bluuebunny/crossref_metadata_2025 huggingface dataset:
Dimer acid structures. The dehydro‐dimer from methyl stearate and di‐tertiary‐butyl peroxide
Authors: Harrison S. A. , Peterson L. E. , Wheeler D. H.
Published: February 2007

Previous work by Sutton, and by Harrison, McCaleb and Wheeler has shown that methyl stearate is converted to dimers plus higher polymers by the action of di‐t‐butyl peroxide. The latter suggested that in the dimer, there was considerable linkage at carbon 2, the carbon ॅ‐ to the COOCH3 group, since the dimer ester was incompletely saponified by the usual procedures.

Further proof of ॅ‐linkage is now presented. A fraction which is predominantly ॅ‐,ॅ艂‐linked dimer was isolated as the nonpolymeric cyclic anhydride (ॅ‐,ॅ艂‐dicetyl succinic anhydride) by molecular distillation from the linear polymeric non‐ॅ‐linked polyanhydride. The isolated cyclic anhydride appeared identical with a synthetic ॅ‐,ॅ艂‐dicetyl succinic anhydride, whose synthesis is described.

The original dimer ester, the ॅ‐,ॅ艂‐cyclic anhydride fraction, and the dimethyl ester derived from it, were examined by mass spectrometry. The expected mol wt were confirmed by the parent ion peaks. Fragmentation patterns indicated appreciable ॅ‐linkage in the original dimer ester, and almost exclusive ॅ‐linkage in the ester from the isolated cyclic anhydride. Aside from preference for the ॅ‐position, joining appears to be randomly distributed.
Vinyl esters of some aldehydic acid acetals
Authors: Pryde E. H. , Moore D. J. , Cowan J. C.
Published: February 2007

Vinylation of azelaaldehydic and brassylaldehydic acid cyclic acetals from ethylene glycol gave excellent yields of the vinyl esters. Under conditions of the vinyl exchange reaction used, acyclic acetals from monohydric alcohols cleaved to give enol‐ethers as major, inseparable impurities. Radical‐initiated polymerization of the pure vinyl esters of the aldehydic‐acid cyclic acetals resulted in crosslinking when initiation was by either peroxide or azobis (isobutyronitrile).
Fatty acids of doxantha seed oil
Authors: Chisholm Mary J. , Hopkins C. Y.
Published: February 2007

The seed oil ofDoxantha unguis‐cati was found to have the following fatty acid composition:cis‐9‐hexadecenoic 64,cis‐11‐octadecenoic 15, oleic 4, hexadecadienoic 1, linoleic 4, palmitic 12 and stearic <1%. The significance of the unusual fat composition is discussed in relation to biosynthetic mechanisms.
Gas‐chromatographic determination of residual hexane in hexane‐extracted soybean flakes
Authors: Black L. T. , Mustakas G. C.
Published: February 2007

A method was developed to determine residual hexane in hexane‐extracted soybean flakes by gasliquid chromatography (GLC). After residual hexane was extracted with pure isooctane, the quantity extracted was determined by GLC. Analyses were run on three different columns. Column efficiency was varied to obtain maximum speed and accuracy. An attenautor was used to amplify the low‐signal output of the extracted residual hexane.

Accuracy of the method was established by analyzing soybean flakes containing 0.01舑7.5% added hexane. The lower limit of accuracy is approx 0.02%, and the time required for analysis is ca. one hr.

Residual hexane present in other kinds of hexane‐extracted oilseed flakes might also be analyzed by this method. It is probable that extraction solvents other than hexane which are infinitely soluble in isooctane can also be determined by the method proposed.
Triacylglycerols of winter butterfat containing configurational isomers of monoenoic fatty acyl residues. I. Disaturated monoenoic triacylglycerols
Authors: Laakso Päivi , Kallio Heikki
Published: February 2007

The triacylglycerols of winter butterfat were fractionated according to the type and degree of unsaturation into six fractions by silver ion high‐performance liquid chromatography (Ag‐HPLC). The acyl carbon number distribution of the triacylglycerols in each fraction was elucidated by reversed‐phase HPLC and mass spectrometry (MS). The MS analysis of each fraction gave deprotonated triacylglycerol [M ‐ H]− ions which were produced by chemical ionization with ammonia. The daughter spectrum of each of the [M ‐ H]− ions provided information on its fatty acid constituents. Successful fractionation of triacylglycerols differing in the configuration of one fatty acyl residue by Ag‐HPLC was important because geometrical isomers could not be distinguished by the MS system used. In addition to the fatty acid compositions, reversed‐phase HPLC analysis demonstrated the purity of the collected fractions: molecules having acis‐trans difference were separated nearly to the baseline. Triacylglycerols differing in the configuration of one fatty acyl residue were not equally distributed in relation to their acyl carbon numbers. This indicates that during the biosynthesis of triacylglycerols,cis‐ andtrans‐fatty acids are processed differently. Although the fatty acid compositions of the corresponding molecular weight species of disaturatedtrans‐ and disaturatedcis‐monoenoic triacylglycerols were similar, there may be differences in the amounts of different fatty acid combinations or in the distribution of fatty acids between the primary and secondary glycerol positions. In addition to the main components, it was possible to analyze minor triacylglycerols, such as molecules containing one odd‐chain fatty acid, by the MS system used.
Determination of positional distribution of short‐chain fatty acids in bovine milk fat on chiral columns
Authors: Itabashi Yutaka , Myher John J. , Kuksis Arnis
Published: February 2007

The positional distribution of acetic and butyric acids in bovine milk fat triacylglycerols was determined by chiral‐phase high‐performance liquid chromatography (HPLC) of the derived diacylglycerols. Enriched fractions of acetic and butyric acid‐containing triacylglycerols were isolated by normal‐phase thin‐layer chromatography (TLC) from a molecular distillate of butter oil, and they were fully hydrogenated. Mixedsn‐1,2(2,3)‐ andX‐1,3‐diacylglycerols of short‐ and long‐chainlength, which were generated by partial Grignard degradation of the hydrogenated triacylglycerols, were isolated by borate‐TLC. The enantiomericsn‐1,2‐andsn‐2,3‐diacylglycerols and theX‐1,3‐diacylglycerols as their 3,5‐dinitrophenylurethanes were resolved by HPLC on chiral columns. Both acetic and butyric acids were exclusively associated with thesn‐ 2,3‐ andX‐1,3‐diacylglycerols of short and long chainlength. These results establish the presence of acetic and butyric acids in thesn‐3‐position of bovine milk fat triacylglycerols. Other short‐and medium‐chainlength acids were found in progressively increasing proportions also in thesn‐1‐ andsn‐2‐positions.
Factors affecting the content of tocopherol in soybean oil
Authors: Chu Yan‐Hwa , Lin Jiuh‐Yaw
Published: February 2007

The state of soybeans prior to extraction affected the tocopherol content of crude soybean oils. Soybean flakes with a thickness of 0.16–0.33 mm had higher extracted oil yield but a slightly lower tocopherol content of the oils than did cracked beans and thicker bean flakes. Highmoisture content and long storage of soybeans resulted in lower tocopherol content in the crude oils, with moisture content being more important than storage time at decreasing the tocopherol content of oils. Soybean oil from stored beans with 15±1% moisture content led to a more significant decrease in the tocopherol content than did oil from stored beans with low (12%) or high (18%) moisture contents. Soybean flakes contaminated with oxidized oil had a significant effect on the decrease of the tocopherol content in crude oils. The high amount of phospholipids in crude soybean oil might result in a smaller decrease in the tocopherol content of oil during heating.
Increasing n‐3 polyunsaturated fatty acid content of fish oil by temperature control of lipase‐catalyzed acidolysis
Authors: Yamane Tsuneo , Suzuki Tomomasa , Hoshino Tamotsu
Published: February 2007

An attempt was made to further increase the content of n‐3 polyunsaturated fatty acid (n‐3 PUFA) of fish oil by lipase‐catalyzed acidolysis (reaction between fish oil and n‐3 PUFA‐enriched free fatty acid) without solvent. A bioreactor system was constructed composed of a water‐jacketed packed‐bed column and a substrate reservoir with a circulation pipeline between the packed‐bed column and the reservoir. By keeping the temperature of the reservoir at −10°C (for the first 20 h), followed by −20°C (for the subsequent 40 h) during the batch acidolysis, crystals of free fatty acid appeared, which were removed intermittently by a cotton plug packed in the tip of the outlet pipe in the reservoir. The n‐3 PUFA content of the triacylglycerol fraction increased a further 10% by the reduced temperature of the reservoir.
Dormancy of alpine and subalpine perennial forbs
Authors: Yoshie Fumio
Published: February 2007

Depth of dormancy of alpine and subalpine perennial forbs in autumn was investigated, which was judged by the number of days required for growth initiation at 24 °C. The depth of dormancy differed depending on Raunkiaer's life‐form and shoot habits. Chamaephytes with perennial shoot‐axes showed shallower dormancy than hemicryptophytes with annual shoot‐axes, and geophytes with annual shoot‐axes showed the deepest dormancy. The results strongly suggest that the dormancy is more endogenously controlled in forbs less hardy to freezing stress. Potential growth ability of alpine herbaceous chamaephytes in autumn is an adaptive advantage, since they utilize the short vegetative period as long as possible. All of the species with annual shoot‐axes had winter buds covered with scales. In plants with perennial shoot‐axes, percentage of winter buds covered with scales increased with increasing depth of dormancy. The results indicate that the shoot apices are well protected by bud scales in forbs with a long endogeneous‐dormant period.
Parental concerns about childhood obesity and the strategies employed to prevent unhealthy weight gain in children
Authors: Crawford David , Timperio Anna , Telford Amanda , Salmon Jo
Published: February 2007

Objectives

To describe parental concerns about their child's weight, to determine the proportion of parents taking preventive action to avoid obesity in their children and the predictors of taking preventive action, and to describe the strategies adopted by parents.

Design

A cross-sectional survey was conducted. Children's heights and weights were measured, and parents completed a questionnaire that included measures of their own weight status, perceptions of their child's weight, concerns about their child's current weight and future weight as an adolescent and adult, and the strategies used to prevent obesity.

Setting

The study was conducted in Melbourne, Australia.

Subjects

A total of 291 families of children aged 5–6 years and 919 families of children aged 10–12 years participated.

Results

Eighty-nine per cent of parents of overweight 5–6-year-olds and 63% of parents of overweight 10–12-year-olds were unaware their child was overweight. Seventy-one per cent of parents of overweight 5–6-year-olds and 43% of parents of overweight 10–12-year-olds were not concerned about their child's current weight. Although 31% of parents of 5–6-year-olds and 43% of parents of 10–12-year-olds were taking action to prevent unhealthy weight gain in their children, less-educated parents were less likely to do so.

Conclusions

Public health programmes are required to raise parental recognition of childhood overweight and of related risk behaviours, and to provide parents with practical strategies to prevent unhealthy weight gain in their children.
Bargaining in Legislatures over Particularistic and Collective Goods
Authors: VOLDEN CRAIG , WISEMAN ALAN E.
Published: February 2007

We develop a bargaining model in which a legislature divides a budget among particularistic and collective goods. By incorporating both private and public goods in a unified model, we uncover nonmonotonic relationships between legislative preferences for collective spending and the amount of the budget actually allocated to collective goods. Put simply, policy proposers can exploit coalition partners' strong preferences for public goods to actually provide fewer public goods in equilibrium while directing more private goods to themselves. These results explain why policy reforms to limit special interest spending often fail. This unified model also sheds new light on when legislatures prefer open or closed amendment rules and when coalitions take different sizes and shapes.
The Genders of Citizenship
Authors: LEONARD STEPHEN T. , TRONTO JOAN C.
Published: February 2007

One important legacy of republicanism is the ideal of good citizenship; a related legacy of republicanism is the equation of citizenship and masculinity. These legacies are at once strange and familiar: today, masculinity and citizenship are often conceptualized as discrete and distinctive identities, and some critics, most notably feminists, suggest that in modern democraciesgoodcitizenship and masculinity may even be contradictory ideals. The source of these conceptual paradoxes is the transformation of gender and civic discourse in the early modern period, particularly the “long eighteenth century.” Understanding the implications of these changes helps us better grasp both the relationship of gender and citizenship today, and how a more effectively engaged and meaningfully egalitarian form of democratic citizenship, for men and women, might be realized.
Mort subite chez les jeunes athlètes
Authors: Gojanovic  , Feihl  , Gremion  , Waeber
Published: February 2007

La mort subite d'origine cardiaque chez le jeune athlète est marquante, tragique et souvent médiatisée, dont l'impact est plus important que son incidence (1–2/100000 par an). L'étiologie principale est la cardiomyopathie hypertrophique, suivie des anomalies coronariennes. On retrouve parfois une myocardite à l'autopsie. Les recommandations d'examen de pré-participation des athlètes exigent une anamnèse et un examen physique ciblés, voire un électrocardiogramme. Un programme de dépistage systématique en Italie a permis de réduire la survenue de ces décès, décès dont la statistique est inexistante en Suisse. Il serait utile d'instaurer un examen de pré-participation standardisé, de même que de s'assurer que les entraîneurs, enseignants en sports et athlètes eux-mêmes sachent reconnaître les fréquents symptômes d'alarme.
Neuropsychologische Diagnostik von Merk- und Lernstörungen mit der MLT-C
Authors: Lepach Anja C. , Petermann Franz , Schmidt Sören
Published: February 2007

Zusammenfassung. Bei der Memory and Learning Testbatterie for Children (MLT-C) handelt es sich um ein Verfahren, das zur Erfassung globaler sowie modalitäts- und funktionsspezifischer Störungen der Merk- und Lernfähigkeit bei 6;0- bis 16;11-Jährigen konzipiert wurde. Die Testbatterie ist in acht Hauptuntertest und sechs optionale Zusatztests gegliedert. Es lassen sich fünf verschiedene Skalen ermitteln: Aufmerksamkeit/Konzentration, Visuelles Merken, Visuelles Lernen, Auditives Merken und Auditives Lernen. Die Testbatterie wurde an 405 Kindern in Deutschland und der Schweiz normiert und auf die teststatistische Gültigkeit der Items überprüft. Die statistischen Kennwerte p und r(it) sind in allen Hauptuntertests mindestens zufrieden stellend. Daraus lässt sich ableiten, dass es sich hier um ein hilfreiches Verfahren zur kindgerechten Diagnostik von Merk- und Lernfähigkeitsstörungen handelt.
Aufmerksamkeitsstörungen im Kindesalter
Authors: Konrad Kerstin , Gilsbach Susanne
Published: February 2007

Zusammenfassung. Der vorliegende Übersichtsartikel beschäftigt sich mit der Bedeutung der funktionellen Kernspintomographie (fMRT) für diagnostische und therapeutische Aspekte von kindlichen Aufmerksamkeitsstörungen. Nach einer kurzen Einführung in die Methode und ihre Besonderheiten bei der Anwendung im Kindesalter, werden Ergebnisse aus fMRT-Studien bei Kindern mit einem Aufmerksamkeitsdefizit/Hyperaktivitätssyndrom (ADHS) zusammengefasst. Abschließend werden weitergehende Chancen und Nutzen der funktionellen Kernspintomographie für die klinische Praxis und zukünftige Forschungsperspektiven diskutiert.
Tests und Tools
Authors: Schmidt-Atzert Lothar
Published: February 2007

Zusammenfassung. Die ASK soll mit insgesamt sieben Subtests die Intelligenzkomponenten Schlussfolgerndes und Kreatives Denken erfassen. Sie wurde für junge Erwachsene mit Bildungsabschluss Abitur entwickelt und an einer entsprechenden Personengruppe normiert. Der Test kann als objektiv und hinreichend reliabel gelten. Die Konstruktvalidität wird insbesondere durch hohe Korrelationen des Schlussfolgernden Denkens mit Verarbeitungskapazität im BIS und hohe Korrelationen des Kreativen Denkens mit einem Test zur verbalen Kreativität belegt. Die beiden Testmodule können zu einem Gesamtwert verrechnet werden, dessen konzeptuelle Bedeutung aber nicht hinreichend belegt ist.
Direct radiative effect of mineral dust and volcanic aerosols in a simple aerosol climate model
Authors: Shell Karen M. , Somerville Richard C. J.
Published: February 2007

Airborne mineral dust can influence the climate by altering the radiative properties of the atmosphere, but the magnitude of the effect is uncertain. An idealized global model is developed to study the dust‐climate system. The model determines the dust longwave and shortwave direct radiative forcing, as well as the resulting temperature changes, based on the specified dust distribution, height, and optical properties. Comparisons with observations and general circulation results indicate that the model produces realistic results for the present‐day dust distribution as well as for volcanic aerosols. Although the model includes many simplifications, it can still provide insight into dust‐climate system behavior. Recent observations suggest that dust may absorb less solar radiation than previously thought. Experiments with the model suggest that previous studies which used more absorbing dust may be underestimating the effect of dust. Increasing the solar single scattering albedo value from 0.85 to 0.97, corresponding to recent measurements, more than doubles the modeled global average top‐of‐the‐atmosphere (TOA) shortwave direct forcing for the present‐day dust distribution, while the surface shortwave forcing is halved. The corresponding temperature decreases are larger for the larger single scattering albedo, and the latent and sensible heat fluxes decreases are smaller. The dust forcing and climate response are approximately linear with respect to optical depth. However, the relationship depends on the relative magnitudes of shortwave versus longwave TOA forcing. Thus the net TOA forcing alone does not determine the steady state climate response.
Kulikovskiy–Sveshnikova–Beghin model of powder snow avalanches: Development and application
Authors: Turnbull B. , McElwaine J. N. , Ancey C.
Published: February 2007

A simple theoretical model, the Kulikovskiy–Sveshnikova–Beghin (KSB) model, is outlined, describing the motion of a particle cloud moving down an incline. This model includes both the entrainment of surrounding ambient fluid and the entrainment of particles from the slope and is equally valid for Boussinesq and non‐Boussinesq flows. However, this model can predict physically impossible densities when there is significant particle entrainment. Modifications to the model are proposed which eliminate this problem by including the entrained snow volume. With the modified model, physically realistic mean densities are predicted which have a significant impact on the Richardson number–dependent ambient entrainment. The improvements are illustrated by comparing analytical solutions to the original and the modified KSB equations for the case of a particle cloud traveling on a slope of constant angle, with constant ambient fluid and particle entrainment. Solving the modified model numerically, predictions are compared with data from several large powder snow avalanches at the Swiss Vallée de la Sionne avalanche test site. The modified KSB model appears to capture the dynamics of the avalanche front well; however, problems remain with relating the theoretical geometry to a real avalanche geometry. The success of this model in capturing the front dynamics shows that with careful assumptions that reflect the physics, it is possible to describe aspects of complex flows such as powder snow avalanches with simple models.
Size dependence of effective Young’s modulus of nanoporous gold
Authors: Mathur Anant , Erlebacher Jonah
Published: February 2007

Nanoporous gold (NPG) is a brittle, three-dimensional, random structure of Au with nanometer scale open porosity that is made by dealloying Au∕Ag alloys in acid. In this work, Young’s modulus of NPG with controlled porosity variation between 3 and 40nm is determined by mechanical testing of ∼100nm thick, free standing, large-grained, stress-free films of NPG using a buckling-based method [C. Stafford et al., Nat. Mater. 3, 545 (2005)]. Results showing a dramatic rise in the effective Young’s modulus of NPG with decreasing ligament size, especially below 10nm are presented, and possible reasons for this behavior are discussed.
Hyperthermia applicator based on a reentrant cavity for localized head and neck tumors
Authors: Ishihara Yasutoshi , Gotanda Yuya , Wadamori Naoki , Matsuda Jin-ichi
Published: February 2007

A new applicator based on a reentrant cavity is proposed for treating localized tumors such as those of the head and neck. In order to effectively heat the localized tumor without causing dissipation of heat into the surrounding normal tissues, the electric field must be localized over the target region. Although a small applicator may produce an appropriate localized electric field, the higher resonant frequency due to downsizing of the equipment results in very poor heating distribution; this occurs due to the changes in electric permittivity and conductivity consequent upon an increase in the resonant frequency. In this article, we introduce a method for reducing the resonant frequency by inserting a dielectric material into the applicator; the efficacy of this method has been determined by calculating the electromagnetic field and heating distribution with the help of the finite element method. By using the proposed applicator, a reduction in the resonant frequency and localized heating over spherical regions 100mm in diameter can be achieved.
Interface formation between poly(9,9-dioctylfluorene) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid)
Authors: Chang Chih-Hao , Liao Jin-Long , Hung Ming-Chin , Chen Show-An
Published: February 2007

By using ultraviolet photoelectron spectroscopy, the hole-injection barrier of poly-(9,9-dioctylfluorene) (PFO) cast on top of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) electrode is found to vary with thickness of both films, as confirmed by current profiles of hole-dominated and bipolar devices. The variation can be attributed to a migration of PSS chain as a dopant into PFO layer, as indicated by the broadening and shifting (towards higher binding energy) of highest occupied molecular orbital edge peak of PFO film. The barrier at the thinnest PEDOT:PSS film (15nm) is found to be the smallest due to the least extent of doping by PSS chains.
Lowering of the L1 ordering temperature of FePt nanoparticles by He+ ion irradiation
Authors: Wiedwald U. , Klimmer A. , Kern B. , Han L. , Boyen H.-G. , Ziemann P. , Fauth K.
Published: February 2007

Arrays of FePt particles (diameter 7nm) with mean interparticle distances of 60nm are prepared by a micellar technique on Si substrates. The phase transition of these magnetic particles towards the chemically ordered L10 phase is tracked for 350kV He+ ion irradiated samples and compared to a nonirradiated reference. Due to the large separation of the magnetically decoupled particles the array can be safely annealed without any agglomeration as usually observed for more densely packed colloidal FePt nanoparticles. The He+ ion exposure yields a significant reduction of the ordering temperature by more than 100K.
Atomic force microscopy images of lyotropic lamellar phases
Authors: Garza C. , Thieghi L. T. , Castillo R.
Published: February 2007

For the very first time, atomic force microscope images of lamellar phases were observed combined with a freeze fracture technique that does not involve the use of replicas. Samples are rapidly frozen, fractured, and scanned directly with atomic force microscopy, at liquid nitrogen temperature and in high vacuum. This procedure can be used to investigate micro-structured liquids. The lamellar phases in Sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/water and in C12E5/water systems were used to asses this new technique. Our observations were compared with x-ray diffraction measurements and with other freeze fracture methods reported in the literature. Our results show that this technique is useful to image lyotropic lamellar phases and the estimated repeat distances for lamellar periodicity are consistent with those obtained by x-ray diffraction.
Direct action of gonadotropin in brain integrates behavioral and reproductive functions
Authors: Yang Eun-Jin , Nasipak Brian T. , Kelley Darcy B.
Published: February 2007

Essential roles for gonadotropins in gonadal development and reproduction are well established. Over the past decade, however, the expression of luteinizing hormone receptor (LHR) has also been reported in the brain of various mammals and birds. Although suggestive, it has not yet been determined whether this expression pattern supports a novel function for gonadotropins. Here, we demonstrate a CNS-mediated role of gonadotropins in a reproductive behavior: the courtship songs of the South African clawed frog,
Xenopus laevis
. Male advertisement calling in this species depends on a nongonadal action of gonadotropin. To determine whether this effect is due to action on the CNS, we administered gonadotropin intracerebroventricularly (ICV) or systemically to intact or castrated males with or without concomitant androgen replacement. In intact and androgen-replaced gonadectomized males, gonadotropin significantly increased calling within 1 h after ICV injection. The effective dosage via ICV injections was less than one hundredth of the effective systemic dose.
In situ
hybridization with a cloned fragment of
Xenopus
LHR revealed strong expression in ventral forebrain areas important for vocal control. Further, gonadotropin treatment of brain
in vitro
up-regulates immunoreactivity for the LHR downstream target,
egr-1
, specifically in these vocal forebrain areas. Up-regulation occurs even when synaptic transmission is suppressed by incubation in Ca
2+
free/high magnesium saline. These results demonstrate a neural role for gonadotropin in the control of calling behavior, potentially mediated via LHRs in forebrain vocal nuclei. Gonadotropin may play a novel integrative role in modulating both reproductive physiology and behavior.
Dietary sequestration of defensive steroids in nuchal glands of the Asian snake
Rhabdophis tigrinus
Authors: Hutchinson Deborah A. , Mori Akira , Savitzky Alan H. , Burghardt Gordon M. , Wu Xiaogang , Meinwald Jerrold , Schroeder Frank C.
Published: February 2007

The Asian snake
Rhabdophis tigrinus
possesses specialized defensive glands on its neck that contain steroidal toxins known as bufadienolides. We hypothesized that
R. tigrinus
does not synthesize these defensive steroids but instead sequesters the toxins from toads it consumes as prey. To test this hypothesis, we conducted chemical analyses on the glandular fluid from snakes collected in toad-free and toad-present localities. We also performed feeding experiments in which hatchling
R. tigrinus
were reared on controlled diets that either included or lacked toads. We demonstrate that the cardiotonic steroids in the nuchal glands of
R. tigrinus
are obtained from dietary toads. We further show that mothers containing high levels of bufadienolides can provision their offspring with toxins. Hatchlings had bufadienolides in their nuchal glands only if they were fed toads or were born to a dam with high concentrations of these compounds. Because geographic patterns in the availability of toxic prey are reflected in the chemical composition of the glandular fluid, snakes in toad-free regions are left undefended by steroidal toxins. Our findings confirm that the sequestration of dietary toxins underlies geographic variation in antipredatory behavior in this species and provide a unique example of sequestered defensive compounds in a specialized vertebrate structure.
Differential requirement for MuSK and dystroglycan in generating patterns of neuromuscular innervation
Authors: Lefebvre Julie L. , Jing Lili , Becaficco Sara , Franzini-Armstrong Clara , Granato Michael
Published: February 2007

Vertebrates display diverse patterns of neuromuscular innervation, but little is known about how such diversity is generated. In mammals, neuromuscular junctions form predominantly at equatorial locations, giving rise to a focal innervation pattern along a central endplate band. In addition, vertebrate striated muscles exhibit two nonfocal neuromuscular patterns, myoseptal and distributed innervation. Although agrin-MuSK-rapsyn signaling is essential for the focal innervation pattern, it is unknown whether the same genetic program also controls synaptogenesis at nonfocal innervation sites. Here we show that one of three transcripts generated by the zebrafish
unplugged
locus,
unplugged
FL, encodes the zebrafish MuSK ortholog. We demonstrate that UnpFL/MuSK is critical for the assembly of focal synapses in zebrafish and that it cooperates with dystroglycan in the formation of nonfocal myoseptal and distributed synapses. Our results provide the first genetic evidence that neuromuscular synapse formation can occur in the absence of MuSK and that the combinatorial function of UnpFL/MuSK and dystroglycan generates diverse patterns of vertebrate neuromuscular innervation.
Cooperative assembly of higher-order Notch complexes functions as a switch to induce transcription
Authors: Nam Yunsun , Sliz Piotr , Pear Warren S. , Aster Jon C. , Blacklow Stephen C.
Published: February 2007

Notch receptors control differentiation and contribute to pathologic states such as cancer by interacting directly with a transcription factor called CSL (for CBF-1/Suppressor of Hairless/Lag-1) to induce expression of target genes. A number of Notch-regulated targets, including genes of the hairy/enhancer-of-split family in organisms ranging from
Drosophila
to humans, are characterized by paired CSL-binding sites in a characteristic head-to-head arrangement. Using a combination of structural and molecular approaches, we establish here that cooperative formation of dimeric Notch transcription complexes on promoters with paired sites is required to activate transcription. Our findings identify a mechanistic step that can account for the exquisite sensitivity of Notch target genes to variation in signal strength and developmental context, enable new strategies for sensitive and reliable identification of Notch target genes, and lay the groundwork for the development of Notch pathway inhibitors that are active on target genes containing paired sites.
Coherence, Consistency, and Cohesion: Clade Selection in Okasha and Beyond
Authors: Haber Matthew H. , Hamilton Andrew
Published: February 2007

Samir Okasha argues that clade selection is an incoherent concept, because the relation that constitutes clades is such that it renders parent-offspring (reproduction) relations between clades impossible. He reasons that since clades cannot reproduce, it is not coherent to speak of natural selection operating at the clade level. We argue, however, that when species-level lineages and clade-level lineages are treated consistently according to standard cladist commitments, clade reproduction is indeed possible and clade selection is coherent if certain conditions obtain. Despite clade selection's logical coherence, however, we share some of Okasha's pessimism. Whether or not clades are a unit of selection is ultimately a question of empirical support and theoretical import.
Thermodynamic Irreversibility: Does the Big Bang Explain What It Purports to Explain?
Authors: Parker Daniel
Published: February 2007

In this paper I examine Albert's (2000) claim that the low entropy state of the early universe is sufficient to explain irreversible thermodynamic phenomena. In particular, I argue that conditionalizing on the initial state of the universe does not have the explanatory power it is presumed to have. I present several arguments to the effect that Albert's ‘past hypothesis’ alone cannot justify the belief in past nonequilibrium conditions or ground the veracity of records of the past.
Scientific Models and the Semantic View of Scientific Theories
Authors: Portides Demetris P.
Published: February 2007

I argue against the conception of scientific models advocated by the proponents of the Semantic View of scientific theories. Part of the paper is devoted to clarifying the important features of the scientific modeling view that the Semantic conception entails. The liquid drop model of nuclear structure is analyzed in conjunction with the particular auxiliary hypothesis that is the guiding force behind its construction and it is argued that it does not meet the necessary features to render it a model of the theory, as the Semantic View demands. Given that this model is indicative of how quantum mechanics is applied in the domain of nuclear physics, I claim that the Semantic View does not adequately account for scientific models.
Heritability and Genetic Causation
Authors: Oftedal Gry
Published: February 2007

The method in human genetics of ascribing causal responsibility to genotype by the use of heritability estimates has been heavily criticized over the years. It has been argued that these estimates are rarely valid and do not trace genetic causation. Recent contributions strike back at this criticism. I present and discuss two opposing views on these matters represented by Richard Lewontin and Neven Sesardic. I suggest that the conflicting perspectives are based in differing concepts of genetic causation and differing motivations and contexts of discussion. I use the distinction between structuring and triggering causes to clarify the basis for the opposing views.
Can Modal Interpretations of Quantum Mechanics Be Reconciled with Relativity?
Authors: Berkovitz Joseph , Hemmo Meir
Published: February 2007

Modal interpretations are hidden-variable, no-collapse interpretations of quantum mechanics that were designed to solve the measurement problem and reconcile this theory with relativity. Yet, as no-go theorems by Dickson and Clifton (1998), Arntzenius (1998) and Myrvold (2002) demonstrate, current modal interpretations are incompatible with relativity. In the mainstream modal interpretations, properties of composite systems are generally unrelated to the properties of their subsystems. We propose holistic and relational interpretations of properties to explain this failure of property composition. Based on these interpretations, we consider strategies for circumventing Myrvold's theorem, which are also effective against the other two theorems.
Background Theories and Total Science
Authors: Magnus P. D.
Published: February 2007

Background theories in science are used both to prove and to disprove that theory choice is underdetermined by data. The alleged proof appeals to the fact that experiments to decide between theories typically require auxiliary assumptions from other theories. If this generates a kind of underdetermination, it shows that standards of scientific inference are fallible and must be appropriately contextualized. The alleged disproof appeals to the possibility of suitable background theories to show that no theory choice can be timelessly or noncontextually underdetermined: Foreground theories might be distinguished against different backgrounds. Philosophers have often replied to such a disproof by focussing their attention not on theories but on Total Sciences. If empirically equivalent Total Sciences were at stake, then there would be no background against which they could be differentiated. I offer several reasons to think that Total Science is a philosophers’ fiction. No respectable underdetermination can be based on it.
Robustness and Conceptual Analysis in Evolutionary Game Theory
Authors: Ernst Zachary
Published: February 2007

A variety of robustness objections have been made against evolutionary game theory. One of these objections alleges that the games used in the underlying model are too arbitrary and oversimplified to generate a robust model of interesting prosocial behaviors. In this paper, I argue that the robustness objection can be met. However, in order to do so, we must attend to important conceptual issues regarding the nature of fairness, justice, and other moral concepts. Specifically, we must better understand the relationship between moral concepts and formal characterizations of games.
Alpha-gamma Angular Correlation and Hyperfine Interaction in the Decay of24998Cf
Authors: F Falk  , A Linnfors  , B Orre  , J E Thun
Published: February 2007

The angular correlation between the main α-transition (5.81 MeV) and the following 388 KeVE1 gamma transition (and in one case also the 333 KeVE1 transition branching from the same level) in the decay of24998Cf to24596Cm has been studied. Thin sources were used. The recoiling daughter ions were allowed to escape into vacuum. The strong hyperfine interaction perturbing the correlation in this case was neutralized by a longitudinal decoupling field with a strength of some kilogauss. The unperturbed values of theA22-coefficients do not support the mixing ratios (L=0,L=2,L=4) from the Bohr-Fröman-Mottelson theory. The correlation was also studied, in silver and nickel surroundings where it was found to be almost unperturbed. In an insulator a strong perturbation was found which was not influenced by the longitudinal field.
Helical Spin Arrangement in Cubic FeGe
Authors: L Ludgren  , O Beckman  , V Attia  , S P Bhattacheriee  , M Richardson
Published: February 2007

The magnetic properties of single crystals of the cubic B20 modification of the metallic compound FeGe have been investigated by means of a vibrating-sample magnetometer and a torsion balance. Transition to an ordered spin structure occurs at 280 K. Magnetization curves below this temperature shown an almost linear field dependence for the [100], [111] directions with a field of about 2 kOe required for saturation at low temperatures, indicating a small magnetocrystalline energy compared to the exchange energy. The saturation moment as extrapolated to zero Kelvin corresponds to 1.0μ
B
. A model with the spins forming a helical screw propagating in the [111] direction at zero field is proposed to explain the observed magnetic properties.
Relativistic Kinematics for N-particle Scattering States. Classical treatment
Authors: Karl-Erik Eriksson
Published: February 2007

Scattering states with N free particles are studied in classical mechanics. Generalized angular variables and angular momentum variables suitable to a relativistic description are introduced. The angular variables are defined as orthogonal coordinates in the (3 N-3)-dimensional space of relative momenta; they are orthogonal also to the total mass which fills the function of radial coordinate. "Grand angular momentum" is defined. It generates mappings of any surface M = const. onto itself. The generators satisfy the Lie algebra of O(3 N-3). Much of the formalism for describing the plane motion of one single particle can be adequately generalized to the free motion of N particles. The connection between grand angular momentum and the N-particle impact parameter is discussed in some detail. The generalization to quantum mechanics will be the subject of a later paper.
Term Analysis of Zr VI, Nb VII and Mo VIII
Authors: Mirza Said-uz-Zafar Chaghtai
Published: February 2007

Term analyses of the 4p-4dand 4p-5stransitions in Zr VI, Nb VII and Mo VIII are described. Interaction between the 4dand 5slevels is discussed, and the whole sequence of Br I-like spectra is briefly reviewed.
Internal Pressure in Solids and Liquids
Authors: G Borelius
Published: February 2007

The internal pressure parameter α, first derived from the compressibility of metals and alkali-halides, is interpreted as α = dW/dV where W is the potential energy and V the volume. This expression enables the evaluation of α from measurements on thermal energy and thermal expansion. With now available experimental results α-values can in this way be obtained for most metals at ordinary temperatures and in some cases these values can be compared with values from very low temperatures and values obtained from melting and the liquid state. Though α must be expected to vary with the volume the variations do not exceed the limits of the present experimental uncertainty. The experimental α-values are used for a determination of the electron density in metals and for an interpretation of the activation energy of diffusion.
Nuclear lifetimes in 37K and 39K
Authors: A Anttila  , M Bister  , E Arminen  , T Kouki
Published: February 2007

The mean lives of levels in 37K and 39K have been measured with the Doppler-shift attenuation method through the 36Ar(p,γ)37K and 38Ar(p,γ)39K reaction. The ions 36Ar (0.337%) and 38Ar (0.063%) were separated into a tantalum backing. The mean lives or their upper limits of the 2 523 keV, 3 020 keV and 7 738 keV states in 39K and of the 2 750 keV state in 37K were determined as τ
m
= 32 ± 12 fs, 21 ± 6 fs, < 4 fs and < 6 fs, respectively. The result obtained for the Q-value of the 38Ar(p,γ)39K reaction was 6 381.2 ± 1.2 keV. Some information concerning the decay of the 38Ar(p,γ)39K E
p = 1 393 keV resonance is also gained. The results on τ are compared with predictions from previous shell-model calculations.
A Pulse Generator for Short Megavolt Pulses with a Risetime in the Nanosecond Region
Authors: N R Nilsson  , L Högberg  , A Svedberg  , J Hipple
Published: February 2007

The design principles of a pulse generator using circular plate capacitors to generate high voltage pulses is described. The properties of such capacitors, discharged in the centre, are utilized to get a fast risetime whilst maintaining a flexible and compact design. The properties of generators with output voltages of 300 kV, 600 kV and 1.2 MV at load impedance of 40 ohms, 60 ohms and 120 ohms respectively, have been studied. The duration of the voltage pulse is approximately 20 nanoseconds.
On Kinematic Singularities of Transversity Amplitudes
Authors: Nils Johannesson
Published: February 2007

A method given by Trueman for obtaining the kinematic singularities of helicity amplitudes is applied to the transversity amplitudes introduced by Kotánski.

The results are in agreement with those found by other methods. In two cases, viz. the physical boundary singularities and the s = 0 singularities for equal incoming and outgoing masses, more explicit formulae are worked out.
The 5g Levels of the Alkali Metals
Authors: Ulf Litzén
Published: February 2007

The wavelengths of the 4f-5gtransitions of the alkali metals as emitted from a hollow-cathode lamp have been measured, and the term values derived from the observations are compared with those predicted by the polarization formula.
Thermal Conductivity of AgCl to 35 kbar
Authors: T Rosander  , G Bäckström
Published: February 2007

The thermal conductivity of polycrystalline AgCl was determined in cylindrical geometry at 300 K. A 27% increase of the conductivity in the pressure range 0-25 kbar was found and there was no evidence for a phase transition below 35 kbar.
Tyrannosaur ageing
Authors: Ricklefs Robert E
Published: February 2007

Rate of ageing in tyrannosaurs was calculated from parameters of Weibull functions fitted to survival curves based on the estimated ages at death of fossilized remains. Although tyrannosaurs are more closely related to birds than to mammals, they apparently aged at rates similar to mammals of comparable size. Rate of growth in body mass of tyrannosaurs was similar to that of large mammals, and their rates of ageing were consistent with the estimated extrinsic mortality, which is strongly correlated with the rate of ageing across birds and mammals. Thus, tyrannosaurs appear to have had life histories resembling present-day large terrestrial mammals. Rate of ageing in warm-blooded vertebrates appears to be adjusted in response to extrinsic mortality and potential lifespan, independently of both physiological and developmental rates. However, individuals in species with the slowest rates of ageing suffer the highest proportion of ageing-related mortality, hence potentially strong selection to further postpone senescence. Thus, the longest observed lifespans in birds, tyrannosaurs and mammals might be close to the maximum possible.
The visual processing of motion-defined transparency
Authors: Curran William , Hibbard Paul B , Johnston Alan
Published: February 2007

Our understanding of how the visual system processes motion transparency, the phenomenon by which multiple directions of motion are perceived to coexist in the same spatial region, has grown considerably in the past decade. There is compelling evidence that the process is driven by global-motion mechanisms. Consequently, although transparently moving surfaces are readily segmented over an extended space, the visual system cannot separate two motion signals that coexist in the same local region. A related issue is whether the visual system can detect transparently moving surfaces simultaneously or whether the component signals encounter a serial ‘bottleneck’ during their processing. Our initial results show that, at sufficiently short stimulus durations, observers cannot accurately detect two superimposed directions; yet they have no difficulty in detecting one pattern direction in noise, supporting the serial-bottleneck scenario. However, in a second experiment, the difference in performance between the two tasks disappears when the component patterns are segregated. This discrepancy between the processing of transparent and non-overlapping patterns may be a consequence of suppressed activity of global-motion mechanisms when the transparent surfaces are presented in the same depth plane. To test this explanation, we repeated our initial experiment while separating the motion components in depth. The marked improvement in performance leads us to conclude that transparent motion signals are represented simultaneously.
Biological solar energy
Authors: Barber James
Published: February 2007

Through the process of photosynthesis, the energy of sunlight has been harnessed, not only to create the biomass on our planet today, but also the fossil fuels. The overall efficiency of biomass formation, however, is low and despite being a valuable source of energy, it cannot replace fossil fuels on a global scale and provide the huge amount of power needed to sustain the technological aspirations of the world population now and in the future. However, at the heart of the photosynthetic process is the highly efficient chemical reaction of water splitting, leading to the production of hydrogen equivalents and molecular oxygen. This reaction takes place in an enzyme known as photosystem II, and the recent determination of its structure has given strong hints of how nature uses solar energy to generate hydrogen and oxygen from water. This new information provides a blue print for scientists to seriously consider constructing catalysts that mimic the natural system and thus stimulate new technologies to address the energy/CO
2
problem that humankind must solve. After all, there is no shortage of water for this non-polluting reaction and the energy content of sunlight falling on our planet well exceeds our needs.