bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability indicating method for famotidine in pharmaceuticals using porous graphitic carbon column
Authors: Helali Nawel , Monser Lotfi
Published: January 2008

A simple, sensitive and rapid HPLC method was developed and validated for the simultaneous determination of famotidine (FMT) and related impurities in pharmaceuticals. Chromatographic separation was accomplished within 10 min on a porous graphitic carbon (PGC) column using 50:50 v/v ACN–water containing 0.5% pentane sulphonic acid (PSA) as the mobile phase. Separation was achieved with a flow rate of 1 mL/min and a detection wavelength of 265 nm. The calibration curves were linear over a concentration range of 1.5–100 μg/mL. The intra‐ and interday RSDs (n = 5) for the retention times and peak area were all less than 2%. The method was sensitive with an LOD (S/N = 3) of 0.1 μg/mL for FMT, imp. C and 0.05 μg/mL for imp. 2, A and D. All recoveries were greater than 98%. The method was demonstrated to be precise, accurate and specific with no interference from the tablet ingredients and separation of the drug peak from the peaks of the degradation products (oxidative degradation and acid and base degradation). The results indicated that the proposed method could be used for the determination of FMT in commercial dosage forms and as a stability‐indicating assay.
A dual spectrophotometric/contactless conductivity detector for CE determination of incompletely separated amino acids
Authors: Zikmundová Jana , Tuma Petr , Opekar František
Published: January 2008

A new application is described of a dual photometric/contactless conductivity detector to CE determination of incompletely separated compounds. These compounds are differentiated when one of them provides signals in both the cells of the detector, whereas the other yields a signal in only one cell. The technique has been applied to determination of proline and tyrosine in a dietary supplement.
A HIF‐1alpha‐related gene involved in cell protection from hypoxia by suppression of mitochondrial function
Authors: Kakinuma Yoshihiko , Katare Rajesh G. , Arikawa Mikihiko , Muramoto Kazuyo , Yamasaki Fumiyasu , Sato Takayuki
Published: January 2008

Recently, we reported that acetylcholine‐induced hypoxia‐inducible factor‐1α protects cardiomyocytes from hypoxia; however, the downstream factors reducing hypoxic stress are unknown. We identified apoptosis inhibitor (AI) gene as being differentially expressed between von Hippel Lindau (VHL) protein‐positive cells with high levels of GRP78 expression and VHL‐negative cells with lower GRP levels, using cDNA subtraction. AI decreased GRP78 level, suppressed mitochondrial function, reduced oxygen consumption and, ultimately, suppressed hypoxia‐induced apoptosis. By contrast, knockdown of the AI gene increased mitochondrial function. Hypoxic cardiomyocytes and ischemic myocardium showed increased AI mRNA expression. These findings suggest that AI is involved in suppressing mitochondrial function, thereby leading to cellular stress eradication and consequently to protection during hypoxia.
Intraspecific patterns of ectoparasite abundances on Paraguayan bats: effects of host sex and body size
Authors: Presley Steven J. , Willig Michael R.
Published: January 2008

Although levels of parasitism can vary greatly among individual bats of the same species, little is known about the characteristics of hosts that affect such variation. Bats were captured via mist nets from June 1995 to July 1997 from 28 localities throughout Paraguay. Over 17 500 ectoparasites were collected from 2909 bats; however, analyses of ectoparasite abundance were restricted to more abundant taxa of host and ectoparasite. We quantified the abundances of 29 taxa of ectoparasite on 19 species of bat host, as well as total abundance of ectoparasites regardless of taxonomic affiliation for 22 species of bat from Paraguay. The effects of host sex and host body size on these estimates of ectoparasite abundance were evaluated separately for each species of host. Ectoparasites did not respond consistently to host body size: ectoparasite abundance increased with host body size in 12 instances and decreased with host body size in 11 instances. Regardless of the existence or direction of effects of host body size on ectoparasite abundance, female hosts generally harboured more ectoparasites than did male hosts. Differences in host quality associated with the sex of bats, especially those related to behaviour, may be a more important determinant of ectoparasite abundance than are differences in size. Opportunities for host transfer are critical for species persistence of ectoparasites; consequently, ectoparasite populations on host individuals that form social groups or colonies should be larger, less prone to stochastic extinction, and have greater opportunity for speciation.
Metamorphism, transient mid‐crustal rheology, strain localization and the exhumation of high‐grade metamorphic rocks
Authors: Groome Wesley G. , Koons Peter O. , Johnson Scott E.
Published: January 2008

We present a series of three‐dimensional numerical models investigating the effects of metamorphic strengthening and weakening on the geodynamic evolution of convergent orogens that are constrained by observations from an exposed mid‐crustal section in the New England Appalachians. The natural mid‐crustal section records evidence for spatially and temporally variable mid‐crustal strength as a function of metamorphic grade during prograde polymetamorphism. Our models address changes in strain rate partitioning and topographic uplift as a function of strengthening/weakening in the middle crust, as well as the resultant changes in deformation kinematics and potential exhumation patterns of high‐grade metamorphic rock. Results suggest that strengthening leads to strain rate partitioning around the zone and suppressed topographic uplift rates whereas weakening leads to strain rate partitioning into the zone and enhanced topographic uplift rates. Deformation kinematics recorded in the orogen are also affected by strengthening/weakening, with complete reversals in shear sense occurring as a function of strengthening/weakening without changes in plate boundary kinematics.
Time domain particle tracking methods for simulating transport with retention and first‐order transformation
Authors: Painter Scott , Cvetkovic Vladimir , Mancillas James , Pensado Osvaldo
Published: January 2008

Particle tracking in the time domain has received increasing attention as a technique for robustly simulating transport along one‐dimensional subsurface pathways. Using a stochastic Lagrangian perspective, integral representations of transport including the effects of advection, longitudinal dispersion, and a broad class of retention models are derived; Monte Carlo sampling of that integral leads directly to new time domain particle tracking algorithms that represent a wide range of physical phenomena. Retention‐time distributions are compiled for key retention models. An extension to accommodate linear transformations such as decay chains is also introduced. Detailed testing using first‐order decay chains and four retention models (equilibrium sorption, limited diffusion, unlimited diffusion, and first‐order kinetic sorption) demonstrate that the method is highly accurate. Simulations using flow fields produced by large‐scale discrete‐fracture network simulations, a transport problem that is difficult for conventional algorithms, demonstrate that the new algorithms are robust and highly efficient.
Thermoelectric properties of directionally solidified half-Heusler compound NbCoSn alloys
Authors: Kimura Yoshisato , Tamura Yukio , Kita Takuji
Published: January 2008

Single- and multiphase samples of the n-type half-Heusler NbCoSn were prepared by directional solidification using the optical floating zone melting method, and the thermoelectric properties of these samples were evaluated. NbCoSn has an excellent thermoelectric power which exceeds −250μVK−1 at around 900K and a relatively high carrier concentration, 4.82×1026m−3. A metalliclike temperature dependence of the electrical resistivity indicates that NbCoSn is a degenerate semiconductor. NbCoSn also shows an excellent power factor, 2.5mWm−1K−2 at about 650K, even without any tuning of the electrical properties which are susceptible to coexisting metallic phases.
Quantum spin Hall effect shows up in a quantum well insulator, just as predicted
Authors: Day Charles
Published: January 2008

The effect, which occurs without a magnetic field, is a new and topologically distinct electronic state.
Face perception in monkeys reared with no exposure to faces
Authors: Sugita Yoichi
Published: January 2008

Infant monkeys were reared with no exposure to any faces for 6–24 months. Before being allowed to see a face, the monkeys showed a preference for human and monkey faces in photographs, and they discriminated human faces as well as monkey faces. After the deprivation period, the monkeys were exposed first to either human or monkey faces for a month. Soon after, the monkeys selectively discriminated the exposed species of face and showed a marked difficulty in regaining the ability to discriminate the other nonexposed species of face. These results indicate the existence of an experience-independent ability for face processing as well as an apparent sensitive period during which a broad but flexible face prototype develops into a concrete one for efficient processing of familiar faces.
Estimating terrestrial uranium and thorium by antineutrino flux measurements
Authors: Dye Stephen T. , Guillian Eugene H.
Published: January 2008

Uranium and thorium within the Earth produce a major portion of terrestrial heat along with a measurable flux of electron antineutrinos. These elements are key components in geophysical and geochemical models. Their quantity and distribution drive the dynamics, define the thermal history, and are a consequence of the differentiation of the Earth. Knowledge of uranium and thorium concentrations in geological reservoirs relies largely on geochemical model calculations. This article describes the methods and criteria to experimentally determine average concentrations of uranium and thorium in the continental crust and in the mantle by using site-specific measurements of the terrestrial antineutrino flux. Optimal, model-independent determinations involve significant exposures of antineutrino detectors remote from nuclear reactors at both a midcontinental and a midoceanic site. This would require major, new antineutrino detection projects. The results of such projects could yield a greatly improved understanding of the deep interior of the Earth.
Diamond exploration in Western Australia
Authors: GEACH CYRIL L.
Published: January 2008

Lamproitic rocks of Western Australia have produced significant amounts of diamond and have given rise to the world's largest diamond mine. This has led to a reappraisal of the relationship between diamond and its host rock as well as new exploration techniques in the search for diamond. Procedures for success follow a modelling system using the most modern methods available in the Earth‐related sciences.
Molecular palaeontology
Authors: CURRY GORDON B.
Published: January 2008

A series of major advances in biology and organic geochemistry has yielded new and extremely powerful methods of recovering, purifying and identifying organic compounds. As a result it is now possible to extract considerable information from the vast reservoir of organic material present in rocks and fossils. New procedures allowing detailed investigation of the structure, composition and interrelationships of living molecules can also provide invaluable information on a timescale of geological proportions.
Flash floods and panic in the fossil record: a tale of 25 titanotheres
Authors: MARTILL DAVID M.
Published: January 2008

The Eocene rocks of southern Wyoming have provided a spectacular discovery of fossil bones and teeth. The remains of 25 titanotheres were found all together in one place less than 100 m square. Some of these horse‐like mammals were young, some very old; and they were part of a herd. The geological and social evidence indicates that they perished together in a flash flood.
Flashfloods, earthquakes and uplift in the Pakistan Himalayas
Authors: BUTLER ROBERT W. H. , OWNEN LEWIS , PRIOR DAVID J.
Published: January 2008

Catastrophic flooding of parts of the frontal plains of the Pakistan Himalayas has occured throughout the historical past. The largest recorded flood (1841) originated from an earthquaketriggered landslip from the flanks of Nanga Parbat, which blocked the Indus river for six months. The earthquake probably occurred on the Liachar thrust, which has been responsible for uplifting the amphibolite facies Nanga Parbat gneisses to the Earth's surface in the last 10 million years. These movements raise serious problems for hydroelectric engineering project in this and other active mountain belts.
Stromatoporoids: a beginner's guide
Authors: KERSHAW STEVE
Published: January 2008

Stromatoporoids are an important group of fossil sponges that form some of the largest reef complexes in the fossil record and are valuable in palaeoecological and facies analysis. They are frequently large and easily studies in the field and in hand specimen. Using their growth forms it is possible to determine some features of sediment deposition rates and changes in their growth direction during life show episodes of turbulence that affected the sea bed. This article intriduces them, and gives practical help to interpret thier growth forms in quaries and cliffs where you may see them on fieldwork. You will realized just how absorbing these fossil sponges can be.
Fluid inclusions
Authors: RANKIN ANDREW H.
Published: January 2008

Fluid inclusions in crystals provide a valuable insight into the nature and origin of ancient mineral‐forming fluids. Fluid inclusions are established geothermometers and geobarometers, but their use as chemical indicators has in the past been hampered by their extremely small size. With the rapid development of a range of modern instrumental microanalytical techniques it is becoming increasingly possible to determine in detail the compositions of various phases present within minute inclusions down to the parts‐per‐million level
Rising sea level
Authors: CARTER BILL
Published: January 2008

Predictions suggest that the world sea level will rise dramatically in the twenty‐first century as a result of atmospheric and oceanic warming arising from the ‘greenhouse effect’. Changing sea level is nothing new to the geologist, but rapid rates of rise over short periods and potentially devastating impacts present a major challenge to society in the need to provide effective management of global biogeochemical cycles.
Storm sedimentation
Authors: BRENCHLEY PATRICK J.
Published: January 2008

Storm‐driven currents can carry sand from the shoreline tens of kilometres out onto the continental shelves where it is moulded by storm waves into a storm‐sand bed showing distinctive sedimentary structures, including hummocky crossstratification. An understanding of the nature of the depositional currents and the processes that form hummocky cross‐stratification comes from the work of oceanographers, observations by geologists and experimental studies in the laboratory, although the conclusions reached are sometimes conflicting. Storm‐sandstone beds provide valuable information about sediment dispersal and depositional systems in nearshore and shelf environments. Hummocky crossstratification indicates the activity of storm waves and hence the approximate depth of ancient shelf seas.
The first geological use of side‐scan sonar
Authors: STRIDE A. H.
Published: January 2008

Side‐scan sonar is now a sophisticated tool providing high‐quality data on the ocean floor. In its early days, however, it gave discouraging results, and for many years it seemed as if it would never provide useful geological information at all.
Sub–fossil Ostracoda and the death of the Aral Sea
Authors: BOOMER IAN
Published: January 2008

The Aral Sea has become increasingly saline since 1960, resulting in decimation of the aquatic biota. Of the 11 ostracod species known to have been alive in the Aral Sea 30 years ago, only one, the euryhaline Cyprideis torosa, lives there today. Recent research has suggested that this species has survived because it is capable of strong hypo–osmotic regulation. The Quaternary history of the sea shows that there have often been water–level fluctuations, but recent dramatic environmental changes have had particularly severe consequences on the ostracod faunas.
Experimental rock deformation: techniques, results and applications to tectonics
Authors: RUTTER ERNEST H.
Published: January 2008

Flow and fracture of rocks in the Earth's crust and upper mantle are evident from the study of rocks in the field, but the same features can be induced in laboratory experiments on rocks at high temperatures and pressures. Through such experiments, the mechanical and other properties can be measured, and used to constrain quantitative modelling of lithospheric dynamics.
THE PHOTO‐REACTIVITY OF AROMATIC SUBSTANCES WITH OXYGEN*
Authors: Rosenberg J. L. , Humphries Frederick S.
Published: January 2008

Summary The quenching reaction of oxygen with photo‐excited aromatics, although almost diffusion‐controlled in many cases, has some specific requirements with respect to the electronic details of the excited state. This is shown in the difference between the quenching constants for monomer and dimer of the same dye, where the dimer is recognized principally by excitation delocalization.

Evidence is reviewed for the view that oxygen becomes vibrationally excited as a result of the quenching reaction, and that this hot oxygen is an essential intermediate in photo‐oxidations. A new result is the stimulation of O2 quenching by CO2, a known catalyst for vibrational relaxation in O2.
A STUDY OF THE EFFECT OF MOLECULAR OXYGEN ON ATOMIC OXYGEN‐HYDROCARBON REACTIONS*
Authors: Allen Eric R. , Cadle Richard D.
Published: January 2008

Abstract— Investigations of the systems O—CH4 and, O—n‐C4H10 have been made, using techniques for producing atomic oxygen in the presence and absence of ground state molecular oxygen. The results indicated that the initial rate of removal of atomic oxygen from both systems was accelerated by the presence of molecular oxygen, whereas the initial rate of removal of hydrocarbon, for n‐butane, was affected little if at all.

The relative concentrations of atomic oxygen, hydrocarbon and molecular oxygen appeared to govern the overall stoichiometry. It is concluded that rate constants observed in the absence of O2 and when [RH] ≥ [O], are probably a more reliable measure of the primary step:

O + RH→Products.
CHEMILUMINESCENT REACTIONS OF SO
Authors: Halstead C. J. , Thrush B. A.
Published: January 2008

Abstract— The rapid bimolecular reaction SO + O3= SO2+O2+ 106 kcal/mole

yields electronically excited SO2 in the 3B1 and 1B2 states with some vibrational excitation, as well as SO2 in its electronic ground state. It is shown that k1= 1.5 x 1012 exp (‐2100/RT) cm2 mole‐1 s‐1 and that the formation of electronically excited SO2 involves higher activation energies.
CHEMILUMINESCENCE QUENCHING TERMS
Authors: Fletcher Aaron N. , Heller Carl A.
Published: January 2008

Abstract— A methodology for the determination of chemiluminescence quenching terms is given. By using the oxidation of tetrakis(dimethylamino)ethylene as an example, it is shown how the nature and magnitude of the quenching terms help to elucidate the reaction mechanism, or how ignoring them can lead to false impressions. It is shown that chemiluminescence quenching effects need not be the same as those for photoluminescence of the same electronically excited species.
ROOT INITIATION, AUXIN LEVEL AND BIOSYNTHESIS OF PHENOLIC COMPOUNDS
Authors: Bastin M.
Published: January 2008

Abstract— With cuttings excised from balsam hypocotyls an analysis was made of the quantitative relations between IAA‐like substances and the presence of naturally occuring phenolic compounds. Results suggest that accumulation of the auxin‐induced roots is a result of an enhanced biosynthesis of phenolic compounds which are inhibitors of the IAA‐oxidizing enzyme.
ULTRAVIOLET ACTION SPECTRA IN PERSPECTIVE: WITH SPECIAL REFERENCE TO MUTATION*
Authors: Giese Arthur C.
Published: January 2008

Abstract— Problems of determining action spectra are considered as well as various types of action spectra for U.V. action upon cell activities. U.V. is an effective mutagenic agent producing point mutations and chromosomal changes. U.V. is readily absorbed by superficial layers of cells in tissues; therefore, special experimental procedures are necessary for induction of mutations in animals or plants. U.V. is, however, suitable for mutagenesis in microorganisms because their cells are small, permitting the radiation to reach the nuclei. Action spectrum studies reveal that u.v. mutagenesis results from absorption of the radiation by nucleic acid. The most prominent alteration in DNA following absorption of u.v. is dimerization of pyrimidines, chiefly thymine. Such a change not only retards DNA replication but results in errors (mutations). U.V. mutagenesis therefore depends upon the conditions before, during and after irradiation. Thus immediate post‐treatment with visible and long u.v. light splits pyrimidine dimers, thereby reversing impending u.v. mutagenesis. For cells kept in the dark, conditions which prevent DNA replication by interfering with the metabolism of the cell provide time for dark repair of the DNA lesion and so for reversal of the impending mutation.
EXCITED STATE INTERACCIÓNS IN MACROMOLECULES*
Authors: LONGWORTH J. W.
Published: January 2008

Abstract— (1) The single tryptophanyl residue of ribonuclease T1 is shown to be in an environment that has no neighboring polar groups. (2) Exciplex formation involving the tryptophanyl residues of urea‐denatured ribonuclease T1 and Staphylococcus nuclease occurs at 298°K, but formation of the complex is suppressed at 77°K. (3) There is no tyrosyl fluorescence or phosphorescence in the luminescence of tryptophanyltyrosine or ribonuclease T1. The only species that emits is the tryptophanyl residue. (4) The transfer of electronic energy absorbed by tyrosyl residues to form a tryptophanyl excited singlet state has been demonstrated, by an analysis of the excitation spectra, for both L‐tryptophanyl‐L‐tyrosine and ribonuclease T1. (5) An interaction between the excited states of tyrosyl residues and vicinal disulfide linkage has been observed with oxytocin and ribonuclease A.

El estado excitado es químicamente diferente del correspondiente estado fundamental, una de las diferencias reside en la distinta interacción con grupos vecinos. Las siguientes reacciones del estado excitado son de particular interés; (a) formación de un complejo con un estado fundamental aromático, “excimer”; (b) formación de un complejo donor‐aceptor con otro compuesto “exciplex”; (c) transferencia de energía electrónica de un compuesto a otro, transferencia de energía; (d) ionización; (f) formación de radicales iibres. Se discutirán ejempios de estas reacciones que involucran el estado excitado singulete de residuos aromáticos en polipéptidos y proteinas, ambos a 298 y 77°K, además del rol que esas interacciones tienen en el comportamiento fluorescente de proteinas, poniendo especial énfasis en dos proteinas, Ribonucleasa T1, y Stuphilococus nuclease. Los estados triplete de residuos de aminoácidos aromáticos en proteinas y polipéptidos no interaccionan fuertemente con grupos vecinos; sin embargo el estado triplete de la tirosina interacciona con una unión de disulfuro adyacente en un oligopéptide y en Ribonucleasa A, y este fenómeno parece estar relacionado con la fotólisis de uniones de sulfuro en proteinas.
PHOTOCHEMICAL CYCLOADDITIONS OF ORGANIC COMPOUNDS
Authors: RIVAS CARLOS , PAYO ELISEO , MANTECÓN JOAQUÍN , CORTÉS LUIS
Published: January 2008

Abstract— Oxetanes were synthesized by 1,2‐photoaddition of benzophenone to several methyl‐substituted furans. The photochemical conversion of oxobicyclic analogues of norbornadiene to the corresponding oxoquadricyclenes was studied, and finally the sensitized 1,2‐photoaddition of citraconic anhydride to furan was accomplished.

Se han sintetizado oxetanos por fotoadición 1,2 de benzofenona a distintos metil furanos. Se ha estudiado la conversión fotoquímica de análogos oxobicíclicos del norbonadieno, y finalmente se ha logrado la fotoadición 1,2 sensitivizada de anhidrido citracónico a furano.
A reproducible means of assessing the metabolic heat status of preterm neonates
Authors: Museux Nathanaëlle , Cardot Virginie , Bach Véronique , Delanaud Stéphane , Degrugilliers Loïc , Agourram Bouchra , Elabbassi Elmountacer Billah , Libert Jean‐Pierre
Published: January 2008

The aim of the present study was to validate the measurement of metabolic heat production using partitional calorimetry (PC) in preterm neonates exposed to a near‐thermoneutral environment in an incubator. In order to reduce experimental uncertainty (due to the different variables involved in the calculation of body heat exchanges between the infant and the environment), the mean radiant temperature and the heat transfer coefficients for convection, radiation and evaporation were measured using a multisegment, anthropometric thermal mannequin which represents a small‐for‐gestational‐age neonate (body surface area: ; simulated birth weight: 1500 g). The metabolic heat production calculated by PC was compared with the results of indirect respiratory calorimetry, which is rarely done in clinical setting since this method interferes with the neonate's environment and requires a high degree of technical preparedness. The oxygen consumption and carbon dioxide production were measured in 20 preterm neonates exposed to thermoneutral and to slightly cool environments . The mean skin temperature was measured by infrared thermography. The measurements were made during well‐established periods of active and quiet sleep. Metabolic heat production was assessed by weighting each value of and by the duration of the sleep stages. Our results showed that there was no significant difference between the two methods in terms of their estimation of metabolic activity at thermoneutrality (mean overall difference: ) and in the cool environment . We observed significant interneonate variability. Partitional calorimetry enabled the prediction of body growth with a daily error of less than 5.3 g for all the neonates at thermoneutrality and for of the subjects in the cool environment. Despite this limitation, we demonstrate here that PC provides reliable information for calculating the energy expenditure of individual preterm neonates on the basis of standard environmental input variables. We suggest that the technique can be advantageously used to assess the energy expenditure and normal growth of these infants.
Geometric characterization of multi‐axis multi‐pinhole SPECT
Authors: DiFilippo Frank P.
Published: January 2008

A geometric model and calibration process are developed for single photon emission computed tomography (SPECT) imaging with multiple pinholes and multiple mechanical axes. Unlike the typical situation where pinhole collimators are mounted directly to rotating gamma ray detectors, this geometric model allows for independent rotation of the detectors and pinholes, for the case where the pinhole collimator is physically detached from the detectors. This geometric model is applied to a prototype small animal SPECT device with a total of 22 pinholes and which uses dual clinical SPECT detectors. All free parameters in the model are estimated from a calibration scan of point sources and without the need for a precision point source phantom. For a full calibration of this device, a scan of four point sources with 360° rotation is suitable for estimating all 95 free parameters of the geometric model. After a full calibration, a rapid calibration scan of two point sources with 180° rotation is suitable for estimating the subset of 22 parameters associated with repositioning the collimation device relative to the detectors. The high accuracy of the calibration process is validated experimentally. Residual differences between predicted and measured coordinates are normally distributed with full width at half maximum and are estimated to contribute root mean square to the reconstructed spatial resolution. Since this error is small compared to other contributions arising from the pinhole diameter and the detector, the accuracy of the calibration is sufficient for high resolution small animal SPECT imaging.
The Fertile Banks of the Thames
Authors: Popper Nicholas S.
Published: January 2008

The Jewel House
. Elizabethan London and the Scientific Revolution.
By Deborah E. Harkness
. Yale University Press, New Haven, CT, 2007. 371 pp. $32.50. ISBN 9780300111965.

The author discusses the activities of Francis Bacon's London contemporaries whose practices helped set the stage for the scientific revolution.
The Cosmic Web in Our Own Backyard
Authors: Ibata Rodrigo A. , Lewis Geraint F.
Published: January 2008

On the largest scales, matter is strung out on an intricate pattern known as the cosmic web. The tendrils of this web should reach right into our own cosmic backyard, lacing the Galactic halo with lumps of dark matter. The search for these lumps, lit up by stars that formed within them, is a major astronomical endeavor, although it has failed to find the huge expected population. Is this a dark matter crisis, or does it provide clues to the complexities of gas physics in the early universe? New technologies in the coming decade will reveal the answer.
Aminoglycosides Affect IntracellularSalmonella entericaSerovars Typhimurium and Virchow
Authors: Menashe Ofir , Kaganskaya Elena , Baasov Timor , Yaron Sima
Published: January 2008

The high antibacterial activity and selectivity of aminoglycosides and their low activity against intracellular bacteria associated with eukaryotic cells make them the antibiotics of choice for the elimination of extracellular bacteria during intracellular studies. Given the evidence that aminoglycosides can penetrate the eukaryotic cell membrane, the goal of this study was to examine the influence of aminoglycosides on macrophage-associatedSalmonella. Herein, we show that gentamicin, kanamycin, and tobramycin at concentrations between 15 to 150 μg ml−1do not kill intracellularSalmonellabut have other effects on the bacterial physiology. By usingSalmonella entericaserovars Typhimurium and Virchow harboring luciferase reporter plasmid, we observed that the light produced by intracellularSalmonelladeclined immediately upon exposure to aminoglycosides, indicating that the bacteria were under stress. The extent of this effect was dependent on the macrophage host, on the identity of the aminoglycoside and its concentration, on the exposure time, and on theSalmonellaserovar.Salmonellaassociated with Nramp1-negative macrophages, in which the phagosomal pH is higher, were more susceptible to aminoglycosides thanSalmonellaassociated with Nramp1-expressing macrophages. These results verify that aminoglycosides affect intracellular bacteria and that the extent of this effect is dependent on the acidity level within the phagosome, suggesting that for the study of intracellular bacteria, the aminoglycoside concentration should be limited to two to five times the MIC for the bacterial strain studied. This precaution should guarantee the complete execution of extracellular bacteria with minimal effects on the intracellular bacteria and the host cells.
Effect of a Polyphenol-Rich Extract from Aloe vera Gel on Experimentally Induced Insulin Resistance in Mice
Authors: Pérez Yolanda Y. , Jiménez-Ferrer Enrique , Zamilpa Alejandro , Hernández-Valencia Marcelino , Alarcón-Aguilar Francisco J. , Tortoriello Jaime , Román-Ramos Rubén
Published: January 2008

Insulin resistance, which precedes type 2 diabetes mellitus (T2DM), is a widespread pathology associated with the metabolic syndrome, myocardial ischemia, and hypertension. Finding an adequate treatment for this pathology is an important goal in medicine. The purpose of the present research was to investigate the effect of an extract from Aloe vera gel containing a high concentration of polyphenols on experimentally induced insulin resistance in mice. A polyphenol-rich Aloe vera extract (350 mg/kg) with known concentrations of aloin (181.7 mg/g) and aloe-emodin (3.6 mg/g) was administered orally for a period of 4 weeks to insulin resistant ICR mice. Pioglitazone (50 mg/kg) and bi-distilled water were used as positive and negative controls respectively. Body weight, food intake, and plasma concentrations of insulin and glucose were measured and insulin tolerance tests were performed. The insulin resistance value was calculated using the homeostasis model assessment for insulin resistance (HOMA-IR) formula. Results showed that the polyphenol-rich extract from Aloe vera was able to decrease significantly both body weight ( p < 0.008) and blood glucose levels ( p < 0.005) and to protect animals against unfavorable results on HOMA-IR, which was observed in the negative control group. The highest glucose levels during the insulin tolerance curve test were in the negative control group when compared to the Aloe vera extract and pioglitazone treated mice ( p < 0.05). In conclusion, Aloe vera gel could be effective for the control of insulin resistance.
THE BETHE–SALPETER EQUATION APPROACH TO BOUND STATE: SCALAR–FERMION CASE AND SCALAR–SCALAR CASE
Authors: CHEN JIAO-KAI , TANG ZHENG-XIN , CHEN QING-DONG
Published: January 2008

The general form of the Bethe–Salpeter wave functions for bound states comprising one scalar constituent and one fermion, or two scalars is presented. Using the reduced Salpeter equation obtained, we can work out the effective nonrelativistic potentials. And one new version of reduced Bethe–Salpeter equation is proposed by extending Gross approximation.
A word from the editor
Authors: Lee Newton
Published: January 2008

Welcome to
ACM Computers in Entertainment
, a premier online magazine featuring video interviews with leading professionals and interesting articles on entertainment technology and its applications.
Happy anniversary, CACM
Authors: Shannon Meg McGinity
Published: January 2008

Sampling the various slices of the telecommunications and computing spectrum over the years.
The battle behind the scenes
Authors: Ashenhurst Robert L.
Published: January 2008

Like Stuart Lynn, I had been a department editor for CACM before becoming its EIC. In fact, the "Computer Systems" department was initiated by Kelly Gotlieb during his editorship. He sent me a letter enclosing a submitted paper that he thought should be published in CACM; however, it fit no existing department. It would appear in the September 1965 issue: Reilly and Federighi's "On Reversible Subroutines and Computers that Run Backwards." A subsequent contribution, of considerably more lasting significance, was published in that same issue: E.W. Dijkstra's "Solution of a Problem in Concurrent Program Control." Indeed, the paper initiated a whole new subdiscipline in the computer operating systems area. Eventually, "Computer Systems" became the department for software/hardware systems papers such as those that now appear in
Transactions on Computer Systems (TOCS)
.
Toward a network architecture that does everything
Authors: Crowcroft Jon
Published: January 2008

In the same way light propagates through a medium, analogous wave-particle principles could help model communications through the future Internet architecture.
Reflections on computer-related risks
Authors: Neumann Peter G.
Published: January 2008

Tracing the history of exposing and elucidating the wide variety of system problems and associated social implications of uses and misuses of computing technology.
Interval based off-line clock synchronization for wireless mesh networks
Authors: Lukas Georg , Herms André , Mahrenholz Daniel
Published: January 2008

Wireless mesh networks suffer from various problems like congestion or packet collisions. To identify and overcome these problems an exact global view of the communication is required. However, it is not possible to observe the whole network from a single location. Instead, a distributed monitoring is necessary, which has to include clock synchronization. We present a new interval-based algorithm for the off-line synchronization of passively monitored network events. It calculates the worst-case time interval for every event on a global clock, while considering inaccuracies caused by processing jitter and non-uniform clock drifts. The experimental evaluation on a live mesh network shows an accuracy of better than 130μ
s
over a four-hop distance, which is below the minimum transmission time of data packets. Thereby, our algorithm creates a highly precise global view of the network, which allows a detailed diagnosis of wireless mesh networks.
Light-weight application monitoring and tuning with embedded gossip
Authors: Zhu Wenbin , Bridges Patrick G. , Maccabe Arthur B.
Published: January 2008

For large-scale, long-running applications, monitoring can be expensive. While traditional trace-based monitoring provides detailed information about an application, it is expensive to record and gather the traced performance data. Processing the voluminous traced data is so demanding that information about the monitored application is only available post-mortem.
PSON
Authors: Shamsi Jawwad , Brockmeyer Monica
Published: January 2008

Predictable Service Overlay Networks (PSON) improve the predictability of Internet communication by providing an estimate of the upper bound on message latency for each path of the overlay. The upper bound serves as an assurance of synchrony and enables applications to order events or make inferences based on non-receipt of a message. For improved performance, PSON also employs overlay routing and overlay configuration. Messages are routed either through the direct overlay path or via a one-hop overlay path such that the selected path is stable and promotes synchrony, while the overlay configuration mechanisms are utilized in order to select nodes that promote predictable communication. The expected impact of PSON is that by utilizing intelligent techniques such as upper bound estimation, routing and configuration, it can harness the unexpected and unreliable Internet substrate to provide a predictable communication overlay for applications.
Debating the Role of Institutions in Political and Economic Development: Theory, History, and Findings
Authors: Engerman Stanley L. , Sokoloff Kenneth L.
Published: January 2008

This essay examines the recent use of the concept of institutions in economics and political science, and the impact of institutions on economic growth and democracy. The discussion includes the definition of institutions, the question of endogenous and exogenous origins of institutions, the role of fixed and flexible institutions, and the relations among different types of institutions. Particular attention is given to recent books by Avner Greif and by Daron Acemoglu & James A. Robinson.
Ancillary Benefits for Climate Change Mitigation and Air Pollution Control in the World's Motor Vehicle Fleets
Authors: Walsh Michael P.
Published: January 2008

The global motor vehicle population has grown very rapidly in the past half century and is expected to continue to grow rapidly for the next several decades, especially in developing countries. As a result, vehicles are a major source of urban air pollution in many cities and are the fastest-growing source of greenhouse emissions. Strategies exist to reduce both problems, but many countries emphasize one over the other rather than pursuing strategies that reduce both concerns. Using diesel as an example, this article illustrates that it is now possible not only to reduce carbon dioxide with the increased use of diesel vehicles but also to improve urban air pollution. Doing so requires both stringent emissions regulations and clean fuels. Several principles contained in the Bellagio Memorandum are highlighted as guides for policy makers.
Osteoprotegerin Inhibits Vascular Calcification Without Affecting Atherosclerosis in

ldlr
(−/−)

Mice
Authors: Morony Sean , Tintut Yin , Zhang Zina , Cattley Russell C. , Van Gwyneth , Dwyer Denise , Stolina Marina , Kostenuik Paul J. , Demer Linda L.
Published: January 2008

Background—

The role of osteoprotegerin in vascular disease is unclear. Recent observational studies show that serum osteoprotegerin levels are associated with the severity and progression of coronary artery disease, atherosclerosis, and vascular calcification in patients. However, genetic and treatment studies in mice suggest that osteoprotegerin may protect against vascular calcification.

Methods and Results—

To test whether osteoprotegerin induces or prevents vascular disease, we treated atherogenic diet–fed

ldlr
(−/−)

mice with recombinant osteoprotegerin (Fc-OPG) or vehicle for 5 months. Vehicle-treated mice developed significant, progressive atherosclerosis with increased plasma osteoprotegerin levels, consistent with observational studies, and ≈15% of these atherosclerotic lesions developed calcified cartilage-like metaplasia. Treatment with Fc-OPG significantly reduced the calcified lesion area without affecting atherosclerotic lesion size or number, vascular cytokines, or plasma cholesterol levels. Treatment also significantly reduced tissue levels of aortic osteocalcin, a marker of mineralization.

Conclusions—

These data support a role for osteoprotegerin in the vasculature as an inhibitor of calcification and a marker, rather than a mediator, of atherosclerosis.
A Climatology of Cold-Season Nonconvective Wind Events in the Great Lakes Region
Authors: Lacke Matthew C. , Knox John A. , Frye John D. , Stewart Alan E. , Durkee Joshua D. , Fuhrmann Christopher M. , Dillingham Sarah M.
Published: January 2008

A 44-yr climatology of nonconvective wind events (NCWEs) for the Great Lakes region has been created using hourly wind data for 38 first-order weather stations during the months of November through April. The data were analyzed in terms of the two National Weather Service (NWS) criteria for a high-wind watch or warning: sustained winds of at least 18 m s−1 for at least 1 h or a wind gust of at least 26 m s−1 for any duration. The results indicate a pronounced southwest quadrant directional preference for nonconvective high winds in this region. Between 70% and 76% of all occurrences that satisfied the NWS criteria for NCWEs were associated with wind directions from 180° through 270°. Within the southwest quadrant, the west-southwest direction is preferred, with 14%–35% of all NCWEs coming from this particular compass heading. This directional preference is borne out in five out of six stations with high occurrences of cold-season NCWEs (Buffalo, New York; Dayton, Ohio; Lansing, Michigan; Moline, Illinois; Springfield, Illinois). Given the geographic spread of these stations, a nontopographic cause for the directional preference of cold-season NCWEs is indicated. The connection between NCWEs and low pressure systems found in this climatology and in case studies suggests that midlatitude cyclone dynamics may be a possible cause of the directional preference.
Bias-Corrected Short-Range Ensemble Forecasts of Near-Surface Variables during the 2005/06 Cool Season
Authors: Yussouf Nusrat , Stensrud David J.
Published: January 2008

A postprocessing method initially developed to improve near-surface forecasts from a summertime multimodel short-range ensemble forecasting system is evaluated during the cool season of 2005/06. The method, known as the bias-corrected ensemble (BCE) approach, uses the past complete 12 days of model forecasts and surface observations to remove the mean bias of near-surface variables from each ensemble member for each station location and forecast time. In addition, two other performance-based weighted-average BCE schemes, the exponential smoothing method BCE and the minimum variance estimate BCE, are implemented and evaluated. Values of root-mean-squared error from the 2-m temperature and dewpoint temperature forecasts indicate that the BCE approach outperforms the routinely available Global Forecast System (GFS) model output statistics (MOS) forecasts during the cool season by 9% and 8%, respectively. In contrast, the GFS MOS provides more accurate forecasts of 10-m wind speed than any of the BCE methods. The performance-weighted BCE schemes yield no significant improvement in forecast accuracy for 2-m temperature and 2-m dewpoint temperature when compared with the original BCE, although the weighted BCE schemes are found to improve the forecast accuracy of the 10-m wind speed. The probabilistic forecast guidance provided by the BCE system is found to be more reliable than the raw ensemble forecasts. These results parallel those obtained during the summers of 2002–04 and indicate that the BCE method is a promising and inexpensive statistical postprocessing scheme that could be used in all seasons.
IRON-DEFICIENCY ANEMIA IS ASSOCIATED WITH CEREBRAL SINOVENOUS THROMBOSIS: A CASE SERIES
Authors: Kavadas Fotini D. , Moharir Mahendranath D. , Brandao Leonardo R. , de Veber Gabrielle
Published: January 2008

INTRODUCTION: Iron-deficiency anemia is a relatively common but preventable condition in children that may have significant adverse implications on children's growth and development. Iron-deficiency anemia has also been sporadically reported in association with cerebral sinovenous thrombosis (CSVT).

OBJECTIVE: The objective of this study was to describe the largest case series to date of iron-deficiency anemia in association with CSVT as an advocacy measure for its prevention in children.

METHODS: Patients were identified through the Canadian Pediatric Ischemic Stroke Registry database (Toronto site). Included were patients who were older than 1 month to 18 years, met criteria for iron-deficiency anemia, and had radiographically confirmed CSVT.

RESULTS: Thirty-six patients who had CSVT and were older than 1 month to 18 years presented to the Hospital for Sick Children, Toronto, from January 2004 to December 2005. Six (17%) of these patients had iron-deficiency anemia; 2 were female adolescents, and 4 were male toddlers. All patients had historical and laboratory evidence of iron-deficiency anemia. Other risk factors, such as dehydration or inflammatory disorders, were present in all patients, but we did not detect significant inherited hypercoagulable disorders or acquired thrombophilia in any of them.

CONCLUSIONS: This report strengthens the evidence of an association between iron-deficiency anemia and CSVT. We suggest that children who have CSVT should be screened for iron deficiency. Advocacy to prevent iron deficiency is important, because this condition may have serious long-term and irreversible developmental consequences.