bluuebunny/crossref_metadata_2025 huggingface dataset:
Methods for the isolation of intact epithelium from the mouse intestine
Authors: Bjerknes Matthew , Cheng Hazel
Published: February 2005

Methods are described for the isolation of intact intestinal epithelium in several novel forms. The first method described is for application to segments of bowel that must be studied without killing the animal, e.g., a resected length of bowel. In this method, the isolated segment is everted onto a glass rod and incubated at 37°C in fresh 30 mM ethylenediaminetetraacetic acid (EDTA) in calcium‐magnesium‐free Hank's balanced salt solution (CMF) for either 15 or 20 minutes. At the end of the incubation, the epithelium is isolated by vibration into a tube of cold CMF. If it is incubated for 20 minutes, the entire epithelium is isolated in the form of single crypt‐villus units. If it is incubated for 15 minutes, the epithelium is isolated in the form of small intact sheets, but not all of the epithelium is removed.

The second method requires the death of the animal but yields better results. The anesthetized animal is perfused through the left ventricle with a fresh 37° solution of EDTA (0.01–30 mM) in CMF. Then the segment of gut is removed, everted onto a glass rod, and the epithelium isolated by vibration into cold CMF. The whole of the epithelium is isolated with this procedure and, with higher concentrations of EDTA, it is isolated in the form of large sheets (1–2 cm2). Structurally inact units could be obtained with either procedure. There was no contamination with underlying nonepithelial elements.

The best results, as determined by morphology and viability, were obtained with the perfusion method using 30 mM EDTA. With this concentration, the whole procedure, from sacrifice of the animal to isolation of the epithelium, requires less than 4 minutes. Procedures are also described for the isolation of either pure intact crypts or of pure intact vill from small intestine. Each of the methods described could be used to isolate the epithelium from any region of the intestinal tract with equal ease. Some applications of the methods are also discussed.
The behavior of substances labeled with 3H‐proline and 3H‐fucose in the cellular processes of odontoblasts and ameloblasts
Authors: Warshawsky H. , Josephsen K.
Published: February 2005

Odontoblasts are cells with single cytoplasmic processes that grow longer as more dentin is elaborated. Ameloblasts also have single processes and it has been postulated that they too grow longer as more enamel is made. Support for this hypothesis was obtained using rat incisors to investigate the behavior of substances labeled with 3H‐proline and 3H‐fucose. A comparison was made between odontoblasts, which have processes known to grow and remain within the dentin, and the ameloblasts whose Tomes' processes are hypothesized to grow and leave remnants in the completed enamel. With 3H‐proline, the odontoblast bodies are labeled at the early time intervals. They synthesize and secrete a layer of intensely labeled predentin, which by 1 and 2 days is converted to mineralized dentin. Matrix deposited after the main pulse is weakly labeled. Odontoblast processes are never labeled in dentin formed prior to injection. With 3H‐fucose, the cell bodies are labeled at the early intervals and the newly formed glycoproteins are deposited into the predentin. Almost immediately, these are progressively added to the dentin at the calcification front. With time a gradient of labeling extends from the unlabeled dentin toward the odontoblast bodies. Unlike the behavior of labeled proteins, by 1 and 2 days labeled glycoproteins appear along the entire length of the odontoblast processes. In the enamel, no Tomes' processes are present during maturation. With 3H‐proline, reactions are adjacent to the cells and diffuse toward, but do not reach the dentino‐enamel junction by 1 and 2 days. With 3H‐fucose, reactions appear over the enamel near the cells. By 1 and 2 days no diffusive pattern is seen, but grains are concentrated near the dentino‐enamel junction, in a region containing holes known to be the beginning of Tomes' processes. Since odontoblast glycoproteins migrate along odontoblast processes, it was postulated that cytoplasmic remnants were present in enamel along which ameloblast glycoproteins could also migrate to reach the holes at the dentino‐enamel junction.
Effects of acid‐stress on epidermal mucous cells of the brown bullhead Ictalurus nebulosus (LeSeur): A morphometric study
Authors: Zuchelkowski Edwin M. , Lantz R. Clark , Hinton David E.
Published: February 2005

The effects of acid water on alcian blue‐periodic acid Schiff's stainable mucosubstances of epidermis from theanterior abdominal wall of brown bullhead catfish, Ictalurus nebulosus, were studied. Standard morphometric techniques were used to determine mucous cell volume density (MCVv) and number density (MCNv) of control (pH 6.8–7.0) and acid‐stressed (pH 5.7–6.15) fish. Mucous cell volume density was significantly increased (P < 0.005) in fish which had been exposed to acid‐stress for five days. Since increase in volume density can arise from either an increase in the size of individual mucous cells (hypertrophy), an increase in the number of mucous cells per unit volume (hyperplasia), or a combination of the two, average cell data were computed. No significant difference in cell diameter or cell volume between treated and control groups was seen. However, the number of mucous cells in acid‐stressed fish was nearly twice (P < 0.005) that of controls. These results demonstrated that acid‐stress resulted in increased number but not volume of mucous cells (i.e., hyperplasia without hypertrophy).
Ultrastructural evidence indicating reorganization at the neuromuscular junction in the normal rat soleus muscle
Authors: Cardasis Constance Ann , Padykula Helen A.
Published: February 2005

The ultrastructural organization of 40 soleus neuromuscular junctions from ten normal young adult male and female Sprague‐Dawley (SD)‐derived rats (Charles River Breeders, CD‐Crl:COBS (SD)BR) has been studied. A smaller sample of motor endplates from the gastrocnemius, diaphragm, and extensor digitorum longus muscles of these rats as well as from the soleus muscles of two adult Wistar (W) rats (Crl:COBS(WI)BR) was included. Widespread ultrastructural reorganization was evident at the soleus neuromuscular junction during the growth period from three to five months of age. A major characteristic of reorganization is the presence of junctional folds not associated with axonal terminals; such sites occur within a single endplate adjacent to areas with typical intact synaptic associations. Additional features possibly related to remodelling are: (1) spatial separation of axonal terminals from the myofiber, (2) intervention of Schwann cell cytoplasm between an axon terminal and myofiber, (3) aggregates of satellite cells, and (4) folded or multilayered basal lamina. These features are most pronounced in the soleus muscle but occur to varying degrees in the neuromuscular junctions of other muscles of SD‐derived rats.

Distinctive characteristics of the rat soleus postjunctional sarcoplasm include the widespread occurrence of myofibrillar components, abundant free and membrane‐associated polysomes, and triads oriented in various planes. Away from such discrete sites, myofibers possess the usual highly oriented organization of myofibrils, T tubules, sarcoplasmic reticulum, and mitochondria.

The soleus muscle is a postural muscle that responds directly to rising workload imposed by continuous body growth during young adulthood by steady myofiber hypertrophy and conversion of motor units (Kugelberg, '76). This changing structural‐functional relationship may be reflected also by ultrastructural remodelling of the neuromuscular junctions reported here.
Prenatal and postnatal development of the cervical portion of the spine in the short‐finned pilot whale Globicephala macrorhyncha
Authors: Ogden John A. , Lee Kendrick E. , Conlogue Gerald J. , Barnett James S.
Published: February 2005

Fusion of the cervical spine in Globicephala macrorhyncha is a prenatal rather than postnatal phenomenon which encompasses all cervical vertebra. This results in a relatively short, nonarticulated, composite cervical spine in this particular species. Cervicothoracic spine segments removed from fetuses demonstrated complete fusion of all cervical vertebra commencing during early prenatal development. C1 and C2 initially developed as a composite central cartilaginous unit, although laterally there was some separation through rudimentary interzone formation. However, C3 through C7 formed individual cartilaginous centra which were divided from each other by thin, well‐demarcated interzones, but without the formation of intervertebral discs (which were concomitantly evident dividing the thoracic, lumbar, and caudal vertebra, and were also present between the seventh cervical and first thoracic vertebra, although this was a very rudimentary intervertebral region). The first primary ossification center appeared in C2. Subsequently, primary ossification occurred in C7, and finally in C2 through C6, with ossification progressing in a craniocaudal fashion in these four vertebra. The centra ossification centers then progressively coalesced in the midline, from C2 to C7, in a craniocaudal sequence. This entire chondroosseous fusion process was completed during early gestation (probably less than 2 to 3 months of prenatal development), so that a composite “single” cervical vertebra developed that characterizes this species at birth and throughout postnatal development. Postnatally, ossification spreads laterally within each centrum, and also progressively removes the vestiges of the intervertebral material. C7 also develops a secondary ossification center, but only in the caudal region. The cranial end of C7 and the remainder of the cervical vertebra do not form secondary centers. An extensive fibrocartilaginous/hyaline cartilage bridge remains between C1 and C2, even after closure of the vertebral physes. Undoubtedly, this allows continued growth in C1 and C2, which become the dominant portion of the cervical unitary vertebra. Eventually, even this synchondrosis will disappear to form a completely osseous cervical mass.
Predicting complete removal of impalpable breast carcinomas using stereotactic radiologically guided surgery
Authors: Schneider J , Lucas R , Tejerina A
Published: February 2005

Device to biospy and excise?
Membrane‐type 1 matrix metalloproteinase is required for normal alveolar development
Authors: Atkinson Jeffrey J. , Holmbeck Kenn , Yamada Susan , Birkedal‐Hansen Henning , Parks William C. , Senior Robert M.
Published: February 2005

Matrix metalloproteinases (MMPs) are expressed during lung development, but their role may be limited, as mice deficient in MMP‐3, 7, 9, or 12 develop a normal adult lung. Because membrane‐type 1 matrix metalloproteinase (MT1‐MMP) is expressed in the developing lung epithelium, we examined the lung structure of MT1‐MMP–deficient (−/−) mice. Branching morphogenesis was normal, but alveolar development was abnormal in the MT1‐MMP−/− lungs with 40% less alveolar surface area at 1 month (P < 0.01). MT1‐MMP−/− airways and alveoli had an abnormal ultrastructural appearance, but epithelial cell differentiation markers were distributed similarly in both strains. There was no evidence of excess extracellular matrix deposition or inflammation at the time points examined. In contrast, by adulthood MMP‐2−/− mice had normal alveolar size and structure, indicating normal alveolar development was not dependent on the ability of MT1‐MMP to activate pro–MMP‐2. These data indicate that MT1‐MMP is required for normal lung development. Developmental Dynamics 232:1079–1090, 2005. © 2005 Wiley‐Liss, Inc.
Optically Active Poly[{methyl(1‐naphthyl)silylene}(o‐phenylene)methylene]‐Poly(ethylene glycol) Block Copolymer Micelles
Authors: Park Sung Young , Kawakami Yusuke
Published: February 2005

Summary: Optically pure (+) and isotactic poly[{methyl(1‐naphthyl)silylene}(o‐phenylene)methylene] terminated with methylphenylchlorosilyl was obtained by the Pt‐catalyzed ring‐opening polymerization of optically pure 1‐methyl‐1‐(1‐naphthyl)‐2,3‐benzosilacyclobut‐2‐ene in the presence of methylphenylchlorosilane as a chain transfer agent. The polymer formed was transformed into a block copolymer by reacting the terminal chlorosilyl group with a commercial poly(ethylene glycol) monomethyl ether. The formation of micelles by the block copolymer in THF‐water mixtures was investigated by fluorescence and UV. More detailed information about the aggregation of the polymer in the micelles was obtained by circular dichroism spectroscopy. It was found that dense aggregates were formed at a concentration higher than the critical micelle concentration. This concentration was higher for lower molecular weight polymer, at higher temperatures, and in more hydrophobic solvent systems. The highly aggregated structure was altered by changing the solvent system.

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The production‐to‐respiration ratio and its implication in Lake Biwa, Japan
Authors: Urabe Jotaro , Yoshida Takehito , Gurung Tek Bahadur , Sekino Tatsuki , Tsugeki Narumi , Nozaki Kentaro , Maruo Masahiro , Nakayama Eiichioro , Nakanishi Masami
Published: February 2005

Production‐to‐respiration (P:R) ratio was estimated at an offshore site of Lake Biwa in order to examine whether the plankton and benthic community is subsidized with allochthonous organic carbon, and to clarify the role of this lake as potential source or sink of carbon dioxide. The respiration rate of protozoan and metazoan plankton was calculated from their biomass and empirical equations of oxygen consumption rates, and that of bacterioplankton was derived from their production rate and growth efficiency. In addition, the carbon mineralization rate in the lake sediments was estimated from the accumulation rate of organic carbon, which was determined using a 210Pb dating technique. On an annual basis, the sum of respiration rates of heterotrophic plankton was comparable to net primary production rate measured by the 13C method. However, when the mineralization rate in the lake sediments was included, the areal P:R ratio was 0.89, suggesting that Lake Biwa is net heterotrophic at the offshore site with the community being subsidized with allochthonous organic carbon. Such a view was supported by the surface water pCO2 that was on average higher than that of the atmosphere. However, the estimate of net CO2 release rate was close to that of carbon burial rate in the sediments. The result suggests that the role of Lake Biwa in relation to atmospheric carbon is almost null at the offshore site, although the community is supported partially by organic carbon released from the surrounding areas.
Distribution of population-based indicators across multiple taxa to assess the status of Gulf of Alaska and Bering Sea groundfish communities
Authors: Mueter Franz J. , Megrey Bernard A.
Published: February 2005

Ecosystem-based approaches to fisheries management require researchers and managers to take into account effects of fishing on other components of the ecosystem, including non-commercial species. Currently, stock assessments in the Northeast Pacific are limited to the most important commercial species, little being known about the status of non-commercial species. Nevertheless, standardized bottom-trawl surveys conducted in the eastern Bering Sea (EBS) and Gulf of Alaska (GoA), although primarily designed to assess commercial species, provide valuable information on the abundance, distribution, and mean weight of numerous taxa. Using a novel statistical approach and survey data for the years 1993–2003, we examined trends in catch per unit effort (cpue), frequency of occurrence, and mean weight of individuals for each taxon. Time trends were computed as the slope of a linear regression of each indicator on year, and were summarized separately for the eastern and western GoA and for the EBS. Within each system, trends were further compared between commercial and non-commercial taxa. Simulations were used to obtain reference distributions for the expected distribution of slopes across many dependent populations. Observed distributions of trends were compared with simulated distributions, suggesting that more taxa than expected showed a decreasing trend in cpue in the EBS, but not in the GoA. These trends likely resulted from low groundfish productivity in the EBS during the 1990s. At the same time, the frequency of occurrence of significantly more taxa than expected increased in the EBS and, to a lesser extent, in the western GoA. Increases in frequency of occurrence were much more common among non-commercial, invertebrate taxa, and may be a response to reductions in trawl fishing effort during the 1990s.
Comparison of pap smear, visual inspection with acetic acid, human papillomavirus DNA‐PCR testing and cervicography
Authors: De Vuyst H. , Claeys P. , Njiru S. , Muchiri L. , Steyaert S. , De Sutter P. , Van Marck E. , Bwayo J. , Temmerman M.
Published: February 2005

Objective

To assess the test qualities of four screening methods to detect cervical intra‐epithelial neoplasia in an urban African setting.

Method

Six hundred fifty‐three women, attending a family planning clinic in Nairobi (Kenya), underwent four concurrent screening methods: pap smear, visual inspection with acetic acid (VIA), PCR for high risk human papillomavirus (HR HPV) and cervicography. The presence of cervical intra‐epithelial neoplasia (CIN) was verified by colposcopy or biopsy.

Result

Sensitivity (for CIN2 or higher) and specificity (to exclude any CIN or cancer) were 83.3% (95% CI [73.6, 93.0]) and 94.6% (95% CI [92.6, 96.5]), respectively, for pap smear; 73.3% (95% CI [61.8, 84.9]) and 80.0% (95% CI [76.6, 83.4]) for VIA; 94.4% (95% CI [84.6, 98.8]) and 73.9% (95% CI [69.7, 78.2]) for HR HPV; and 72.3% (95% CI [59.1, 85.6]) and 93.2% (95% CI [90.8, 95.7]) for cervicography.

Conclusion

The pap smear had the highest specificity (94.6%) and HPV testing the highest sensitivity (94.4%). The visual methods, VIA and cervicography, were similar and showed an accuracy in between the former two tests.
Searching for party effects in post-communist Ukraine
Authors: Thames Frank C.
Published: February 2005

Initial studies of legislative behavior in post-communist Ukraine suggest that party affiliation plays a significant role in legislator voting decisions. Yet, the intense debate in the US Congress literature on party effects suggests that finding effects can be problematic. The article contends that there was evidence of party effects in the mixed-member Verkhovna Rada (1998e 2002). An analysis of party switching demonstrates that those parliamentary parties linked to powerful political and economic elites were able to affect substantively the preferences of party switchers. While this analysis establishes the existence of party effects, the ability of a party to affect deputies does not depend on the strength of the party label as it does in the US case.
Robust parsing with weighted constraints
Authors: FOTH KILIAN , MENZEL WOLFGANG , SCHRÖDER INGO
Published: February 2005

Based on constraint optimization techniques, an architecture for robust parsing of natural language utterances has been developed. The resulting system is able to combine possibly contradicting evidence from a variety of information sources, using a plausibility-based arbitration procedure to derive fairly rich structural representations, comprising aspects of syntax, semantics and other description levels of language. The results of a series of experiments are reported which demonstrate the high potential for robust behaviour with respect to ungrammaticality, incomplete utterances, and temporal pressure.
Multivariate Reliabilitäts- und Generalisierbarkeitstheorie in der Lehrevaluationsforschung
Authors: Mutz Rüdiger
Published: February 2005

Zusammenfassung: Die Evaluation der akademischen Lehre ist gekennzeichnet durch die Anwendung von Fragebogeninventaren unter unterschiedlichen Bedingungen (Zeitpunkte, Lehrende, Veranstaltungstypen, ...). Die Gütekriterien dieser Verfahren werden jedoch meist als allgemein gültig angegeben. Mit der Generalisierbarkeitstheorie (GT) und im Weiteren der multivariaten Reliabilitäts- und Validitätstheorie (MRVT) von Wittmann (1985) wird diese implizite Annahme der Bedingungskonstanz der Reliabilität selbst empirisch prüfbar. Im Rahmen eines Projektes zur Evaluation des Studiengangs “Forstwissenschaft” 1996 in Freiburg beurteilten 59 Studierende des 2.Semesters und 38 Studierende des 8.Semesters wiederholt zeitlich gestaffelte Blocklehrveranstaltungen mit dem “Heidelberger Inventar zur Lehrevaluation” (HILVE). Es zeigte sich zwar eine hohe multivariate totale Reliabilität und Generalisierbarkeit des HILVE-Inventars, dennoch waren nicht unerhebliche Dispositionseffekte und eine hohe Variabilität des studentischen Urteils innerhalb und zwischen Lehrveranstaltungen nachweisbar. Der HILVE erweist sich jedoch als änderungssensitiv für die Anwendung in der Lehrevaluation.
Die Wirkung von Modellpersonen auf das bereichsspezifische Selbstwissen des Rezipienten
Authors: van Ophuysen Stefanie , Hannover Bettina
Published: February 2005

Zusammenfassung. Welchen Einfluss hat die Präsentation von Modellpersonen auf das bereichsspezifische Selbstkonzept der Rezipienten? In unserem Experiment wurde eine Modellperson bei einer Tätigkeit (Spielen eines Autorennens am Computer) dargestellt, in der unsere Versuchspersonen entweder vorher schon Erfahrungen gesammelt hatten (Personen mit bereichsspezifischem Selbstwissen) oder nicht (Personen ohne bereichsspezifisches Selbstwissen). Wir untersuchten die Annäherung der Selbstbeschreibung der Versuchsteilnehmer an die Eigenschaften, die durch das Modell repräsentiert wurden. Probanden ohne bereichsspezifisches Selbstkonzept ließen sich durch die Modellperson stärker beeinflussen als Teilnehmer mit entsprechendem Selbstwissen. Während bei den Personen ohne domänenspezifisches Selbstkonzept die Sympathie für das Modell keinen Einfluss auf den Modelleffekt hatte, ließen sich diejenigen mit einem einschlägigen Selbstbild stärker von einem sympathischen als von einem wenig sympathischen Modell beeinflussen. Dies wird als Indiz dafür gewertet, dass Personen, die bereits relevantes bereichsspezifisches Selbstwissen erworben haben, durch eine Modellperson dargebotene Information anders verarbeiten als Personen, die noch nicht über einschlägiges Selbstwissen verfügen.
Mentoren, Karriere und Geschlecht: Eine Feldstudie mit Führungskräften aus dem Personalbereich
Authors: Blickle Gerhard , Boujataoui Mohamed
Published: February 2005

Zusammenfassung. In einer Feldstudie mit 325 Führungskräften aus dem Personalbereich mit einem Frauenanteil von 28 Prozent wurde untersucht, welche Art von Unterstützung als hilfreich für die eigene Laufbahnentwicklung beurteilt wurde, von welchen Personen diese Unterstützung gewährt wird und wie gut es weiblichen Nachwuchskräften gelingt, an karriereförderlichen Unterstützungsbeziehungen zu partizipieren. Es zeigten sich folgende Ergebnisse: Frauen hatten häufiger nur Kollegen und Kolleginnen als Unterstützer. Formale Programme ordneten weibliche Nachwuchskräfte überproportional seltener Vorgesetzten zu, während männliche Nachwuchskräfte durch Programme überproportional häufig Vorgesetzten als Unterstützer zugeordnet wurden. Laufbahnunterstützer in einer Vorgesetztenposition gaben am meisten karrierebezogene Unterstützung und ihnen wurde am meisten zugearbeitet. Im Vergleich der drei Mentoringfunktionen karrierebezogene Unterstützung, emotionale Unterstützung und Vorbildfunktion wurde für die berufliche Entwicklung das karrierebezogene Mentoring als am bedeutsamsten eingeschätzt. Diese Befunde werden methodenkritisch sowie vor dem Hintergrund der Netzwerktheorie des Mentoring diskutiert.
Cyclogenesis in the deep ocean beneath Western Boundary Currents: A process‐oriented numerical study
Authors: Kämpf Jochen
Published: February 2005

A two‐layer shallow‐water equation model is applied to a flat‐bottom ocean on the f plane to explore instability mechanisms in Western Boundary Current (WBC) that lead to the formation of strong cyclones in the deep ocean underneath. Findings reveal a tight coupling of surface meandering and deep cyclogenesis, in agreement with observational evidence. Barotropic cyclones develop in timescales of 5–10 days and attain swirl speeds of >50 cm/s (depends on initial strength of WBC) on a diameter of ∼100 km. Cyclogenesis is driven by advection of relative vorticity in the surface ocean and failure of the thermocline to respond rapidly enough to the associated sea level variations. Findings suggest that cyclogenesis and the associated strong abyssal flows (benthic storms) are ubiquitous features of WBCs and other frontal flows.
Quality and compatibility analyses of global aerosol products derived from the advanced very high resolution radiometer and Moderate Resolution Imaging Spectroradiometer
Authors: Jeong Myeong‐Jae , Li Zhanqing , Chu D. Allen , Tsay Si‐Chee
Published: February 2005

There exist numerous global aerosol products derived from various satellite sensors, but little insight has been gained about their compatibility and quality. This study presents a comparison of two prominent global aerosol products derived over oceans from the advanced very high resolution radiometer (AVHRR) under the Global Aerosol Climatology Project (GACP) (Mishchenko et al., 1999) and the Moderate Resolution Imaging Spectroradiometer (MODIS) (Tanré et al., 1997). The comparisons are for monthly mean aerosol optical thickness (AOT) and Ångström exponent (α) at a spatial resolution of 1 × 1 degree. The two monthly AOT products showed substantial discrepancies, with a tendency of higher values from MODIS than from GACP/AVHRR, especially near the coasts of major aerosol outbreak regions. Individual monthly AOT values have poor correlation, but their regional means are moderately correlated (correlation coefficient 0.5 < R < 1.0). While cloud screening has often been argued to be a major factor explaining large discrepancies, this study shows that differences in aerosol models in the two retrieval algorithms can lead to large discrepancies. Contributions of the size distribution are more significant than the refractive index. The noisiness of the GACP/AVHRR aerosol retrievals seem to be partially influenced by radiometric uncertainties in the AVHRR system, but it is unlikely a major factor to explain the observed systematic discrepancies between the MODIS and GACP/AVHRR AOTs. For α, correlations between MODIS and GACP/AVHRR are lower (0.2 < R < 0.7) than AOT. The MODIS α shows a well‐behaved dependence on the AOT contingent upon the aerosol type, while the GACP/AVHRR α has little correlation with the AOT. The high sensitivity in the selection of aerosol models to radiometric errors may be a primary reason for the worse comparison of α. Part of the discrepancies in α is attributed to different aerosol size distributions.
Matrix-seeded growth of nitride semiconductor nanostructures using ion beams
Authors: Weng X. , Ye W. , Clarke S. J. , Goldman R. S. , Rotberg V. , Daniel A. , Clarke R.
Published: February 2005

We have examined the matrix-seeded growth of narrow-gap nitride nanostructures in nitrogen ion implanted GaAs and InAs. Low-energy implantation followed by rapid thermal annealing (RTA) results in the formation of 2–3 nm sized amorphous precipitates in a crystalline matrix. On the other hand, high-energy implantation results in an amorphous layer, with or without crystalline remnants. When the ion-beam-synthesized amorphous matrix is a continuous amorphous layer, subsequent RTA leads to the formation of 4–5 nm zinc blende (ZB)-GaN-rich crystallites in an amorphous matrix. When this matrix contains crystalline remnants, subsequent RTA leads to the formation of 2–4 nm ZB-GaN-rich crystallites within the amorphous regions. These results suggest that the matrix plays an important role in the nucleation and growth of narrow-gap nitride nanostructures, and that matrix-seeded growth may provide an opportunity to control the structure and properties of the nanostructures.
Tuning of cross-linking and mechanical properties of laser-deposited poly (methyl methacrylate) films
Authors: Süske Erik , Scharf Thorsten , Krebs Hans-Ulrich , Panchenko Elena , Junkers Tanja , Egorov Mark , Buback Michael , Kijewski Harald
Published: February 2005

The chemical composition, amount of cross-linking and its influence on the mechanical properties of poly(methyl methacrylate) (PMMA) thin films produced by pulsed laser deposition (PLD) at a wavelength of 248nm under ultrahigh vacuum were investigated by infrared spectroscopy, scanning electron microscopy, size-exclusion chromatography, thermogravimetric analysis, and nanoindentation experiments. The films consist of two components, one fraction with a molecular weight well below that of the target material and a second fraction, which is cross-linked. Compared to bulk material, the Young’s modulus of the film is increased. The amount of cross-linking in the film can be tuned by the applied laser fluence leading to changes of the mechanical properties.
Leaf morphology, photochemistry and water status changes in resprouting Quercus ilex during drought
Authors: Peña-Rojas Karen , Aranda Xavier , Joffre Richard , Fleck Isabel
Published: February 2005

Functional and morphological (structural) characteristics of Quercus ilex L. leaves under drought stress were studied in the forest and in a nursery. We compared undisturbed individuals (controls) with resprouts emerging after clear-cut or excision. When soil water availability was high, gas-exchange was similar in resprouts and controls, despite higher midday leaf water potential, midday leaf hydration and relative water content (RWC). In moderate drought, stomatal closure was found to limit photosynthesis in controls, and in severe drought non-stomatal limitations of photosynthesis were also greater than in resprouts. Leaf structure and chemical composition changed under drought stress. Leaves tended to be smaller in controls with increasing drought, and resprouts had larger leaves and lower leaf mass area (LMA). The relationship between nitrogen (N) content and LMA implied lower N investment in photosynthetic components in controls, which could be responsible for their increased non-stomatal limitation of photosynthesis. Changes were more apparent in leaf density (D) and thickness (T), components of LMA. Decreases in D were related to reductions in cell wall components: hemicellulose, cellulose and lignin. In resprouts, reduced D and leaf T accounted for the higher mesophyll conductance (gmes) to CO2 measured.
Transcarboxylase: One of Nature's Early Nanomachines
Authors: Carey Paul R. , Sönnichsen Frank D. , Yee Vivien C.
Published: February 2005

The enzyme transcarboxylase (TC) catalyzes an unusual reaction; TC transfers a carboxylate group from methylmalonyl‐CoA to pyruvate to form oxaloacetate and propionyl‐CoA. Remarkably, to perform this task in Propionii bacteria Nature has created a large assembly made up of 30 polypeptides that totals 1.2 million daltons. In this nano‐machine the catalytic machinery is repeated 6 ‐ 12 times over using ordered arrays of replicated subunits. The latter are sites of the half reactions. On the so‐called 12S subunit a biotin cofactor accepts carboxylate, ‐ CO2‐, from methylmalonyl‐CoA. The carboxylated‐biotin then translocates to a second subunit, the 5S, to deliver the carboxylate to pyruvate. We have not yet characterized the intact nanomachine, however, using a battery of biophysical techniques, we have been able to derive novel, and sometimes unexpected, structural and mechanistic insights into the 12S and 5S subunits. Similar insights have been obtained for the small 1.3S subunit that acts as the biotin carrier linking the 12S and 5S forms. Interestingly, some of these insights gained for the 12S and 5S subunits carry over to related mammalian enzymes such as human propionyl‐CoA carboxylase and human pyruvate carboxylase, respectively, to provide a rationale for their malfunction in disease related mutations.
IUBMB Life, 56: 575‐583, 2004
Detailed 3D seismic imaging of a fault zone beneath Lake Geneva, Switzerland
Authors: Scheidhauer M. , Marillier F. , Thierry P.
Published: February 2005

An efficient high‐resolution (HR) three‐dimensional (3D) seismic reflection system for small‐scale targets in lacustrine settings was developed. In Lake Geneva, near the city of Lausanne, Switzerland, the offshore extension of a complex fault zone well mapped on land was chosen for testing our system. A preliminary two‐dimensional seismic survey indicated structures that include a thin (<40 m) layer of subhorizontal Quaternary sediments that unconformably overlie south‐east‐dipping Tertiary Molasse beds and a major fault zone (Paudèze Fault Zone) that separates Plateau and Subalpine Molasse (SM) units.

A 3D survey was conducted over this test site using a newly developed three‐streamer system. It provided high‐quality data with a penetration to depths of 300 m below the water bottom of non‐aliased signal for dips up to 30° and with a maximum vertical resolution of 1.1 m. The data were subjected to a conventional 3D processing sequence that included post‐stack time migration. Tests with 3D pre‐stack depth migration showed that such techniques can be applied to HR seismic surveys.

Delineation of several horizons and fault surfaces reveals the potential for small‐scale geologic and tectonic interpretation in three dimensions. Five major seismic facies and their detailed 3D geometries can be distinguished. Three fault surfaces and the top of a molasse surface were mapped in 3D. Analysis of the geometry of these surfaces and their relative orientation suggests that pre‐existing structures within the Plateau Molasse (PM) unit influenced later faulting between the Plateau and SM. In particular, a change in strike of the PM bed dip may indicate a fold formed by a regional stress regime, the orientation of which was different from the one responsible for the creation of the Paudèze Fault Zone. This structure might have later influenced the local stress regime and caused the curved shape of the Paudèze Fault in our surveyed area.
Somatostatin immunoreactivity in quail pterygopalatine ganglion
Authors: Schrödl Falk , De Stefano M. Egle , Minvielle Francis , Brehmer Axel , Neuhuber Winfried L.
Published: February 2005

In the ciliary ganglion of the chicken and quail, somatostatin (SOM) is an exclusive marker for parasympathetic postganglionic neurons innervating the choroid. A second parasympathetic pathway projecting to the choroid originates from the pterygopalatine ganglion. The aim of this study was to investigate SOM immunoreactivity in the pterygopalatine ganglion of the Japanese quail (Coturnix coturnix japonica) and on neurons within the choroid, the intrinsic choroidal neurons (ICN). We did so using immunohistochemistry and subsequent light, electron and confocal laser scanning microscopy. Pterygopalatine neurons were characterized by nNOS‐immunohistochemistry or NADPH‐diaphorase cytochemistry. SOM immunoreactivity was absent in the perikarya, but neurons were densely surrounded by SOM‐positive nerve fibres. Electron microscopy revealed that these fibres formed contacts with and without membrane specializations on pterygopalatine neurons. In the choroid, neuronal nitric‐oxide synthase (nNOS)‐immunoreactive ICN were likewise closely apposed by SOM‐immunoreactive nerve fibres, as revealed by confocal microscopy. There was no detectable co‐localization of the markers. In the absence of tracing studies, it is open to speculation whether SOM immunoreactivity originates from preganglionic fibres of the superior salivatory nucleus, postganglionic fibres of the ciliary ganglion or fibres of the brainstem via as yet unknown pathways. SOM may regulate the production of NO in pterygopalatine neurons and ICN, respectively, and is therefore involved in neuronal circuits regulating ocular homeostasis.
The origin of extrinsic nitrergic axons supplying the human eye
Authors: Gottanka Johannes , Kirch Wolfram , Tamm Ernst R.
Published: February 2005

Nitrergic nerve fibres of intrinsic and extrinsic origin constitute an important component of the autonomic innervation in the human eye. The intrinsic source of nitrergic nerves are the ganglion cells in choroid and ciliary muscle. In order to obtain more information on the origin of extrinsic nitrergic nerves in the human eye, we obtained superior cervical, ciliary, pterygopalatine and trigeminal ganglia from six human donors, and stained them for neuronal nitric oxide synthase (nNOS) and nicotinamide adenine dinucleotide phosphate‐diaphorase (NADPH‐D). In the superior cervical ganglia, nNOS/NADPH‐D‐positive varicose axons were observed whereas perikarya were consistently negative. Fewer than 1% of perikarya in the ciliary ganglia were labelled for nNOS/NADPH‐D. The diameter of nNOS/NADPH‐D‐positive ciliary perikarya was between 8 and 10 µm, which was markedly smaller than the diameter of the vast majority of negative perikarya in the ciliary ganglion. More than 70% of perikarya in the pterygopalatine ganglia were intensely labelled for both nNOS and NADPH‐D. In trigeminal ganglia, 18% of perikarya were nNOS/NADPH‐D‐positive. The average diameter of trigeminal nNOS/NADPH‐D perikarya was between 25 and 45 µm. Pterygopalatine and trigeminal ganglia are the most likely sources for extrinsic nerve fibres to the human eye.
Cellular inflammatory response induced by sensory denervation of the conjunctiva in monkeys
Authors: Oduntan Alabi O.
Published: February 2005

The inflammatory response induced by sensory denervation of the cornea, neuroparalytic (neurotrophic) keratitis, has been widely reported in the literature. Clinical evidence has shown that the conjunctiva also responds to sensory denervation, but little is known of the cytology of the conjunctival tissue response to denervation. The purpose of this study therefore was to investigate the cytological aspects of tissue response induced in the conjunctiva of monkeys by sensory denervation. Intracranial ophthalmic neurotomy was carried out in three monkeys, maxillary neurotomy in four, combined ophthalmic and maxillary neurotomy in two, and infraorbital nerve transaction in one monkey. These various operations were performed for other experimental purposes, but the conjunctival tissues from the animals were suitable and available to study the cytology of the inflammatory response induced in the tissue following the sensory denervation. The cytological changes were studied using light microscopy. Complete or severe ophthalmic nerve transection induced significant inflammatory responses, which were largely confined to the tarsal region of the conjunctiva. The responses included a substantial increase in the infiltration of the epithelium by polymorphonuclear leucocytes and severe disruption of the epithelium. The number of macrophages in the conjunctiva also increased. The response induced by maxillary denervation, however, was not as pronounced as that induced by sensory denervation. The restriction of the conjunctival tissue response to the tarsal region was considered to be due to the friction between the tarsal conjunctiva (and the hard tarsal plate) and the cornea during blinking. This study shows that sensory denervation of the conjunctiva elicits an inflammatory response characterized by substantial infiltration of the epithelium by neutrophil and macrophage and disorganization of the conjunctival tissue.
SPECTROSCOPY OF THE HYDROGEN AND ANTI-HYDROGEN ATOMS IN EXTERNAL FIELDS
Authors: LABZOWSKY LEONTI , SHARIPOV VASILY , SOLOVYEV DMITRI , PLUNIEN GÜNTER , SOFF GERHARD
Published: February 2005

The spectroscopical properties of hydrogen (H) and anti-hydrogen [Formula: see text] atoms in external electric and magnetic fields are discussed. This problem became important in connection with the recent experimental success in production of [Formula: see text] atoms. The main features of these experiments are briefly reviewed. The proposals for the search of the CPT violation via comparison of the H and [Formula: see text] spectra are shortly discussed. The spectroscopical differences between H and [Formula: see text] atoms in external magnetic fields and in parallel magnetic and electric fields are described in detail. It is proven that the positions of the maxima of the frequency distributions for transition probabilities in external electric field for H and [Formula: see text] atoms will deviate if the non-resonant corrections to the Lorentz line profile are taken into account.
Strain Accommodation in GaSb/AlSb Superlattices on (001) GaSb Substrates with AlSb Buffers
Authors: Villaflor Antonio Basanes , Yoshizawa Masamitsu , Kimata Morihiko
Published: February 2005

We report the observation that AlSb layers thinner than the epilayer critical thickness for the onset of plastic relaxation undergo lattice relaxation when used as buffers for GaSb/AlSb superlattices on (001) GaSb substrates. It is found that this is induced by the external stress from the overlaying superlattice, and that the mechanism is consistent with relaxation processes involving the nucleation and expansion of half-loops earlier suggested for strained epilayers. Photoluminescence spectroscopy conforms with the in-plane strains calculated from double-crystal and small-angle X-ray diffraction measurements.
Electron Tunneling Measurements of High-Tc Superconductor Bi-Sr-Ca-Cu-O by STM
Authors: Hasegawa Tetsuya , Suzuki Hideyuki , Yaegashi Seiji , Takagi Hidenori , Kishio Kohji , Uchida Shin-ichi , Kitazawa Koichi , Fueki Kazuo
Published: February 2005

The tunneling spectra of T
c=80 K single crystal and 110 K polycrystalline specimens have been measured at 4 K using a scanning tunneling microscope with a tungsten counter electrode. For the 80 K phase, we estimated the energy gaps 2Δ/k
B
T
c to be 4.9–5.3 and 4.2–5.0 in the directions perpendicular and parallel to the a-b plane, respectively, while 2Δ/k
B
T
c for the 110 K phase was in the range of 3.4–4.2. The energy gap data obtained in the present study will be discussed in terms of the anisotropy and coupling strength of the superconductivity.
New Oxide Superconductor: CaSr2(Cu0.83Bi0.17)3Oz
Authors: Belokoneva E. L. , Leonyuk L. I. , Leonyuk N. I. , Moshchalkov V. V. , Gippius A. A. , Nyan Ho Hyu
Published: February 2005

The new high T
c oxide superconductor CaSr2(Cu0.83Bi0.17)3O
z
has been found with T
c=75 K in as-grown single crystals and lattice parameters a=3.802 Å, b=12.901 Å, c=3.296 Å and γ=107.14°.
Picosecond VUV Anti-Stokes Raman Laser Pumped by a KrF Laser
Authors: Takahashi Akihiko , Maeda Mitsuo , Muraoka Katsunori , Akazaki Masanori
Published: February 2005

Generation of picosecond vacuum ultraviolet pulses by anti-Stokes stimulated Raman Scattering (ASRS) in hydrogen gas is reported. A tunable picosecond KrF excimer laser (30 ps FWHM, 12 mJ) is used as a pump source, and a series of anti-Stokes lines up to the 9th order (128.8 nm) is efficiently generated. The transient effects due to the finite decay time of the Raman medium are discussed for the present picosecond ASRS experiment.
MOCVD Growth of ZnSxSe1-x Epitaxial Layers Lattice-Matched to GaP Substrates
Authors: Mitsuishi Iwao , Mitsuhashi Hiroshi , Kukimoto Hiroshi
Published: February 2005

ZnS
x
Se1-x
epitaxial layers have been grown on GaP (100) substrates by metalorganic chemical vapor deposition (MOCVD). The layer lattice-matched to the substrate shows a better surface morphology and a narrower line width of X-ray diffraction rocking curve.
Simple Calculation on Topography of Focused-Ion-Beam Sputtered Surface
Authors: Ishitani Tohru , Ohnishi Tsuyoshi
Published: February 2005

An analytical model of surface topography evolution during ion sputtering is applied to investigate the eroded profile in a steady state during scanning focused-ion-beam (FIB) sputtering. Some calculations are carried out to demonstrate the eroded profile under the known parameters, i.e. sputtering yield as a function of ion incident angle, the FIB profile, and the FIB scan speed. The present approach is useful to obtain roughly the characteristics of FIB sputtering such as the erosion rate and the length and gradient angle of the step-like slope formed on the eroded surface.
Effects of Growth Temperature and V/III Ratio on MOCVD-Grown GaAs-on-Si
Authors: Nozaki Shinji , Noto Nobuhiko , Egawa Takashi , Wu Albert T. , Soga Tetsuo , Jimbo Takashi , Umeno Masayoshi
Published: February 2005

Effects of growth temperature and V/III ratio on surface morphology, crystallinity and residual impurities of MOCVD-grown GaAs-on-Si have been studied. The effects are different from those on MOCVD-grown GaAs-on-GaAs. The difference arises from the heteroepitaxial problems. High silicon concentrations are found in all the GaAs-on-Si, and the electrical activation of silicon as a donor reaches 100% for higher growth temperatures. Crystallinity improves but surface morphology degrades with increasing growth temperature. The trade-off between crystallinity and surface morphology has been eliminated by the three-step growth process.
Automatic Acoustic Measurement System by Mechanical Resonance of Continuous Sound Waves
Authors: Fukami Takeshi
Published: February 2005

Using the mechanical resonance of continuous sound waves with frequency higher than 5 MHz, an automatic measurement system is set up for simultaneous measurements of sound velocity and attenuation coefficient in thin disk samples. It is confirmed that the change of sound velocity Δυs/υ0, can be measured automatically with relative accuracy within 10-5 with changing temperatures at rates from 60 k/h to 3 k/h.
A Predischarge Doping Method for Hydrogenated Amorphous Silicon Films
Authors: Yano Kensaku , Miyagawa Ryohei , Furukawa Akihiko , Harada Nozomi
Published: February 2005

A new slight boron doping method, predischarge doping, for a-Si:H films was investigated. Highly resistive borondoped a-Si:H films with 1011∼1012 (Ω·cm) orders of magnitude have been realized without mobility-lifetime product decrease. The mobility-lifetime product value was nearly the same as that for undoped films.
Dependence of GaAs Ion-Implanted Layer Characteristics on Substrate Resistivity and Residual Acceptor Concentration
Authors: Baumgartner M. , Löhnert K.
Published: February 2005

The properties of ion-implanted layers in undoped s.i. GaAs substrates have been studied and found to be correlated to the initial bulk resistivity of the wafers, which in turn is determined by the content of residual shallow acceptors. With decreasing resistivity from \gtrsim 108 Ωcm to \lesssim 107 Ωcm the implanted layer sheet resistance decreases, the pinch-off voltage increases and the carrier profiles become broader. High purity material with very low background acceptor concentration shows highest carrier activation and superior reproducibility and appears to be favourable for ion-implantation applications.
The results are in agreement with the substrate barrier model.
Modulation-Doped Multi-Quantum Well (MD-MQW) Lasers. II. Experiment
Authors: Uomi Kazuhisa , Mishima Tomoyoshi , Chinone Naoki
Published: February 2005

Detailed experimental results on p-type modulation-doped multi-quantum well (MD-MQW) lasers are discussed. The GaAs/GaAlAs MD-MQW laser was grown by low temperature (600°C) molecular beam epitaxy using Be as the p-type dopant. The realization of the p-type MD-MQW structure was fully confirmed by high resolution secondary ion mass spectroscopy, transmission electron microscopy, and photoluminescence measurement. An ultrahigh relaxation oscillation frequency of up to 30 GHz was realized, which is 2.5 times that of undoped MQW lasers and also 5 times that of double heterostructure lasers. In addition, the spectral chirping width of p-type MD-MQW lasers was experimentally confirmed to be 1/5 that of undoped MQW lasers. These improvements result from the enhancement of the differential gain due to the modulation doping effect in addition to the quantum size effect. These results are in good agreement with the theoretical analyis.