bluuebunny/crossref_metadata_2025 huggingface dataset:
Recherches sur les hétérostéroïdes. V. Synthèse et configuration des éthers méthyliques de la benzo‐15,16‐ et de la cyclohexano‐15,16‐méthoxy‐2 diaza‐8,13 oestrone
Authors: Redeuilh GÉRard , Viel Claude , Leroy FranÇOise , Hospital Michel
Published: April 2009

Synthèses stéréospécifiques des hétérostéroïdes mentionnés ci‐dessus, par cyclisation réductrice de la diméthoxy‐6,7 phtalimidoéthyl‐1 dihydro‐3,4 isoquinoléine. Détermination de leur configuration par spectroscopie IR et de RMN, et par radiocristallographie.
Rates and mechanisms of indole and 3‐Methylindole polymerization in cation exchange resin beads
Authors: Youmans Hubert L. , Rush James B. , Brown Van H.
Published: April 2009

Batch extraction and polymerization of indole and 3‐methylindole (skatole) with acidic cation exchange resins functioned as pseudo first‐order reactions. Activation energies of 3.4 and 5.7 keal/mole indicated greater steric hindrance to skatole polymerization, as would be expected from 2,2′ bonding of skatole compared to 3,2′ bonding for indole. Linear polymerization occurred, although a heterocyclic ring opened at the trimer stage of poly(indole). 2‐Methylindole did not polymerize.

General acid‐base catalysis caused unreproducible partial depolytnerization when the polymers were extracted from resin beads. Thus, compounds chromatographically separated probably were of lower degree of polymerization than were the polymers formed in the resin matrix.
Preparation of some perhydrothiazolo[3,2‐a] [1,3,5] triazine‐2,4‐diones
Authors: Bigg D. C. H. , Purvis S. R.
Published: April 2009

2‐Dialkylamino‐δ2‐thiazolines were found to react with aryl isocyanates to give 1,3‐diaryl‐8a‐dialkylaminoperhydrothiazolo[3,2‐a ] [ 1,3,5]triazine‐2,4‐diones (IIa‐c), while p‐toluenesulphonyl isocyanate gave a 1:1 adduct (VII). No reaction was observed with alkyl or aryl isothiocyanates.
Mass spectral fragmentation pattern of 2,2′‐Bipyridyls. Part III. 2‐(2‐pyridyl)quinoline and 2,2′‐Biquinoline
Authors: Keats N. G. , Summers L. A.
Published: April 2009

The mass spectral fragmentation patterns of 2‐(2‐pyridyl)quinoline and 2,2′‐biquinoline are reported. The former rearranges to acridine derivatives on electron impact while the latter shows very little fragmentation.
Mass spectral fragmentation of 4‐oxo‐4H‐pyrazole 1‐oxides and 1,2‐dioxides
Authors: Hansen John F. , O'Hare Michael J.
Published: April 2009

The characteristic fragmentation pattern in the mass spectra of 4‐oxo‐4H‐pyrazole 1‐oxides and 4‐oxo‐4H‐pyrazole 1,2‐dioxides involves scission of the ring into two fragments by cleavage of the nitrogen‐nitrogen bond and one of the bonds to the carbonyl carbon. Loss of carbon monoxide or oxygen from the molecular ion is not observed.
Thermal decomposition of s‐2‐benzothiazole thiocarbonates
Authors: Chen C. H.
Published: April 2009

Thermal decompositions of S‐2‐benzothiazole thiocarbonates have been investigated. The results are best rationalized by an Sni ion‐pair return mechanism from which S‐substituted benzothiazoles are the major products obtained. The ready ionization of the carbon‐oxygen bond of thiocarbonates at elevated temperature renders a concerted Sni mechanism (internal substitution with allylic rearrangement) inoperative. Of particular interest is the mixed benzo‐thiazole‐2‐thiol and 2‐thione compound isolated from the decomposition of 2 (or 3)‐halogen‐substituted ethyl (or propyl) thiocarbonates. Evidence is presented that the thione 14 results from the nucleophilic opening of the cyclic intermediate, 2,3‐dihydrothiazolo[2,3‐b]benzothi‐azolium chloride (20). The latter is readily formed under the experimental condition by intramolecular cyclization of the corresponding 2‐(2‐chloroethyl)benzothiazole (23), a primary product from the decomposition of S‐2‐benzothiazole 2‐chloroethylthiocarbonate (7).
Hashish (1): Ceric ammonium nitrate oxidation of Δ6a, 1 0 a‐tetrahydrocannabinols (THC's)
Authors: Razdan Raj K. , Dalzell Haldean C. , Herlihy Patricia
Published: April 2009

A procedure is described for the conversion of acetates of Δ6a, 1 0 a‐THC's (2 and 4a) to their corresponding 7‐oxo‐derivatives (3a, b, d and 4b) by oxidation with ceric ammonium nitrate. The differences between the nmr spectra of these 7‐oxo‐derivatives and the 10‐oxo‐THC (1) are discussed. The 7‐oxo‐derivatives show THC‐like activity in mice albeit less than their corresponding THC's.
Use of the mannich reaction in the synthesis of bispidine
Authors: Ruenitz Peter C. , Smissman Edward E.
Published: April 2009

A three‐step synthesis of bispidine (1) is described. Mannich condensation of N‐benzyl‐4‐piperidone, formaldehyde, and benzylamine afforded N,N′‐dibenzylbispidinone (5), which was reduced under modified Wolff‐Kishner conditions to yield N,N′ ‐dibenzylbispidine (6). Catalytic debenzylation of this compound gave 1.
Synthesis of carbohydrate‐saccharin conjugates
Authors: Szarek Walter A. , Depew Catherine , Jones J. K. N.
Published: April 2009

The synthesis of some carbohydrate‐saccharin conjugates has been achieved by treatment of sugar derivatives containing “isolated” hydroxyl groups with equimolar amounts of saccharin, diethyl azodicarboxylate, and triphenylphosphine. Both C‐N‐linked and C‐O‐linked compounds can be obtained.
1,2,3‐thiadiazolo[5,4‐b]pyrimidin‐4(5H)ones
Authors: Hymans William E.
Published: April 2009

The synthesis of 1,2,3‐thiadiazolo[5,4‐d]pyrimidin‐4(5H)ones substituted in the 6‐position with hydrogen, all possible isomers of alkyl methyl through butyl, and 2,2‐dirnethylpropyl is deseribed.
Chemistry of Thienopyridines. XXIV. Two Transformations of Thieno[ 2,3‐b] pyridine 7‐Oxide
Authors: Ktemm L. H. , Hartling Ross
Published: April 2009

Refluxing thieno[2,3‐b ]pyridine 7‐oxide (1) with aeetic anhydride plus subsequent hydrolysis produced a mixture of thieno[2,3‐b]pyrid‐6(7H)one (2) (13%) and 5‐hydroxythieno[2,3‐b]‐pyridine (4) (4%). Refluxing 1 with phosphorus oxychloride yielded a mixture of 4‐ and 6‐chloro‐thieno[2,3‐b]pyridines, (5) (54%) and (6) (31%), respectively. Compound 6 was also obtained directly from 2 (31%). A mechanistic rationalization for the isomerization of 1 to form 2 and 4 is presented. Marked differences in the mass spectral fragmentations of these three isomeric compounds are noted.
Magnetic circular dichroism spectra of some s‐triazolo[1,5‐b] isoquinolin‐5(H)ones, 1,2‐dihydro‐6h‐s‐tetrazino[2,3‐b]isoquinolin‐6‐ones and related compounds
Authors: Higashi M. , Yamaguchi H.
Published: April 2009

Magnetic circular dichroism spectra of s‐triazolo[ 1,5‐b]isoquinolin‐5(H)ones, 1,2‐dihydro‐6H‐s‐tetrazino[2,3‐b] isoquinolin‐6‐ones and realted compounds were measured. The molecular symmetry of these compounds is so low that the MCD spectra contain only the Faraday parameter B. It appears that the magnitude and sign of the B term depends on the nature of the subslituents and of electron migration from endo‐ or exo‐nitrogen to oxygen, respectively.
Exogenous applications of salicylic acid affect quality and yield of strawberry grown under antifrost heated greenhouse conditions
Authors: Karlidag Huseyin , Yildirim Ertan , Turan Metin
Published: April 2009

Abiotic stress is becoming more prevalent as the intensity of agriculture and the demand for farmable land are ever increasing. Besides drought and salinity stress, chilling or freezing stress is one of the most important limiting factors of crop production all around the world. Salicylic acid (SA) is a common plant‐produced signal molecule that is responsible for inducing resistance to a number of biotic and abiotic stresses. This study was conducted to determine the effect of foliar SA applications on fruit‐quality characteristics and yield of strawberry under antifrost heated greenhouse conditions in two successive experiments. Spraying of 1 mM SA (1 mM) was done once (SA1), twice (SA2), three times (SA3), or four times (SA4) during the vegetation period with 7 d intervals. Concentrations of chlorophyll and minerals were measured in leaves, and vitamin C (ascorbic acid), total soluble solids (TSS), titratable acidity (TA), and color (a*) in fruits. Fruit weight, early yield, and total yield were also determined. Foliar applications of SA positively affected TSS and ascorbic acid (AA) content of strawberry fruits. Salicylic acid treatments had no effect on TA of strawberry fruits. SA4 treatment gave the greatest a* in fruit and chlorophyll‐concentration values in the leaves. It was shown that SA treatments increased the content of all nutrients in the leaves of strawberry plants, and greater values often were obtained from SA3 and SA4 treatments. The early yield and total yield of strawberry were significantly affected by SA applications, among which SA3 and SA4 resulted in the highest early and total yields. The present study suggests that SA3 and SA4 treatments can ameliorate the deleterious effects of low temperatures on strawberry plants and that SA application may offer an economical and simple method for low‐temperature protection.
Characterization of the role of the Escherichia coli periplasmic chaperone SurA using differential proteomics
Authors: Vertommen Didier , Ruiz Natividad , Leverrier Pauline , Silhavy Thomas J. , Collet Jean‐François
Published: April 2009

Little is known on how β‐barrel proteins are assembled in the outer membrane (OM) of Gram‐negative bacteria. SurA has been proposed to be the primary chaperone escorting the bulk mass of OM proteins across the periplasm. However, the impact of SurA deletion on the global OM proteome has not been determined, limiting therefore our understanding of the function of SurA. By using a differential proteomics approach based on 2‐D LC‐MSn, we compared the relative abundance of 64 OM proteins, including 23 β‐barrel proteins, in wild‐type and surA strains. Unexpectedly, we found that the loss of SurA affects the abundance of eight β‐barrel proteins. Of all the decreased proteins, FhuA and LptD are the only two for which the decreased protein abundance cannot be attributed, at least in part, to decreased mRNA levels in the surA strain. In the case of LptD, an essential protein involved in OM biogenesis, our data support a role for SurA in the assembly of this protein and suggest that LptD is a true SurA substrate. Based on our results, we propose a revised model in which only a subset of OM proteins depends on SurA for proper folding and insertion in the OM.
Nano‐Kompetenzen ‐ Analyse zum Bedarf der Weiterbildung in Nano‐Unternehmen
Authors: Baron Waldemar , Schumann Uwe
Published: April 2009

Innovative, wettbewerbsfähige Nano‐Unternehmen sind auf bedarfsgerecht qualifizierte Beschäftigte angewiesen. Wie diese Unternehmen aufgestellt sind und welchen Weiterbildungsbedarf sie sehen, ist der Studie „Weiterbildungsbedarf in Unternehmen der Nanotechnologie”︁ zu entnehmen, die vom Bundesministerium für Bildung und Forschung (BMBF) in Auftrag gegeben, vom VDI Technologiezentrum koordiniert und vom ISW‐Institut durchgeführt worden ist. Die Studie bietet Orientierungswissen für Bildungsanbieter, Institute und Unternehmen.
Postinjury Abdominal Compartment Syndrome: Are We Winning the Battle?
Authors: Balogh Zsolt J. , van Wessem Karlijn , Yoshino Osamu , Moore Frederick A.
Published: April 2009

Postinjury (primary) abdominal compartment syndrome (ACS) was described more than 15 years ago as severe abdominal distension with high peak airway pressures, CO2 retention, and oliguria, which led to unplanned re‐exploration after damage‐control laparotomy. Later, a more elusive type of ACS was recognized, which develops without abdominal injuries (secondary ACS). Both syndromes were recently characterized, their independent predictors were identified, and preventive strategies were developed to reduce their incidence. Once viewed as a syndrome with almost uniform mortality, systematic preventative strategies and therapeutic efforts have reduced the prevalence, morbidity, and mortality of the syndrome. This review was designed to summarize the recent advances in the management of ACS, to classify the currently available evidence, and to identify future directions of research and clinical care.
Unipolarity, State Behavior, and Systemic Consequences
Authors: Ikenberry G. John , Mastanduno Michael , Wohlforth William C.
Published: April 2009

The United States emerged from the 1990s as an unrivaled global power to become a “unipolar” state. This extraordinary imbalance has triggered global debate. Governments and peoples around the world are struggling to understand to how an American-centered unipolar system operates—and to respond to it. What is the character of domination in a unipolar distribution? To what extent can a unipolar state translate its formidable capabilities into meaningful influence? Will a unipolar world be built around rules and institutions or be based more on the unilateral exercise of unipolar power? Scholars too are asking these basic questions about unipolarity and international relations theory. The individual contributions develop hypotheses and explore the impact of unipolarity on the behavior of the dominant state, on the reactions of other states, and on the properties of the international system. Collectively, they find that unipolarity does have a profound impact on international politics. international relations under conditions of unipolarity force a rethinking of conventional and received understandings about the operation of the balance of power, the meaning of alliance partnerships, the logic of international economic cooperation, the relationship between power and legitimacy, and the behavior of satisfied and revisionist states.
Unipolarity
Authors: Jervis Robert
Published: April 2009

In analyzing the current unipolar system, it is useful to begin with structure. No other state or plausible coalition can challenge the unipole's core security, but this does not mean that all its values are safe or that it can get everything that it wants. Contrary to what is often claimed, standard balance of power arguments do not imply that a coalition will form to challenge the unipole. Realism also indicates that rather than seeking to maintain the system, the unipole may seek further expansion. To understand the current system requires combining structural analysis with an appreciation of the particular characteristics of the current era, the United States, and its leaders. Doing so shows further incentives to change the system and highlights the role of nuclear proliferation in modifying existing arrangements.
Antarctic Drilling Recovers Stratigraphic Records From the Continental Margin
Authors: Harwood David , Florindo Fabio , Talarico Franco , Levy Richard , Kuhn Gerhard , Naish Tim , Niessen Frank , Powell Rose , Pyne Alex , Wilson Gary
Published: April 2009

The Antarctic Geological Drilling (ANDRILL) program—a collaboration between Germany, Italy, New Zealand, and the United States that is one of the larger programs endorsed by the International Polar Year (IPY; http://www.ipy.org)—successfully completed the drilling phase of the Southern McMurdo Sound (SMS) Project in December 2007. This second drill core of the program's campaign in the western Ross Sea, Antarctica, complements the results of the first drilling season [Naish et al., 2007] by penetrating deeper into the stratigraphic section in the Victoria Land Basin and extending the recovered time interval back to approximately 20 million years ago.
Thermal expansion of solutions of deuteromethane in fullerite C60 at low temperatures. Isotopic effect
Authors: Dolbin A. V. , Vinnikov N. A. , Gavrilko V. G. , Esel’son V. B. , Manzheliĭ V. G. , Gadd G. E. , Moricca S. , Cassidy D. , Sundqvist B.
Published: April 2009

The thermal expansion of CD4 solutions in the orientational glass C60 with molar concentration of deuteromethane 20 and 50% has been investigated in the temperature range 2.5–23K. The orientational glass CD4–C60 undergoes a first-order phase transition in the temperature interval 4.5–55K. This transition is manifested as hysteresis of the linear thermal expansion coefficient α as well as maxima in the temperature dependences α(T) and τ1(T), where τ1 is the characteristic thermalization time of the experimental samples. The characteristic re-orientation times of the C60 molecules and the characteristic phase transformations occurring in the experimental solutions are determined. The results of the present study are compared with the results of a similar study of the solution CH4–C60. It is concluded that tunneling rotation of the CH4 and CD4 molecules occupying interstitial positions in the fullerite C60 lattice occurs.
Three-dimensional imaging of carbon using an elastic scattering coincidence technique
Authors: Radović Iva Bogdanović , Siketić Zdravko , Skukan Natko , Jakšić Milko
Published: April 2009

A setup is described for an elastic scattering coincidence technique installed at an ion microprobe facility. This setup is developed for three-dimensional (3D) profiling of light elements in thin transmission targets. In the present paper, 3D imaging of carbon is demonstrated. Recoiled carbon atoms together with carbon ions scattered from the target are detected in coincidence using particle detectors placed symmetrically around the beam direction at 45°. Capabilities of the technique concerning depth resolution and sensitivity have been tested on thin samples of known composition. 3D imaging of carbon in 2 μm thick aluminum foil was achieved with a sensitivity for carbon of around 1 at. %, a depth resolution of 100 nm, and a lateral resolution of 2–3 μm.
Direct formation of InAs quantum dots grown on InP (001) by solid-source molecular beam epitaxy
Authors: Fuster David , Rivera Antonio , Alén Benito , Alonso-González Pablo , González Yolanda , González Luisa
Published: April 2009

We have developed a growth process that leads to the direct formation of self-assembled InAs quantum dots on InP(001) by solid-source molecular beam epitaxy avoiding the previous formation of quantum wires usually obtained by this technique. The process consists of a periodically alternated deposition of In and As correlated with InAs(4×2)↔(2×4) surface reconstruction changes. Based on the results obtained by in situ characterization techniques, we propose that the quantum dots formation is possible due to the nucleation of In droplets over the InAs(4×2) surface during the In deposition step and their subsequent crystallization under the As step.
Ferromagnetic properties of epitaxial La2NiMnO6 thin films grown by pulsed laser deposition
Authors: Kitamura M. , Ohkubo I. , Kubota M. , Matsumoto Y. , Koinuma H. , Oshima M.
Published: April 2009

La 2 NiMnO 6 (LNMO) thin films were fabricated on (100) oriented SrTiO3 single crystal substrates by pulsed laser deposition method. The film growth conditions were found to significantly affect the magnetic moment and ferromagnetic transition temperature of LNMO films. Epitaxial LNMO films exhibiting the ferromagnetism equivalent to that of bulk polycrystal were grown only in such a narrow region of growth temperature and oxygen pressure that stabilized Ni2+–O–Mn4+ superexchange ferromagnetic interaction. Out of this narrow region, the ferromagnetism is significantly suppressed by the appearance of secondary phases, locally disordered Ni and Mn ions, and oxygen vacancies.
Thirty Years on: Iran's “Silent Revolution”
Authors: Marsh Steve
Published: April 2009

2009 is the thirtieth anniversary of the Iranian Revolution. In 2006 the Bush administration ranked Iran as posing arguably the greatest single threat to America. And throughout 2008 that administration insisted all options were open in dealing with Iran, including preventative strikes. Yet, unlike its decisive intervention to establish Iran as a client state in the 1950s, the US has thus far been unable to force the changes it desires in and from Iran's leadership. This article argues that to help understand this situation it is important to recognize that the Iranian Revolution was and remains nurtured by a contemporaneous “silent revolution” in the international oil industry, even if the Ahmadinejad regime's economic policies especially threaten currently to squander some of the potential afforded by it.
Bumble-bees learn the value of social cues through experience
Authors: Leadbeater Ellouise , Chittka Lars
Published: April 2009

Natural selection should lead animals to use social cues (SC) when they are useful, and disregard them when they are not. Theoretical investigation predicts that individuals should thus employ social learning ‘strategies’, but how might such context specificity be achieved on a proximate level? Operant conditioning, whereby the use of SC is reinforced through rewarding results, provides a potential mechanism. We investigate the role of reinforcement in joining behaviour in bumble-bees,
Bombus terrestris
. When bees visit unfamiliar flower species, they prefer to probe inflorescences where others are also foraging, and here we show that such behaviour is promoted through experience when conspecific presence reliably predicts reward. Our findings highlight a straightforward, but rarely discussed, mechanism by which animals can be selective about when to use SC.
Does reproductive isolation evolve faster in larger populations via sexually antagonistic coevolution?
Authors: Gay L. , Eady P.E. , Vasudev R. , Hosken D.J. , Tregenza T.
Published: April 2009

Sexual conflict over reproductive investment can lead to sexually antagonistic coevolution and reproductive isolation. It has been suggested that, unlike most models of allopatric speciation, the evolution of reproductive isolation through sexually antagonistic coevolution will occur faster in large populations as these harbour greater levels of standing genetic variation, receive larger numbers of mutations and experience more intense sexual selection. We tested this in bruchid beetle populations (Callosobruchus maculatus) by manipulating population size and standing genetic variability in replicated lines derived from founders that had been released from sexual conflict for 90 generations. We found that after 19 generations of reintroduced sexual conflict, none of our treatments had evolved significant overall reproductive isolation among replicate lines. However, as predicted, measures of reproductive isolation tended to be greater among larger populations. We discuss our methodology, arguing that reproductive isolation is best examined by performing a matrix of allopatric and sympatric crosses whereas measurement of divergence requires crosses with a tester line.
On uniqueness in the problem of gravity–capillary water waves above submerged bodies
Authors: Motygin Oleg V. , McIver Philip
Published: April 2009

In this paper, we consider the two-dimensional linear problem of wave–body interaction with surface tension effects being taken into account. We suggest a criterion for unique solvability of the problem based on symmetrization of boundary integral equations. The criterion allows us to develop an algorithm for detecting non-uniqueness (finding trapped modes) for given geometries of bodies; examples of numerical computation of trapped modes are given. We also prove a uniqueness theorem that provides simple bounds for the possible non-uniqueness parameters.
Rising atmospheric carbon dioxide concentration and the future of C
4
crops for food and fuel
Authors: Leakey Andrew D.B.
Published: April 2009

Crops with the C
4
photosynthetic pathway are vital to global food supply, particularly in the tropical regions where human well-being and agricultural productivity are most closely linked. While rising atmospheric [CO
2
] is the driving force behind the greater temperatures and water stress, which threaten to reduce future crop yields, it also has the potential to directly benefit crop physiology. The nature of C
4
plant responses to elevated [CO
2
] has been controversial. Recent evidence from free-air CO
2
enrichment (FACE) experiments suggests that elevated [CO
2
] does not directly stimulate C
4
photosynthesis. Nonetheless, drought stress can be ameliorated at elevated [CO
2
] as a result of lower stomatal conductance and greater intercellular [CO
2
]. Therefore, unlike C
3
crops for which there is a direct enhancement of photosynthesis by elevated [CO
2
], C
4
crops will only benefit from elevated [CO
2
] in times and places of drought stress. Current projections of future crop yields have assumed that rising [CO
2
] will directly enhance photosynthesis in all situations and, therefore, are likely to be overly optimistic. Additional experiments are needed to evaluate the extent to which amelioration of drought stress by elevated [CO
2
] will improve C
4
crop yields for food and fuel over the range of C
4
crop growing conditions and genotypes.
Colimitation of a freshwater herbivore by sterols and polyunsaturated fatty acids
Authors: Martin-Creuzburg Dominik , Sperfeld Erik , Wacker Alexander
Published: April 2009

Empirical data providing evidence for a colimitation of an herbivore by two or more essential nutrients are scarce, particularly in regard to biochemical resources. Here, a graphical model is presented, which describes the growth of an herbivore in a system with two potentially limiting resources. To verify this model, life-history experiments were conducted with the herbivore
Daphnia magna
feeding on the picocyanobacterium
Synechococcus elongatus
, which was supplemented with increasing amounts of cholesterol either in the presence or the absence of saturating amounts of eicosapentaenoic acid (EPA). For comparison,
D. magna
was raised on diets containing different proportions of
S. elongatus
and the cholesterol- and EPA-rich eukaryotic alga
Nannochloropsis limnetica
. Somatic and population growth of
D. magna
on a sterol- and EPA-deficient diet was initially constrained by the absence of sterols. With increased sterol availability, a colimitation by EPA became apparent and when the sterol requirements were met, the growth-limiting factor was shifted from a limitation by sterols to a limitation by EPA. These data imply that herbivores are frequently limited by two or more essential nutrients simultaneously. Hence, the concept of colimitation has to be incorporated into models assessing nutrient-limited growth kinetics of herbivores to accurately predict demographic changes and population dynamics.
The evolution of covert, silent infection as a parasite strategy
Authors: Sorrell Ian , White Andrew , Pedersen Amy B. , Hails Rosemary S. , Boots Mike
Published: April 2009

Many parasites and pathogens cause silent/covert infections in addition to the more obvious infectious disease-causing pathology. Here, we consider how assumptions concerning superinfection, protection and seasonal host birth and transmission rates affect the evolution of such covert infections as a parasite strategy. Regardless of whether there is vertical infection or effects on sterility, overt infection is always disadvantageous in relatively constant host populations unless it provides protection from superinfection. If covert infections are protective, all individuals will enter the covert stage if there is enough vertical transmission, and revert to overt infections after a ‘latent’ period (susceptible, exposed, infected epidemiology). Seasonal variation in transmission rates selects for non-protective covert infections in relatively long-lived hosts with low birth rates typical of many mammals. Variable host population density caused by seasonal birth rates may also select for covert transmission, but in this case it is most likely in short-lived fecund hosts. The covert infections of some insects may therefore be explained by their outbreak population dynamics. However, our models consistently predict proportions of covert infection, which are lower than some of those observed in nature. Higher proportions of covert infection may occur if there is a direct link between covert infection and overt transmission success, the covert infection is protective or the covert state is the result of suppression by the host. Relatively low proportions of covert transmission may, however, be explained as a parasite strategy when transmission opportunities vary.
Trade-offs between activity and thermoregulation in a small carnivore, the least weaselMustela nivalis
Authors: Zub K. , Szafrańska P.A. , Konarzewski M. , Redman P. , Speakman J.R.
Published: April 2009

We studied factors influencing daily energy expenditures (DEE) of male least weasels (Mustela nivalis) using the doubly labelled water technique. The relationship between ambient temperature and DEE formed a triangular pattern, characterized by invariance of the maximum DEE and an inverse relationship between minimum DEE and temperature. A simple energetic model relating the DEE of male weasels to activity time (AT) and ambient temperature predicted that, across seasons, less than 10 per cent of measurements approach the upper bound of observed DEE. Male weasels were able to maintain a relatively constant maximum energy output across varying temperatures by adjusting their AT to changes in temperature. They achieved maximum energy expenditures in winter due to high thermoregulatory costs, and in spring and summer due to high levels of physical activity. This pattern exemplifies a ‘metabolic niche’ of a small mammal having extremely high energy expenditures primarily driven by ambient temperature.
Why tropical forest lizards are vulnerable to climate warming
Authors: Huey Raymond B. , Deutsch Curtis A. , Tewksbury Joshua J. , Vitt Laurie J. , Hertz Paul E. , Álvarez Pérez Héctor J. , Garland Theodore
Published: April 2009

Biological impacts of climate warming are predicted to increase with latitude, paralleling increases in warming. However, the magnitude of impacts depends not only on the degree of warming but also on the number of species at risk, their physiological sensitivity to warming and their options for behavioural and physiological compensation. Lizards are useful for evaluating risks of warming because their thermal biology is well studied. We conducted macrophysiological analyses of diurnal lizards from diverse latitudes plus focal species analyses of Puerto RicanAnolisandSphaerodactyus. Although tropical lowland lizards live in environments that are warm all year, macrophysiological analyses indicate that some tropical lineages (thermoconformers that live in forests) are active at low body temperature and are intolerant of warm temperatures. Focal species analyses show that some tropical forest lizards were already experiencing stressful body temperatures in summer when studied several decades ago. Simulations suggest that warming will not only further depress their physiological performance in summer, but will also enable warm-adapted, open-habitat competitors and predators to invade forests. Forest lizards are key components of tropical ecosystems, but appear vulnerable to the cascading physiological and ecological effects of climate warming, even though rates of tropical warming may be relatively low.
Reversal of evolutionary downsizing caused by selective harvest of large fish
Authors: Conover David O. , Munch Stephan B. , Arnott Stephen A.
Published: April 2009

Evolutionary responses to the long-term exploitation of individuals from a population may include reduced growth rate, age at maturation, body size and productivity. Theoretical models suggest that these genetic changes may be slow or impossible to reverse but rigorous empirical evidence is lacking. Here, we provide the first empirical demonstration of a genetically based reversal of fishing-induced evolution. We subjected six populations of silverside fish (
Menidia menidia
) to three forms of size-selective fishing for five generations, thereby generating twofold differences among populations in mean weight and yield (biomass) at harvest. This was followed by an additional five generations during which size-selective harvest was halted. We found that evolutionary changes were reversible. Populations evolving smaller body size when subjected to size-selective fishing displayed a slow but significant increase in size when fishing ceased. Neither phenotypic variance in size nor juvenile survival was reduced by the initial period of selective fishing, suggesting that sufficient genetic variation remained to allow recovery. By linear extrapolation, we predict full recovery in about 12 generations, although the rate of recovery may taper off near convergence. The recovery rate in any given wild population will also depend on other agents of selection determined by the specifics of life history and environment. By contrast, populations that in the first five generations evolved larger size and yield showed little evidence of reversal. These results show that populations have an intrinsic capacity to recover genetically from harmful evolutionary changes caused by fishing, even without extrinsic factors that reverse the selection gradient. However, harvested species typically have generation times of 3–7 years, so recovery may take decades. Hence, the need to account for evolution in managing fisheries remains.
Arithmetic in newborn chicks
Authors: Rugani Rosa , Fontanari Laura , Simoni Eleonora , Regolin Lucia , Vallortigara Giorgio
Published: April 2009

Newly hatched domestic chicks were reared with five identical objects. On days 3 or 4, chicks underwent free-choice tests in which sets of three and two of the five original objects disappeared (either simultaneously or one by one), each behind one of two opaque identical screens. Chicks spontaneously inspected the screen occluding the larger set (experiment 1). Results were confirmed under conditions controlling for continuous variables (total surface area or contour length; experiment 2). In the third experiment, after the initial disappearance of the two sets (first event, FE), some of the objects were visibly transferred, one by one, from one screen to the other (second event, SE). Thus, computation of a series of subsequent additions or subtractions of elements that appeared and disappeared, one by one, was needed in order to perform the task successfully. Chicks spontaneously chose the screen, hiding the larger number of elements at the end of the SE, irrespective of the directional cues provided by the initial (FE) and final (SE) displacements. Results suggest impressive proto-arithmetic capacities in the young and relatively inexperienced chicks of this precocial species.
Implications of vaccination and waning immunity
Authors: Heffernan J.M. , Keeling M.J.
Published: April 2009

For infectious diseases where immunization can offer lifelong protection, a variety of simple models can be used to explain the utility of vaccination as a control method. However, for many diseases, immunity wanes over time and is subsequently enhanced (boosted) by asymptomatic encounters with the infection. The study of this type of epidemiological process requires a model formulation that can capture both the within-host dynamics of the pathogen and immune system as well as the associated population-level transmission dynamics. Here, we parametrize such a model for measles and show how vaccination can have a range of unexpected consequences as it reduces the natural boosting of immunity as well as reducing the number of naive susceptibles. In particular, we show that moderate waning times (40–80 years) and high levels of vaccination (greater than 70%) can induce large-scale oscillations with substantial numbers of symptomatic cases being generated at the peak. In addition, we predict that, after a long disease-free period, the introduction of infection will lead to far larger epidemics than that predicted by standard models. These results have clear implications for the long-term success of any vaccination campaign and highlight the need for a sound understanding of the immunological mechanisms of immunity and vaccination.
Long-term changes in deep-water fish populations in the northeast Atlantic: a deeper reaching effect of fisheries?
Authors: Bailey D.M. , Collins M.A. , Gordon J.D.M. , Zuur A.F. , Priede I.G.
Published: April 2009

A severe scarcity of life history and population data for deep-water fishes is a major impediment to successful fisheries management. Long-term data for non-target species and those living deeper than the fishing grounds are particularly rare. We analysed a unique dataset of scientific trawls made from 1977 to 1989 and from 1997 to 2002, at depths from 800 to 4800 m. Over this time, overall fish abundance fell significantly at all depths from 800 to 2500 m, considerably deeper than the maximum depth of commercial fishing (approx. 1600 m). Changes in abundance were significantly larger in species whose ranges fell at least partly within fished depths and did not appear to be consistent with any natural factors such as changes in fluxes from the surface or the abundance of potential prey. If the observed decreases in abundance are due to fishing, then its effects now extend into the lower bathyal zone, resulting in declines in areas that have been previously thought to be unaffected. A possible mechanism is impacts on the shallow parts of the ranges of fish species, resulting in declines in abundance in the lower parts of their ranges. This unexpected phenomenon has important consequences for fisheries and marine reserve management, as this would indicate that the impacts of fisheries can be transmitted into deep offshore areas that are neither routinely monitored nor considered as part of the managed fishery areas.
The factor structure of the SF‐36 in Parkinson's disease
Authors: Banks Pauline , Martin Colin R.
Published: April 2009

Rationale, aims and objectives  The concept of quality of life (QoL) has emerged as an important psychological dimension in individuals experiencing Parkinson's disease (PD). The current study sought to determine the factor structure of the Medical Outcomes Study Short‐Form 36 (SF‐36) version 2 in patients with PD in order to evaluate how this measure might best be used to assess QoL in this clinical population.

Method  Confirmatory factor analyses were conducted on self‐report SF‐36 data from 339 individuals diagnosed with PD. Six structural models of the SF‐36 were evaluated against the participants' data.

Results  The underlying factor structure of the SF‐36 in PD was observed to be inconsistent with the assumed measurement model of SF‐36 but consistent with contemporary theoretical models of the instrument.

Conclusions  The use of the SF‐36 in individuals with PD can be recommended when eight subscales are used and reported. Evidence to support the use of the instrument as a two‐subscale measure of physical health and mental health components was not found.
Drug‐adherence questionnaires not valid for patients taking blood‐pressure‐lowering drugs in a primary health care setting
Authors: Van De Steeg Nina , Sielk Martin , Pentzek Michael , Bakx Carel , Altiner Attila
Published: April 2009

Purpose  To validate two established questionnaires [Morisky and Medication Adherence Report Scale (MARS‐5)] for the measurement of medical adherence of patients treated with antihypertensive drugs in primary care in Germany.

Setting  General practitioners (GPs) and their patients in North Rhine‐Westphalia, Germany.

Methods  GPs were asked to recruit 12 consecutive patients using blood‐pressure‐lowering medication for at least 12 months. Patients were asked to fill out both the Morisky and MARS‐5 questionnaires. The medication possession ratio (MPR) was calculated as reference standard for patients' medication adherence by using GPs' electronic patient records. The results of the questionnaires were then compared with the reference standard.

Results  A total of 14 GPs recruited 163 patients of which 128 were included in the analysis. Of the 128 patients, 52% were females; the age ranged from 44 to 96 years (mean 71). The overall adherence rate measured by the MPR was 62.1%. Compared to the reference standard, the Morisky Scale had a sensitivity of 31.9%, a specificity of 72.8% and a positive likelihood ratio (+LR) of 1.18. The MARS‐5 had a sensitivity of 8.5%, a specificity of 97.4% and a +LR of 3.28.

Conclusion  The Morisky Scale and the MARS‐5 cannot be recommended for measuring the adherence to antihypertensive drugs in a general practice setting in Germany at this point. These results emphasize the necessity to validate questionnaires in a specific setting before using them as instruments within a trial different from the original setting(s) of validation.
The Arabidopsis cyclin‐dependent kinase‐activating kinase CDKF;1 is a major regulator of cell proliferation and cell expansion but is dispensable for CDKA activation
Authors: Takatsuka Hirotomo , Ohno Ryoko , Umeda Masaaki
Published: April 2009

Cyclin‐dependent kinases (CDKs) play an essential role in cell cycle regulation during the embryonic and post‐embryonic development of various organisms. Full activation of CDKs requires not only binding to cyclins but also phosphorylation of the T‐loop domain. This phosphorylation is catalysed by CDK‐activating kinases (CAKs). Plants have two distinct types of CAKs, namely CDKD and CDKF; in Arabidopsis, CDKF;1 exhibits the highest CDK kinase activity in vitro. We have previously shown that CDKF;1 also functions in the activation of CDKD;2 and CDKD;3 by T‐loop phosphorylation. Here, we isolated the knockout mutants of CDKF;1 and showed that they had severe defects in cell division, cell elongation and endoreduplication. No defect was observed during embryogenesis, suggesting that CDKF;1 function is primarily required for post‐embryonic development. In the cdkf;1 mutants, T‐loop phosphorylation of CDKA;1, an orthologue of yeast Cdc2/Cdc28p, was comparable to that in wild‐type plants, and its kinase activity did not decrease. In contrast, the protein level and kinase activity of CDKD;2 were significantly reduced in the mutants. Substitution of threonine‐168 with a non‐phosphorylatable alanine residue made CDKD;2 unstable in Arabidopsis tissues. These results indicate that CDKF;1 is dispensable for CDKA;1 activation but is essential for maintaining a steady‐state level of CDKD;2, thereby suggesting the quantitative regulation of a vertebrate‐type CAK in a plant‐specific manner.
A qualitative study of patient perspectives of health‐related quality of life in colorectal cancer: comparison with disease‐specific evaluation tools
Authors: Wilson T. R. , Birks Y. F. , Alexander D. J.
Published: April 2009

Aim  Little is known about the factors that patients with colorectal cancer (CRC) consider as important in shaping their health‐related quality of life (HrQoL) and whether these are adequately represented by currently used HrQoL instruments. The aim of this study was to determine which areas of HrQoL are important to patients with CRC and to establish whether these areas are represented by validated questionnaires.

Method  Semi‐structured interviews were conducted with 20 patients who were undergoing treatment or follow up for potentially curable CRC. The areas of HrQoL that were important to the patients were identified from the interview data using a qualitative thematic framework analysis. These themes were then compared with the item content of two CRC‐specific HrQoL questionnaires, FACT‐C and QLQ‐C30/CR38.

Results  The interviews identified 10 themes considered by patients to be important determinants of their HrQoL. These comprised control, normality, fatigue, uncertainty, information, emotional support, self‐image, coping, symptoms and emotionally challenging events. Both HrQoL instruments contained questions that concerned some of the themes identified, but none of the FACT‐C scales and only three from QLQ‐C30/CR38 produced scores from which clinicians could identify problems in these areas.

Conclusion  Identifying and addressing areas of concern for patients may assist clinicians in improving HrQoL outcomes. However, validated instruments currently used in CRC provide little information with regard to these areas.
Systematized Contact Dermatitis and Montelukast in an Atopic Boy
Authors: Castanedo‐Tardan Mari Paz , González Mercedes E. , Connelly Elizabeth A. , Giordano Kelly , Jacob Sharon E.
Published: April 2009

Abstract:  Upon ingestion, the artificial sweetener, aspartame is metabolized to formaldehyde in the body and has been reportedly associated with systemic contact dermatitis in patients exquisitely sensitive to formaldehyde. We present a case of a 9‐year‐old Caucasian boy with a history of mild atopic dermatitis that experienced severe systematized dermatitis after being started on montelukast chewable tablets containing aspartame. Patch testing revealed multiple chemical sensitivities which included a positive reaction to formaldehyde. Notably, resolution of his systemic dermatitis only occurred with discontinuation of the montelukast chewables.
Loop Diuretic Use and Rates of Hip Bone Loss and Risk of Falls and Fractures in Older Women
Authors: Lim Lionel S. , Fink Howard A. , Blackwell Terri , Taylor Brent C. , Ensrud Kristine E.
Published: April 2009

OBJECTIVES: To determine whether loop diuretic use is associated with hip bone loss and greater risk of falls and fractures in older women.

DESIGN: Prospective cohort study from August 1992 to April 2004.

SETTING: Four regions in the United States from the Study of Osteoporotic Fractures (SOF).

PARTICIPANTS: Women aged 65 and older (N=8,127) with medication use data who participated in the fourth SOF examination, from which three study cohorts were derived.

MEASUREMENTS: Bone mineral density (BMD) of the total hip assessed using dual‐energy X‐ray absorptiometry at the fourth and sixth examinations (n=2,980); recurrent (≥2) falls in the year after the fourth examination (n=6,244); and incident fracture, including nonspine (n=6,778) and hip fracture (n=7,272).

RESULTS: After multivariable adjustment, loop diuretic users had greater loss of total hip BMD than nonusers (mean annualized % BMD −0.87 vs −0.71, P=.03) after a mean of 4.4±0.6 years. The risks of recurrent falls (odds ratio=0.99, 95% confidence interval (CI)=0.71–1.39), nonspine (relative risk (RR)=1.04, 95% CI=0.90–1.21), and hip fracture (RR=1.03, 95% CI=0.81–1.31) were not greater in loop diuretic users than in nonusers.

CONCLUSION: In this cohort of older women, loop diuretic use was associated with a small but significantly higher rate of hip bone loss than nonuse after a mean duration of 4.4 years, although the risk of falls or fracture did not differ between the two groups.
Percutaneous Epicardial Left Atrial Appendage Closure: Preliminary Results of an Electrogram Guided Approach
Authors: FRIEDMAN PAUL A. , ASIRVATHAM SAMUEL J. , DALEGRAVE CHARLES , KINOSHITA MASAYOSHI , DANIELSEN ANDREW J. , JOHNSON SUSAN B. , HODGE DAVID O. , MUNGER THOMAS M. , PACKER DOUGLAS L. , BRUCE CHARLES J.
Published: April 2009

Background: Pharmacologic therapies to prevent stroke in atrial fibrillation (AF) have numerous limitations, prompting the development of device‐based therapies. We investigated whether an electrogram‐based approach using a novel hollow suture can safely capture and ligate the left atrial appendage (LAA).

Methods and Results: A novel system for closure of the LAA within the confines of the closed pericardium with a single sheath puncture was tested in 4 dogs. The tool used to grasp the appendage was fitted with electrodes and utilized electrical navigation to identify and confirm LAA capture. A hollow suture preloaded with a mechanical support wire to permit its manipulation and fluoroscopic visualization was advanced over the grasper, and the wire removed after the suture was positioned. The LAA was successfully closed in all dogs. In 2 dogs, after closure, a thoracotomy was performed and the LAA amputated without bleeding, confirming closure integrity. Necropsy confirmed closure in all animals.

Conclusions: Using electrical navigation, percutaneous epicardial LAA ligation with a remotely tightened suture was performed successfully within the confines of the intact pericardial space. This technique may allow decreasing the risk of stroke in AF patients without the need for thoracotomy or an endocardially placed prosthetic device.