utility of this method was demonstrated by applying it to 102,551 maize (Zea mays) expressed sequence tag sequences. A total of 14,832 candidate polymorphisms were identified with an SNP redundancy score of two or greater. Segregation of these SNPs with haplotype indicates that candidate SNPs with high redundancy and cosegregation confidence scores are likely to represent true SNPs. This was confirmed by validation of 264 candidate SNPs from 27 loci, with a range of redundancy and cosegregation scores, in four inbred maize lines. The SNP transition/transversion ratio and insertion/deletion size frequencies correspond to those observed by direct sequencing methods of SNP discovery and suggest that the majority of predicted SNPs and insertion/deletions identified using this approach represent true genetic variation in maize.
The Activity of the Chloroplastic Ndh Complex Is Regulated by Phosphorylation of the NDH-F Subunit
Authors: Lascano H. Ramiro , Casano Leonardo M. , Martı́n Mercedes , Sabater Bartolomé
Published: May 2003

Hydrogen peroxide (H2O2) induces increases, to different degrees, in transcripts, protein levels, and activity of the Ndh complex (EC 1.6.5.3). In the present work, we have compared the effects of relatively excess light, H2O2, dimethylthiourea (a scavenger of H2O2), and/or EGTA (a Ca2+chelator) on the activity and protein levels of the Ndh complex of barley (Hordeum vulgare cv Hassan) leaf segments. The results show the involvement of H2O2 in the modulation of both the protein level and activity of the Ndh complex and the participation of Ca2+ mainly in the activity regulation of pre-existing protein. Changes in Ndh complex activity could not be explained only by changes in Ndh protein levels, suggesting posttranslational modifications. Hence, we investigate the possible phosphorylation of the Ndh complex both in thylakoids and in the immunopurified Ndh complex using monoclonal phosphoamino acid antibodies. We demonstrate that the Ndh complex is phosphorylated in vivo at threonine residue(s) of the NDH-F polypeptide and that the level of phosphorylation is closely correlated with the Ndh complex activity. The emerging picture is that full activity of the Ndh complex is reached by phosphorylation of its NDH-F subunit in a H2O2- and Ca2+-mediated action.
An innovative maintenance system for emergency lighting
Authors: Tse W.L. , Chan W.L. , Lai S.S.
Published: May 2003

Fire regulations of different countries require that a monthly test is carried out on each battery back‐up emergency lighting to check for functionality. Existing practice requires a team of maintenance staff to carry out the test manually at each lighting point, which is unreliable, inefficient and tedious. An innovative maintenance system is proposed to cater for this issue. It has several advantages over the existing practice – high reliability, cost effectiveness and user friendliness. With simple modification and the inclusion of LonWorks technology, an intelligent control node is proposed for carrying out the test regularly and sending the test results to a main terminal at a remote centre over a control network. Any defective lighting point can be easily spotted and repairs can be carried out promptly. Also, the system can be integrated with the existing building automation system to form an integrated system to facilitate building management.
Venue contingency planning for the Sydney 2000 Olympic Games
Authors: Stamatakis Haralabos , Gargalianos Dimitris , Afthinos Yiannis , Nassis Pantelis
Published: May 2003

Identifies major issues of the contingency planning process covered by the Sydney Organizing Committee of Olympic Games (SOCOG) with regard to the various venues. For the evaluation of the findings theAustralian Business Excellence Frameworkhas been used. The methodology includes a literature review and five in‐depth interviews with individuals who played an active role in the planning process. The results indicate that as far as the overall planning process is concerned, there has been: a lack of communication between the three levels of hierarchy within SOCOG 2000 (senior management, contingency planning project team and venue teams); a limited involvement of the venue management in the process in all levels; a poor follow up regarding the evaluation and the documentation of the contingency plans made; and a considerable inadequacy in terms of “real life” exercises that would enable the venue teams’ personnel to practice what has been planned.
‘Law in Context’ Revisited
Authors: Selznick Philip
Published: May 2003

Although ‘Law in Context’ is a well‐known motto for law‐and‐society scholarship, the idea could benefit from closer examination. This paper introduces a principle of `fidelity to context' and suggests that contexts may be transcended by invoking general purposes and principles. These issues have special relevance for contextual analysis of free speech, academic freedom, and other rights and responsibilities. I also consider the relevance of legal pluralism, and the contextual analysis of human rights.
Action Potentials in Basal and Oblique Dendrites of Rat Neocortical Pyramidal Neurons
Authors: Antic Srdjan D.
Published: May 2003

Basal and oblique dendrites comprise ∼2/3 of the total excitable membrane in the mammalian cerebral cortex, yet they have never been probed with glass electrodes, and therefore their electrical properties and overall impact on synaptic processing are unknown. In the present study, fast multi‐site voltage‐sensitive dye imaging combined with somatic recording was used to provide a detailed description of the membrane potential transients in basal and oblique dendrites of pyramidal neurons during single and trains of action potentials (APs). The optical method allowed simultaneous measurements from several dendrites in the visual field up to 200 μm from the soma, thus providing a unique report on how an AP invades the entire dendritic tree. In contrast to apical dendrites, basal and oblique branches: (1) impose very little amplitude and time course modulation on backpropagating APs; (2) are strongly invaded by the somatic spike even when somatic firing rates reach 40 Hz (activity‐independent backpropagation); and (3) do not exhibit signs of a ‘calcium shoulder’ on the falling phase of the AP. A compartmental model incorporating AP peak latencies and half‐widths obtained from the apical, oblique and basal dendrites indicates that the specific intracellular resistance (Ri) is less than 100 Ω cm. The combined experimental and modelling results also provide evidence that all synaptic locations along basal and oblique dendrites, situated within 200 μm from the soma, experience strong and near‐simultaneous (latency < 1 ms) voltage transients during somatic firing. The cell body, axon hillock and basal dendritic compartments achieve unique synchronization during each AP. Therefore, with respect to a retrograde signal (AP), basal and proximal oblique dendrites should be considered as an integral part of the axo‐somatic compartment.
Interaction between Excitatory and Inhibitory Metabotropic Pathways in the Guinea‐Pig Antrum
Authors: Teramoto N. , Hirst G. D. S.
Published: May 2003

Intracellular recordings were made from isolated bundles of the circular muscle layer of guinea‐pig gastric antrum and the responses evoked by stimulating nitrergic nerve fibres were examined. Nitrergic inhibitory junction potentials (nitrergic‐IJPs), evoked by trains of stimuli, had small amplitudes and were associated with a reduction in the rate of occurrence and amplitude of spontaneously occurring depolarizing potentials, termed unitary potentials. Nitrergic‐IJPs were abolished either by membrane hyperpolarization or by 4,4′‐diisothiocyano‐2,2′‐stilbene disulfonic acid (DIDS); both of these abolished the discharge of unitary potentials. Membrane depolarization increased the rate of discharge of unitary potentials so that they summed to give rise to a regenerative potential. Nitrergic nerve stimulation abolished regenerative potentials; this inhibition did not result from a change in threshold for the initiation of regenerative potentials, rather it occurred at some stage after the gating process. Inhibitory nitrergic nerve responses were blocked by L‐nitroarginine (NOLA) and oxadiazolo quinoxalin‐1‐one (ODQ), an inhibitor of soluble guanylate cyclase. The observations suggest that the inhibition of regenerative potentials results from an interaction between an inhibitory and an excitatory metabotropic pathway.
Purinergic and Adrenergic Ca2+ Transients during Neurogenic Contractions of Rat Mesenteric Small Arteries
Authors: Lamont Christine , Vainorius Enrikas , Wier W. Gil
Published: May 2003

Contraction of small arteries is regulated by the sympathetic nervous system, but the Ca2+ transients during neurally stimulated contraction of intact small arteries have not yet been recorded. We loaded rat mesenteric small arteries with the fluorescent Ca2+ indicator fluo‐4 and mounted them in a myograph that permitted simultaneous (i) high‐speed confocal imaging of fluorescence from individual smooth muscle cells, (ii) electrical stimulation of perivascular nerves, and (iii) recording of isometric tension. Sympathetic neuromuscular transmission was achieved by electrical field stimulation (EFS) (frequency, 10 Hz; pulse voltage, 40 V; pulse duration, 0.2 ms) in the presence of capsaicin and scopolamine (to inhibit ‘sensory’ and cholinergic nerves, respectively). During the first 20 s of EFS, force rose to a small peak and then declined. During this time, junctional Ca2+ transients (jCaTs) were present at relatively high frequency. We have previously attributed jCaTs to influx of Ca2+ through post‐junctional P2X receptors activated by ATP. Propagating asynchronous Ca2+ waves, previously associated with bath‐applied α1‐adrenoceptor agonists, were not initially present. During the next 2.5 min of EFS, force rose slowly, and asynchronous propagating Ca2+ waves appeared. The selective α1‐adrenoceptor antagonist prazosin abolished both the slowly developing contraction and the Ca2+ waves, but reduced the initial transient contraction by only ∼25 %. During 3 min of EFS in prazosin, the frequency of jCaTs declined markedly; at sites at which at least one jCaT occurred, the average probability of a jCaT was 0.008 ± 0.002 pulse−1 in the first 20 s and 0.0007 ± 0.0002 pulse−1 in the last 20 s. We suggest that (i) ATP released from sympathetic varicosities activates the initial, transient, contraction and the activator Ca2+ is derived largely from jCaTs, and (ii) sympathetically released noradrenaline (NA) activates the later, major contraction through mechanisms involving α1‐adrenoceptors and which are associated with propagating Ca2+ waves.
Episodic Tremor and Slip on the Cascadia Subduction Zone: The Chatter of Silent Slip
Authors: Rogers Garry , Dragert Herb
Published: May 2003

We found that repeated slow slip events observed on the deeper interface of the northern Cascadia subduction zone, which were at first thought to be silent, have unique nonearthquake seismic signatures. Tremorlike seismic signals were found to correlate temporally and spatially with slip events identified from crustal motion data spanning the past 6 years. During the period between slips, tremor activity is minor or nonexistent. We call this associated tremor and slip phenomenon episodic tremor and slip (ETS) and propose that ETS activity can be used as a real-time indicator of stress loading of the Cascadia megathrust earthquake zone.
MEMS TECHNOLOGY FOR ADVANCED TELECOMMUNICATION APPLICATIONS
Authors: LEE HEE-GOOK , PARK JAE YEONG , BU JONG UK , YEE YOUNGJOO
Published: May 2003

MEMS (Micro Electro Mechanical Systems) technology is becoming a crucial enabling technology for optical and RF telecommunication applications due to the performance, cost and integration advantages. All-optical switches and silicon optical benches for optical network systems and RF MEMS components such as RF MEMS switches, tunable capacitors, high Q inductors, and thin film bulk acoustic resonators for miniaturized single chip RF transceivers are discussed. Despite all the promising aspects, practical problems to be addressed for successful commercialization are not trivial. By reviewing optical and RF MEMS research activities and some of the implementation examples, key success factors of MEMS components for the commercialization are discussed.
ENVIRONMENTAL SENSING OF CHEMICAL AND BIOLOGICAL WARFARE AGENTS IN THE THz REGION
Authors: SAMUELS ALAN C. , WOOLARD DWIGHT L. , GLOBUS TATIANA , GELMONT BORIS , BROWN ELLIOTT R. , JENSEN JAMES O. , SUENRAM RICHARD , LOEROP WILLIAM R.
Published: May 2003

Discrimination between hazardous materials in the environment and ambient constituents is a fundamental problem in environmental sensing. The ubiquity of naturally occurring bacteria, plant pollen, fungi, and other airborne materials makes the task of sensing for biological warfare (BW) agents particularly challenging. The spectroscopic properties of the chemical warfare (CW) agents in the long wavelength infrared (LWIR) region are important physical properties that have been successfully exploited for environmental sensing. However, in the case of BW agents, the LWIR region affords less distinction between hazardous and ambient materials. Recent studies of the THz spectroscopic properties of biological agent simulants, particularly bacterial spores, have yielded interesting and potentially useful spectral signatures of these materials. It is anticipated that with the advent of new THz sources and detectors, a novel environmental sensor could be designed that exploits the peculiar spectral properties of the biological materials. We will present data on the molecular spectroscopy of several CW agents and simulants as well as some THz spectroscopy of the BW agent simulants that we have studied to date, and discuss the prospectus with regard to detection probabilities through the application of sensor system modeling.
MATERIALS FOR STRAINED SILICON DEVICES
Authors: MOONEY P. M.
Published: May 2003

Strained Si devices exhibit enhanced carrier mobility compared to that of standard Si CMOS devices of the same dimensions. Recent strained Si CMOS device results are reviewed. Materials issues related to the strained Si/relaxed SiGe heterostructures required for a strained Si CMOS technology are discussed.
System-on-Chip Integration
Authors: DOERING ROBERT R.
Published: May 2003

Numerous "signal-processing products" are now driving the semiconductor market for SOC solutions enabling real-time performance, low-cost, low-power, portability, etc. A primary limit on the types of electronic (or other) functions that will be integrated into future SOCs is cost of integration, which tends to grow non-linearly with process complexity and chip area. A near-continuum of System-on/in-X solutions is emerging between traditional System-on-Chip and System-on-Board. These approaches span the tradeoff between bandwidth and cost. For the foreseeable future, digital CMOS will continue to serve as a "host platform" for integrating a wide range of mechanical, optical, biological, and, perhaps, even "quantum" technologies.
ULTRA-THIN SOI TRANSISTORS FOR ULTIMATE CMOS TECHNOLOGY: FUNDAMENTAL PROPERTIES AND APPLICATION PERSPECTIVES
Authors: ESSENI D. , SANGIORGI E. , MASTRAPASQUA M. , FIEGNA C. , CELLER G. K. , SELMI L.
Published: May 2003

In this paper we present experimental data or electron mobility in Ultra-Thin SOI MOSFETs operating in Single- and Double-Gate Mode. Mobility is measured for silicon thicknesses down to 5nm and for temperatures ranging from 225K to 375K. At large inversion densities (Ninv) ultra-thin SOI exhibit higher mobility than heavily doped bulk MOS and a small dependence of mobility on silicon thickness (TSI). However, at small Ninv the mobility is clearly reduced for decreasing TSI, possibly due to enhanced phonon scattering in the thin quantum well. Compared to Single-Gate, a modest but unambiguous mobility improvement is observed in Double-Gate mode, for silicon films around 10nm and small inversion densities. The mobility increase is more pronounced at low temperatures.
ELECTROTEXTILES
Authors: ETHRIDGE E. , URBAN D.
Published: May 2003

ElectroTexitles, the merging of electronics and textiles, is a new and novel technical area that leverages a fortuitous synergism between the electronics and textile industries. At some time in the future, we will look back upon what is happening now as turning point in the history of how electronic systems are fabricated. This session provides a summary of the technical challenges and some early technical results.
OPTIMIZATION OF WHITE ALL-SEMICONDUCTOR LAMP FOR SOLID-STATE LIGHTING APPLICATIONS
Authors: ŽUKAUSKAS ARTŪRAS , VAICEKAUSKAS RIMANTAS , IVANAUSKAS FELIKSAS , SHUR MICHAEL S. , GASKA REMIS
Published: May 2003

A stochastic method is used to optimize white all-semiconductor lamps composed of tree, four, and five primary light-emitting diodes (LEDs) with Gaussian spectra and realistic line widths typical of AlGalnP and AlGalnP LEDs. Within an optimal set of central wavelengths and relative powers, a trade-off between luminous efficacy and the general color rendering index can be performed. The quadrichromatic all-semiconductor lamp is shown to meet most needs of deluxe general lighting. However, practical implementation of this lamp requires substantial improvement of LEDs in the yellow-green region (~570 nm).
POLAR-OPTICAL PHONON ENHANCEMENT OF HARMONIC GENERATION IN SCHOTTKY DIODES
Authors: GELMONT B. , WOOLARD D. , CHEN S.
Published: May 2003

Polar-optical phonons have an important influence on polar semiconductor device behavior, in polar crystals at very high frequency, because they directly perturb the effective material permittivity in the vicinity of the transverse polar-optical vibration frequency. This phenomenon leads to dramatic nonlinear effects on the resistive and the reactive physics at the Schottky barrier interface. Hence this physical effect provides a mechanism with the potential for producing significant levels of power at higher harmonics. We have established a simulator that combines the modified harmonic-balance circuit analysis technique with a polar-optical phonon hydrodynamic transport model to determine the maximum power generation and/or power efficiency in the second harmonic. An abrupt junction model that includes the polar-optical phonon dynamics in a depletion layer was developed and utilized in this study. Simulation results have revealed a dramatic influence on the second harmonic power of the Schottky diode at the transverse polar-optical frequency and in the vicinity of one-half of the transverse polar-optical frequency. The transverse polar-optical frequency in GaAs is 7.78 THz and this is a rather high for practical applications. Bismuth trisulfide ( Bi 2 S 3) has been identified as a polar material that has the transverse polar-optical frequency on the order of 300 GHz, which is in a range more suited to THz-frequency multiplier applications. The dependence of the second harmonic power of the Schottky diode on the frequency demonstrates two enhanced peaks in the vicinity of the transverse polar-optical frequency. These preliminary results suggest that Bi 2 S 3 Schottky diode based multipliers have potential as enhanced sources within the terahertz regime.
THERMAL MANAGEMENT IN OPTOELECTRONICS
Authors: JOHNSTONE DANIEL K.
Published: May 2003

One of the primary considerations in lasers and detectors for infrared is the operating temperature and its effect on device performance. Several research areas are converging on the problem to cooperatively propel devices operating in the infrared to new levels. The fabrication of devices is advancing by better understanding of defects, and growth of the materials and structures is better able to control the desired crystallinity and composition. Also, the active region of the device may be shielded from the heat and phonon generation processes can be reduced by appropriate design of the structures and selection of materials. Furthermore, typically bulky coolers can be miniaturized and integrated with the device during the fabrication process. Each of these areas are being pursued with the expectation that some of the alternatives down each path win be mutually beneficial toward the goal of catapulting laser operating temperatures, and detection of weak infrared signals at longer wavelength in smaller packages. Better device fabrication and integrated cooling, both in device structure and added integrated coolers, should contribute to the proliferation and benefits of infrared lasers and detectors.
SPECTRAL RESPONSE MEASUREMENTS OF SHORT WAVE INFRARED DETECTORS (SWIR)
Authors: REFAAT TAMER F. , ABEDIN M. NURUL , SINGH UPENDRA N.
Published: May 2003

Quantum detectors are critical components in infrared lidar receivers. They convert the optical return signal into electrical signal compatible with electronic data processing and storage devices. The detectors used in this study comprise InGaAs PIN diodes and InGaAsSb avalanche photodiodes (APDs) for short wave infrared applications and Si APDs, with different structures, for near-infrared applications. The spectral response of these infrared detectors utilized for lidar receivers was studied with respect to operating temperature and external bias voltage. Variation of these spectral responses as a function of bias voltage and temperature was determined. This variation is employed to estimate errors in the detected lidar return signal. Results of this research finding are reported in this article.
Electron-Beam Tomography Coronary Artery Calcium and Cardiac Events
Authors: Kondos George T. , Hoff Julie Anne , Sevrukov Alexander , Daviglus Martha L. , Garside Daniel B. , Devries Stephen S. , Chomka Eva V. , Liu Kiang
Published: May 2003

Background—

Conventional coronary artery disease (CAD) risk factors fail to explain nearly 50% of CAD events. This study examines the association between electron-beam tomography (EBT) coronary artery calcium (CAC) and cardiac events in initially asymptomatic low- to intermediate-risk individuals, with adjustment for the presence of hypercholesterolemia, hypertension, diabetes, and a history of cigarette smoking.

Methods and Results—

The study was performed in 8855 initially asymptomatic adults 30 to 76 years old (26% women) who self-referred for EBT CAC screening. Conventional CAD risk factors were elicited by use of a questionnaire. After 37±12 months, information on the occurrence of cardiac events was collected and confirmed by use of medical records and death certificates. In men, events (n=192) were associated with the presence of CAC (RR=10.5,
P
<0.001), diabetes (RR=1.98,
P
=0.008), and smoking (RR=1.4,
P
=0.025), whereas in women, events (n=32) were linked to the presence of CAC (RR=2.6,
P
=0.037) and not risk factors. The presence of CAC provided incremental prognostic information in addition to age and other risk factors.

Conclusions—

The association between EBT CAC and cardiac events observed in this study of initially asymptomatic, middle-aged, low to intermediate-risk individuals presenting for screening suggests that in this group, knowledge of the presence of EBT CAC provides incremental information in addition to that defined by conventional CAD risk assessment.
Chymase Inhibition Prevents Cardiac Fibrosis and Improves Diastolic Dysfunction in the Progression of Heart Failure
Authors: Matsumoto Takehiro , Wada Atsuyuki , Tsutamoto Takayoshi , Ohnishi Masato , Isono Takahiro , Kinoshita Masahiko
Published: May 2003

Background—

Angiotensin (Ang) II, which plays a crucial role in the cardiac remodeling process, is generated via angiotensin-converting enzyme (ACE); however, an alternative generation pathway, chymase, which is stored in the mast cells, also exists in the heart. Cardiac chymase is insensitive to ACE inhibitors (ACEIs), and heart chymase promotes interstitial fibrosis by affecting collagen metabolism via transforming growth factor-β in vitro. Therefore, selective chymase blockade seems to be an important strategy in the prevention of cardiac remodeling

Methods and Results—

We evaluated the effects of a specific chymase inhibitor, SUNC8257 (Chy I; 10 mg/kg twice a day; n=7), on changes in cardiac structures, Ang II levels, and gene expressions, which are characterized as molecular markers for fibrosis, in dogs with tachycardia induced heart failure (HF). In HF, the number of chymase enzyme–positive mast cells increased in the left ventricle (LV) compared with the normal group; however, Chy I significantly decreased the mast cell density and cardiac Ang II levels. Despite no significant differences in LV systolic function compared with the vehicle group, Chy I decreased LV end-diastolic pressure and shortened the prolongation of τ. Chy I suppressed collagen-type I and III and transforming growth factor-β mRNA levels and decreased fibrosis in the LV compared with the vehicle.

Conclusion—

The chymase pathway may be critical for cardiac diastolic dysfunction accompanied with fibrosis. Chronic chymase inhibition may therefore become an important strategy in the prevention of cardiac remodeling in HF.
Feedback in Hypothesis Testing: An ERP Study
Authors: Papo David , Baudonniére Pierre-Marie , Hugueville Laurent , Caverni Jean-Paul
Published: May 2003

We used event-related potentials (ERPs) to probe the effects of feedback in a hypothesis testing (HT) paradigm. Thirteen college students serially tested hypotheses concerning a hidden rule by judging its presence or absence in triplets of digits and revised them on the basis of an exogenous performance feedback. ERPs time-locked to performance feedback were then examined. The results showed differences between responses to positive and negative feedback at all cortical sites. Negative feedback, indicating incorrect performance, was associated to a negative deflection preceding a P300-like wave. Spatiotemporal principal component analysis (PCA) showed the interplay between early frontal components and later central and posterior ones. Lateralization of activity was selectively detectable at frontal sites, with a left frontal dominance for both positive and negative feedback. These results are discussed in terms of a proposed computational model of trial-to-trial feedback in HT in which the cognitive and emotive aspects of feedback are explicitly linked to putative mediating brain mechanisms. The properties of different feedback types and feedback-related deficits in depression are also discussed.
Facilitation of Implicit Motor Learning by Weak Transcranial Direct Current Stimulation of the Primary Motor Cortex in the Human
Authors: Nitsche Michael A. , Schauenburg Astrid , Lang Nicolas , Liebetanz David , Exner Cornelia , Paulus Walter , Tergau Frithjof
Published: May 2003

Transcranially applied weak direct currents are capable of modulating motor cortical excitability in the human. Anodal stimulation enhances excitability, cathodal stimulation diminishes it. Cortical excitability changes accompany motor learning. Here we show that weak direct currents are capable of improving implicit motor learning in the human. During performance of a serial reaction time task, the primary motor cortex, premotor, or prefrontal cortices were stimulated contralaterally to the performing hand. Anodal stimulation of the primary motor cortex resulted in increased performance, whereas stimulation of the remaining cortices had no effect. We conclude that the primary motor cortex is involved in the acquisition and early consolidation phase of implicit motor learning.
Heat shock protein 70 binds caspase-activated DNase and enhances its activity in TCR-stimulated T cells
Authors: Liu Qing-Li , Kishi Hiroyuki , Ohtsuka Kenzo , Muraguchi Atsushi
Published: May 2003

DNA fragmentation is a hallmark of cells undergoing apoptosis and is mediated mainly by the caspase-activated DNase (CAD or DNA-fragmentation factor 40 [DFF40]), which is activated when released from its inhibitor protein (ICAD or DFF45) upon apoptosis signals. Here we analyzed the effect of heat shock protein 70 (Hsp70) on CAD activity in T-cell receptor (TCR)–induced apoptosis using a T-cell line (TAg-Jurkat). Overexpression of Hsp70 significantly augmented the apoptotic cell death as well as DNA fragmentation in CD3/CD28- or staurosporine-stimulated cells. Following stimulation of cells with CD3/CD28 or staurosporine, Hsp70 was coprecipitated with free CAD, but not with CAD associated with ICAD. Furthermore, the purified Hsp70 dose-dependently augmented DNA-fragmentation activity of caspase-3–activated CAD in a cell-free system. Peptide-binding domain–deleted Hsp70 could neither bind nor augment its activity, while adenosine triphosphate (ATP)–binding domain–deleted Hsp70 or the peptide-binding domain itself bound CAD and augmented its activity. These results indicate that the the binding of Hsp70 to the activated CAD via the peptide-binding domain augments its activity. Although CAD lost its activity in an hour after being released from ICAD in vitro, its activity was retained after an hour of incubation in the presence of Hsp70, suggesting that Hsp70 may be involved in stabilization of CAD activity. Finally, CAD that had been coprecipitated with Hsp70 from the cell lysate of staurosporine-activated 293T cells induced chromatin DNA fragmentation and its activity was not inhibited by ICAD. These results suggest that Hsp70 binds free CAD in TCR-stimulated T cells to stabilize and augment its activity.
An evaluation of neurobehavioural problems as perceived by family members and levels of family stress 1–3 years following traumatic brain injury in Japan
Authors: Watanabe Yuriko , Shiel Agnes , Asami Toyoko , Taki Kenji , Tabuchi Kazuo
Published: May 2003

Objective: To ascertain the proportion of patients with traumatic brain injury (TBI) admitted to a Japanese district hospital and to evaluate the levels of stress and anxiety in families living with those TBI patients.

Design: A retrospective study of patients admitted to hospital from April 1995 to March 1997 and a questionnaire study of family members of survivors.

Setting and subjects: All patients referred or transferred to the Emergency Department at the Saga Medical School Hospital, Japan with a primary diagnosis of TBI were studied. Family members living with TBI patients were sent questionnaires.

Main outcome measures: The Barthel Index, the Patient Competency Rating Scale, the modified Caregiver Strain Index and the Hospital Anxiety and Depression Scale.

Results: There were 34 patients who required hospitalization for care relating to TBI. Of these, nine family members took part in the questionnaire study. Three carers reported fairly high levels of stress and another three carers were considered to be at risk of anxiety and depression. There was a tendency for family members who reported that patients had difficulties in performing behavioural tasks to have higher levels of stress themselves.

Conclusion: These preliminary results showed that family members experienced certain levels of stress and were also at risk of anxiety and depression. The impact of TBI on families as well as patients should receive more attention.
Inter-rater reliability of the Barthel ADL Index: how does a researcher compare to a nurse?
Authors: Richards Suzanne H , Peters Tim J , Coast Joanna , Gunnell David J , Darlow Mary-Anne , Pounsford John
Published: May 2003

Objectives: To investigate whether a nonclinical research assistant, using standardized scoring criteria, can reliably administer the Barthel Activities of Daily Living (ADL) Index in a sample of elderly inpatients.

Design: Paired comparison of nurse and nonclinical research assistant Barthel Index assessments.

Setting: Acute hospital wards from two hospitals in a UK Healthcare Trust, with a catchment population of approximately 224 000 people.

Methods: A consecutive sample of 94 elderly patients with a variety of medical problems.

Main outcome measures: Barthel ADL Index, Folstein Mini-Mental Status Examination.

Results: Whilst the inter-rater reliability of the Barthel Index was within acceptable boundaries, two items out of ten had only fair agreement and low crude agreement (transfer and dressing) on Cohen's kappa scores.

Conclusions: Depending on the differences observed in any particular context, the Barthel Index can be applied with reasonable reliability by nonclinical staff applying the standardized scoring criteria. It should be noted, however, that the kappa coefficients between clinical and nonclinical assessors tend to be lower than those found when comparing two clinically trained assessors in previous research.
Clinical assessment of rehabilitation potential of the older patient: a pilot study
Authors: Cunningham C , Horgan F , O'Neill D
Published: May 2003

Clinical assessment of ‘rehabilitation potential’ is an everyday occurrence in hospitals, where scarcity of dedicated rehabilitation facilities require clinicians to decide who is most likely to benefit from extended rehabilitation. We examined the reliability of this judgement by different interdisciplinary team members in 27 consecutive admissions to a geriatric rehabilitation ward. The reliability of a clinical judgement was in general quite poor (kappa = 0.21). A more reliable means of determining patient ‘rehabilitation potential’ is needed.
The Frontal Lobe Score: part I: construction of a mental status of frontal systems
Authors: Ettlin Thierry M , Kischka Udo , Beckson Michael , Gaggiotti Manuela , Rauchfleisch Udo , Benson D Frank
Published: May 2003

Objective: To develop a bedside mental status examination to assess the behavioural effects of damage to the frontal lobes.

Design: A prospective clinical comparison of patients with cerebral lesions of different locations.

Subjects: A total of 118 subjects were examined: 27 patients with cerebral lesions confined to the frontal lobes, 25 patients with cerebral lesions without involvement of the frontal lobes, 18 patients with mixed frontal/nonfrontal lesions, and 48 normal control subjects.

Measures: Twenty-three mental status tests, clinical examinations and rating scales that had been reported as indicative of frontal lobe function were brought together. By statistical analysis, 12 tests and a neurobehavioural rating scale were selected. These constitute the Frontal Lobe Score (FLS).

Results: The FLS detected pure frontal lesions with a sensitivity of 77.7%. It discriminated patients with frontal lesions from normal control subjects with a specificity of 100%. Differentiation from patients with nonfrontal lesions was obtained with a specificity of 84%.

Conclusion: The Frontal Lobe Score is a useful screening instrument for the clinical detection of effects of frontal lobe damage.
Physical fitness training for wheelchair ambulation by the arm crank propulsion technique
Authors: Mukherjee Goutam , Bhowmik Partha , Samanta Amalendu
Published: May 2003

Objective: To observe the effect of endurance training on novice users of an arm-propelled three-wheeled chair (APTWC), powered by asynchronous arm crank propulsion, in actual locomotive conditions.

Study design: A continuous endurance training programme was administered by instructing subjects to propel themselves at free chosen speed (FCS) for 15 minutes, twice daily. Data were collected at two-week intervals consecutively and this was continued until the maximum beneficial effect was achieved.

Setting: The study was conducted in outdoor settings similar to those the users encountered in their everyday life.

Subjects: Twelve male paraplegics (below T10), age 30.5 ± 8.59 years, weight 41.75 kg (± 5.76) recommended to use the APTWC as an ambulatory device.

Intervention: The propulsion speed (metres per minute), peak heart rate (beats per minute) and oxygen uptake (litres per minute) were measured in consecutive sessions at two-week intervals. Physiological cost index (beats m-1), oxygen consumption (ml kg-1 min-1) and oxygen cost (ml kg-1 m-1) were derived to assess fitness level.

Results: Significant changes were observed in the variables following endurance training for 12 weeks. The propulsion speed increased considerably and the cardiorespiratory parameters were found to be reduced. One-way analysis of variance was done for each parameter separately for seven sets of readings taken to assess the overall change over the study period of 12 weeks. The F-ratios were found to be significant (p < 0.01) in each case, except for body weight and oxygen uptake. The pairwise comparison of the biweekly results of the parameters which showed an overall significant change over the study period revealed that after the first two weeks there was considerable change (p < 0.01) for all the parameters. The trend was upward for speed and downward for the other cardiovascular stress parameters. These trends continued until the 10th week showing significant change, after which the values become stable as was revealed by the statistical tests (p > 0.05). The percentage difference in the mean values from the initial stage (before training) to the 12th week ranged from 10.44% in the case of heart rate to 69.70% in the case of propulsion speed.

Conclusion: Self-ambulation at free chosen speed regularly for 10–12 weeks provides efficiency and improves fitness status required for wheelchairs driven by an asynchronous arm crank propulsion technique and no special exercise programme is required.
Walking ability as a measure of treatment effect in early rheumatoid arthritis
Authors: Hamilton Jennifer , Brydson Gillian , Fraser Susan , Grant Margaret
Published: May 2003

Objective: To assess the clinical usefulness of a prototype walkmat system in patients with early rheumatoid arthritis (RA).

Subjects: Twenty-four subjects with early RA and symptomatic forefoot disease requiring therapy with second-line drugs were recruited.

Design: Each subject underwent clinical assessment together with gait analysis on the contact sensitive walkmat system and Kistler forceplate before and after six months of treatment with second-line drugs. Two subjects were lost to follow-up.

Results: There was the expected improvement in disease activity in response to therapy. Significant differences were also demonstrated in defined gait parameters that indicated improved weight-bearing and enhanced forefoot propulsion.

Conclusion: Medical therapy improved walking ability in patients with RA and the walkmat system provided a useful adjunct to existing outcome measures in the assessment of lower limb function.