bluuebunny/crossref_metadata_2025 huggingface dataset:
The generation of misfit dislocations in facet-controlled growth of AlGaN∕GaN films
Authors: Cherns D. , Sahonta S.-L. , Liu R. , Ponce F. A. , Amano H. , Akasaki I.
Published: November 2004

The relaxation of tensile stresses in AlGaN layers grown on GaN∕(0001)sapphire by facet-controlled epitaxial lateral overgrowth is reported. It is shown that a-type misfit dislocations are introduced at inclined {112¯2} AlGaN∕GaN interfaces, with strong evidence for a half-loop nucleation and glide mechanism driven by shear stresses present on the (0001) slip plane. In addition to relieving misfit stresses, these dislocations introduce grain rotations of up to 10−2rad across the AlGaN∕GaN boundaries, leading to tilt boundaries at the meeting front between laterally growing wings and between regions growing in the lateral and [0001] directions. The effects of these processes on the defect density in subsequent layers are examined.
Enhanced magnetoresistance in ferromagnetic Pr0.85Ca0.15MnO3∕ferroelectric Ba0.6Sr0.4TiO3 superlattice films
Authors: Murugavel P. , Padhan P. , Prellier W.
Published: November 2004

Artificial superlattices designed with a ferromagnetic Pr0.85Ca0.15MnO3 insulating layer and ferroelectric Ba0.6Sr0.4TiO3 layer were grown on (100) SrTiO3 substrates. The magnetotransport properties were measured with the current perpendicular to the plane geometry. An increase in magnetoresistance (MR), with no significant low-field effect, was observed as the amount of ferroelectric Ba0.6Sr0.4TiO3 layer thickness increases even up to 9 unit cells. For example, the superlattice [(Pr0.85Ca0.15MnO3)10(Ba0.6Sr0.4TiO3)9]25 shows a 35% MR at 100K, though the Pr0.85Ca0.15MnO3 film was a robust insulator with negligible MR even at a high applied magnetic field. Similar superlattice structure, (Pr0.85Ca0.15MnO3)∕(SrTiO3) did not show any enhancement in MR. We discussed that the enhanced MR could be due to the ferroelectric spacer layer and the associated magnetoelectric coupling.
Electrostatic field-induced surface instability
Authors: Du Danxu , Srolovitz David
Published: November 2004

We examine the thermodynamics and evolution of the morphology of a metal surface in the presence of a large electric field. A flat surface is unstable for all finite electric fields E with a critical wavelength proportional to E−1 or E−2 at small and large fields, respectively. The instability wavelength that grows the fastest during surface diffusion-limited evolution scales in the same manner. Such instabilities are important for scanning probe microscopies and are becoming increasingly important in microelectromechanical systems applications as device dimensions are reduced.
Field-tuned magnetocaloric effect in metamagnetic manganite system
Authors: Gomes A. M. , Garcia F. , Guimarães A. P. , Reis M. S. , Amaral V. S.
Published: November 2004

We have investigated the origin of the huge magnetocaloric effect in a manganite system with ferro–antiferromagnetic phase mixture at low temperatures. We carried out magnetic measurements in fields up to 100 kOe in order to show that both a high hysteretic behavior and a metamagnetic transition in the antiferromagnetic state are responsible for the large magnetic entropy change. The temperature where the maximum of the magnetic entropy change occurs can be tuned by varying the maximum value of the applied magnetic field to the system. This last procedure can open a new perspective for charge-ordered manganite applications to magnetic refrigeration at low temperatures.
Large magnetoresistance effects near room temperature in manganite heterojunction
Authors: Sun J. R. , Xiong C. M. , Shen B. G.
Published: November 2004

Magnetoresistive property of a heterojunction composed of Pr0.6Ca0.4MnO3 (PCMO) and Nb-doped SrTiO3 (STON) has been experimentally studied. A rather complex current–voltage relation characterized by the appearance of a low-bias electric breakdown prior to the reverse current saturation process is observed. The magnetic field shows a strong depression to this electric breakdown and, as a result, leads to a great change of junction resistance. It is interesting that the magnetoresistance thus produced, remains huge, ∼1600% under a field of 5T [defined as R(H)∕R(0)−1], in a broad temperature range well above the Curie temperature of PCMO, which indicates a different mechanism of the magnetic field effect of PCMO∕STON from other manganites and manganite-based heterojunctions. A qualitative explanation is given based on an analysis about the influence of interfacial defects on Hall electric field.
Hydrogen-induced metallization of a preoxidized 3C-SiC(100)3×2 surface
Authors: Silly M. G. , Radtke C. , Enriquez H. , Soukiassian P. , Gardonio S. , Moras P. , Perfetti P.
Published: November 2004

We investigate atomic hydrogen interaction with a preoxidized Si-rich 3C-SiC(100)3×2 surface by synchrotron radiation-based valence band, and Si2p and C1s core level photoemission spectroscopies. Atomic hydrogen exposure results in (i) Fermi level built-up in the valence band, (ii) band bending, and (iii) the three Si2p surface components shifting to lower binding energies. These features indicate H-induced surface metallization. This finding opens perspectives in the metallization at the subnanometric scale of passivated semiconductor surfaces.
Effect of encapsulation temperature on Si:P δ-doped layers
Authors: Goh K. E. J. , Oberbeck L. , Simmons M. Y. , Hamilton A. R. , Clark R. G.
Published: November 2004

We present a systematic study of the effect of encapsulation temperature on dopant segregation and electronic transport in Si:P δ-doped layers. We demonstrate that while limited dopant segregation and complete electrical activation can be achieved at room temperature, a δ-doped layer encapsulated at ∼250°C represents the best compromise between high electrical quality (mobility ∼61cm2V−1s−1 and phase coherence length ∼72nm at 4.2K) and minimal dopant segregation. Higher encapsulation temperatures are shown to lead to significant dopant segregation.
Self-pulsation and optical injection locking for multielectrode distributed feedback lasers using phase-shift-induced modes
Authors: Nishikawa Satoshi , Gotoda Mitsunobu , Nishimura Tetsuya , Tokuda Yasunori
Published: November 2004

We present a method of lasing mode control by taking advantage of phase-shifted grating for multielectrode distributed feedback lasers. By applying this method to stabilize the dual lasing modes, we demonstrated not only self-pulsating through beating phenomena, but also optical injection locking for external signals at very high frequency regions.
Equine osteoarthritis: a brief review of the disease and its causes
Authors: Schlueter Angela E , Orth Michael W
Published: November 2004

Degenerative joint diseases, such as osteoarthritis, adversely impact the health of the equine athlete as well as the economics of the equine industry. Our understanding of the aetiology of osteoarthritis, although not nearly exhaustive, has increased substantially in recent years. Molecules, including cytokines, inflammatory mediators, and metalloproteinases, have been identified and associated with the progression of joint disease. Several factors, including trauma to the joint, immobilization, conformation, shoeing, and ageing, have been linked with osteoarthritis. Our continued efforts into elucidating critical biological mediators and risk factors, coupled with better chondroprotective therapies and diagnostic tools, should facilitate our ability to maintain the skeletal health of the equine athlete
Brief report. Acute respiratory tract infections in Indian children with special reference to Mycoplasma pneumoniae
Authors: Pandey A , Chaudhry R , Nisar N , Kabra SK
Published: November 2004

A total of 70 Indian children of either sex and under 5 years of age who were admitted to the All India Institute of Medical Sciences, New Delhi during a 1-year period (January 1994-December 1994) with complaints suggestive of acute respiratory tract infections (ARTI), were investigated for bacterial aetiology of infection with special reference to Mycoplasma pneumoniae. Microbial aetiology could be established in 44/70 (62.8 per cent) of cases of ARTI. Mycoplasma pneumoniae infection was seen in 21/70 (30 per cent), aerobic bacteria in 14/70 (20 per cent), Chlamydia pneumoniae in 2/70 (2.8 per cent), and mixed infection with mycoplasma either with bacteria and/or chlamydia in 7/70 (10 per cent). However, in 26/70 (37.1 per cent) cases no cause could be detected. Diagnosis of infection with M.pneumoniae was based on culture in 2/20 (10 per cent) cases, antigen detection in throat swab by indirect immunofluorescence assay using specific antibody in 16/70 (22.8 per cent) cases, and demonstration of IgM antibody in serum by serodia Myco II particle agglutination test in 17/70 (24.2 per cent). Streptococcus pneumoniae (9/70, 12.8 per cent) and Staphylococcus aureus (5/70, 7.1 per cent) were the aerobic isolates from blood in these patients. Results of this study indicate that M.pneumoniae plays a significant role in respiratory tract infection in an Indian paediatric population. Rapid diagnostic procedures, such as antigen detection and IgM antibody demonstration, should be used more widely to determine the infective aetiology early in the course of illness. The study also highlights the mixed aetiology in ARTI in children, which has important therapeutic implications.
Spectral Entropy and Bispectral Index as Measures of the Electroencephalographic Effects of Sevoflurane
Authors: Ellerkmann Richard Klaus , Liermann Vidal-Markus , Alves Thorsten Michael , Wenningmann Ingobert , Kreuer Sascha , Wilhelm Wolfram , Roepcke Heiko , Hoeft Andreas , Bruhn Jörgen
Published: November 2004

Background

Recently, entropy algorithms have been proposed as electroencephalographic measures of anesthetic drug effects. Datex-Ohmeda (Helsinki, Finland) introduced the Entropy Module, a new electroencephalographic monitor designed for measuring depth of anesthesia. The monitor calculates a state entropy (SE) computed over the frequency range of 0.8-32 Hz and a response entropy (RE) computed over the frequency range of 0.8-47 Hz. The authors investigated the dose-response relation of SE and RE during sevoflurane anesthesia in comparison with the Bispectral Index (BIS).

Methods

Sixteen patients were studied without surgical stimulus. Anesthesia was induced by sevoflurane inhalation with a tight-fitting facemask. Sevoflurane concentrations were increased and subsequently decreased and increased two to four times until the measurement was stopped and patients were intubated for surgery. The performances of SE, RE, and BIS to predict the estimated sevoflurane effect site concentration, obtained by simultaneous pharmacokinetic and pharmacodynamic modeling, were compared by calculating the correlation coefficients and the prediction probability.

Results

State entropy, RE, and BIS values decreased continuously over the observed concentration range of sevoflurane. Correlation coefficients were slightly but not significantly better for entropy parameters (0.87 +/- 0.09 and 0.86 +/- 0.10 for SE and RE, respectively) than for BIS (0.85 +/- 0.12). Calculating the prediction probability confirmed these results with a prediction probability of 0.84 +/- 0.05 and 0.82 +/- 0.06 for SE and RE, respectively, and 0.80 +/- 0.06 for BIS.

Conclusion

State entropy and RE seem to be useful electroencephalographic measures of sevoflurane drug effect.
Combinations of Bupivacaine, Fentanyl, and Clonidine for Lumbar Epidural Postoperative Analgesia
Authors: Sveticic Gorazd , Gentilini Andrea , Eichenberger Urs , Zanderigo Eleonora , Sartori Valentina , Luginbühl Martin , Curatolo Michele
Published: November 2004

Background

The authors developed and applied a method to optimize the combination of bupivacaine, fentanyl, and clonidine for continuous postoperative lumbar epidural analgesia.

Methods

One hundred eighteen patients undergoing knee or hip surgery participated in the study. Postoperative epidural analgesia during 48 h after surgery was optimized under restrictions dictated by side effects. Initially, eight combinations of bupivacaine, fentanyl, and clonidine (expressed as drug concentration in the solution administered) were empirically chosen and investigated. To determine subsequent combinations, an optimization model was applied until three consecutive steps showed no decrease in pain score. For the first time in a clinical investigation, a regression model was applied when the optimization procedure led to combinations associated with unacceptable side effects.

Results

The authors analyzed 12 combinations with an allowed bupivacaine concentration range of 0-2.5 mg/ml, a fentanyl concentration range of 0-5 microg/ml, and a clonidine concentration range of 0-5 microg/ml. The best combinations of bupivacaine, fentanyl, and clonidine concentrations were 1.0 mg/ml-1.4 microg/ml-0.5 microg/ml, 0.9 mg/ml-3.0 microg/ml-0.3 microg/ml, 0.6 mg/ml-2.5 microg/ml-0.8 microg/ml, and 1.0 mg/ml-2.4 microg/ml-1.0 microg/ml, respectively, all producing a similarly low pain score. The incidence of side effects was low. The application of the regression model to combinations associated with high incidence of motor block successfully directed the optimization procedure to combinations within the therapeutic range.

Conclusions

The results support further study of the combinations of bupivacaine, fentanyl, and clonidine mentioned above for postoperative analgesia after knee and hip surgery. This novel optimization method may be useful in clinical research.
Effect of Different Cost Drivers on Cost per Anesthesia Minute in Different Anesthesia Subspecialties
Authors: Schuster Martin , Standl Thomas , Wagner Joachim A. , Berger Jürgen , Reißmann Hajo , am Esch Jochen Schulte
Published: November 2004

Background

Little is known about differences in costs to provide anesthesia care for different surgical subspecialties and which factors influence the subspecialty-specific costs.

Methods

In this retrospective study, the authors determined main cost components (preoperative visit, intraoperative personnel costs, material and pharmaceutical costs, and others) for 10,843 consecutive anesthesia cases from a 6-month period in the 10 largest anesthesia subspecialties in their university hospital: ophthalmology; general surgery; obstetrics and gynecology; ear, nose, and throat surgery; oral and facial surgery; neurosurgery; orthopedics; cardiovascular surgery; traumatology; and urology. Using regression analysis, the effect of five presumed cost drivers (anesthesia duration, emergency status, American Society of Anesthesiologists physical status of III or higher, patient age younger 6 yr, and placement of invasive monitoring) on subspecialty-specific costs per anesthesia minute were analyzed.

Results

Both personnel costs for anesthesiologists and total costs calculated per anesthesia minute were inversely correlated with the duration of anesthesia (adjusted R2 = 0.75 and 0.69, respectively), i.e., they were higher for subspecialties with short cases and lower for subspecialties with longer cases. The multiple regression model showed that differences in anesthesia duration alone accounted for the majority of the cost differences, whereas the other presumed cost drivers added only little to explain subspecialty-specific cost differences.

Conclusions

Different anesthesia subspecialties show significant and financially important differences regarding their specific costs. Personnel costs and total costs are highest for subspecialties with the shortest cases. Other analyzed cost drivers had little effect on subspecialty-specific costs. In the light of these cost differences, a detailed cost analysis seems necessary before the profitability of an anesthesia subspecialty can be assessed.
Testing for Granger causality between industrial output and CPI in the presence of regime shift
Authors: Khalik Salman A. , Shukur Ghazi
Published: November 2004

In this paper, we focus on the Granger causality test in the presence of regime shift. We apply a vector autoregressive (4) model on Swedish series of industrial output and consumer price index for the period 1980:1‐1998:6. To test for causality, three different test methods namely the single equation Likelihood Ratio test, the systemwise Rao's F‐ test and the Bootstrap test, have been used in this study. We show that when the assumption of parameter constancy is violated, due to the occurrence of the structural changes, Granger causality tests can provide misleading inference about the underlining relationship of causality.
Corruption: a non‐parametric analysis
Authors: McAdam Peter , Rummel Ole
Published: November 2004

This paper considers the distributional dynamics of a well‐known corruption index. Specifically, we are interested in evaluating whether corruption is best characterized as multimodal (i.e. pointing to clusters of countries with persistently different levels of corruption) and whether there have been significant changes (i.e. convergence or divergence) in the distribution of the perception of corruption across countries and over time. Using non‐parametric kernel density methods, our findings lend support to concerns expressed in the theoretical literature – namely, that corruption can be highly persistent, and characterized by multiple equilibria. This highlights and corroborates the conclusion that anti‐corruption campaigns must be sustained to be effective.
EFFECTS OF FIXATIVES ON THE ULTRASTRUCTURE OF PHYSODES IN VEGETATIVE CELLS OF SCYTOSIPHON LOMENTARIA (SCYTOSIPHONACEAE, PHAEOPHYTA)1
Authors: Clayton Margaret N. , Beakes Gordon W.
Published: November 2004

The effects of different glutaraldehyde‐osmium fixation schedules on the ultrastructure of the vegetative cells from the meristematic regions of Scytosiphon lomentaria (Lyngbye) Link fronds are described. The best overall preservation of cell structure was obtained with a 2 h fixation in 2.5–3.5% glutaraldehyde in 0.1 M cacodylate buffered seawater (pH 7.0), followed after washing by 1 h post fixation in 1% osmium tetroxide. The addition of 1% caffeine to the glutaraldehyde fixative resulted in better retention and spatial localization of the electron dense phenolic deposits within the cells. Particular attention was paid to the effects of the various fixation schedules on the electron‐dense material within the cells and the images obtained were compared with previous accounts of brown algal cells. It is proposed that the term physode should be restricted to the discrete electron dense spherical bodies within the vacuoles and not applied to electron dense material in general. Although the organization of Scytosiphon cells was similar to that previously reported in the Scytosiphonaceae, the organization of the plasmodesmata into pit fields is at variance with previous accounts.
SURVEY OF SELECTED SEA WEEDS FOR SIMULTANEOUS PHOTOPRODUCTION OF HYDROGEN AND OXYGEN1
Authors: Greenbaum E. , Ramus J.
Published: November 2004

Ten seaweed species were surveyed for simultaneous photoevolution of hydrogen and oxygen. In an attempt to induce hydrogenase activity (as measured by hydrogen photoproduction) the seaweeds were maintained under anaerobiosis in CO2‐free seawater for varying lengths of time. Although oxygen evolution was observed in every alga studied, hydrogen evolution was not observed. One conclusion of this research is that, in contrast to the microscopic algae, there is not a single example of a macroscopic alga for which the photoevolution of hydrogen has been observed, in spite of the fact that there are now at least nine macroscopic algal species known for which hydrogenase activity has been reported (either by dark hydrogen evolution or light‐activated hydrogen uptake). These results are in conflict with the conventional view that algal hydrogenase can catalyze a multiplicity of reactions, one of which is the photoproduction of molecular hydrogen. Two possible explanations for the lack of hydrogen photoproduction in macroscopic algae are presented. It is postulated that electron acceptors other than carbon dioxide can take up reducing equivalents from Photosystem I to the measurable exclusion of hydrogen photoproduction. Alternatively, the hydrogenase system in macroscopic algae may be primarily a hydrogen‐uptake system with respect to light‐activated reactions. A simple kinetic argument based on recent measurements of the photosynthetic turnover times of simultaneous light‐activated hydrogen and oxygen production is presented that supports the second explanation.
AMMONIUM INDUCED PHOTOSYNTHETIC SUPPRESSION IN AMMONIUM LIMITED DUNALIELLA TERTIOLECTA (CHLOROPHYTA)1
Authors: Turpin David H.
Published: November 2004

Dunaliella tertiolecta (Butcher) was grown in chemostat culture over a wide range of ammonium limited growth rates. The addition of ammonium caused a rapid temporary suppression of photosynthetic carbon fixation. The magnitude of ammonium induced photosynthetic suppression increased with the severity of ammonium limitation. Cells growing at rates greater than ca. 80%μmax exhibited no photosynthetic suppression in response to additions of the limiting nutrient. The duration of photosynthetic suppression was related to the concentration of added ammonium. Immediately following the suppression, photosynthesis was enhanced with respect to the controls. The eventual degree of enhancement increased with the concentration of added ammonium. Steady‐state cellular chlorophyll concentrations, photosynthetic rates, and assimilation numbers are reported.
RHODELLA RETICULATASP. NOV., A NEW COCCOID RHODOPHYTAN ALGA (PORPHYRIDIALES)1,2
Authors: Deason Temd R. , Butler Gary L. , Rhyne Charles
Published: November 2004

A new coccoid rhodophytan species is described and compared with other species in the genusRhodella.Thylakoids in the pyrenoid characterize the new species and indicate a closer relationships ofRhodellatoPorphyridiumthan was previously indicated.
NEW ENDOLITHIC CYANOPHYTES FROM THE NORTH ATLANTIC OCEAN. II. HYELLA GIGAS LUKAS & GOLUBIC SP. NOV. FROM THE FLORIDA CONTINENTAL MARGIN1
Authors: Lukas Karen J. , Golubic Stjepko
Published: November 2004

A new species of endolithic cyanophyte, Hyella gigas Lukas and Golubic (Order: Pleurocapsales), differs from other species of Hyella by its larger cell and filament dimensions and its laminated, often pigmented sheath. It bores into mollusk shells and other marine carbonate substrates on the east coast of North America, the Bahama Islands and the Northern Mediterranean Sea, where it is found from near mean low water down to 25 m depth. This comparatively shallow maximum depth is probably due to the limited capacity of Hyella gigas to adapt to changing light quality and intensity. We reject the suppression of the genus Hyella as proposed by Drouet and Daily.
THE FLAGELLAR APPARATUS OFENTOCLADIA VIRIDISMOTILE CELLS, AND THE TAXONOMIC POSITION OF THE RESURRECTED FAMILY ULVELLACEAE (ULVALES, CHLOROPHYTA)1
Authors: O'Kelly Charles J. , Floyd Gary L.
Published: November 2004

The flagellar apparatuses of the quadriflagellate zoo‐spores and biflagellate female gametes of the marine chaetophoracean algaEntocladia viridisReinke are significantly different from those of algae belonging to Chaetophoraceae sensu stricto, but closely resemble those of ulvacean genera. These differences permit the taxonomic reassignment of certain marine chaetophoracean genera and an evaluation of the flagellar apparatus features used to characterize the class Ulvophyceae. Critical features of the zoospore include arrangement of the four basal bodies into an upper and a lower pair with the proximal ends of the upper basal bodies overlapping, terminal caps, proximal sheaths connected to one another by striated bands, and a cruciate microtubular rootlet system having a3‐2–3‐2alternation pattern and striated microtubule‐associated components that accompany the two‐membered rootlets. An indistinct distal fiber occurs just anterior to the basal bodies, and is closely associated with the insertion into the flagellar apparatus of the three‐membered rootlets. The flagellar apparatus demonstrates 180° rotational symmetry, and its components show counterclockwise absolute orientation when viewed from above. Newly described features include the prominently bilobed structure of the terminal caps on the upper basal body pair, and the presence of both a granular zone and an additional single microtubule anterior to each of the four rootlets, an arrangement termed the “stacked rootlet configuration.” Rhizoplasts were not observed and are presumed to be absent. The gamete is identical, except for the absence of the lower basal body pair and the presence of an electron‐dense membrane associated structure that resembles the mating structure found inUlvagametes. These findings, correlated with life history data, sporangial and gametangial structure and developmental patterns, chloroplast pigment arrays, and vegetative cell ultrastructural features, compel the removal ofEntocladia viridisand similar members of the marine Chaetophoraceae to a separate family, the Ulvellaceae. The latter is referred to the order Ulvales of the Ulvophyceae. The counterclockwise absolute orientation of components, and terminal caps, may be the most consistent flagellar apparatus features of ulvophycean green algae, while variations in other features previously considered diagnostic for the Ulvophyceae may serve instead to identify discrete lineages within this class.
NORTH CAROLINA MARINE ALGAE. XI. A NEW SPECIES OF HELMINTHOCLADIA (LIAGORACEAE, NEMALIALES, RHODOPHYTA) WITH A REAPPRAISAL OF THE GENERIC LIMITS OF HELMINTHOCLADIA AND HELMINTHORA1
Authors: Searles Richard B. , Lewis Sara M.
Published: November 2004

A new species in the Liagoraceae (Nemaliales) having vegetative and male reproductive characteristics usually associated with the genus Helminthora is assigned to Helminthocladia (as Helminthocladia andersonii Searles & Lewis) on the basis of the shape of the conical carpogonial protoplast, three‐celled carpogonial filament, development of the carposporophyte from both cells formed by division of the zygote and development of the involucre without the formation of a bridge around the zygote or formation of rhizoids from the involucre. All of these are consistent characteristics of Helminthocladia and distinguish its species from those of Helminthora.
FINE STRUCTURE OF THE SNOW ALGA (CHLAMYDOMONAS NIVALIS) AND ASSOCIATED BACTERIA1
Authors: Weiss Richard L.
Published: November 2004

Chlamydomonas nivalis(Bau.) Wille is present in red snow as large spherical resting cells. Fine structural studies reveal an abundance of clear granules in the cytoplasm and occasional starch grains in the chloroplast. Individual cells display a thick cell wall with a smooth outer surface. Cells may be surrounded by a loose fibrous network in which encapsulated bacteria are seen. The bacteria have a characteristic Gram‐negative cell wall and constrictive mode of division. The algal‐bacterial association appears to be characteristic of red snow populations.
PRESENCE AND DISTRIBUTION OF BROMINE IN THYSANOCLADIA DENSA (SOLIERIACEAE, GIGARTINALES), A MARINE RED ALGA FROM THE GREAT BARRIER REEF1
Authors: Pallaghy Charles K. , Minchinton Jeff , Kraft Gerald T. , Wetherbee Richard
Published: November 2004

Electron‐probe X‐ray microanalysis of freeze dried sections of growing branch tips of Thysanocladia densa Sander shows high concentrations of bromine in the region of the medulla. Indirect evidence infers that the Br is associated with intercellular, granular deposits which accumulate within the mucilage of the medulla. The concentration of Br decreases in older regions of the thalli.
THE MARINE, PLANKTONIC DIATOMS THALASSIOSIRA OCEANICA SP. NOV. AND T. PARTHENEIA1
Authors: Hasle Grethe Rytter
Published: November 2004

The diatom clone 13–1 isolated from the Sargasso Sea by Dr. R. R. L. Guillard as Cyclotella nana Hust. or Thalassiosira pseudonana Hasle and Heimdal is described as a separate species, Thalassiosira oceanica sp. nov. An amplified diagnosis of Thalassiosira partheneia Schrader is given, and a comparison of the two species is made based on light and electron microscopy. Similarities are present in the apparent distribution pattern, cell size, and girdle structure. Differences are present in the shape of the areolae of the valvocopula and the copula, in the structure of the vela of these bands, in the texture of the external valve surface, in the morphology of the strutted processes, in the location of the labiate process, in the distance between the marginal strutted processes, and by the presence of a marginal ridge in T. oceanica. Fifteen nanoplanktonic (maximum diameter = 20 UmUm) Thalassiosira species are listed, among them T. oceanica and T. partheneia.
QUALITATIVE AND QUANTITATIVE OBSERVATIONS ON AQUATIC ALGAL COMMUNITIES AND RECOLONIZATION WITHIN THE BLAST ZONE OF MT. ST. HELENS, 1980 AND 19811
Authors: Ward Amelia K. , Baross John A. , Dahm Clifford N. , Lilley Marvin D. , Sedell James R.
Published: November 2004

Despite the destruction and total rearrangement of much of the area north of Mt St. Helens, many different species of algae became established in the aquatic systems located in the blast zone within 3–4 months after the eruption of May 18, 1980. Initial sites of intense algal activity were found in benthic regions associated with warm springs and in the littoral and phytoplanktonic communities of some small lakes. In the summers of 1980–81, overall phytoplankton numbers and activity were low in the large lakes closest to the crater (e.g. Spirit Lake). However, diatoms, blue‐green and green algal isolates from these lakes were obtained in laboratory cultures on a reduced inorganic medium used to enumerate metal and sulfur oxidizing bacteria. Species of Nodularia, Pseudanabaena, Anabaena, Oscillatoria, Nitzschia, Tribonema, Chlamydomonas, Chlorella, and microflagellates (predominantly cryptomonads) were among the more common forms found in preserved samples or isolated in cultures.
LIFE HISTORY AND HYBRIDIZATION STUDIES ONGIGARTINA STELLATAANDPETROCELIS CRUENTA(RHODOPHYTA) IN THE NORTH ATLANTIC1
Authors: Guiry Michael D. , West John A.
Published: November 2004

Fourteen isolates of the crustose marine red algaPetrocelis cruentaJ. Agardh from various localities in the British Isles, France (including the type locality), Spain and Portugal gave rise in culture to dioecious foliose plants identifiable asGigartina stellata(Stackhouse) Batters although two isolates formed only sterile foliose blades. A total of 145 isolates ofGigartina stellatawere also grown in culture from various localities in the U.S.A. (Maine), the British Isles, Iceland, Denmark, France, Spain and Portugal using both carpospores and vegetative blade apices. Two basic types of life history were found among these isolates: a direct‐type life history involving the formation of further foliose plants from carpospores, some isolates of which also form spermatangia on the same papillae as the cystocarps; and a heteromorphic‐type in which only crustose plants resemblingPetrocelis cruentaare formed from carpospores. Only heteromorphic‐type life histories were found from Spain and Portugal. Both life history types were found in plants from the U.S.A., the British Isles and northern France. Only direct‐type life histories were found in plants from Iceland and Denmark. SomePetrocelis‐like crusts derived from field collectedG. stellatacarpospores andPetroceliscrusts of hybrid progeny formed tetrasporangia in 8:16 h LD, 10° C but not in 8:16 h LD, 15° C; 16:8 h LD 10° C or 15° C; and 10:6.5:1: 6.5 h LDLD, 10° C. The spores thus formed were viable and produced normal dioecious male and female gametophytes. Short day and low temperature conditions appear necessary for tetrasporogenesis. The results from crossing experiments with 32 male and 27 female isolates of the heteromorphic‐type derived from bothG. stellataandP. cruentashowed that two virtually non‐interbreeding populations with a high degree of geographical separation exist in the north‐eastern Atlantic. Morphological differences between plants from each population are described. On the basis of culture and crossing results,Petrocelis cruentaJ. Agardh is placed in synonymy withGigartina stellata(Stackhouse in Withering) Batters.
EFFECTS OF PHOTON FLUENCE RATE AND LIGHT SPECTRUM COMPOSITION ON GROWTH, PHOTOSYNTHESIS AND PIGMENT RELATIONS IN GRACILARIA SP.1
Authors: Beer Sven , Levy Israel
Published: November 2004

The optimal photon fluence rate for growth of tha llus tips of Gracilaria sp. was low (about 100 μE·–2·1); higher photon fluence rates inhibited growth. Both phycoerythrin (PE) and chlorophyll (chl) contents decreased with increasing photon fluence rates (up to 100 μE·–m–2s–1) in a fashion inverse to the growth response. Chl/PE ratios varied directly as the growth response over a larger photon fluence rate range. The peak chl/PE ratios were obtained at a photon fluence rate optimal for growth, suggesting that this parameter may be used to estimate in situ growth rates. A low compensation point (about 7 μE·–2s–1) was observed for low light (15 μE·–2s–1) grown plants. This compensation point was also obtained for growth in the long–term (5–6 weeks) experiments. Plants grown at 60 and 140 μE·–2s–1 showed higher light compensation and saturation points, suggesting that the variations in pigment composition found between the different treatments determine the photosynthetic responses at sub–optimal photon fluence rates. Photosynthetic rates at light saturation were the same, on a biomass basis, for plants grown at the various photon fluence rates. Thus, the photosynthetic dark reactions were not influenced by previous light regimes. It is suggested that maximal photosynthetic rates expressed on a biomass basis better reflect the potential productivity at tight saturation than if expressed on a pigment basis. Gracilaria sp. grew better under non–filtered fluorescent and greenish than under reddish and blue–enriched light of equal and sub–optimal photon, fluence rate. However, the pigment relations of the algae did not change in a direction complementary to the light composition at which they grew. This, together with the relatively higher photosynthetic rates under reddish and blueish light for plants previously grown under reddish and blueish light, suggests that adaptations to variouslight spectra are based on mechanisms different from complementary chromatic adaptation of the pigments.
INTERCEPTION OF ATMOSPHERIC FIXED NITROGEN AS AN ADAPTIVE ADVANTAGE OF SCUM FORMATION IN BLUE‐GREEN ALGAE1
Authors: Lewis William M.
Published: November 2004

Scum formation by blue‐green algae has been interpreted as a nonadaptive failure of the buoyancy control mechanism and, alternatively, as an adaptive mechanism to reduce inorganic carbon limitation. Data from Lake Valencia, Venezuela, are used to illustrate the principle that scum formers intercept significant amounts of fixed N deposited from the atmosphere at the water surface. Interception of fixed N at the surface can confer a significant selective advantage for populations that are strongly N limited, as in Lake Valencia. This additional adaptive advantage to scum formation may be alternative lo or complementary to the possible relief of carbon limitation.
A SIMPLIFIED, RAPID METHOD FOR IDENTIFYING MATING TYPE IN ALGAE: RESULTS WITH THE PANDORINA MORUM (CHLOROPHYCEAE) SPECIES COMPLEX1
Authors: Coleman Annette W. , Maguire Mark J.
Published: November 2004

As a collection expands, increasing numbers of test crosses are required to identify new isolates in algal species containing numerous pairs of mating types. A short‐cut is described that utilizes a reduced number of preliminary test crosses. The method was used successfully with the colonial green flagellate, Pandorina morum Bory de St. Vincent, to identify a new pair of milling types (syngen) from Japan and five new isolates from China of a previously known syngen. When tested on the 20 previously described syngens, it revealed one unexpected multi‐clone effect on mating. The method should be valuable for identifying newly collected clones, examining potential, interactions among incompatible mating types, and for screening other highly specific inter‐organism interactions such as host‐parasite infections.
Preference and performance of the hyperparasitoid Syrphophagus aphidivorus (Hymenoptera: Encyrtidae): fitness consequences of selecting hosts in live aphids or aphid mummies
Authors: Buitenhuis R. , Boivin G. , Vet L. E. M. , Brodeur J.
Published: November 2004

Abstract.  1. Theoretical models predict that ovipositional decisions of parasitoid females should lead to the selection of the most profitable host for parasitoid development. Most parasitoid species have evolved specific adaptations to exploit a single host stage. However, females of the aphid hyperparasitoid Syrphophagous aphidivorus (Mayr) (Hymenoptera: Encyrtidae) display a unique and atypical oviposition behaviour by attacking either primary parasitoid larvae in live aphids, or parasitoid pupae in dead, mummified aphids.

2. In the laboratory, the correlation between host suitability and host preference of S. aphidivorus on the host Aphidius nigripes Ashmead parasitising the aphid Macrosiphum euphorbiae (Thomas) was investigated.

3. The relative suitability of the two host stages was determined by measuring hyperparasitoid fitness parameters (survival, development time, fecundity, sex ratio, and adult size of progeny), and calculating the intrinsic rate of population increase (rm). Host preference by S. aphidivorus females and the influence of aphid defence behaviour on host selection was also examined.

4. Hyperparasitoid offspring performance was highest when developing from hosts in aphid mummies and females consistently preferred this host to hosts in parasitised aphids. Although aphid defensive behaviour may influence host selection, it was not a determining factor. Ecological and evolutionary processes that might have led to dual oviposition behaviour in S. aphidivorus are discussed.
Parasitoid behaviour: predicting field from laboratory
Authors: Casas Jerome , Swarbrick Susan , Murdoch William W.
Published: November 2004

Abstract. 1. Most of what is known about parasitoid behaviour comes from laboratory observations: field quantitative observations on searching parasitoids are extremely difficult to do and are rare. The basic components ofAphytis melinus's response to California red scale (Aonidiella aurantii) were studied in the laboratory: encounter, rejection, drumming, probing, oviposition, and host‐feeding. It was then asked whether these observations provided a reliable guide to behaviour in the field in a situation that was very different from the laboratory.

2. Field observations were carried out on bark on the trunk and interior branches of trees where live scale density is extremely high in patches, dead scale make up 90% of all scale, and could be expected to interfere withAphytissearch.

3. The laboratory observations predicted well the time taken in the field for each basicevent(drumming or probing) and average times spent on a scale. Also well predicted were the distributions of times spent on drumming, probing, and total time on a scale. Rejection rates were much higher in the field. Thus, the laboratory studies predicted foraging behaviour in the field with variable success; potential explanations for observed mismatch between laboratory and field and its possible larger implications are discussed.
Adult mortality and oviposition rates in field and captive populations of the blowfly Lucilia sericata
Authors: Pitts K. M. , Wall R.
Published: November 2004

Abstract.  1. Adult mortality and oviposition rates were determined for populations of the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae). This species is of economic importance as the primary agent of sheep myiasis throughout north‐western Europe.

2. Populations of marked flies in six, 1 m3, outdoor field cages and unmarked wild flies at two farms in south‐west England were studied simultaneously between May and September 1998.

3. In the field, wild female L. sericata were caught and aged using a combination of wing‐fray and ovarian dissection techniques. Survivorship analysis gave estimates of mortality of 1.94% (± 0.037) and 2.09% (± 0.044) per day‐degree and mean life expectancy of 51.5 and 47.9 day‐degrees above a threshold of 11 °C, at the two farms studied. Mean lifetime reproductive output in the field was estimated to be 159.6 and 138.4 eggs per female at the two farms respectively.

4. The survivorship of cohorts of marked female flies in cages was followed by counting the number of dead individuals each day; the mortality rate of these flies was 0.81% per day‐degree (± 3.49 × 10−4%) and the mean life expectancy was 123.1 day‐degrees above a threshold of 11 °C. Mortality rate was shown to increase significantly with average ambient temperature and relative humidity lagged for two sample periods (approximately 10 days). Oviposition rate also increased with average temperature but declined with average relative humidity. A best‐fit multiple regression model incorporating both ambient temperature and humidity explained 60.5% of the variance in the pattern of oviposition.

5. The differences between the field and cage populations highlight the caution required when extrapolating life‐history parameters from artificial to natural habitats.
Induction of macrophage scavenger receptor MARCO in nonalcoholic steatohepatitis indicates possible involvement of endotoxin in its pathogenic process
Authors: Yoshimatsu Mika , Terasaki Yasuhiro , Sakashita Naomi , Kiyota Emi , Sato Hiroo , Van Der Laan Luc J. W. , Takeya Motohiro
Published: November 2004

Nonalcoholic steatohepatitis (NASH) is one of the life‐threatening hepatic diseases; however, its pathogenesis is still unknown. To evaluate the causative role of hyperlipidaemia and high‐fat diet, we compared C57BL/6 mice with inherited hyperlipidaemic model mice (LDLR–/–mice and ApoE–/–mice) fed a normal or a high‐fat diet. LDLR–/–and ApoE–/–mice fed the normal diet showed significantly higher serum cholesterol level than that of C57BL/6 mice fed the high‐fat diet. These mice, however, have shown neither significant elevation of serum alanine transaminase (ALT) level nor histopathologic features of steatohepatitis. High‐fat diet groups of all three strains showed histopathological characteristics of steatohepatitis with elevated serum ALT levels and high expression of macrophage scavenger receptor MARCO mRNA in the liver. Semiquantitative endotoxin analysis showed an elevated serum endotoxin level in the portal vein but not in the vena cava in ApoE–/–mice fed the high‐fat diet. These results indicate that long‐term feeding of a high‐fat diet induces NASH, whereas hyperlipidaemia alone is not enough to induce NASH. Liver‐restricted induction of MARCO in mice with high‐fat diet and portal endotoxaemia in ApoE–/–mice fed the high‐fat diet suggest the possible involvement of endotoxin in the pathogenesis of NASH.
Co‐stimulation of human breast cancer cells with transforming growth factor‐β and tenascin‐C enhances matrix metalloproteinase‐9 expression and cancer cell invasion
Authors: Ilunga Kalembeyi , Nishiura Rika , Inada Hiroyasu , El‐Karef Amro , Imanaka‐Yoshida Kyoko , Sakakura Teruyo , Yoshida Toshimichi
Published: November 2004

Transforming growth factor‐β (TGF‐β), tenascin‐C (TN‐C) and matrix metalloproteinases (MMPs) have been demonstrated independently to be associated with disease progression and poor prognosis in patients with breast cancer. The present study explored effects of TGF‐β and TN‐C on MMP‐9 expression and cancer invasion. An experimental study was designed to analyse MDA‐MB‐231 breast cancer cells, known for their high invasiveness, after stimulation with TGF‐β1 and/or TN‐C. TGF‐β1 stimulated TN‐C expression in the cells. Co‐stimulation of MDA‐MB‐231 cells with TN‐C and TGF‐β increased MMP‐9 expression at both the gene (28‐fold) and the protein levels. The in vitro invasion also increased (4‐fold). GM6001 inhibited the invasion induced by the co‐stimulation. The combined effect of TN‐C and TGF‐β resulted in enhanced MMP‐9 expression and cancer invasion in vitro.
Population Treatment for Addictions
Authors: Prochaska James O.
Published: November 2004

Addictive behaviors are major causes of chronic disease, premature death, and high health care costs. Such behaviors have not been treated seriously by health care systems, and this is a major reason why such systems face an unhealthy future. Treating addictions seriously requires complementing a traditional individual-patient paradigm with a population paradigm, an action paradigm with a stage paradigm, clinic practices with home-based practices, a clinician paradigm with a computer paradigm, and programs that focus on changing single behaviors with programs that focus on changing multiple behaviors.
Effect of efavirenz treatment on the pharmacokinetics of nelfinavir boosted by ritonavir in healthy volunteers
Authors: La Porte C. J. L. , De Graaff‐Teulen M. J. A. , Colbers E. P. H. , Voncken D. S. , Ibanez S. Marco , Koopmans P. P. , Hekster Y. A. , Burger D. M.
Published: November 2004

Aims

A once‐daily (q.d.) nucleoside‐sparing regimen can prevent mitochondrial toxicity, overcome viral resistance and improve compliance. In the present study the effect of efavirenz on the pharmacokinetics and tolerability of once‐daily nelfinavir/ritonavir was evaluated in healthy subjects.

Methods

This was a multiple‐dose, open‐label, single‐group, two‐period study in 24 healthy subjects. Each received from days 1–10 (period 1): 1875 mg nelfinavir plus 200 mg ritonavir q.d. with a 300‐kcal snack. During days 11–20 (period 2) efavirenz 600 mg q.d. was added to the regimen. Blood samples were collected up to 24 h after dosing on days 10 (period 1) and 20 (period 2). High‐performance liquid chromatography methods were used for the determination of the concentrations of all compounds. The main pharmacokinetic parameters were calculated using noncompartmental methods.

Results

All subjects completed the study. After the first period mean nelfinavir AUC0−24 h, Cmax and C24 were 49.6 mg h−1 l−1, 5.0 mg l−1 and 0.37 mg l−1, and the sum of nelfinavir plus its active metabolite M8 C24 was 0.83 mg l−1. The relative bioavailability, expressed as a geometric mean ratio (90% confidence interval) for nelfinavir AUC0−24 h, Cmax and C24 of period 2 compared with period 1 was: 1.30 (1.21, 1.40), 1.29 (1.19, 1.40) and 1.48 (1.32, 1.66). The sum of nelfinavir and M8 C24 in period 2 was 0.99 mg l−1, an increase of 19%. No serious adverse events occurred.

Conclusions

The studied regimens were well tolerated. Nelfinavir/ritonavir given together with efavirenz resulted in a 48% higher mean C24 concentration for nelfinavir, and the sum of nelfinavir and M8 C24 concentrations was 0.99 mg l−1. Efavirenz exposure in this study was similar to that reported previously, and therefore can be used effectively in combination with ritonavir and nelfinavir.