bluuebunny/crossref_metadata_2025 huggingface dataset:
Vesicular–arbuscular endomycorrhizal inoculum production. II. Experiments with maize (Zea mays) and other hosts in nutrient flow culture
Authors: Elmes R. P. , Mosse B.
Published: February 2008

Experiments are described that led to a better understanding of nutrient requirements for mycorrhizal development in nutrient flow (NFT) culture. For maize infected with Glomus mosseae, solution P concentration around 0.5 mg L−1 was optimal, giving approximately 50% infection. With more P, infection quickly decreased, and it was also low with only 0.3 mg L−1 P. Critical solution P was thus much lower than for Phaseolus vulgaris infected with Glomus fasciculatum (E3). When rock phosphate was used as P source, solution pH was very important because of its effect on P solubility. Nitrogen source ([Formula: see text] versus [Formula: see text]) was important for the same reason. Ca levels also affected mycorrhizal development, the optimum concentration for maize (above 15 mg L−1) being higher than that needed for beans. Maize also had a much higher Fe requirement. The relative merits of rock versus soluble P are discussed. Observations are also are reported on inoculation techniques for NFT and on mycorrhizal infection with other host–endophyte combinations.
Requirement for sorbitol (D-glucitol) as carbon source for in vitro propagation of Malus robusta No. 5
Authors: Pua E.-C. , Chong Calvin
Published: February 2008

Meristem tip explants of Malus robusta Rehd. No. 5 were successfully initiated in vitro on nutrient medium with sorbitol but not with glucose, sucrose, or fructose, each supplied at 30 g/L. Cultures, subsequently subcultured and multiplied on sorbitol medium, produced the highest number of shoots and had the highest shoot fresh and dry weights, followed in descending order by cultures grown on glucose, sucrose, and fructose media. Decreasing the proportion of sorbitol and increasing that of sucrose in the carbon source fraction (30 g/L total) resulted in decreasing shoot number and shoot weight accompanied by increasing leaf/stem ratio and compactness of the shoot cultures. After 32 days on agar medium with 0.5 mg/L indolebutyric acid in the presence of either sorbitol or sucrose, 85% rooting was achieved.
Effects of heat shock on nuclear organization in Plasmodia of Physarum polycephalum
Authors: Cadrin M. , Ashraf M. , Lafontaine J. G.
Published: February 2008

Plasmodial interphase nuclei were subjected to heat shocks and their ultrastructure was studied after 5, 10, and 15 min at 41 °C as well as during recuperation at normal temperature (26 °C). It was observed that the interphase chromatin, nucleoplasm, and nucleolus are already affected after a 5-min exposure of the plasmodia to a supranormal temperature. The nucleolar granular component rapidly transforms into densely packed material and the nucleoplasm takes on a coarser appearance. Spherical bodies approximately 0.15 μm in diameter are also formed. During recovery, after a 15-min heat shock, modifications in nuclear structure are also quite rapid. Most particularly, nucleolar organization is still more affected than during heat shocks and the nucleolus shows numerous irregular lacunae. Part of the intranucleolar chromatin migrates to the nucleolar surface where it forms conspicuous protrusions. By the end of a 3-h recovery period, nuclear morphology has reverted to normal except that the nucleolus still exhibits a slightly loose organization.
A comparative study of Gomontia polyrhiza and Chlorojackia pachyclados gen. et sp. nov. (Chlorophyta)
Authors: Nielsen Ruth , Correa Juan
Published: February 2008

Culture studies of Gomontia polyrhiza from Canada and Denmark verify the presence of this species in the two countries and confirm the life history. Chlorojackia pachyclados gen. et sp. nov. has some features in common with Gomontia, but the presence of a parenchymatous thallus, vegetative cells with lobed chloroplast, different pattern of germination of the unicellular stage, and inability to grow into a calcareous substrate distinguish the new entity from Gomontia. In culture, C. pachyclados has a heteromorphic life history, with production of unicellular and parenchymatous thalli influenced to some extent by temperature.
New records and new taxa of fungi from the mycorrhizae of terrestrial orchids of Alberta
Authors: Currah R. S. , Sigler L. , Hambleton S.
Published: February 2008

Pure cultures of endophytic fungi were obtained from the mycorrhizae of some native Alberta orchids (Amerorchis rotundifolia, Calypso bulbosa, Coeloglossum viride, Corallorhiza maculata, Platanthera dilatata, P. hyperborea, P. obtusata). Isolates of Rhizoctonia constituted the largest group of endophytes, but few could be identified to species. One of these strains was identified as Rhizoctonia repens, a species reported to be a ubiquitous and common mycorrhizal fungus of orchids. Another strain produced the teleomorph stage and was identified as Ceratobasidium obscurum. Rhizoctonia anaticula Currah, sp.nov. is described based on five isolates bearing monilioid cells linked by prominent, narrow connections. A second group of isolates consisted of sterile, greenish black to grey fungi. After prolonged incubation, eight of these isolates formed conidia. Two isolates produced phialoconidia and were identified as Phialocephala fortinii. Five isolates, demonstrating sympodial development of conidia in the apical region of swollen or unswollen hyaline conidiogenous cells, are disposed in Leptodontidium orchidicola Sigler & Currah, sp.nov. The remaining conidial isolate was identified as Trichocladium opacum. Two isolates, resembling Rhizoctonia in cultural features, sporulated and are described as Trichosporiella multisporum Sigler & Currah, sp.nov.
Effects of irradiance, temperature, and water status on growth and photosynthetic capacity in Hyptis suaveolens
Authors: Wulff Renata D.
Published: February 2008

Plants of Hyptis suaveolens Poit. were grown in controlled conditions at two temperature regimes and at three levels of irradiance. Shading reduced total dry weight and specific leaf weight and increased leaf area ratios. While at the higher irradiance, an increase in temperature promoted growth; at lower light levels, plants grew better at the lower temperature regime. Relative growth rates and net assimilation rates calculated over the interval between two harvests showed similar trends. Gas exchange rates at saturating irradiance, measured by infrared gas analysis, were significantly higher for plants grown at the higher light levels. An increase in temperature up to approximately 37 °C increased gas exchange rates, but at high temperatures (42 °C) plants grown at a lower temperature showed a significantly lower photosynthesis rate than those grown at high temperature. Photosynthesis rates decreased soon after withdrawal of water when shoot water potentials were still high. Thus, plants of Hyptis suaveolens show potential for acclimation to shading and to temperature, which may be a factor in their colonizing ability. Their low drought tolerance, however, probably plays a role in restricting growth to the wet season of the year.
Vegetation patterns and environment of some alpine plant communities on Lakeview Mountain, southern British Columbia
Authors: Ratcliffe Marilyn J. , Turkington Roy
Published: February 2008

Selected alpine plant communities of Lakeview Mountain in Cathedral Provincial Park of southern British Columbia were examined, as well as the corresponding abiotic factors of soils and microclimate. Multivariate analysis of percentage cover data revealed three major community types, dominated by Kobresia myosuroides (Vill.) Fiori, by Carex scirpoidea Michx., or by Carex scirpoidea and Carex capitata L. codominating. Abundant small-scale patterns in the form of significant associations between species were detected in all communities. Possible mechanisms generating these positive and negative associations are discussed and it is suggested that the species themselves, as well as abiotic factors, may be strong determinants of vegetation patterning. Species morphology, especially the root systems, may be the more important feature. The relative competitive abilities of these three major dominants may be a critical factor affecting the distribution of communities at the study site.
Utilization of carbon from shoot photosynthesis and nodule CO2 fixation in the fixation and assimilation of nitrogen by alfalfa root nodules
Authors: Ta T. C. , Macdowall F. D. H. , Faris M. A.
Published: February 2008

The products of CO2 and N2 fixation in alfalfa (Medicago sativa L.) were followed after supplying 14CO2 to the shoot system while the root was exposed to 15N2 or after supplying both labels to the root. Photosynthate was transported to the nodules in less than 1 h and was distributed throughout the plant primarily in the neutral (sugars) fraction (over 80%), while the basic (amino acids and amides) and acidic (organic acids) fractions each contained only 5 to 10% of the total radioactivity. At midday the nodules fixed more than twice the amount of carbon that they received as fresh photosynthate. Calculations showed that nodule dark CO2 fixation may contribute about 12% of the total carbon-skeleton requirement for the assimilation of fixed nitrogen. The assimilation of fixed nitrogen appears to use carbon derived from a pool of photosynthate that accumulates in the nodules in the morning. The products of nodule dark CO2 fixation, which amounted to about 2.5% of total plant CO2 fixation, were partitioned to the shoots after 30 min. Most of the radioactivity (70%) from nodule dark CO2 fixation was incorporated into the basic fraction; the rest (30%) was recovered in the acidic fraction and little radioactivity was detected in the neutral fraction. Fixed nitrogen from 15N2 was rapidly assimilated into organic compounds, at about 22 μmol · plant−1 · h−1, especially into Asn (80%), with only a small portion of the nitrogen remaining in the form of NH3. The fixed and assimilated 15N accumulated first in the nodules and then was rapidly transported to the shoots for further metabolism.
Cellular differentiation in Venturia inaequalis ascospores during germination and penetration of apple leaves
Authors: Smereka K. J. , Machardy W. E. , Kausch A. P.
Published: February 2008

The penetration of the apple leaf cuticle by ascospores of Venturia inaequalis was studied by using ultrastructural and cytochemical techniques. A time-course developmental sequence is presented. Attachment of ascospores to the leaf surface appears to be by a mucilaginous substance and is followed by germination and penetration pore formation. The penetration pore is a circular opening adjacent to the leaf. It appears to form by degradation of the fungal wall and is bordered by a thickening of fungal wall material. Above the penetration pore, an infection sac forms from invagination and extension of the fungal plasmalemma. This structure has been reported only in V. inaequalis. Infection sac development initiates when the fungal plasmalemma appears to be forced into a dome shape. The dome flattens out and the membrane folds back upon itself, circumscribing the margin of the pore. The folded membrane becomes apposed, resulting in a circular belt of junctional structures which morphologically resemble molluscan septate junctions. As the infection sac enlarges, additional junctions form wherever the infection sac membrane abuts with the fungal plasmalemma. Selective staining with phosphotungstic acid revealed that the infection sac membrane becomes differentiated from the fungal plasmalemma. The infection sac enlarges and accumulates a dense matrix that appears to penetrate into the cuticle, causing ultrastructural changes in host tissues. The infection hypha, which is an extension of the infection sac membrane, breaches the cuticle without any apparent mechanical pressure.
Relations of hyphae to host cells in smut galls caused by species of Tilletia, Tolyposporium, and Ustilago
Authors: Luttrell E. S.
Published: February 2008

Transmission electron microscopy demonstrated that the mycelium in developing galls induced by smut fungi in the Tilletiaceae (Tilletia caries on Triticum aestivum) and Ustilaginaceae (Ustilago nuda on Hordeum vulgare, U. maydis on Zea mays, and Tolyposporium penicillariae on Pennisetum glaucum) may be both intercellular and intracellular. In T. caries the mycelium is mostly intercellular, in U. nuda it is both intercellular and intracellular, and in U. maydis and T. penicillariae it is mostly intracellular. Unconstricted hyphae penetrate the host cell wall, invaginate the host plasmalemma, and become surrounded by a tubular encasement as they cross the host cell. The encasement fuses with the wall on both sides of the host cell, and points of entry and exit have the same appearance. Hyphae traversing host cells resemble infection threads of nodule bacteria. None of these fungi form haustoria. Prior to sporulation masses of hyphae develop in cavities produced by differential growth of host tissues or by disintegration of host cells. Hyphae in such extracellular masses are designated “lacunal hyphae.”
Vascular system of the floret of Alopecurus carolinianus (Gramineae)
Authors: Pizzolato Thompson Demetrio
Published: February 2008

The interconnecting vascular system of the floret of Alopecurus carolinianus Walter begins as a single, collateral bundle, which enters the rachilla and becomes reorganized into a diarch pattern while ascending between the glumes. During a pronounced posterior enlargement, the rachilla bundle becomes connected with the median and four lateral bundles of the lemma. Above the trace to the lemma median, elements of a xylem discontinuity surrounded by those of a sieve-element plexus form in the rachilla bundle. Higher, a trace consisting of elements of the xylem discontinuity and the plexus enters the anterior and the posterior stamen. Two bundles, the lowest portion of the pistil vasculature, rise eccentrically from the xylem discontinuity and sieve-element plexus at the level of the stamen traces. The bundles condense into one which rotates counterclockwise and connects with the anterior sieve tube of the pistil. The xylem discontinuity of the bundle now in the pistil begins to diminish, and the sieve elements fan out to the sides and posterior of the xylem discontinuity. From the sieve elements one or two posterolaterals emerge toward the styles. The bundle of diffuse sieve elements in a semicircle behind the diminishing xylem discontinuity is now the placental bundle of the pistil. After its xylem discontinuity and then its sieve elements fade out, the placental bundle merges with the ovule at the chalaza.
Studies in Crataegus (Rosaceae, Maloideae). XVI. Taxonomy of C. series Rotundifoliae in Ontario
Authors: Smith P. G. , Phipps J. B.
Published: February 2008

The taxonomy of Crataegus series Rotundifoliae in Ontario was reevaluated on the basis of new morphometric and reproductive behavioral data. Five species, C. chrysocarpa Ashe, C. dodgei Ashe, C. irrasa Sarg., C. lumaria Ashe, and C. margaretta Ashe, and three varieties, C. chrysocarpa Ashe var. aboriginum (Sarg.) Kruschke, C. chrysocarpa Ashe var. phoenicea Palmer, and C. dodgei Ashe var. flavida (Sarg.) Smith & Phipps (comb.nov.), are recognised. These taxa are described and illustrated. Maps are given for taxa whose distribution is substantially modified from previous studies. A key to Ontario series Rotundifoliae is also presented.
Évolution du rapport des sexes de populations de Rumex acetosella le long d'une succession postculturale
Authors: Escarré Josep , Houssard Claudie , Briane Jean Paul
Published: February 2008

The sex ratios of natural populations of Rumex acetosella L. have been recorded during two growing seasons, along a successional gradient of abandoned agricultural fields of various ages (from 6 months to 15 years old), south of Paris. At the same time, male and female ramets have been collected to determine the resource allocation pattern of the different organs. We have observed that females of Rumex acetosella L. were more frequent than males at the younger stages, and that males predominated at the older ones. Concomitantly, there was a decrease in aboveground biomass and in the reproductive effort of the two sexes in the field, with increasing community maturity. The decrease in reproductive effort was confirmed, in controlled conditions, in the female genets only. Females always produced a higher reproductive effort and a higher aboveground biomass than males, which may explain why they were more abundant in the younger successional stages. Otherwise, our results show that sexual reproduction represented a high energetic cost which tended to consume root resources. Females, and mainly those of the younger stages which presented a high reproductive effort, may suffer more than males. The latter, which were more vigorous in vegetative reproduction and less affected by flower production than females, prevailed at older stages.
Comparative morphology and flavolan content of Rhizobium loti induced effective and ineffective root nodules on Lotus species, Leuceana leucocephala, Carmichaelia flagelliformis, Ornithopus sativus, and Clianthus puniceus
Authors: Pankhurst Clive E. , Hopcroft Douglas H. , Jones William T.
Published: February 2008

The morphology of Rhizobium loti induced root nodules and the flavolan content of nodulated roots of several Lotus species, Leuceana leucocephala, Carmichaelia flagelliformis, Ornithopus sativus, and Clianthus puniceus were examined. Rhizobium loti strain NZP2037 formed effective (Nod+Fix+) nodules on all legumes, but strain NZP2213 formed Nod+Fix+ nodules only on Lotus corniculatus var. cree and ineffective (Nod+Fix−) nodules on all other legumes. The Nod+Fix− nodules developed by NZP2213 showed morphologies ranging from the complete absence of bacteria within “tumour-like” structures to the development of nodules containing bacteria that were either not released or only incompletely released from infection threads. Within nodules formed by NZP2213 on Lotus corniculatus var. hirsutus and Carmichaelia flagelliformis the rhizobia had multiplied extensively within unwalled, plasma membrane bound, infection droplets. Flavolans rich in prodelphinidin, which is toxic towards NZP2213, were present in the roots of Lotus angustissimus, Lotus pedunculatus, Lotus subbiflorus, and Leuceana leucocephala, but only trace amounts of flavolan were found in the roots of Carmichaelia flagelliformis, Ornithopus sativus, and Clianthus puniceus.
Ardissonia crystallina (Bacillariophyceae) : une étude en microscopie électronique à balayage des éléments structuraux des valves
Authors: Poulin Michel , Cardinal André , Bérard-Therriault Lyse
Published: February 2008

The authors propose a more substantial description, fully agreeing with the new generic description, of Ardissonia crystallina (C. A. Agardh) Grunow (Fragilariaceae), the only species of this genus observed on the littoral coasts of Quebec. The information results mainly from observations obtained with scanning electron microscopy.
Experimental investigation of fibre-reinforced concrete deck slabs without internal steel reinforcement
Authors: Mufti Aftab A. , Jaeger Leslie G. , Bakht Baidar , Wegner Leon D.
Published: February 2008

It is now well established that concrete deck slabs of slab-on-girder bridges subjected to concentrated loads develop an internal arching system provided that certain conditions of confinement of the concrete are met. Because of this arching system, the deck slab, being predominantly in compression, fails in punching shear rather than in flexure. This aspect of deck slab behaviour, coupled with the corrosion problems associated with steel reinforcement in concrete, has prompted the authors to investigate the feasibility of fibre-reinforced concrete decks that are entirely devoid of steel. Through tests on a small number of half-scale models, it has been established that fibre-reinforced concrete slab with inexpensive non-ferrous fibres is indeed feasible, provided that the top flanges of the steel girders are connected just below the deck by transverse steel straps and the concrete deck is joined to the girders and diaphragms by shear connectors. The straps and shear connectors together provide the restraint necessary for development of the internal arching system in the slab, whilst the fibres control cracking due to the effects of shrinkage and temperature in the concrete. This paper describes the exploratory model tests and presents their results. Key words: deck slab, fibre-reinforced concrete, internal arching, punching shear, slab-on-girder bridge.
Diving behaviour of the sperm whale, Physeter macrocephalus, off the Galapagos Islands
Authors: Papastavrou Vassili , Smith Sean C. , Whitehead Hal
Published: February 2008

Sperm whales, Physeter macrocephalus, were tracked by means of a recording depth sounder in the waters off the Galapagos Islands. At depths of less than 300 m the whales generally dived nearly vertically at 60–100 m/min. At greater depths their descents were usually slower. Between February and April 1985, they dived to about 420 m, which is approximately the depth of the oxygen minimum. In 1987, a year of warmer water temperatures, they usually dived about 70 m shallower. There was no apparent diurnal variation in dive depths. None of the whales tracked dived to the ocean floor. Whales dived for about 40 min, followed by 10 min at the surface. Sperm whales usually started to make regular clicks when 150–300 m deep. Young calves appeared not to make prolonged deep dives. Our results are generally consistent with other direct information on the diving behaviour of relatively undisturbed sperm whales, but often conflict with results obtained using sonar for sperm whales being chased by whale catchers.
Cougar predation on bighorn sheep in southwestern Alberta during winter
Authors: Ross P. Ian , Jalkotzy Martin G. , Festa-Bianchet Marco
Published: February 2008

Predation by cougars (Puma concolor) upon bighorn sheep (Ovis canadensis) was studied in southwestern Alberta during winters from 1985–1986 to 1993–1994. We examined 320 kills and found that ungulates provided >99% of the biomass consumed by cougars in November–April. All ungulate species found within the study area were taken by cougars. Predation on bighorn sheep varied greatly from year to year; cougars were known to kill 0–13% of the November sheep population, and 0–57% of over-winter sheep mortality consisted of known cougar kills. Of 29 bighorns killed by cougars, 13 were lambs. The remainder ranged in age from 1 to 17 years and included 9 ewes and 7 rams. Cougar predation on bighorn sheep appears to be largely an individual, learned behaviour; most cougars rarely killed sheep, but some preyed heavily upon them. One female killed 9% of the population and 26% of the lambs over a single winter. For mountain-dwelling ungulates that occur in small groups, the presence of one or a few individual specialist predators may strongly and unpredictably influence demography and behaviour.
ON THE RELATIONSHIP BETWEEN THE CLASS OF A LIE ALGEBRA AND THE CLASSES OF ITS SUBALGEBRAS
Authors: SUANMALI SUTHATHIP
Published: February 2008

A classical nilpotency result considers finite p-groups whose proper subgroups all have class bounded by a fixed number n. We consider the analogous property in nilpotent Lie algebras. In particular, we investigate whether this condition puts a bound on the class of the Lie algebra. Some p-group results and proofs carry over directly to the Lie algebra case, some carry over with modified proofs and some fail. For the final of these cases, a certain metabelian Lie algebra is constructed to show a case when the p-groups and Lie algebra cases differ.
RATIONAL SUBSETS IN HNN-EXTENSIONS AND AMALGAMATED PRODUCTS
Authors: LOHREY MARKUS , SÉNIZERGUES GÉRAUD
Published: February 2008

Several transfer results for rational subsets and finitely generated subgroups of HNN-extensions G = 〈 H,t; t-1 at = φ(a) (a ∈ A) 〉 and amalgamated free products G = H *A J such that the associated subgroup A is finite. These transfer results allow to transfer decidability properties or structural properties from the subgroup H (resp. the subgroups H and J) to the group G.
IS DARK ENERGY ABNORMALLY WEIGHTING?
Authors: ALIMI JEAN-MICHEL , FÜZFA ANDRÉ
Published: February 2008

We investigate the possibility that dark energy does not couple to gravitation in the same way as ordinary matter, yielding a violation of the weak and strong equivalence principles on cosmological scales. We build a transient mechanism in which gravitation is pushed away from general relativity (GR) by a Born–Infeld (BI) gauge interaction acting as an "abnormally weighting (dark) energy" (AWE). This mechanism accounts for the Hubble diagram of far-away supernovae by cosmic acceleration and time variation of the gravitational constant while accounting naturally for the present tests on GR.
COHERENT ATOM SOURCES FOR ATOM INTERFEROMETRY IN SPACE: THE ICE PROJECT
Authors: BOUYER PHILIPPE
Published: February 2008

Atomic quantum sensors are a major breakthrough in the technology of time and frequency standards as well as ultraprecise sensing and monitoring of accelerations and rotations. They apply a new kind of optics based on matter waves. Today, atomic clocks are the standard for time and frequency measurement at the highest precisions. Inertial and rotational sensors using atom interferometers have already shown similar potential for replacing state-of-the-art sensors in other fields. With Bose–Einstein condensates, also referred as atom lasers, the traditional experiments with atom interferometers can be greatly improved. Testing of fundamental principles, studies of atomic properties, applications as inertial sensors, and measurements of fundamental constants can benefit from the brightness (intensity and small momentum spread) of these coherent sources. In addition, the coherence properties of condensates may allow BEC-based atom interferometers to approach the Heisenberg detection limit. This corresponds to a measurement precision which scales like 1/N for N atoms and not like [Formula: see text] as for independent measurements on N atoms. We present here the recent progress toward the acheivement of new coherent atomic sources, i.e. atom lasers, that will be use in space-based atom interferometers. We introduce new concepts of atom accelerometers and gyrometers that take advantage of the high collimation and coherence properties of atoms lasers and report on the development of a 0-g coherent atom interferometer (ICE) that will be used to test the ultimate performances of atom accelerometers in space.
DARK ENERGY TASK FORCE: FINDINGS AND RECOMMENDATIONS
Authors: CAHN ROBERT N.
Published: February 2008

NASA, NSF, and the Department of Energy established the Dark Energy Task Force to examine the opportunities for exploration of dark energy and to report on the various techniques that might be employed to further our understanding of this remarkable phenomenon. The Task Force examined dozens of white papers outlining the plans of teams to measure dark energy's properties. I present here the findings and recommendations of the Task Force. Our methodology is explained in another talk at this conference.
THE SEARCH FOR DARK MATTER FROM SPACE AND ON THE EARTH
Authors: CLINE DAVID B.
Published: February 2008

We first show that the MOND concept is very unlikely: nonbaryonic dark matter exists. We then discuss dwarf special galaxies that in some cases appear to be nearly pure dark matter systems. The search for dark matter particles can be carried out from space (sterile neutrinos neutralino annihilation) or on the Earth (direct detection). We describe progress in these areas and focus on the progress of the ZEPLIN II detector now taking data.1,2.
GRAVITOELECTROMAGNETISM AND DARK ENERGY IN SUPERCONDUCTORS
Authors: DE MATOS CLOVIS JACINTO
Published: February 2008

A gravitomagnetic analog of the London moment in superconductors could explain the anomalous Cooper pair mass excess reported by Janet Tate. Ultimately the gravitomagnetic London moment is attributed to the breaking of the principle of general covariance in superconductors. This naturally implies nonconservation of classical energy–momentum. A possible relation with the manifestation of dark energy in superconductors is questioned.
THE CLOCK MISSION OPTIS
Authors: DITTUS HANSJÖRG , LÄMMERZAHL CLAUS
Published: February 2008

Clocks are an almost universal tool for exploring the fundamental structure of theories related to relativity. For future clock experiments, it is important for them to be performed in space. One mission which has the capability to perform and improve all relativity tests based on clocks by several orders of magnitude is OPTIS. These tests consist of (i) tests of the isotropy of light propagation (from which information about the matter sector which the optical resonators are made of can also be drawn), (ii) tests of the constancy of the speed of light, (iii) tests of the universality of the gravitational redshift by comparing clocks based on light propagation, like light clocks and various atomic clocks, (iv) time dilation based on the Doppler effect, (v) measuring the absolute gravitational redshift, (vi) measuring the perihelion advance of the satellite's orbit by using very precise tracking techniques, (vii) measuring the Lense–Thirring effect, and (viii) testing Newton's gravitational potential law on the scale of Earth-bound satellites. The corresponding tests are not only important for fundamental physics but also indispensable for practical purposes like navigation, Earth sciences, metrology, etc.
ATOMIC QUANTUM SENSORS IN SPACE
Authors: VAN ZOEST T. , MÜLLER T. , WENDRICH T. , GILOWSKI M. , RASEL E. M. , ERTMER W. , KÖNEMANN T. , LÄMMERZAHL C. , DITTUS H. J. , VOGEL A. , BONGS K. , SENGSTOCK K. , LEWOCZKO W. , PETERS A. , STEINMETZ T. , REICHEL J. , NANDI G. , SCHLEICH W. , WALSER R.
Published: February 2008

In this article we present actual projects concerning high resolution measurements developed for future space missions based on ultracold atoms at the Institut für Quantenoptik (IQ) of the University of Hannover. This work involves the realization of a Bose–Einstein condensate in a microgravitational environment and of an inertial atomic quantum sensor.
NEW FORMS OF QUANTUM MATTER NEAR ABSOLUTE ZERO TEMPERATURE
Authors: KETTERLE WOLFGANG
Published: February 2008

In my talk at the workshop on fundamental physics in space I described the nanokelvin revolution which has taken place in atomic physics. Nanokelvin temperatures have given us access to new physical phenomena including Bose–Einstein condensation, quantum reflection, and fermionic superfluidity in a gas. They also enabled new techniques of preparing and manipulating cold atoms. At low temperatures, only very weak forces are needed to control the motion of atoms. This gave rise to the development of miniaturized setups including atom chips. In Earth-based experiments, gravitational forces are dominant unless they are compensated by optical and magnetic forces.

The following text describes the work which I used to illustrate the nanokelvin revolution in atomic physics. Strongest emphasis is given to superfluidity in fermionic atoms. This is a prime example of how ultracold atoms are used to create well-controlled strongly interacting systems and obtain new insight into many-body physics.
DETECTING STERILE DARK MATTER IN SPACE
Authors: KUSENKO ALEXANDER
Published: February 2008

Space-based instruments provide new and, in some cases, unique opportunities to search for dark matter. In particular, if dark matter comprises sterile neutrinos, the X-ray detection of their decay line is the most promising strategy for discovery. Sterile neutrinos with masses in the keV range could solve several long-standing astrophysical puzzles, from supernova asymmetries and the pulsar kicks to star formation, reionization, and baryogenesis. The best current limits on sterile neutrinos come from Chandra and XMM-Newton. Future advances can be achieved with a high-resolution X-ray spectrometry in space.
SPACETIME: PROBING FOR 21ST CENTURY PHYSICS WITH CLOCKS NEAR THE SUN
Authors: MALEKI LUTE , PRESTAGE JOHN
Published: February 2008

We will describe a space mission study based on three high-precision atomic clocks, flying to within six solar radii of the Sun, for a test of the possible variation of the fine structure constant, α. The three clocks are based on transitions in three different atomic species. Measurement of the drift in ratios between the frequencies generated by each clock will probe for the variation of α. Since the response of each atomic species to a change in α has a specific signature, this measurement will provide sensitive and unambiguous results. The sensitivity of this experiment to a changing α is comparable to the sensitivity of recent tests based on observational astronomy, exceeding the geophysical bounds on α variations. Thus, the experiment will provide a compelling reaffirmation or refutation of astronomical observations, and represents an important test of the models aimed at bridging physics of the quantum to the cosmos.
RUBIDIUM BOSE–EINSTEIN CONDENSATE UNDER MICROGRAVITY
Authors: LEWOCZKO-ADAMCZYK W. , PETERS A. , VAN ZOEST T. , RASEL E. , ERTMER W. , VOGEL A. , WILDFANG S. , JOHANNSEN G. , BONGS K. , SENGSTOCK K. , STEIMNETZ T. , REICHEL J. , KÖNEMANN T. , BRINKMANN W. , LÄMMERZAHL C. , DITTUS H. J. , NANDI G. , SCHLEICH W. P. , WALSER R.
Published: February 2008

Weightlessness promises to substantially extend the science of quantum gases toward presently inaccessible regimes of low temperatures, macroscopic dimensions of coherent matter waves, and enhanced duration of unperturbed evolution. With the long-term goal of studying cold quantum gases on a space platform, we currently focus on the implementation of an 87 Rb Bose–Einstein condensate (BEC) experiment under microgravity conditions at the ZARM drop tower in Bremen (Germany). Special challenges in the construction of the experimental setup are posed by a low volume of the drop capsule (< 1 m3) as well as critical vibrations during capsule release and peak decelerations of up to 50 g during recapture at the bottom of the tower. All mechanical and electronic components have thus been designed with stringent demands on miniaturization, mechanical stability and reliability. Additionally, the system provides extensive remote control capabilities as it is not manually accessible in the tower two hours before and during the drop. We present the robust system and show results from first tests at the drop tower.
ATOMIC CLOCK ENSEMBLE IN SPACE: AN UPDATE
Authors: SALOMON C. , CACCIAPUOTI L. , DIMARCQ N.
Published: February 2008

Atomic Clock Ensemble in Space (ACES) is a mission in fundamental physics that will operate a new generation of atomic clocks in the microgravity environment of the International Space Station. Fractional frequency stability and accuracy of a few parts in 1016 will be achieved. The on-board time base, distributed on the Earth via a microwave link, will be used to perform space-to-ground as well as ground-to-ground comparisons of atomic frequency standards. Based on these comparisons, ACES will perform fundamental physics tests (Einstein's theories of special and general relativity, the search for drift of fundamental constants, the Standard Model extension and tests of string theories) and develop applications in time and frequency metrology, time scales, geodesy, global positioning and navigation. After an overview of the mission concept and its scientific objectives, the present status of ACES instruments and subsystems will be discussed.
TESTING RELATIVITY AT HIGH ENERGIES USING SPACEBORNE DETECTORS
Authors: STECKER F. W.
Published: February 2008

The Gamma-Ray Large Area Space Telescope (GLAST), to be launched in the fall of 2007, will measure the spectra of distant extragalactic sources of high energy γ-rays, particularly active galactic nuclei and γ-ray bursts. GLAST can look for energy-dependent γ-ray propagation effects from such sources as a signal of Lorentz invariance violation (LIV). These sources should also exhibit the high energy cutoffs predicted to be the result of intergalactic annihilation interactions with low energy photons having a flux level as determined by various astronomical observations. Such annihilations result in electron–positron pair production above a threshold energy given by 2me in the center-of-momentum frame of the system, assuming Lorentz invariance. If Lorentz invariance is violated, this threshold can be significantly raised, changing the predicted absorption turnover in the observed spectrum of the sources. Stecker and Glashow have shown that the existence of such absorption features in the spectra of extragalactic sources puts constraints on LIV. Such constraints have important implications for some quantum gravity and large extra dimension models. Future spaceborne detectors dedicated to measuring γ-ray polarization can look for birefringence effects as a possible signal of loop quantum gravity.

As shown by Coleman and Glashow, a much smaller amount of LIV has potential implications for possibly suppressing the "GZK cutoff" predicted to be caused by the interactions of cosmic rays having multijoule energies with photons of the 2.7 K cosmic background radiation in intergalactic space. Owing to the rarity of such ultrahigh energy cosmic rays, their spectra are best studied by a UV-sensitive satellite detector which looks down on a large volume of the Earth's atmosphere to study the nitrogen fluorescence tracks of giant air showers produced by these ultrahigh energy cosmic rays. We discuss here, in particular, a two-satellite mission called OWL, which would be suited for making such studies.
NEW PHYSICS WITH 1020 eV NEUTRINOS AND ADVANTAGES OF SPACE-BASED OBSERVATION
Authors: WEILER THOMAS J.
Published: February 2008

Nature accelerates cosmic particles to energies as high as 1020 eV. The rates for neutrino-initiated quasi-horizontal air showers (HASs) and upgoing air showers (UASs) have different dependences on σν N. Therefore, a measurement of HAS and UAS rates would allow an inference of σν N at energies far beyond what is conceivable with terrestrial accelerators. At a minimum, such a measurement provides a microscope/telescope for QCD evolution. More ambitiously, such a measurement may reveal energy thresholds of completely new physics. The feasibility of this measurement is examined. Favorable conclusions result, especially for proposed space-based observatories. The latter benefit from a larger field of view and from a UAS rate enhanced by [Formula: see text] over oceans compared to over land.
A MULTIVARIATE VARIANCE GAMMA MODEL FOR FINANCIAL APPLICATIONS
Authors: SEMERARO PATRIZIA
Published: February 2008

In this paper we subordinate a multivariate Brownian motion with independent components by a multivariate gamma subordinator. The resulting process is a generalization of the bivariate variance gamma process proposed by Madan and Seneta [7], mentioned in Cont and Tankov [4] and calibrated in Luciano and Schoutens [5] as a price process. Our main contribution here is to introduce a multivariate subordinator with gamma margins. We investigate the process, determine its Lévy triplet and analyze its dependence structure. At the end we propose an exponential Lévy price model.
Uncoupling protein-2 modulates the lipid metabolic response to fasting in mice
Authors: Sheets Anthony R. , Fülöp Péter , Derdák Zoltán , Kassai Andrea , Sabo Edmond , Mark Nicholas M. , Paragh György , Wands Jack R. , Baffy György
Published: February 2008

Uncoupling protein-2 (UCP2) regulates insulin secretion by controlling ATP levels in β-cells. Although UCP2 deficiency improves glycemic control in mice, increased expression of UCP2 interferes with glucose-stimulated insulin secretion. These observations link UCP2 to β-cell dysfunction in type 2 diabetes with a perplexing evolutionary role. We found higher residual serum insulin levels and blunted lipid metabolic responses in fasted ucp2−/−mice, supporting the concept that UCP2 evolved to suppress insulin effects and to accommodate the fuel switch to fatty acids during starvation. In the absence of UCP2, fasting initially promotes peripheral lipolysis and hepatic fat accumulation at less than expected rates but culminates in protracted steatosis, indicating diminished hepatic utilization and clearance of fatty acids. We conclude that UCP2-mediated control of insulin secretion is a physiologically relevant mechanism of the metabolic response to fasting.
Activation of the intracellular renin-angiotensin system in cardiac fibroblasts by high glucose: role in extracellular matrix production
Authors: Singh Vivek P. , Baker Kenneth M. , Kumar Rajesh
Published: February 2008

The occurrence of a functional intracellular renin-angiotensin system (RAS) has emerged as a new paradigm. Recently, we and others demonstrated intracellular synthesis of ANG II in cardiac myocytes and vascular smooth muscle cells that was dramatically stimulated in high glucose conditions. Cardiac fibroblasts significantly contribute to diabetes-induced diastolic dysfunction. The objective of the present study was to determine the existence of the intracellular RAS in cardiac fibroblasts and its role in extracellular matrix deposition. Neonatal rat ventricular fibroblasts were serum starved and exposed to isoproterenol or high glucose in the absence or presence of candesartan, which was used to prevent receptor-mediated uptake of ANG II. Under these conditions, an increase in ANG II levels in the cell lysate represented intracellular synthesis. Both isoproterenol and high glucose significantly increased intracellular ANG II levels. Confocal microscopy revealed perinuclear and nuclear distribution of intracellular ANG II. Consistent with intracellular synthesis, Western analysis showed increased intracellular levels of renin following stimulation with isoproterenol and high glucose. ANG II synthesis was catalyzed by renin and angiotensin-converting enzyme (ACE), but not chymase, as determined using specific inhibitors. High glucose resulted in increased transforming growth factor-β and collagen-1 synthesis by cardiac fibroblasts that was partially inhibited by candesartan but completely prevented by renin and ACE inhibitors. In conclusion, cardiac fibroblasts contain a functional intracellular RAS that participates in extracellular matrix formation in high glucose conditions, an observation that may be helpful in developing an appropriate therapeutic strategy in diabetic conditions.
Intrapulmonary shunting and pulmonary gas exchange during normoxic and hypoxic exercise in healthy humans
Authors: Lovering Andrew T. , Romer Lee M. , Haverkamp Hans C. , Pegelow David F. , Hokanson John S. , Eldridge Marlowe W.
Published: February 2008

Exercise-induced intrapulmonary arteriovenous shunting, as detected by saline contrast echocardiography, has been demonstrated in healthy humans. We have previously suggested that increases in both pulmonary pressures and blood flow associated with exercise are responsible for opening these intrapulmonary arteriovenous pathways. In the present study, we hypothesized that, although cardiac output and pulmonary pressures would be higher in hypoxia, the potent pulmonary vasoconstrictor effect of hypoxia would actually attenuate exercise-induced intrapulmonary shunting. Using saline contrast echocardiography, we examined nine healthy men during incremental (65 W + 30 W/2 min) cycle exercise to exhaustion in normoxia and hypoxia (fraction of inspired O2 = 0.12). Contrast injections were made into a peripheral vein at rest and during exercise and recovery (3–5 min postexercise) with pulmonary gas exchange measured simultaneously. At rest, no subject demonstrated intrapulmonary shunting in normoxia [arterial Po2 (PaO2) = 98 ± 10 Torr], whereas in hypoxia (PaO2 = 47 ± 5 Torr), intrapulmonary shunting developed in 3/9 subjects. During exercise, ∼90% (8/9) of the subjects shunted during normoxia, whereas all subjects shunted during hypoxia. Four of the nine subjects shunted at a lower workload in hypoxia. Furthermore, all subjects continued to shunt at 3 min, and five subjects shunted at 5 min postexercise in hypoxia. Hypoxia has acute effects by inducing intrapulmonary arteriovenous shunt pathways at rest and during exercise and has long-term effects by maintaining patency of these vessels during recovery. Whether oxygen tension specifically regulates these novel pathways or opens them indirectly via effects on the conventional pulmonary vasculature remains unclear.
Laser in situ Keratomileusis following the Implantation of Iris-Fixated Phakic Intraocular Lenses
Authors: Meltendorf Christian , Cichocki Magdalena , Kohnen Thomas
Published: February 2008

Purpose: This study aims to assess the safety, efficacy, predictability, stability and complications associated with laser in situ keratomileusis (LASIK) for the correction of residual refractive errors following implantation of iris-fixated phakic intraocular lenses (pIOLs). Methods: In this retrospective interventional case series of 92 eyes, an iris-fixated pIOL (Artisan®) was implanted to correct myopia and myopic astigmatism. In 10 eyes, a residual refractive error was treated using LASIK. Visual acuity testing, subjective refraction, slitlamp examination and tonometry were all performed preoperatively, then 3 months following pIOL implantation and 1 year after LASIK treatment. The endothelial cell density was measured both prior to pIOL implantation and following LASIK therapy. Results: Comparison of preoperative and postoperative best-corrected visual acuity revealed that none of the combined operated eyes forfeited ≧2 lines of visual acuity after LASIK. Uncorrected visual acuity for all 10 eyes after LASIK was ≧0.8. LASIK made a 61.5% mean reduction in astigmatism possible. Compared to the initial examination, the mean endothelial cell loss after LASIK treatment was 4.1%. Conclusions: For correction of residual refractive errors following iris-fixated phakic IOL implantation, LASIK appears to be a safe and effective procedure. Larger numbers of patients are required to verify this conclusion.
Deep Sclerectomy versus Trabeculectomy with Low-Dosage Mitomycin C: Four-Year Follow-Up
Authors: Cillino Salvatore , Di Pace Francesco , Casuccio Alessandra , Cillino Giovanni , Lodato Gaetano
Published: February 2008

Aims: To compare the long-term effects of low-dosage mitomycin C (MMC) in both deep sclerectomy (DSMMC) and trabeculectomy (TPMMC) on intraocular pressure (IOP). Methods: Analysis of extended follow-up of data from a prospective clinical trial. Forty patients were originally randomised to undergo either DSMMC (19 eyes) or TPMMC (21 eyes). Follow-up was performed at postoperative day 1, weeks 1, 2 and 3, as well as months 1, 3, 6, 9, 12, 18, 24, 36 and 48. Two- to three-week data were not included in the statistical analysis. Postoperative complications, number of antiglaucoma medications and IOP were recorded at each visit. Complete (no medications) and qualified (with or without medications) successes were assessed at 2 target IOPs (≤21 and ≤17 mm Hg) and evaluated by Kaplan-Meier curves. Results: At 48 months, the mean IOP (± SD) was 17.6 ± 3.4 and 17.8 ± 3.6 mm Hg in the DSMMC and TPMMC eyes, respectively, a significant reduction from preoperative IOP in each group (p < 0.0005). Complete success was achieved at the ≤21 mm Hg target IOP in 10 (52.6%) and 14 (66.6%) eyes and qualified success in 15 (78.9%) and 18 (85.7%) eyes in the DSMMC and TPMMC groups, respectively. There were no differences in the Kaplan-Meier curves. Hypotony and shallow anterior chamber were significantly more frequent in the TPMMC group. Conclusions: Either procedure controlled IOP efficaciously at our endpoint. Low-dosage MMC can be considered a mild enhancement of deep sclerectomy IOP-lowering effect.