bluuebunny/crossref_metadata_2025 huggingface dataset:
High Altitude Laboratories
Authors: Korff Serge A.
Published: January 2009

In a recent article on “High Altitude Laboratories” in Physics Today, November, 1950, page 17, the need for additional laboratory facilities in the equatorial zone was stressed. No sooner had the issue of Physics Today reached some members of the medical fraternity than the author began to receive letters pointing out an omission from the account of existing stations. Indeed four of these letters arrived one day in the same mail. Evidently such distinguished individuals as Dr. Warren Weaver are also keenly interested in this problem.
The stockpiling and rationing of scientific manpower
Authors: Smyth Henry D.
Published: January 2009

On December 16 the President declared a state of national emergency. Such a declaration, and the facts behind it, naturally influence all our present thoughts and plans. Some of us are filled with emotion and can think only in terms of immediate action. This is not good enough. Regardless of the outcome of the situation in Korea, this country now faces the necessity of planning not only for the coming months but for the coming decade and the decade after that. We may not have to fight a full-scale war. We profoundly hope that we shall not. But we know now that we must prepare to resist aggression with all our strength for the foreseeable future. We shall have to increase greatly the armed forces of this country, using our material resources and our manpower in the wisest possible way. In every aspect of civilian life the first concern of each citizen must be the long-range value to the country of what he is doing. In the period ahead of us, no citizen can be deferred from national service in this sense.
Scientific liaison offices
Authors: Gray Dwight E.
Published: January 2009

At the present time some eight foreign nations maintain official scientific liaison offices in this country. Six of these—representing Australia, Canada, the Netherlands, New Zealand, South Africa and the United Kingdom—are located in Washington; the other two—for Denmark and Sweden—are in New York although the representatives do much of their work in Washington. Now there are fashions in words just as there are in automobile styles and women's hats, and the word “liaison” is one which reached the full flower of fashionableness during World War II. As a result it has been tossed about with considerable abandon ever since. It has been my impression that its use almost always raises two questions in people's minds; one is “How do you spell it?” and the other is “Just what does it mean?”. The purpose of this account is to answer the second query with regard to the liaison application mentioned above.
Pocono Conference
Authors: Smoluchowski R.
Published: January 2009

On lattice imperfections
Experimental infrared spectroscopy
Authors: Strong John
Published: January 2009

The infrared spectrum was discovered by Herschel in 1800. He found that a thermometer was heated by invisible radiations when he placed it beyond the red end of a solar spectrum formed by a glass prism. From this primitive discrimination between the visible and invisible, experimental physicists have refined their procedures until now the 15,000 cm−1 compass of that invisible spectrum is resolved into some 30,000 separable subdivisions of 1/2 cm−1 width, with prospects of resolving it into 200,000 subdivisions in the near future.
The undergraduate and the American Institute of Physics
Authors: Osgood Thomas H.
Published: January 2009

The American Institute of Physics, now in its twentieth year, has from its inception been concerned with the general welfare of physicists. It has specifically assumed the responsibilities of encouraging, of coordinating, of stimulating, conserving, and developing their activities; of safeguarding their professional status; and of informing the policy-making groups of government, industry, and education of the contribution that physics and physicists can make to the well-being of the nation, both in times of armed neutrality and of war. Some parts of this program have been accomplished by the concerted efforts of small groups of members acting on temporary or continuing committees, others by the broad program of publication that the Institute has sponsored. The present uneasy international situation, recurring military necessities, the increasing technological bias of civilization in those parts of the world that possess high standards of living, and the manifold potential uses of nuclear energy have combined to place upon physicists a present value which, even if somewhat exaggerated in the popular mind, nevertheless compensates in part for the comparative obscurity in which they languished during the first forty years of the century. Another consequence of these same factors is that the traditional concept of the solitary research physicist has been swept away entirely. In his place there is now a team of which each member, from the most brilliant to the most humble, plays his appointed part. It is, therefore, not only a natural activity but a bounden duty of the Institute to concern itself with the problem of maintaining the necessary flow of physicists at all levels of competence and of adjusting the flow to the probable future demand.
Polarization in Washington
Authors: Ballard Stanley S.
Published: January 2009

Optical Society meeting reported
The quality of education in physics
Authors: Harnwell G. P.
Published: January 2009

The last five years have been boom years for research and have seen a bull market for physicists. Research in physics and its fruits are referred to daily in the press. Under the forced draft of military support, research budgets are many times their pre-war values and they are still mounting. This stimulus has been as wisely applied as the best of judgment could devise, and the debt of physics to the Office of Naval Research, the Atomic Energy Commission, and other government support is appreciatively acknowledged in nearly every scientific paper to appear. The increase in the number of these research contributions is almost equally impressive; in 1945 the Physical Review printed about 6000 pages and in 1950 nearly 13,000.
Engineering and pure science
Authors: Swann W. F. G.
Published: January 2009

I have often wondered why the cathedrals of mediaeval times didn't fall down. If I enter one of these edifices I feel disturbed by a number of conflicting emotions. I say to myself: “Now, Swann, you are not an architect, and you do not know anything about building churches. However, you do know a little bit about the theory of elasticity and how to calculate the stresses in various structures; you know a little bit about the things which are fundamental in providing that the cathedral shall not fall down, and yet, the fellow who designed that dome did not have any knowledge at all of these matters.” I start with the feeling that I ought to be able to design a much better dome than he has, and yet, if somebody sentenced me to this task, and even if I should, in my own humble way, muddle through the calculation necessary in my opinion to insure safety, I should never have the courage to erect the dome until I had talked with some practical engineer and asked him whether he thought that my dome really would stand up in practice, or tumble down, to my great disappointment and humiliation.
New light on the origin of cosmic rays
Authors: Beiser Arthur
Published: January 2009

The problem of the origin of the cosmic radiation has provoked much controversy in recent years. The proponents of a literally cosmic origin (see, for example, the article by Serge A. Korff in Physics Today, January, 1950) survey the properties of this radiation and what is known of the universe and conclude that the cosmic rays must be either the product of some interstellar mechanism or energetic particles “left over” from the creation of the universe itself. Those who favor the hypothesis of the origination of cosmic rays within the solar system (Edward Teller, Physics Today, August, 1949), on the basis of much the same empirical information, arrive at a considerably different result. As is frequently the case when two apparently opposing points of view, both expounded with equally convincing logic, are held on a problem, the actual solution as it appears today seems to combine important features of both.
Physics at Carnegie Tech
Authors: Smoluchowski Louise R.
Published: January 2009

“It is a terrible institution, this American cocktail party,” Professor Richard Becker said recently. “Everyone crowds into a hot, smoky room where it is impossible to listen to each other speak. There are never enough chairs. In Europe there is a chair for every guest. And here no one leaves at the end of the party. A party should have an ending.” Professor Becker does not pretend that he enjoys cocktail parties. He will, however, comment more kindly upon the lunches at the Faculty Club at the Carnegie Institute of Technology where he is completing a one year's visiting professorship on leave of absence from Göttingen University. Here you can find him during the noon hour (or hours) with his colleagues from the physics department and there is a chair for everyone and the conversation is definitely listened to.
Photo Processing
Authors: Marcus Bernard
Published: January 2009

First Research and Development Conference
Operations research with special reference to nonmilitary research
Authors: Research Committee on Operations
Published: January 2009

Operations research (or, as the British say, Operational Research) is the name of an applied science, extensively developed during World War II in the British and American armed forces. Its subject matter is “operations”, in the usual military or management sense of the word.
Basic research in the Office of Naval Research
Authors: Gray Dwight E.
Published: January 2009

On November 12, 1950 the Washington Post carried a laudatory editorial on the recently established National Science Foundation in which the writer viewed with high anticipation its possibilities for the advancement of fundamental scientific research in the United States and implied that this was an area which necessarily had been largely neglected by the military services. The editorial stated, “the accent in military programs is always on applied science whereas so-called pure or basic research is the fuel of all later applications.” A week or two later Rear Admiral T. A. Solberg, then Chief of Naval Research, answered this editorial in a letter in which he expressed complete agreement with the words of commendation on the establishment of the Foundation, but took strong exception to the implication that no one in the Department of Defense had been concerned with basic research. He pointed out, “The Office of Naval Research (ONR) has been designated by Congress and the Navy to conduct pure and basic research in broad fields in physical and medical science of Navy interest,” and added that as of that moment ONR was administering more than 1,200 contract-research programs in over 200 university and industrial laboratories, about 90 percent of which were in basic research “with no ‘applied’ strings attached.”
Canadian Physicists Meet
Authors: Rowles W.
Published: January 2009

Sixth Annual Congress held in Montreal
The role of scientific institutes in American education
Authors: Lawson A. W.
Published: January 2009

Until recent years, the traditional pattern of American graduate schools has been frozen along divisional and departmental lines. Natural cleavages have developed from this pattern which are far more serious than good-natured interprofessional rivalry. The old saw that the chemical Tweedle-Dees make very inaccurate measurements on very pure substances while their physical twins are merely mirror images, although amusing, nevertheless contains some very arresting truth. The fact of the matter is that the departmental scheme is not in itself adequate to cope with the myriad problems of modern organized research. In these days of increasing cost and complexity, the continued leadership of our universities in fundamental research requires a reconsideration of policy by our graduate schools.
Photodissociation of the propargyl and propynyl (C3D3) radicals at 248 and 193 nm
Authors: Crider Paul E. , Castiglioni Luca , Kautzman Kathryn E. , Neumark Daniel M.
Published: January 2009

The photodissociation of perdeuterated propargyl (D2CCCD) and propynyl (D3CCC) radicals was investigated using fast beam photofragment translational spectroscopy. Radicals were produced from their respective anions by photodetachment at 540 and 450 nm (below and above the electron affinity of propynyl). The radicals were then photodissociated at 248 or 193 nm. The recoiling photofragments were detected in coincidence with a time- and position-sensitive detector. Three channels were observed: D2 loss, CD+C2D2, and CD3+C2. Observation of the D loss channel was incompatible with this experiment and was not attempted. Our translational energy distributions for D2 loss peaked at nonzero translational energy, consistent with ground state dissociation over small (<1 eV) exit barriers with respect to separated products. Translational energy distributions for the two heavy channels peaked near zero kinetic energy, indicating dissociation on the ground state in the absence of exit barriers.
A simple ideal magnetohydrodynamical model of vertical disruption events in tokamaks
Authors: Fitzpatrick R.
Published: January 2009

A simple model of axisymmetric vertical disruption events (VDEs) in tokamaks is presented in which the halo current force exerted on the vacuum vessel is calculated directly from linear, marginally stable, ideal-magnetohydrodynamical (MHD) stability analysis. The basic premise of the model is that the halo current force modifies pressure balance at the edge of the plasma, and therefore also modifies ideal-MHD plasma stability. In order to prevent the ideal vertical instability, responsible for the VDE, from growing on the very short Alfvén time scale, the halo current force must adjust itself such that the instability is rendered marginally stable. The model predicts halo currents which are similar in magnitude to those observed experimentally. An approximate nonaxisymmetric version of the model is developed in order to calculate the toroidal peaking factor for the halo current force.
Step well quantum cascade laser emitting at 3 THz
Authors: Scalari Giacomo , Amanti Maria I. , Fischer Milan , Terazzi Romain , Walther Christoph , Beck Mattias , Faist Jérôme
Published: January 2009

A quantum cascade laser based on a three well active module and emitting at 3 THz is demonstrated. The optical transition is vertical in real space and localized in an Al0.03Ga0.97As quantum well. Maximum operating temperature of 123 K in pulsed mode is reported, with threshold current densities as low as 110 A/cm2 at 10 K and 175 A/cm2 at 100 K. High slope efficiency values testify the good internal quantum efficiency of the structure.
Silicon nanocrystal luminescence coupled to whispering gallery modes in optical fibers
Authors: Bianucci P. , Rodríguez J. R. , Clements C. M. , Veinot J. G. C. , Meldrum A.
Published: January 2009

Oxide-embedded silicon nanocrystals (Si-NCs) are a promising material for microphotonics, particularly when coupled to high quality factor (Q-factor) optical cavity modes. By glazing smooth nanocrystalline films from a solution-based precursor onto the surface of optical fibers, the Si-NC luminescence can be strongly coupled into the optical modes of the fiber. Well-developed whispering gallery modes occur in the luminescence of the Si-NCs measured perpendicular to the fiber axis, showing detection-limited Q-factors in the emission spectrum. In addition to providing high Q-factor fluorescence without the need for lithographic procedures, the physical versatility of a nanocrystal-coated fiber suggests possible refractometric applications.
Magnetization reversal and interlayer coupling in Co50Fe50 nanomagnets
Authors: Murthy V. Satya Narayana , Krishnamoorthi C. , Mahendiran R. , Adeyeye A. O.
Published: January 2009

We investigated magnetization reversal mechanism in elliptical shaped nanomagnets made from single layer and pseudospin valve Co50Fe50 films. The structures were fabricated using deep ultraviolet lithography and the lift-off process. We observed that the magnetization reversal process of the single layer elements is strongly dependent on the film thickness. For thickness tCoFe=10 nm, the magnetization reversal process is dominated by a systematic coherent rotation, whereas for tCoFe=60 nm, the reversal process is mediated by vortex nucleation, displacement, and annihilation. By exploiting the thickness dependence of the magnetization reversal process, pseudospin valve nanomagnets from two Co50Fe50 thicknesses (10 and 60 nm) were fabricated. We also investigated the effect of interlayer exchange coupling in pseudospin valve structures by varying the Cu spacer layer (tCu). For tCu≤5 nm, the two ferromagnetic layers are found to be strongly coupled by exchange interaction. The strength of the coupling is significantly dependent on temperature. For tCu≥20 nm, the two Co50Fe50 layers are antiferromagnetically coupled at 300 K. As the temperature is reduced below 50 K, we observed a clear transition from antiferromagnetic to ferromagnetic coupling.
Structural and ferroelectric properties of spray deposited sodium nitrite:poly(vinyl alcohol) composite films
Authors: Sekhar K. C. , Nautiyal Arvind , Nath R.
Published: January 2009

The composite films of sodium nitrite (NaNO2) and poly(vinyl alcohol) (PVA) have been deposited by spray technique at different substrate temperatures. The x-ray diffraction study revealed structural distortion (b/a ratio) in the composite films. The field-emission scanning electron microscopy images suggest that PVA polymer facilitate the homogeneous distribution of spherical grains of NaNO2 with less porosity. The grain size is found to increase with the deposition temperature. The study of hysteresis loop characteristics gave optimum Pr at deposition temperature of 200 °C, which may be due to large structural distortion and less porosity. The back switching calculations and the switching characteristics indicate that 180° domains contribute more in the composite than the pure NaNO2 film. The 1/ϵ0(dP/dE)-E curves exhibit two coercive fields correspond to 180° and 90° domains. The composite film also showed improved fatigue characteristics.
Optically induced spin-polarized transport in a two-level quantum dot
Authors: Ke Sha-Sha , Lü Hai-Feng , Li Gao-Xiang
Published: January 2009

We analyze theoretically the pumped spin current and its shot noise spectra in a two-level quantum dot system, where the dot is irradiated by circularly polarized light. The device operates at a certain chemical potential configuration in the absence of magnetic field and ferromagnetic spin injection. The spin-resolved shot noise can be modulated by the light nonmonotonously and always indicates a sub-Poissonian type.
Formation and impact of hot spots on the performance of organic photovoltaic cells
Authors: Steim Roland , Choulis Stelios A. , Schilinsky Pavel , Lemmer Uli , Brabec Christoph J.
Published: January 2009

The failure mechanisms of organic solar cells under reverse bias conditions were investigated. Localized inhomogenities, so-called “hot spots,” leading to increased leakage currents under reverse bias, were identified as the dominant origin for failure. The intensity of hot spots does increase with the duration under reverse bias voltage. Cells with a higher leakage current density (i.e., >100 μA/cm−2 at −1 V) have a significant higher probability for dominant failure, while devices with low leakage current densities show less degradation under reverse bias stressing.
Direct observation of single dopant atom in light-emitting phosphor of β-SiAlON:Eu2+
Authors: Kimoto Koji , Xie Rong-Jun , Matsui Yoshio , Ishizuka Kazuo , Hirosaki Naoto
Published: January 2009

Rare-earth doped nitride attracts considerable attention because of its application as a light-emitting phosphor. The atomic site of dopants in a crystal is important for the development of advanced materials. Here, we directly observe a single Eu dopant atom in phosphor β-SiAlON using scanning transmission electron microscopy (STEM). A STEM annular dark-field image reveals that a Eu dopant exists in a continuous atomic channel in a β-Si3N4 structure. The image contrast of the single Eu dopant is confirmed based on the comparison of experimental and simulation results.
Osmotic stress induced by sodium chloride, sucrose or trehalose improves cryotolerance and developmental competence of porcine oocytes
Authors: Lin Lin , Kragh Peter M. , Purup Stig , Kuwayama Masashige , Du Yutao , Zhang Xiuqing , Yang Huanming , Bolund Lars , Callesen Henrik , Vajta Gábor
Published: January 2009

Exposure of porcine oocytes to increased concentrations of NaCl prior to manipulation has been reported not only to increase cryotolerance after vitrification, but also to improve developmental competence after somatic cell nuclear transfer (SCNT). In the present study we compared the effects of NaCl with those of concentrated solutions of two non-permeable osmotic agents, namely sucrose and trehalose, on the cryotolerance and developmental competence of porcine oocytes. In Experiment 1, porcine in vitro-matured cumulus–oocyte complexes (COCs; n = 1200) were exposed to 588 mOsmol NaCl, sucrose or trehalose solutions for 1 h, allowed to recover for a further 1 h, vitrified, warmed and subjected to parthenogenetic activation. Both Day 2 (where Day 0 is the day of activation) cleavage and Day 7 blastocyst rates were significantly increased after NaCl, sucrose and trehalose osmotic treatments compared with untreated controls (cleavage: 46 ± 5%, 44 ± 7%, 45 ± 4% and 26 ± 6%, respectively; expanded blastocyst rate: 6 ± 1%, 6 ± 2%, 7 ± 2% and 1 ± 1%, respectively). In Experiment 2, COCs (n = 2000) were treated with 588 mOsmol NaCl, sucrose or trehalose, then used as recipients for SCNT (Day 0). Cleavage rates on Day 1 did not differ between the NaCl-, sucrose-, trehalose-treated and the untreated control groups (92 ± 3%, 95 ± 3%, 92 ± 2% and 94 ± 2%, respectively), but blastocyst rates on Day 6 were higher in all treated groups compared with control (64 ± 2%, 69 ± 5%, 65 ± 3% and 47 ± 4%, respectively). Cell numbers of Day 6 blastocysts were higher in the control and NaCl-treated groups compared with the sucrose- and trehalose-treated groups. In conclusion, treatment of porcine oocytes with osmotic stress improved developmental competence after vitrification combined with parthenogenetic activation, as well as after SCNT.
The Indian Ocean Dipole and malaria risk in the highlands of western Kenya
Authors: Hashizume Masahiro , Terao Toru , Minakawa Noboru
Published: January 2009

Epidemics of malaria in the East African highlands in the last 2 decades have often been associated with climate variability, particularly the El Niño-Southern Oscillation (ENSO). However, there are other factors associated with malaria risk and there is increased interest in the influences of the Indian Ocean Dipole (IOD), a climate mode of coupled ocean–atmosphere variability, on East African rainfall. This study explores the relationship between IOD and the number of malaria patients in 7 hospitals from 2 districts in the western Kenyan highlands, controlling for the effects of ENSO. We examined temporal patterns (1982–2001) in the number of malaria cases in relation to the dipole mode index (DMI), defined as the difference in sea surface temperature anomaly between the western (10°S-10°N, 50°-70°E) and eastern (10°S-0°, 90°-110°E) tropical Indian Ocean. We used Poisson regression models, adjusted for ENSO index Niño 3 region (NINO3), seasonal and interannual variations. The number of malaria patients per month increased by 3.4%–17.9% for each 0.1 increase above a DMI threshold (3–4 months lag). Malaria cases increased by 1.4%–10.7% per month, for each 10 mm increase in monthly rainfall (2–3 months lag). In 6 of 7 places, there was no evidence of an association between NINO3 and the number of malaria cases after adjusting for the effect of DMI. This study suggests that the number of malaria cases in the western Kenyan highlands increases with high DMI in the months preceding hospital visits.
Demographic models and IPCC climate projections predict the decline of an emperor penguin population
Authors: Jenouvrier Stéphanie , Caswell Hal , Barbraud Christophe , Holland Marika , Strœve Julienne , Weimerskirch Henri
Published: January 2009

Studies have reported important effects of recent climate change on Antarctic species, but there has been to our knowledge no attempt to explicitly link those results to forecasted population responses to climate change. Antarctic sea ice extent (SIE) is projected to shrink as concentrations of atmospheric greenhouse gases (GHGs) increase, and emperor penguins (
Aptenodytes forsteri
) are extremely sensitive to these changes because they use sea ice as a breeding, foraging and molting habitat. We project emperor penguin population responses to future sea ice changes, using a stochastic population model that combines a unique long-term demographic dataset (1962–2005) from a colony in Terre Adélie, Antarctica and projections of SIE from General Circulation Models (GCM) of Earth's climate included in the most recent Intergovernmental Panel on Climate Change (IPCC) assessment report. We show that the increased frequency of warm events associated with projected decreases in SIE will reduce the population viability. The probability of quasi-extinction (a decline of 95% or more) is at least 36% by 2100. The median population size is projected to decline from ≈6,000 to ≈400 breeding pairs over this period. To avoid extinction, emperor penguins will have to adapt, migrate or change the timing of their growth stages. However, given the future projected increases in GHGs and its effect on Antarctic climate, evolution or migration seem unlikely for such long lived species at the remote southern end of the Earth.
Microarray analysis sheds light on the dedifferentiating role of agouti signal protein in murine melanocytes via the Mc1r
Authors: Le Pape Elodie , Passeron Thierry , Giubellino Alessio , Valencia Julio C. , Wolber Rainer , Hearing Vincent J.
Published: January 2009

The melanocortin-1 receptor (MC1R) is a key regulator of pigmentation in mammals and is tightly linked to an increased risk of skin cancers, including melanoma, in humans. Physiologically activated by α-melanocyte stimulating hormone (αMSH), MC1R function can be antagonized by a secreted factor, agouti signal protein (ASP), which is responsible for the lighter phenotypes in mammals (including humans), and is also associated with increased risk of skin cancer. It is therefore of great interest to characterize the molecular effects elicited by those MC1R ligands. In this study, we determined the gene expression profiles of murine melan-a melanocytes treated with ASP or αMSH over a 4-day time course using genome-wide oligonucleotide microarrays. As expected, there were significant reductions in expression of numerous melanogenic proteins elicited by ASP, which correlates with its inhibition of pigmentation. ASP also unexpectedly modulated the expression of genes involved in various other cellular pathways, including glutathione synthesis and redox metabolism. Many genes up-regulated by ASP are involved in morphogenesis (especially in nervous system development), cell adhesion, and extracellular matrix-receptor interactions. Concomitantly, ASP enhanced the migratory potential and the invasiveness of melanocytic cells in vitro. These results demonstrate the role of ASP in the dedifferentiation of melanocytes, identify pigment-related genes targeted by ASP and by αMSH, and provide insights into the pleiotropic molecular effects of MC1R signaling that may function during development and may affect skin cancer risk.
VEGF-mediated disruption of endothelial CLN-5 promotes blood-brain barrier breakdown
Authors: Argaw Azeb Tadesse , Gurfein Blake T. , Zhang Yueting , Zameer Andleeb , John Gareth R.
Published: January 2009

Breakdown of the blood-brain barrier (BBB) is an early and significant event in CNS inflammation. Astrocyte-derived VEGF-A has been implicated in this response, but the underlying mechanisms remain unresolved. Here, we identify the endothelial transmembrane tight junction proteins claudin-5 (CLN-5) and occludin (OCLN) as targets of VEGF-A action. Down-regulation of CLN-5 and OCLN accompanied up-regulation of VEGF-A and correlated with BBB breakdown in experimental autoimmune encephalomyelitis, an animal model of CNS inflammatory disease. In cultures of brain microvascular endothelial cells, VEGF-A specifically down-regulated CLN-5 and OCLN protein and mRNA. In mouse cerebral cortex, microinjection of VEGF-A disrupted CLN-5 and OCLN and induced loss of barrier function. Importantly, functional studies revealed that expression of recombinant CLN-5 protected brain microvascular endothelial cell cultures from a VEGF-induced increase in paracellular permeability, whereas recombinant OCLN expressed under the same promoter was not protective. Previous studies have shown CLN-5 to be a key determinant of trans-endothelial resistance at the BBB. Our findings suggest that its down-regulation by VEGF-A constitutes a significant mechanism in BBB breakdown.
Biosynthesis of the
Caenorhabditis elegans
dauer pheromone
Authors: Butcher Rebecca A. , Ragains Justin R. , Li Weiqing , Ruvkun Gary , Clardy Jon , Mak Ho Yi
Published: January 2009

To sense its population density and to trigger entry into the stress-resistant dauer larval stage,
Caenorhabditis elegans
uses the dauer pheromone, which consists of ascaroside derivatives with short, fatty acid-like side chains. Although the dauer pheromone has been studied for 25 years, its biosynthesis is completely uncharacterized. The
daf-22
mutant is the only known mutant defective in dauer pheromone production. Here, we show that
daf-22
encodes a homolog of human sterol carrier protein SCPx, which catalyzes the final step in peroxisomal fatty acid β-oxidation. We also show that
dhs-28
, which encodes a homolog of the human
d
-bifunctional protein that acts just upstream of SCPx, is also required for pheromone production. Long-term
daf-22
and
dhs-28
cultures develop dauer-inducing activity by accumulating less active, long-chain fatty acid ascaroside derivatives. Thus,
daf-22
and
dhs-28
are required for the biosynthesis of the short-chain fatty acid-derived side chains of the dauer pheromone and link dauer pheromone production to metabolic state.
RETRACTED: A prion of yeast metacaspase homolog (Mca1p) detected by a genetic screen
Authors: Nemecek Julie , Nakayashiki Toru , Wickner Reed B.
Published: January 2009

Saccharomyces cerevisiae
can be infected with four amyloid-based prions: [URE3], [
PSI
+
], [
PIN
+
], and [
SWI
+
], due to self-propagating aggregation of Ure2p, Sup35p, Rnq1p and Swi1p, respectively. We searched for new prions of yeast by fusing random segments of yeast DNA to
SUP35MC
, encoding the Sup35 protein lacking its own prion domain, selecting clones in which Sup35MC function was impaired. Three different clones contained parts of the Q/N-rich amino-terminal domain of Mca1p/Yca1p with the Sup35 part of the fusion protein partially inactive. This inactivity was dominant, segregated 4:0 in meiosis, and was efficiently transferred by cytoplasmic mixing. The inactivity was cured by overexpression of Hsp104, but the prion could arise again in the cured strain (reversible curing). Overproduction of the Mca1 N-terminal domain induced the de novo appearance of the prion form of the fusion. The prion state, which we name [MCA], was transmitted to the chromosomally encoded Mca1p based on genetic, cytological and biochemical tests.
Independent saturation of three TrpRS subsites generates a partially assembled state similar to those observed in molecular simulations
Authors: Laowanapiban Poramaet , Kapustina Maryna , Vonrhein Clemens , Delarue Marc , Koehl Patrice , Carter Charles W.
Published: January 2009

Two new crystal structures of
Bacillus stearothermophilus
tryptophanyl-tRNA synthetase (TrpRS) afford evidence that a closed interdomain hinge angle requires a covalent bond between AMP and an occupant of either pyrophosphate or tryptophan subsite. They also are within experimental error of a cluster of structures observed in a nonequilibrium molecular dynamics simulation showing partial active-site assembly. Further, the highest energy structure in a minimum action pathway computed by using elastic network models for Open and Pretransition state (PreTS) conformations for the fully liganded TrpRS monomer is intermediate between that simulated structure and a partially disassembled structure from a nonequilibrium molecular dynamics trajectory for the unliganded PreTS. These mutual consistencies provide unexpected validation of inferences drawn from molecular simulations.
Confirmation of tubal patency in hysterosalpingo‐contrast sonography by transvaginal hydrolaparoscopy
Authors: AHINKO‐HAKAMAA KATJA MAARIT , HUHTALA HEINI , TINKANEN HELENA
Published: January 2009

Objective. To confirm tubal patency in hysterosalpingo‐contrast sonography (HyCoSy) by transvaginal hydrolaparoscopy (THL). Design. A prospective study. Setting. Infertility clinic at a university hospital. Population. Fifty‐six infertile women with a history of tubal risk factor(s) who underwent HyCoSy and THL between 2003 and 2006. Methods. After performing HyCoSy, the tubal patency was verified by THL. Results. Altogether, 51 women and 101 tubes could be examined. Using HyCoSy, 61 of the tubes were considered patent and 40 occluded. THL confirmed 82 tubes patent and 19 occluded. Of 61 tubes found to be patent in HyCoSy, 60 were also patent in THL. In contrast, of 40 tubes occluded in HyCoSy only 18 tubes were confirmed to be occluded by THL. The concordance was 77%. The sensitivity of HyCoSy was 95%, the specificity 73%, the negative predictive value 98% and the positive predictive value 45%. Conclusions. HyCoSy is a reliable method when tubal patency is demonstrated. In cases of suspected tubal occlusion, THL is an inexpensive and safe outpatient procedure to exclude benign tubal spasm and confirm the presence of true occlusion.
Fetal outcome in severe maternal morbidity: Too many stillbirths
Authors: CHAM MAMADY , SUNDBY JOHANNE , VANGEN SIRI
Published: January 2009

Objective. We determined the stillbirth rates among singleton births in Gambian hospitals. Contribution of severe obstetric complications was given special attention. Design. A multi‐center retrospective review. Setting. Three obstetric referral hospitals. Sample. Fetal outcomes in 826 women with severe maternal morbidity out of 3,280 singleton deliveries. Methods. All women with severe maternal morbidity reported in the investigated hospitals between January and June 2006 were identified and their cases reviewed. For each case, information about fetal outcome and the mother's age, parity, obstetric complications and delivery mode was abstracted from maternity records. Main outcome measures. Stillbirth rates and the impact of health service factors. Results. There were excessively high stillbirth rates with an eight‐fold increased risk among women with severe obstetric complications (310/1,000 births), compared to women without complications (51/1,000 births). Hemorrhage, anemia, sepsis and hypertensive pregnancy disorders were associated with higher stillbirth rates. Dystocia cases had a relatively lower stillbirth rate. In women with severe obstetric complications, vaginal delivery was associated with a four‐fold increased risk of stillbirth compared to cesarean section. Conclusion. Severe maternal morbidity has significant impact on stillbirth rates. Better access to emergency obstetric care and improved intrapartum care will significantly reduce stillbirth rates in poor settings of the world, such as The Gambia.
Villoglandular papillary adenocarcinoma of the uterine cervix: A diagnostic challenge
Authors: KORACH JACOB , MACHTINGER RONIT , PERRI TAMAR , VICUS DANIEL , SEGAL JACOB , FRIDMAN EDDIE , BEN‐BARUCH GILAD
Published: January 2009

Villoglandular papillary adenocarcinoma (VGA) is a rare subtype of cervical adenocarcinoma. It tends to appear in younger women and its indolent behavior permits fertility‐preserving treatments. Pathologically, VGA presents a diagnostic challenge. The aim of our study was to evaluate the reliability of histological assessment for pre‐treatment diagnosis of VGA. The data from the outpatient files of 12 patients in whom VGA had been diagnosed were reviewed. Median age at diagnosis was 38.8 years (range 27–65). Final pathology results confirmed VGA in nine patients. Of these, only two had been correctly diagnosed preoperatively, while in three, the initial biopsies were benign or pre‐malignant. In four patients, the biopsy results had been interpreted as an invasive malignant tumor necessitating hysterectomy. The final histological report on the remaining three patients was invasive cervical adenocarcinoma. We conclude that pre‐treatment diagnosis should not be based solely on a simple punch biopsy because of its low rate of diagnostic accuracy.
Invasive prenatal diagnostic practice in Denmark 1996 to 2006
Authors: VESTERGAARD CHRISTINA H. F. , LIDEGAARD ØJVIND , TABOR ANN
Published: January 2009

The Danish National Board of Health recommended in 2004 routine ultrasound scanning in week 12 with nuchal translucency measurement, combined with the double test to all pregnant women. Those who were found to have a risk of trisomy 21 higher than 1:300 were offered amniocentesis or chorionic villus sampling (CVS). The total number of pregnancies in Denmark with an invasive prenatal procedure decreased from 6,929 in 1996 to 3,103 in 2006, the percentage of CVS increased from 45 to 69%, and the percentage of women below 35 years among those undergoing invasive procedures increased from 38 to 52%. The mean gestational age at which the procedures were done increased – for CVS from week 11 to 13, and for amniocentesis from week 16 to 17. We thus achieved to more than double the offer of prenatal screening and at the same time reduce the number of invasive procedures by 55%.
Limited knowledge on progestogen‐only contraception and risk of venous thromboembolism
Authors: BERGENDAL ANNICA , ODLIND VIVECA , PERSSON INGEMAR , KIELER HELLE
Published: January 2009

Objective. To assess the current knowledge concerning progestogen‐only contraception (POC) and risks of venous thromboembolism (VTE). Design and setting. Systematic review of the literature on observational and analytical studies reporting risk estimates for VTE in women exposed to POCs. Methods and main outcome measures. We performed a computerized literature search in the Pub Med, Embase, and the Cochrane Library for studies published between 1966 and February 13, 2008. Based on the evaluated studies we calculated an overall risk estimate for VTE in association with POC. Results. Four case‐control studies and one cohort study were included. Of the case‐control studies, three reported an increased risk and one a decreased risk of VTE. The cohort study found divergent results depending on the type of statistical analysis used. None of the results was statistically significant. The overall odds ratio for POC‐associated VTE in the four case‐control studies was 1.45 (95% CI = 0.92–2.26). Conclusions. The risk of VTE associated with use of POCs is poorly investigated. The slightly elevated overall risk estimate might suggest an association between POC and an increased risk for VTE. The results must, however, be interpreted with caution due to the possibility of residual confounding. Well‐designed studies with sufficient statistical power to evaluate risks of VTE with POC are warranted.
Pre‐pregnancy transabdominal cerclage
Authors: THUESEN LEA LANGHOFF , DINESS BIRGITTE RODE , LANGHOFF‐ROOS JENS
Published: January 2009

A consecutive series of 45 women with one or more previous second trimester deliveries, who had a pre‐pregnancy transabdominal cerclage (TAC) from 1999 to July 2007, was followed until January 2008.

Within the observation period 50 pregnancies occurred in 36 women. Seven resulted in first trimester abortions, none in second trimester abortions or deliveries, and six were on‐going pregnancies. In the remaining 37 pregnancies the fetal salvage rate was 100%, and cesarean section was performed after 34 weeks (mean 36+5 weeks) in 36 (97%) pregnancies. One woman had three successful pregnancies following the procedure. No serious complications were associated with the application of TAC. One woman had a hysterectomy following cesarean section.

Pre‐pregnancy TAC is a procedure with few complications and excellent outcome. The method may be considered in women with a second trimester fetal loss, when cervical incompetence cannot be ruled out.
Abstract Rule Learning for Visual Sequences in 8‐ and 11‐Month‐Olds
Authors: Johnson Scott P. , Fernandes Keith J. , Frank Michael C. , Kirkham Natasha , Marcus Gary , Rabagliati Hugh , Slemmer Jonathan A.
Published: January 2009

The experiments reported here investigated the development of a fundamental component of cognition: to recognize and generalize abstract relations. Infants were presented with simple rule‐governed patterned sequences of visual shapes (ABB, AAB, and ABA) that could be discriminated from differences in the position of the repeated element (late, early, or nonadjacent, respectively). Eight‐month‐olds were found to distinguish patterns on the basis of the repetition, but appeared insensitive to its position in the sequence; 11‐month‐olds distinguished patterns over the position of the repetition, but appeared insensitive to the nonadjacent repetition. These results suggest that abstract pattern detection may develop incrementally in a process of constructing complex relations from more primitive components.
Translocation or just location? Pseudopodia affect fluorescent signals
Authors: Dewitt Sharon , Darley Richard L. , Hallett Maurice B.
Published: January 2009

The use of fluorescent probes is one of the most powerful techniques for gaining spatial and temporal knowledge of dynamic events within living cells. Localized increases in the signal from cytosolic fluorescent protein constructs, for example, are frequently used as evidence for translocation of proteins to specific sites within the cell. However, differences in optical and geometrical properties of cytoplasm can influence the recorded intensity of the probe signal. Pseudopodia are especially problematic because their cytoplasmic properties can cause abrupt increases in fluorescent signal of both GFP and fluorescein. Investigators should therefore be cautious when interpreting fluorescence changes within a cell, as these can result from either translocation of the probe or changes in the optical properties of the milieu surrounding the probe.
Decremental Response to High-Frequency Trains of Acetylcholine Pulses but Unaltered Fractional Ca2+ Currents in a Panel of “Slow-Channel Syndrome” Nicotinic Receptor Mutants
Authors: Elenes Sergio , Decker Michael , Cymes Gisela D. , Grosman Claudio
Published: January 2009

The slow-channel congenital myasthenic syndrome (SCCMS) is a disorder of the neuromuscular junction caused by gain-of-function mutations to the muscle nicotinic acetylcholine (ACh) receptor (AChR). Although it is clear that the slower deactivation time course of the ACh-elicited currents plays a central role in the etiology of this disease, it has been suggested that other abnormal properties of these mutant receptors may also be critical in this respect. We characterized the kinetics of a panel of five SCCMS AChRs (αS269I, βV266M, ɛL221F, ɛT264P, and ɛL269F) at the ensemble level in rapidly perfused outside-out patches. We found that, for all of these mutants, the peak-current amplitude decreases along trains of nearly saturating ACh pulses delivered at physiologically relevant frequencies in a manner that is consistent with enhanced entry into desensitization during the prolonged deactivation phase. This suggests that the increasingly reduced availability of activatable AChRs upon repetitive stimulation may well contribute to the fatigability and weakness of skeletal muscle that characterize this disease. Also, these results emphasize the importance of explicitly accounting for entry into desensitization as one of the pathways for burst termination, if meaningful mechanistic insight is to be inferred from the study of the effect of these naturally occurring mutations on channel function. Applying a novel single-channel–based approach to estimate the contribution of Ca2+ to the total cation currents, we also found that none of these mutants affects the Ca2+-conduction properties of the AChR to an extent that seems to be of physiological importance. Our estimate of the Ca2+-carried component of the total (inward) conductance of wild-type and SCCMS AChRs in the presence of 150 mM Na+, 1.8 mM Ca2+, and 1.7 mM Mg2+ on the extracellular side of cell-attached patches turned out be in the 5.0–9.4 pS range, representing a fractional Ca2+ current of ∼14%, on average. Remarkably, these values are nearly identical to those we estimated for the NR1-NR2A N-methyl-d-aspartate receptor (NMDAR), which has generally been considered to be the main neurotransmitter-gated pathway of Ca2+ entry into the cell. Our estimate of the rat NMDAR Ca2+ conductance (using the same single-channel approach as for the AChR but in the nominal absence of extracellular Mg2+) was 7.9 pS, corresponding to a fractional Ca2+ current of 13%.
Four Ca2+ Ions Activate TRPM2 Channels by Binding in Deep Crevices near the Pore but Intracellularly of the Gate
Authors: Csanády László , Törőcsik Beáta
Published: January 2009

TRPM2 is a tetrameric Ca2+-permeable channel involved in immunocyte respiratory burst and in postischaemic neuronal death. In whole cells, TRPM2 activity requires intracellular ADP ribose (ADPR) and intra- or extracellular Ca2+, but the mechanism and the binding sites for Ca2+ activation remain unknown. Here we study TRPM2 gating in inside-out patches while directly controlling intracellular ligand concentrations. Concentration jump experiments at various voltages and Ca2+ dependence of steady-state single-channel gating kinetics provide unprecedented insight into the molecular mechanism of Ca2+ activation. In patches excised from Xenopus laevis oocytes expressing human TRPM2, coapplication of intracellular ADPR and Ca2+ activated ∼50-pS nonselective cation channels; K1/2 for ADPR was ∼1 µM at saturating Ca2+. Intracellular Ca2+ dependence of TRPM2 steady-state opening and closing rates (at saturating [ADPR] and low extracellular Ca2+) reveals that Ca2+ activation is a consequence of tighter binding of Ca2+ in the open rather than in the closed channel conformation. Four Ca2+ ions activate TRPM2 with a Monod-Wymann-Changeux mechanism: each binding event increases the open-closed equilibrium constant ∼33-fold, producing altogether 106-fold activation. Experiments in the presence of 1 mM of free Ca2+ on the extracellular side clearly show that closed channels do not sense extracellular Ca2+, but once channels have opened Ca2+ entering passively through the pore slows channel closure by keeping the “activating sites” saturated, despite rapid continuous Ca2+-free wash of the intracellular channel surface. This effect of extracellular Ca2+ on gating is gradually lost at progressively depolarized membrane potentials, where the driving force for Ca2+ influx is diminished. Thus, the activating sites lie intracellularly from the gate, but in a shielded crevice near the pore entrance. Our results suggest that in intact cells that contain micromolar ADPR a single brief puff of Ca2+ likely triggers prolonged, self-sustained TRPM2 activity.