bluuebunny/crossref_metadata_2025 huggingface dataset:
Crab-eating in the diamondback terrapinMalaclemys terrapin: dealing with dangerous prey
Authors: Davenport John , Spikes Martha , Thornton Sarah M. , Kelly Bridget O.
Published: May 2009

Male diamondback terrapins,Malademys terrapin(190–240 g; 101–117 mm carapace length; 11–8 ±0–6 mm maximum jaw gape) selected small littorinids (<12 mm shell height) and mussels (<30 mm shell length) when offered prey of a range of sizes (at 26°C and 34‰. Jaw gape appeared to be the main constraint on feeding on molluscs. Responses to crabs were complex. Small crabs (10–25 mm carapace width) were eaten whole. Medium-sized crabs (30–50 mm carapace width) were ‘cropped’ (i.e.walking legs were eaten without killing the crabs). Large crabs (52–75 mm carapace width) were usually avoided, though terrapins sometimes took legs from pairs 3 or 4. Experiments with medium-sized crabs showed that diamondbacks evaluated crabs visually before attacking and preferred to eat crabs without chelipeds, rather than crabs with one or two chelipeds. Terrapins carried out attacks on medium-sized crabs from the side or rear and preferentially cropped leg pair 4 (the furthest from the chelipeds), even though leg pair 4 was significantly less valuable energetically than other leg pairs. Evidence is presented to show that cropping behaviour allows terrapins to exploit crabs which are too large to eat whole because of the constraints of jaw gape and the hard, smooth surface of the crab cephalothorax. Limb cropping is as energetically profitable as eating small crabs whole, but the threat posed by chelipeds causes terrapins to attack crab prey in the order small>medium>large.
Feeding spectrum of squid Sthenoteuthis oualaniensis (Oegopsida) in the eastern Pacific
Authors: Shchetinnikov A. S.
Published: May 2009

The stomach contents of 235 specimens of the squid Sthenoteuthis oualaniensis (4·3–36·5 cm mantle length, ML) were examined. A detailed list of 60 species of prey, comprising young and adult squid, is given together with their frequency of occurrence and proportional contribution. The size and number of each food item was investigated. Three ontogenetic size-groups of S. oualaniensis were distinguished: I, fry and young (4–10 cm ML), micronektonic epipelagic plankton-eaters; II, transient critical size group (10–15 cm ML), converting from feeding on planktonic crustaceans and fish larvae to myctophid fishes; III, medium-sized (adult) nyctoepipelagic nektonic predators (15–36·5 cm ML), feeding primarily on myctophids and secondarily on squid. Myctophids (genera Symbolophorus, Myctophum and Hygophum) were the most abundant prey in the diet of adult S. oualaniensis from different parts of its distribution.
Swimming and body orientation of Notolepis rissoi in relation to lateral line and visual function
Authors: Janssen John , Pankhurst Neville W. , Harbison G. Richard
Published: May 2009

When observed from a submersible, the mesopelagic paralepidid Notolepis rissoi (Pisces: Paralepididae) will hover head up with the body at about 45°. The fish's swimming motion is restricted to the extreme caudal region with most of the body rigid. The trunk lateral-line canal ends at about the position that caudal motion becomes noticeable and there is a great decrease in neuromast size near the posterior end of the canal. The size of the neuromasts is also inversely related to the percentage of red muscle at the same body level. The eyes have an aphakic space oriented dorso-anteriorly at about 45° to the body axis so that during hovering the aphakic space is oriented vertically. Retinal anatomy indicates that photoreceptors opposite the aphakic space appear to enhance resolution at the cost of sensitivity, whilst lateral photoreceptors enhance sensitivity at the expense of resolution. We interpret the swimming attitude and mechanics as adaptations to minimize self-induced oscillations which would be deleterious to visual and lateral-line function.
Genetic divergence between branched and unbranched forms of the thecate hydroidAglaophenia pluma
Authors: Thorpe J. P. , Ryland J. S. , Cornelius P. F. S. , Beardmore J. A.
Published: May 2009

Samples of branched and unbranched forms of the marine thecate hydroidAglaophenia pluma(L.) (Hydrozoa, Plumulariidae) were collected from the western and eastern sides respectively of Carmarthen Bay (South Wales). Tissue from various colonies of each type was cleaned of epifauna and homogenized for horizontal starch gel electrophoresis. Useful results were obtained for 14 enzyme loci coding for a total of 11 different enzymes. Eleven of the 14 loci showed no common allele between the branched and unbranched forms. Nei's genetic identity was estimated as 0·18 and genetic distance as 1·7. Such a high level of genetic differentiation between morphotypes provides strong evidence that the populations are reproductively isolated and should be regarded as distinct species. It is suggested that the branched form may beAglaophenia parvulaBale, a species until recently better known from the southern hemisphere. Morphological distinctions between the two species are discussed.
Biometrics, Carbon and Nitrogen Content in the Ophiuroid Ophiothrix Fragilis
Authors: Davoult D. , Degros N. , Janquín M. A. , Soyez B.
Published: May 2009

Relationships between size, wet weight, dry weight, carbon and nitrogen content were determined in Ophiothrix fragilis (Echinodermata: Ophiuroidea). Such relationships appeared very useful when studying dynamic processes such as nutrition, growth, excretion or reproduction, considered as fluxes of carbon and nitrogen in the ecosystem.

Relationships between size, wet weight, dry weight, ash free dry weight, carbon and nitrogen content of organisms are of fundamental interest in ecological studies of ecosystems. They allow us to understand and quantify the role of a species as it stores, consumes or produces organic matter during its life cycle. Determination of conversion factors are time-consuming but very useful for estimating flows in the ecosystem (Brey et al., 1988). Some compilations of conversion factors have been published (Båmstedt, 1981; Rumohr et al., 1987).

Ophiothrix fragilis (Abildgaard) is the dominant species of the ‘pebbles with sessile epifaunal community’ (Davoult, 1990), located in the Dover Strait (eastern Channel), where tidal currents are very strong. It is considered as an efficient suspension feeder (Roushdy & Hansen, 1960; Warner, 1971) and lives in dense populations (1000–2000 individuals m-2; Davoult, 1989) which are assumed to have a significant effect on the fluxes of organic matter from the pelagic to the benthic system and on the fluxes of ammonium to the water column (Davoult et al., 1991).

Individuals were sampled in May and June 1991 off the Cape Gris-Nez (50°55′N 1°35′E). Two-hundred individuals were measured (diameter ±01 mm, after Guille, 1964), dried at 60°C for 48 h, weighed (±0·1 mg), burnt at 520°C for 6 h (Anonymous, 1986), and the ash weighed (±0·1 mg). Total organic carbon and nitrogen content were determined with a CHN element analyser (Carlo Erba 1106): after a flash combustion in a helium stream temporarily enriched with pure oxygen, quantitative combustion was achieved by passing gases over Cr2O3 after a transfer through a reduction reactor to eliminate the excess of oxygen; components were separated in a chromato-graphic column, eluted, then measured by a thermal conductivity detector. Thirty-eight dried ophiuroids were ground with a micro-grinder, then two sub-samples (except for individuals <2 mm) were weighed at ±1 μg (76 measurements).
The Reproductive Maturity of the Common Eel
Authors: Cunningham J. T.
Published: May 2009

In the Museum of the Royal College of Surgeons, in London, there are two specimens of the common eel, in which the ovaries are much enlarged, greatly distending the abdomen, and evidently very nearly ripe. Both those specimens were presented by Mr. Geo. Buckeridge, a salesman in Billingsgate Market, who deals largely in eels. The following are certain particulars concerning the specimens:—

(1) Length 15 in., weight 4½ oz. Presented Jan. 4, 1894.

(2) Length 19 in., girth round the abdomen 5½in., weight 10¼ oz. Presented Sept. 25, 1895.
Observations at Sea and in the Markets
Authors: Cunningham J. T.
Published: May 2009

At Grimsby there are a number of trawlers—some steamers and some sailing vessels, which are locally called Cleethorpers, and regularly fish on the grounds near the Humber, returning to port at the end of the week. I went out in one of these, the S.S. Rhine, on July 22nd. My object was to examine the grounds near the mouth of the Humber and the Wash, in order to compare them with the grounds off the German coast. We shot the trawl at 2 p.m. the same day, having steamed 55 miles by the log from the Newsand Lightship, at a position a few miles west of the Coal Pit or N.E. Hole, as it is named on the chart illustrating Mr. Holt's description of the Grimsby Trawl Fishery. The depth during the haul was 13 to 18 fathoms. The temperature at the surface was 58° F.
Report on the Sponge Fishery of Florida and the Artificial culture of Sponges
Authors: Allen E. J.
Published: May 2009

I. The Florida Sponge Fishery .—History of the Fishery. Kinds of sponges taken. Relative value of sponges. Methods of procuring sponges. Curing the sponges. Sponge grounds reduced in value through over—fishing.

Sponge Culture Experiments.—historical.

Experiments of Buccicli. —Description of apparatus used, and manner in which the experiments were conducted. Buccich concluded that sponge cuttings would grow to marketable size in seven years.

Experiments in Florida.—Sponge cuttings said to grow more rapidly, increasing to from four to six times their original size in six months, when placed under favourable conditions.

Memorandum by Mr. Benedict, of U.S. National Museum,.—Sponge culture experiments do not appear to have been tried to any great extent. Fishermen opposed to anything of the kind as likely to lead to monopoly, and the cutting off their means of subsistence.

Would Sponge—Culture By Cuttings Be Profitable—Marenzeller points out that this would depend on whether pieces of a sponge would in a given time together attain a greater weight than the original sponge would have reached if left undisturbed.

Suggested Experiments.—Suggestions by Mr. Bidder {see below). Fishing by means of divers, or dredging, should be tried in deeper water.
The Fourth Report of the Danish Biological Station
Authors: Stead F. B.
Published: May 2009

>The Plaice in Danish Waters.—The Fourth Report of the Danish Biological Station consists of a lengthy paper by Dr. C. G. J. Petersen “on the Biology of our Flat-fishes and on the Decrease of our Flat-fish Fisheries,” which was awarded a prize by Det Kongelige danske Videnskabernes Selskab, and which certainly deserves the careful attention of all who are interested in fishery questions. The first chapter gives a fairly complete account of some of the main features in the life history of the plaice in the Danish seas, together with shorter notes on other flat-fishes; the second and third are occupied by a discussion of the reasons for the deterioration of the fisheries, and of the remedial measures by which this evil may in the future be prevented. The paper is supplemented by five appendices, one of which, on the post-larval stages of flat-fishes, is of particular interest. For the full English translation with which we are provided English naturalists can but express their gratitude to the author.
Biochemical-Genetic and Acrorhagial Characteristics of Pedal Disc Colour Phenotypes of Actinia Equina
Authors: Donoghue A. M. , Quicke D. L. J. , Brace R. C.
Published: May 2009

Previous work has shown that three ecologically disinct morphs can be identified amongst beadlet anemones, Actinia equina L., ranging in column coloration from red to brown (Quicke, Donoghue & Brace, 1983; Quicke & Brace, 1984; Quicke et al. 1985). Each is adapted to a different inter-tidal range, and is characterized by a multi-locus gene complex, which includes loci encoding a number of metabolically important enzymes, pedal disc coloration and probably strength of pedal attachment. They have been named the upper (U), mid (M) and lower (L) shore morphs, and are relatively most abundant on the upper mid, lower mid and low shores respectively. Members of the U morph are typically homozygous slow and fast at a hexokinase locus and a malate dehydrogenase locus respectively, whereas those of the L morph are typically homozygous for the other allele at each of these loci; M morph individuals are heterozygous at both.
The Influence of Nutritional State on the Circulatory and Respiratory Physiology of the Shore Crab,Carcinus Maenas
Authors: Depledge M. H.
Published: May 2009

The oxygen-carrying capacity of the blood of decapod crustaceans fluctuates widely. Salinity stress results in doubling of haemocyanin concentration within 24–48 h inCarcinus maenas(Boone & Schoeffeniels, 1979) while in the lobster,Homarus gammarusrespiratory pigment levels are very low prior to and following moulting (Spoek, 1974). In general, however, the most important factor regulating haemocyanin concentration is nutritional state. Following starvation low values are recorded (Wieser, 1965; Uglow, 1969; Djangmah, 1970) and there are concomitant reductions in ventilation, oxygen consumption and cardiac output (Ansell, 1973; Marsden, Newell & Ahsanullah, 1973; Wallace, 1973). The interrelationships between these events are poorly understood.
Bactericidal Activity of Coelomic Fluid of the Sea Urchin, Echinus Esculentus, on Different Marine Bacteria
Authors: Service Matthew , Wardlaw Alastair C.
Published: May 2009

Coelomic fluid from the edible sea urchin Echinus esculentus (L.) has in vitro bactericidal activity against the marine pseudomonad, designated strain No. 111 (Wardlaw & Unkles, 1978). This particular bacterial strain was chosen because of its highly characteristic jet-black, agar-digesting colonies on marine agar plates which permitted it to be easily distinguishable from contaminants in bactericidal tests. Bactericidal activity is localised in the cellular components of the coelomic fluid, particularly in the red spherule cells (Messer & Wardlaw, 1980) and is demonstrable in almost all animals tested.
Biochemical Genetic Variation, Growth and Regeneration of the Sea Anemone,Metridium, of British Shores
Authors: Bucklin Ann
Published: May 2009

Sessile organisms capable of asexual reproduction may be expected to show much genetic differentiation among local populations: mating between distant individuals is unlikely and genetic drift will contribute to differentiation since habitats can be colonized by one or a few individuals. This study investigates genetic differentiation of populations of the sea anemoneMetridium senile(L.) in Great Britain. Individuals ofM. senileare sessile and reproduce both sexually, by free-spawning of gametes, and asexually, by regeneration of fragments torn from the pedal disc.Metridium senileis one of the most common and widespread of British sea anemones (Manuel, 1981); reports place it at an enormous number and variety of sites around Britian (unpublished results of surveys by the Underwater Conservation Society of the United Kingdom). The extensive geographic range and variability of the species have confounded attempts to determine the taxonomic status of the ecological and morphological forms, but make it an interesting system for genetic analysis.
Reproductive and Nutritional Periodicities in Populations of the European Sea-Urchin,Echinus Esculentus(Echinodermata: Echinoidea) from the English Channel
Authors: Nichols D. , Bishop G. M. , Sime A. A. T.
Published: May 2009

The European sea-urchin,Echinus esculentusL., occurs from Finnmark in the north to the Canaries in the south. Around Britain, it is found from the Isle of Portland, English Channel, throughout most of the fully saline waters of the western and northern coasts, and in the North Sea as far south as Flamborough Head. Though it occurs between tide-marks in a few places, it is generally common from about 5 m depth below c.d. to about 100 m, though it is recorded from about 200 m depth (A. M. Clark, personal communication). It is a principal browser on the reefs on which it occurs, and feeds preferentially on kelp sporelings and other algae when it occurs in the photic zone, and on encrusting invertebrates and protochordates below the depth at which algae occur (De Ridder & Lawrence, 1982).E. esculentusis said to migrate inshore prior to spawning, and then retreat to deeper water in late spring (Elmhirst, 1922; Stott, 1931; personal observation), but a rigorous study of these apparent movements has yet to be undertaken. Echinoids fare better on a diet principally of algae than on one of animal material (Lawrence, 1975), so it might be assumed that the winter inshore migration could bring an urchin into a nutritionally richer area for the final developmental phase of gametogenesis.
A Comparative Study of the Reproductive Cycles of Three Northumberland Populations of Chaetozone Setosa (Polychaeta:Cirratulidae)
Authors: Christie Graeme
Published: May 2009

During a study of the reproductive cycle of a subtidal population of Chaetozone setosa Malmgren at an 80 m station off the Northumberland coast (Christie, 1981), the discovery of morphological and reproductive differences in an intertidal population lead to an extended comparative study of three Northumberland populations. The two additional populations chosen for comparison are situated at Low Newton by the Sea and Holy Island, Northumberland. All three populations are located within a maximum distance of 65 km from each other which makes these populations very close on a geographical scale.
Ammonium-Limited Continuous Culures of Skeletonema Costatum in Steady and Transitional State: Experimental Results and Model Simulations
Authors: Maske Helmut
Published: May 2009

The physiological response of ammonium-limited continuous cultures of Skeletonema costatum (Grev.)Cleve to steady-state and transient conditions was tested and compared to simulations with a Droop-type quota model and a four-state variable model (internal amino acid pool added to the quota model). External ammonium, free internal amino acids, protein, silicate and culture-cell volume were measured.

All cultures showed reproducible changes in growth and uptake kinetics due to spontaneous cell-cycle synchronization of the populations. Under steady-state conditions protein decreased with increasinggrowth rate from 82%; cell-nitrogen to 52% and free internal amino acids increased from 2·5% cell-nitrogen to 8%. Under transient conditions amino acids could reach 25% of cell-nitrogen.

A comparison of model and culture results yielded the following information: Both models could simulate steady-state and most transient conditions. The dependence of the quota on steady-state growth rate is not the result of changes in amino acid or protein pool size. The amino acid pool, an intermediary step in the nitrogen assimilation, does not serve to increase the time lag in growth response significantly. The four-state variable model reproduced under most conditions the behaviour of theamino acid pool without the use of feedback control mechanisms on the rate of uptake. The models could simulate a strong increase in growth rate except when it was initiated by impulse dilution of the culture. Then growth response was controlled by epigenetic mechanisms induction of enzyme synthesis). (6) The maximum nutrient uptake rate per culture cell volume of Skeletonema is inversely related to cell size.
‘The Bourgeois Woman and the Half-Naked One’: Or the Indian Nation's Contradictions Personified
Authors: CIOTTI MANUELA
Published: May 2009

This paper explores the interplay between development, identity politics and middle-class aspirations amongst low-caste Chamar women in rural north India. It argues that this interplay has reinvigorated notions of women's domesticity, education and modern conjugality as they emerged in the reforms and ‘modernising’ efforts of sections of Indian society, since the nineteenth century, in their encounter with the colonial ‘civilising mission’. It will show how the long-term effects of this ‘legacy’, through its reconfiguration and appropriation by members from a low caste, have affected a historically marginalised community in their pursuit of middle-class aspirations. In addition to the criticality of Indian women and their gender roles as ‘sites’ where nation and community transformations are symbolically and practically negotiated, scholars of South Asia have also highlighted the separation between historical and anthropological discourses on women. This paper brings these discourses together and addresses this separation by showing that Chamar appropriation of the ‘modernising’ agenda has initiated a dual process. On the one hand, a minority of women have embarked on an embourgeoisement trajectory predicated on education, ‘modern motherhood’ and aspirations to white collar employment, and on the other hand, underprivileged women (with their ‘unfit’ personas) have become increasingly vulnerable to stigmatisation as a result of being in ‘menial labour’. It is further argued that dialectic study of the ‘two [groups of] Chamar women’ will provide an insightful lens through which inner conflicts within low-caste communities in contemporary India may be understood, and suggests that there are contradictory trends concerning women, their development prospects, and their membership within the nation.
On the astrobiological relevance of viruses in extraterrestrial ecosystems
Authors: Jalasvuori Matti , Örmälä Anni-Maria , Bamford Jaana K.H.
Published: May 2009

Viruses are the dominant form of genetically reproducing entities on Earth. Yet, viruses are mostly neglected in the context of astrobiology due to their non-living nature. In this discussion it is considered whether viruses are likely to be transferred within bacterial endospores to other planetary bodies through lithopanspermia. Interestingly, it seems possible that ecosystems of panspermial origin might yield biospheres in which viruses are absent. The evolutionary pathway of life in these systems might differ significantly from the path observed on Earth. We hypothesize that the difference in the two potential ways for the emergence of life, those being panspermial or local origin, on any certain planet could be clarified by analyzing the diversity of virosphere on the planet. The use of viruses as putative biomarkers is also discussed and studied.
Insight into the origin of the Tengchong intraplate volcano and seismotectonics in southwest China from local and teleseismic data
Authors: Lei Jianshe , Zhao Dapeng , Su Youjin
Published: May 2009

A high‐resolution tomographic image of the crust and upper mantle under Yunnan Province in southwest China was determined by using a large number of teleseismic data measured precisely from digital seismograms as well as local‐ earthquake arrival times recorded by the dense Yunnan seismic network. The grid spacing of the tomographic model is ∼70 km × 78 km in the horizontal directions and 4–70 km in depth. Our resulting model shows a clear low‐velocity (low‐V, <−0.3% with respect to the average one‐dimensional velocity model) column extending from the surface down to about 400‐km depth under the active Tengchong volcano and some high‐velocity (high‐V) anomalies existing in the mantle transition zone. Furthermore, the low‐V anomaly extends horizontally toward the northeast at ∼250‐ to 400‐km depth. Combining our tomographic results with geochemical and geological investigations, we infer that the Tengchong volcano is a rift‐related volcano caused by the subduction and dehydration of the Indian plate as well as corner flow in the mantle wedge, though the subducted slab is a continental plate. Our results show that the upwelling flow under Tengchong originates at ∼400‐km depth. A prominent low‐V anomaly along the Red River fault zone extends down to the upper mantle (∼100‐km depth), reflecting that the Red River fault zone may have cut through the crust to the upper mantle. The two Dayao earthquakes (M 6.1 and M 6.2) in 2003 occurred on the margin of high‐V anomalies and are underlain by a prominent low‐V anomaly in the lower crust and upper mantle, suggesting that the Dayao earthquakes may be associated with fluids released from the dehydration of the subducted Indian slab. These results are significantly improved compared with previous studies and provide new seismic constraints on the dynamic processes of the India‐Asia collision.
Turbulent supply of nutrients to phytoplankton at the New England shelf break front
Authors: Hales Burke , Hebert Dave , Marra John
Published: May 2009

We present observations from deployments of a microstructure turbulence instrument (the Towed Microstructure and Auxiliary Sensor Instrument) aboard a pumping profiling vehicle (the Lamont Pumping SeaSoar) towed behind a research vessel at the New England shelf break front in August 2002. From these we determined coincident fine‐scale vertical eddy diffusivity and gradients of nitrate, phosphate, and silicate on several transects spanning the front. We then quantified vertical turbulent nutrient fluxes through the base of the euphotic zone (defined as the 1% light level), the base of the density transition zone, maximum nutrient gradients (the nutriclines), and the depth of maximum stratification (the pycnocline). Vertical eddy diffusivity estimates spanned a wide range from near‐molecular levels at the pycnocline to values exceeding 10−3 m2 s−1 at depth and in the surface layers. Vertical nutrient fluxes were maximal at the 1% light level and decreased by 2 orders of magnitude as they moved upward through the water column to the depth of the pycnocline. Nutrient fluxes were enhanced shoreward of the front because of high mixing rates and nutrient gradients at the depth of the 1% light level. Nitrate fluxes there averaged about 6 × 10−5 mmol N m−2 s−1, sufficient to support a net community productivity of 30 mmol C m−2 d−1. Seaward of the front, these fluxes averaged about 1 × 10−5 mmol N m−2 s−1 and would support correspondingly lower productivity. A small part of the upward flux appeared to support a silicifying community of phytoplankton that consumed phosphate in proportion to nitrate at about double the canonical Redfield stoichiometry.
Forecasting and nowcasting improvement in cloudy regions with high temporal GOES sounder infrared radiance measurements
Authors: Li Zhenglong , Li Jun , Menzel W. Paul , Nelson James P. , Schmit Timothy J. , Weisz Elisabeth , Ackerman Steven A.
Published: May 2009

In an effort to extend the high temporal resolution Geostationary Operational Environmental Satellite (GOES) infrared sounding retrievals from clear to cloudy skies, a synthetic regression‐based cloudy sounding retrieval algorithm has been developed and applied to GOES 12 sounder measurements. Comparisons against radiosondes at the Atmospheric Radiation Measurement Program at Southern Great Plains site from August 2006 to May 2007 and the conventional radiosondes network over the continental United States from January 2007 to November 2008 both show that the retrievals of moisture under thin cloud conditions perform similarly to those under the clear‐sky conditions. The largest improvements are found in the upper level integrated precipitable water vapor (PW) or PW3. Also in the case of low thick clouds, PW3 is usually improved significantly. In addition, the retrieved cloud parameters are consistent with the false RGB composite images. With the addition of the soundings under low thick or thin cloud conditions, the area without soundings is reduced by 57% in the selected case. The application to a tornadic storm on 24 April 2007 reveals that the GOES cloudy sounding retrievals are more useful at the early stage of the storm, when nearby clouds are considered thin or broken. The GOES cloudy sounding algorithm reveals more pronounced and extensive convective instability, and it does so earlier than the clear‐sky‐only results. The cloudy sounding retrievals have the potential to provide an earlier warning to forecasters.
On the late northward propagation of the West African monsoon in summer 2006 in the region of Niger/Mali
Authors: Drobinski P. , Bastin S. , Janicot S. , Bock O. , Dabas A. , Delville P. , Reitebuch O. , Sultan B.
Published: May 2009

This paper investigates the fine‐scale dynamical processes at the origin of the late northward migration of the monsoon flow in summer 2006 in the region of Niger and Mali (onset on 3 July 2006 compared to the climatological onset date, 24 June). Compared to a 28‐year climatology, 2006 NCEP‐2 reanalyses show evidence of an anomalous pattern during 10 days between 25 June and 3 July 2006, characterized by the African Easterly Jet (AEJ) blowing from the northeast along a narrow northeast/southwest band located over the Hoggar and Air mountains associated with an unusually strong northeasterly harmattan in the lee of the mountains. Using data collected during the African Monsoon Multidisciplinary Analysis (AMMA) experiment and mesoscale numerical simulations, this study shows evidence of interaction between the AEJ and the orography supported by the reduced gravity shallow water theory which explains the enhancement of the harmattan downstream of the Hoggar and Air mountains in summer 2006. The enhanced harmattan contributes to move southward the intertropical discontinuity (ITD) defined as the interface between the cool moist southwesterly monsoon flow and the warm dry harmattan. Finally, an interaction between the ITD and African Easterly waves contributes to propagate the ITD southward retreat about 1500 km to the west of the Hoggar and Air mountains.
Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates?
Authors: Pierce J. R. , Adams P. J.
Published: May 2009

Although controversial, many observations have suggested that low‐level cloud cover correlates with the cosmic ray flux. Because galactic cosmic rays have likely decreased in intensity over the last century, this hypothesis, if true, could partly explain 20th century warming, thereby upsetting the consensus view that greenhouse‐gas forcing has caused most of the warming. The “ion‐aerosol clear‐air” hypothesis suggests that increased cosmic rays cause increases in new‐particle formation, cloud condensation nuclei concentrations (CCN), and cloud cover. In this paper, we present the first calculations of the magnitude of the ion‐aerosol clear‐air mechanism using a general circulation model with online aerosol microphysics. In our simulations, changes in CCN from changes in cosmic rays during a solar cycle are two orders of magnitude too small to account for the observed changes in cloud properties; consequently, we conclude that the hypothesized effect is too small to play a significant role in current climate change.
Electron spin resonance of charge carriers and antiferromagnetic clusters in Ge0.99Cr0.01 nanowires
Authors: Morgunov R. B. , Dmitriev A. I. , Tanimoto Y. , Kazakova O.
Published: May 2009

We report an electron spin resonance study of Ge nanowires doped with chromium. The Ge0.99Cr0.01 nanowires contain both diluted Сr3+ and Сr2+ ions and a large amount of Cr-based nanoclusters revealing spin-glass properties at T<60 K. The observed antiferromagnetic resonance at low temperatures is attributed to Ge–Cr nanoclusters. Additionally, we detect an asymmetric, isotropic resonant line clearly distinguished in the whole temperature range, T=4–300 K, which corresponds to a paramagnetic resonance of the charge carriers in the Ge0.99Cr0.01 nanowires. On the base of our previous studies, we compare properties of the charge carriers in germanium nanowires doped with different transition metals. We demonstrate that the effective g-factor related to charge carriers is reduced with an increase in the spin-orbital interaction in the row: Mn2+, Cr2+, Fe3+, and Co2+.
Temperature scaling of dynamic hysteresis in Zr-rich PbZr1−xTixO3 ceramics
Authors: Chen Xuefeng , Dong Xianlin , Zhang Honglin , Feng Ningbo , Nie Hengchang , Cao Fei , Wang Genshui , Gu Yan , He Hongliang
Published: May 2009

The temperature scaling relations of the dynamic hysteresis were investigated in Zr-rich lead zirconate titanate (PZT) bulk ceramics. At each relation curve, there is a discontinuous district corresponding to the low- and high-temperature phase transitions. The temperatures are divided into low-T region and high-T region. At each temperature region, three power-law scaling relations were obtained for hysteresis area ⟨A⟩, coercivity Ec, and remnant polarization Pr with T, respectively. The six temperature scaling relations are field dependent and the simplified forms are different from the results obtained from the soft and hard PZT ceramics.
Optical properties of carbon nanotubes in a composite material: The role of dielectric screening and thermal expansion
Authors: Berger S. , Iglesias F. , Bonnet P. , Voisin C. , Cassabois G. , Lauret J.-S. , Delalande C. , Roussignol P.
Published: May 2009

We report on environmental effects on the optical properties of single-wall carbon nanotubes in a gelatin-based composite material designed to foster their photoluminescence. We show that the dielectric screening of excitons due to the surrounding medium is responsible for a sizeable shift of the luminescence lines, which hardly depends on the tube geometry. In contrast, the temperature dependence (from 4 to 300 K) of the luminescence is clearly chirality dependent; the first and second excitonic lines shift in opposite directions with a magnitude that can be related quantitatively to a strain-induced modification of the electronic structure due to an expansivity mismatch between the nanotube and the matrix.
Self-consistent theory for near-field distribution and spectrum with quantum wires and a conductive grating in terahertz regime
Authors: Huang Danhong , Gumbs Godfrey , Lin Shawn-Yu
Published: May 2009

In the presence of the optical polarization produced by a quantum-wire array in proximity with a conductive grating on the top of a semi-infinite doped semiconductor with a period much smaller than the wavelength of an electromagnetic field, both the near-field distribution and spectra were studied. The calculations were carried out with the use of a self-consistent linear response theory for an impinging weak electromagnetic field, which, in turn, was determined from Maxwell’s equations with an induced nonlocal polarization field. Due to a resonant quantum effect, we found that the quantum wires strongly enhanced not only the transmission field for p polarization but also the reflection field for s polarization. When the quantum wires were placed at an edge of the groove formed by a channel in the grating, the induced destructive interference between different discrete diffraction modes of a transverse field was found, which led to a dip in the reflection spectrum for both s and p polarizations as well as in the s-polarized transmission spectrum.
Effect of Co doping on the magnetotransport properties of La0.45Sr0.55MnO3 perovskite
Authors: Ying Y. , Dai N. V. , Eom T. W. , Lee Y. P.
Published: May 2009

We investigated the magnetotransport properties of polycrystalline La0.45Sr0.55Mn1−xCoxO3 (0≤x≤0.15). Ferromagnetism is enhanced with the doping of Co ions in La0.45Sr0.55MnO3, but the antiferromagnetism is nearly destroyed in the low-temperature region. The Mn3+–Mn4+ double-exchange (DE) and Co2+–Mn4+ ferromagnetic (FM) superexchange interactions are mainly responsible for the magnetic properties of the doped system. With increased Co doping, the insulating properties and the magnetoresistance (MR) effect are simultaneously enhanced. This indicates that the Co doping strengthens both the Mn3+–Mn4+ DE and Co2+–Mn4+ FM superexchange interactions. The Co doping increases the disorder in the system, causing the MR effect to increase with decreasing temperature.
Cytocompatibility of modified a-C:H film deposited on complicated polymeric medical apparatus
Authors: Kanasugi K. , Ohgoe Y. , Hirakuri K. K. , Fukui Y.
Published: May 2009

In this study, in order to biologically evaluate the surface condition of the a-C:H film which was deposited on a complicated polymeric medical apparatus by using rf plasma chemical vapor deposition technique with a special three-dimensional-type electrode, we have investigated the cytocompatibility to the a-C:H film with and without plasma post-treatment. The a-C:H film surface was modified with argon (Ar) and oxygen (O2) plasma post-treatment to change the surface condition of the a-C:H film. The effects of the plasma post-treatment of a-C:H film deposited on a complicated object were estimated by using an Ar-laser Raman microscopy (Raman), a wettability measurement, a x-ray photoelectron spectrometer, and an atomic force microscopy. Additionally, the cellular adhesions of a-C:H film with and without plasma post-treatments were carried out under cell culture by in vitro studies. As results, The surface properties of a-C:H film on a complicated polymeric medical apparatus were controlled by surface modifications with Ar and O2 plasma post-treatment. Additionally, the cell cultures by in vitro studies have shown good cell growth on all the a-C:H film surface. Moreover, it was observed that cellular growth/adhesion was controlled by surface conditions of the a-C:H film with and without plasma post-treatments.
Tensor coordinates in noncommutative mechanics
Authors: Amorim Ricardo
Published: May 2009

A consistent classical mechanics formulation is presented in such a way that, under quantization, it gives a noncommutative quantum theory with interesting new features. The Dirac formalism for constrained Hamiltonian systems is strongly used, and the object of noncommutativity θij plays a fundamental rule as an independent quantity. The presented classical theory, as its quantum counterpart, is naturally invariant under the rotation group SO(D).
Automated system for spectrophotometric detection of liquid phase hydrogen peroxide for concentrations up to 5% w/w
Authors: Pashkova Aneta , Svajda Karel , Black Gary , Dittmeyer Roland
Published: May 2009

An automated flow injection analysis system for H2O2 detection in the liquid phase, based on the photometric determination of the complex between hydrogen peroxide and a titanium (IV) reagent is presented. The system was tested for monitoring the H2O2 concentration in a lab-scale experimental setup for H2O2 direct synthesis. In its final configuration, the developed system allows a reliable and reproducible determination of H2O2 for a broad concentration interval between 1.02×10−3 mol l−1 and 1.16 mol l−1.
The effective slip length and vortex formation in laminar flow over a rough surface
Authors: Niavarani Anoosheh , Priezjev Nikolai V.
Published: May 2009

The flow of viscous incompressible fluid over a periodically corrugated surface is investigated numerically by solving the Navier–Stokes equation with the local slip and no-slip boundary conditions. We consider the effective slip length which is defined with respect to the level of the mean height of the surface roughness. With increasing corrugation amplitude the effective no-slip boundary plane is shifted toward the bulk of the fluid, which implies a negative effective slip length. The analysis of the wall shear stress indicates that a flow circulation is developed in the grooves of the rough surface provided that the local boundary condition is no-slip. By applying a local slip boundary condition, the center of the vortex is displaced toward the bottom of the grooves and the effective slip length increases. When the intrinsic slip length is larger than the corrugation amplitude, the flow streamlines near the surface are deformed to follow the boundary curvature, the vortex vanishes, and the effective slip length saturates to a constant value. Inertial effects promote vortex flow formation in the grooves and reduce the effective slip length.
Temperature dependence of optical properties of InAs/GaAs self-organized quantum dots
Authors: Baira M. , Bouzaïene L. , Sfaxi L. , Maaref H. , Marty O. , Bru-Chevallier C.
Published: May 2009

Self-organized InAs/GaAs quantum dots (QDs) were grown by molecular beam epitaxy. The photoluminescence, its power, and temperature dependences have been studied for the ensembles of InAs QDs embedded in GaAs matrix to investigate the interband transition energies. Theoretical calculations of confined electron (heavy-hole) energy in the InAs/GaAs QDs have been performed by means of effective mass approximation, taking into account strain effects. The shape of the InAs QDs was modeled to be a convex-plane lens. The calculated interband transition energies were compared with the results of the photoluminescence spectra. The calculated interband transition energy from the ground electronic subband to the ground heavy-hole state was in reasonable agreement with the transition energy obtained by the photoluminescence measurement.
A synthetic jet produced by electrowetting-driven bubble oscillations in aqueous solution
Authors: Ko Sung Hee , Lee Seung Jun , Kang Kwan Hyoung
Published: May 2009

We developed a method to actuate oscillation of a sessile bubble in a fluid to produce steady streaming within the fluid. This method is based on time-periodic control of the wettability of the bubble by electrowetting. Jet velocity is proportional to oscillation amplitude and is greatest at natural oscillation frequencies. Analytical and numerical analyses indicate that the jet is produced by steady streaming in the Stokes layer.
Multishock comparison of dense gaseous H2+He mixtures up to 30 GPa
Authors: Gu Y. J. , Chen Q. F. , Cai L. C. , Chen Z. Y. , Zheng J. , Jing F. Q.
Published: May 2009

Time-resolved spectral radiation histories of the gaseous H2+He mixtures under shock loadings were measured by using a six-wavelength channel pyrometer. The initial gaseous mixtures had a mole component of H2:He=1:1.21, which were shocked from room temperature and initial pressure of 20 MPa to a pressure range of 1–30 GPa and temperature range of 3000–7000 K by means of a two-stage light-gas gun. Multishock reverberations between the base-plate and sapphire window can be observed up to the fifth-shock compressions. The experimental data are in good agreement with self-consistent fluid variational theory calculations in which the dissociation process of hydrogen molecules and various interactions among atomic and molecular species are taken into account.
Measurement of small birefringence and loss in a nonlinear single-mode waveguide
Authors: Rogers Daniel J. , Richardson Christopher J. K. , Goldhar Julius , Clark Charles W.
Published: May 2009

We design and fabricate a birefringent semiconductor waveguide for application to nonlinear photonics, demonstrating that it is possible to engineer a small birefringence into such a device using multiple core layers. We also demonstrate a simple technique to accurately determine small waveguide birefringence using a differential measurement, present useful methods for coupling light into and out of the device, and make estimates of coupling and linear device losses.
Insight from first principles into the nature of the bonding between water molecules and 4d metal surfaces
Authors: Carrasco Javier , Michaelides Angelos , Scheffler Matthias
Published: May 2009

We address the nature of the bond between water molecules and metal surfaces through a systematic density-functional theory (DFT) study of H2O monomer adsorption on a series of close-packed transition metal surfaces: Ru(0001), Rh(111), Pd(111), and Ag(111). Aiming to understand the origin behind energetic and structural trends along the 4d series we employ a range of analysis tools such as the electron reactivity function, decomposition of densities of states, electron density differences, and inspection of individual Kohn–Sham orbitals. The results obtained from our DFT calculations allow us to rationalize the bonding between water and transition metal surfaces as a balance of covalent and electrostatic interactions. A frontier orbital scheme based on so-called two-center four-electron interactions between the molecular orbitals of H2O—mainly the 1b1— and d-band states of the surface proves incisive in understanding these systems.
Nearly constant dielectric loss behavior in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) biodegradable polyester
Authors: Ke Shanming , Huang Haitao , Ren Li , Wang Yingjun
Published: May 2009

The measurement of dielectric spectroscopy over a broad frequency range of 0.01–107 Hz has been conducted to examine the segmental motions in poly[3-hydroxybutyrate-co-3-hydroxyvalerate] (PHBV) biopolymers. The ac conductivity at either low temperatures or high frequencies is almost temperature independent, indicating clearly that the nearly constant loss (NCL) phenomenon also takes place in polymers. The respective data were analyzed by adding a NCL term to the Jonscher relation. NCL in PHBV is discussed to be originated from the vibrational motion model. PHBV may have potential application as a biodegradable dielectric material.
Evolution of the plasma composition of a high power impulse magnetron sputtering system studied with a time-of-flight spectrometer
Authors: Oks Efim , Anders André
Published: May 2009

The plasma of a high power impulse magnetron sputtering system has been investigated using a time-of-flight spectrometer. The target materials included high sputter yield materials (Cu, Ag), transition metals (Nb, Cr, Ti), and carbon (graphite); the sputtering gases were argon, krypton, and nitrogen, and two different target thicknesses were selected to consider the role of the magnetic field strength. Measurements for selected combinations of those parameters give quantitative information on the transition from gas-dominated to metal-dominated (self-sputtering) plasma, on the fractions of ion charge states, and in the case of molecular gases, on the fraction of atomic and molecular ions.
Anomalous diffusion of chains in semicrystalline ethylene polymers
Authors: Wang Liying , Gao Xiuzhi , Sun Zhibo , Feng Jiwen
Published: May 2009

The chain diffusion between crystalline and amorphous/interfacial regions in semicrystalline ethylene homo- and copolymers was investigated by means of solid-state NMR. It was found that the crystalline chain segment diffusion along the chain-folded path is anomalous and can be characterized by the scaling relation of mean-square displacement, ⟨s2⟩∼t1/2.
Nonstandard conserved Hamiltonian structures in dissipative/damped systems: Nonlinear generalizations of damped harmonic oscillator
Authors: Pradeep R. Gladwin , Chandrasekar V. K. , Senthilvelan M. , Lakshmanan M.
Published: May 2009

In this paper we point out the existence of a remarkable nonlocal transformation between the damped harmonic oscillator and a modified Emden-type nonlinear oscillator equation with linear forcing, ẍ+αxẋ+βx3+γx=0, which preserves the form of the time independent integral, conservative Hamiltonian, and the equation of motion. Generalizing this transformation we prove the existence of nonstandard conservative Hamiltonian structure for a general class of damped nonlinear oscillators including Liénard-type systems. Further, using the above Hamiltonian structure for a specific example, namely, the generalized modified Emden equation ẍ+αxqẋ+βx2q+1=0, where α, β, and q are arbitrary parameters, the general solution is obtained through appropriate canonical transformations. We also present the conservative Hamiltonian structure of the damped Mathews–Lakshmanan oscillator equation. The associated Lagrangian description for all the above systems is also briefly discussed.