bluuebunny/crossref_metadata_2025 huggingface dataset:
The thermodynamic interaction of N-methyllactams with cyclohexane and methanol
Authors: Živný Antonín , Biroš Ján , Pouchlý Julius
Published: August 2009

The study deals with the dependence of thermodynamic interaction of the N-methylamine group in N-methyllactams with the acid hydrogen atom of methanol on the size of the lactam ring. The heats of mixing of N-methyl-4-butanelactam, N-methyl-6-hexanelactam, N-methyl-7-heptanelactam and N-methyl-8-octanelactam with methanol and cyclohexane were measured, and the data thus obtained were treated in terms of Barker’s quasichemical theory. In a series of N-methyllactam-cyclohexane systems the mixing is endothermic, and the heats of mixing decrease with increasing size of the lactam ring. On the contrary, the mixing of N-methyllactams with methanol proceeds exothermically; first, the heats of mixing decrease depending on the lactam ring size, but for N-methyl-8-octanelactam they are very close to values obtained for N-methyl-4-butanelactam. However, with increasing ring size the energy of interaction between the N-methylamide group and the acid hydrogen atom of methanol increases. Such apparent discrepancy may be explained, in particular, by an opposite effect of the interaction between this group and the alkyl hydrogen atom.
Diffusion model for deposition of epitaxial GaAs layers prepared by the MOCVD method
Authors: Leitner Jindřich , Voňka Petr , Stejskal Josef , Klíma Přemysl , Hladina Rudolf
Published: August 2009

The authors proposed and treated quantitatively a kinetic model for deposition of epitaxial GaAs layers prepared by reaction of trimethylgallium with arsine in hydrogen atmosphere. The transport of gallium to the surface of the substrate is considered as the controlling process. The influence of the rate of chemical reactions in the gas phase and on the substrate surface on the kinetics of the deposition process is neglected. The calculated dependence of the growth rate of the layers on the conditions of the deposition is in a good agreement with experimental data in the temperature range from 600 to 800°C.
Characterization of the hydrophobic properties of amino acids on the basis of their partition and distribution coefficients in the 1-octanol-water system
Authors: Chmelík Josef , Hudeček Jiří , Putyera Karol , Makovička Jiří , Kalous Vítěz , Chmelíková Jitka
Published: August 2009

The hydrophobic properties of amino acid side chains were characterized on the basis of the partition process in the 1-octanol-water system. The partition coefficients were calculated from the published data and the distribution coefficients were determined experimentally on the basis of a double partition process utilizing the fact that the amino acids pass almost completely into the aqueous phase in the partition process. When the volumes of water and 1-octanol are suitably selected, this fact permits avoidance of the difficulties associated with the determination of amino acids in 1-octanol, where their solubilities are very low. Our scale is the only complete experimental scale based on the partition process of amino acids in the 1-octanol-water system. It follows from comparison of the calculated and the experimental data with the values published for the distribution coefficients of N-acetyl amides of amino acids that the best agreement was achieved for hydrophobic amino acids, while greater differences were observed for hydrophilic amino acids. These differences, expressed as the logarithm of the distribution coefficients, correspond to an average of 0.08 for nonpolar amino acids and 0.30 for acidic and basic amino acids: expressed as relative deviations, these values correspond to 2-10% for nonpolar amino acids, and 5-30% for charged amino acids.
The interactions of tensides with calconalide I
Authors: Němcová Irena , Valcl Oldřich , Makovička Jiří
Published: August 2009

A study was made of the effect of cationogenic, anionogenic and nonionogenic tensides on the absorption spectra and dissociation constant of calconalide I. It was found that the changes in the absorption spectra are a result of influences on the dissociation of the dye and a shift in the equilibrium between the tautomeric forms. The mechanism of the effect of the tenside on dye dissociation was also discussed.
Large qualitative models of complex chemical and bioengineering processes
Authors: Dohnal Mirko
Published: August 2009

Qualitative model is a theoretical background of commonsense. Complex qualitative models can have prohibitively many solutions (qualitative states). Therefore a qualitative analogy of such classical quantitative tools as e.g. the decomposition is developed. Practical applications of decomposition principle is nearly always ad hoc. Therefore two case studies are presented in details, a chemical process (mixer, chemical reactor, separator) and an anaerobic fermentor.
Thermolysis of some thiourea derivatives
Authors: Gaber Abd El-Aal M. , Aly Morsy M. , Atalla Ahmed A.
Published: August 2009

Thermolysis of N/benzoyl-N’,N’-diphenylthiourea (BDTU)(I) at 250°C gives NH3, H2S, H2O, benzaldehyde, benzil, benzonitrile, diphenylamine, diphenylcyanamide, 2-phenylbenzimidazole, benzoyl isothiocyanate, carbazole and 2-phenylbenzthiazole, whereas, thermolysis of N-benzoyl-N'-o-tolylthiourea (BTTU) (II) under the same conditions afford NH3, H2S, H2O, benzaldehyde, benzil, benzonitrile, o-toluidine, o-tolyl isothiocyanate, o-tolylcyanamide, benzoyl isothiocyanate and N,N’-di-o-tolylthiourea. The main feature of these thermolyses is homolysis of the amide and thioamide bonds providing free radicals that undergo the common reactions involving H-abstraction, dimerization, coupling, fragmentation, rearrangement and cyclization. A suitable mechanism has been suggested to account for the observed products.
X-ray fluorescence spectroscopic analysis of bromine in pharmaceutical formulations
Authors: Raggi Maria Augusta , Lucchini Federico , Da Re Paolo
Published: August 2009

A fast and accurate method is proposed for the determination of bromine in pharmaceutical formulations. The method is based on the application of X-ray fluorescence spectroscopy to solid samples and can be used for the assay of total bromine in various chemical media. It has high reliability provided that the appropriate matrix effect correction is employed, through the use of the scattered W-line from the X-ray tube as an internal standard.
Fused imidazo-, pyrimido- and 1,3-diazepino[1,2-c]pteridines from o-aminopyrazinecarbonitriles
Authors: Ried Walter , Russ Thomas
Published: August 2009

A series of partially hydrogenated imidazo[1,2-c]pteridines IXa – IXc, XIa - XIf and XVa - XVc, pyrimidol[1,2-c]pteridines XIIa - XIId and XVIa - XVIc, and 1,3-diazepinol[1,2-c]pteridines XIIIa - XIIIc and XVII have been prepared from 2-amino-3-cyanopyrazines I via reactions of I with alkanediamines II - IV and subsequent condensation of the resulting intermediates V - VII with orthoesters VIII, aldehydes X and ketones XIV.
Synthesis and tubulin interaction of thiocolchicines containing an isothiocyanato group. Synthesis of C(2)-deuterated and C(2)-14C-labeled 7-isothiocyanatodeacetamidothiocolchicine
Authors: Muzaffar Anjum , Hamel Ernest , Bai Rouli , Brossi Arnold
Published: August 2009

Synthesis of isothiocyanato substituted thiocolchicines XI - XIV is described. Introduction of an isotope label is demonstrated with the deuterated isothiocyanate XII and the 14C-labeled analog XIII. These isothiocyanates inhibit tubulin polymerization at low concentration. In addition, the 14C-labeled XIII forms covalent bond(s) with tubulin. Unfortunately, the covalent reaction while rapid, is not inhibited by preincubation of tubulin with colchicine. The covalent interaction of XIII with tubulin thus appears to be nonspecific, limiting its use as a marker of the colchicine binding site on tubulin.
Oxidation studies on β-lactam antibiotics: In-vitro antimicrobial activity of the oxidized products of 3-heteroarylthiomethyl-ceph-3-ems
Authors: Singh Rajeshwar , Singh Maya P. , Micetich Ronald G.
Published: August 2009

Various products from the oxidation of 3-heteroarylthiomethyl-ceph-3-ems using m-chloroperbenzoic acid (m-CPBA) and hydrogen peroxide in acetic acid in varying stoichiometric ratios have been isolated, identified and their in vitro antimicrobial activity determined. The oxidized compounds with the 2-aminothiazol-4-yl-(Z)-2-methoxyiminoacetamido side chain showed better antibacterial activity against various Gram negative bacteria compared to the unoxidized compounds.
Synthesis and antibacterial activity of new 7-substituted fluoroquinolones
Authors: Rádl Stanislav , Kovářová Lenka
Published: August 2009

Reaction of substituted 3-carboxyquinolone derivatives IIIa, IIIb, IIIc, and IV with 4-pyridone ethylene ketal in pyridine afforded corresponding 7-substituted derivatives VIa, VIb, VIc, and VIIa, respectively. Acidic deprotection of these compounds yielded respective oxo derivatives VId,VIe, VIf, and VIIb which were converted to their oximes If, Ig, Ih, and IIb.
The effect of aromatic substitution on neuroleptic activity in 1-piperazino-3-phenylindans. A comparison based on a new D-2 receptor model with corresponding 10-piperazino-10,11-dihydrodibenzo[b,f]thiepins
Authors: Bøgesø Klaus P. , Sommer Michael Bech
Published: August 2009

The validity of a new dopamine D-2 receptor interaction model based on conformational analysis and least-squares superimposition studies of the indan derivative tefludazine and the thiepin derivative octoclothepin was further tested by comparison of the effect of aromatic substitution on D-2 antagonistic activity in two series of indan and thiepin derivatives. The indan series include new derivatives substituted in the 4-, 7-, 2’- and 3’-position. The substitution effects were largely parallel with one important exception: Only 6-substituted indans have significant neuroleptic activity while both 8- and 7-substituted thiepin derivatives have neuroleptic activity. In indans additional fluorination in the 2’- or 4’-position is demanded to give potent neuroleptic activity, while a 3’-fluoro-substituted derivative was inactive. Fluorination is not necessary in thiepins although 3-fluoro derivatives have a significant prolonged duration of action. Considering the differences in physico-chemical properties, metabolism and pharmacokinetics between the two series, the largely parallel substitution effects support the new D-2 receptor model.
Polarographic and spectrophotometric behaviour of some N-p-phenyl substituted benzamidines
Authors: Squella Juan A. , Nuñez-Vergara Luis J. , Rodríguez Hernan , Márquez Amelia , Rodríguez-Mellado Jose M. , Blázquez Manuel , Roldán Emilio , Dominguez Manuel
Published: August 2009

Five N-p-phenyl substituted benzamidines were studied by DC and DP polarography in a wide pH range. Coulometric results show that the overall processes are four-electron reductions. Logarithmic analysis of the waves indicate that the process are irreversible. The influence of the pH on the polarographic parameters was also studied. A UV spectrophotometric study was performed in the pH range 2-13. In basic media some variations in the absorption bands were observed due to the dissociation of the amidine group. A determination of the pK values was made by deconvolution of the spectra. Correlations of both the electrochemical parameters and spectrophotometric pK values with the Hammett substituent constants were obtained.
Indirect determination of chlorophenols by atomic absorption spectrometry (AAS) after extraction of their ionic associates involving the dipyridylocopper(II) or phenanthrolinocopper(II) complex
Authors: Stužka Václav , Krejčí Jana
Published: August 2009

A novel method was developed for the indirect determination of chlorophenols by AAS after extraction of their ionic associates involving the dipyridylocopper(II) (CuDP) or phenanthrolinocopper(II) (CuPH) complex into nitrobenzene, o-dichlorbenzene or methyl isobutyl ketone. Nitrobenzene appeared to be particularly suitable for the extraction of the CuDP associate, methyl isobutyl ketone, for the extraction of the CuPH associate. Thee method is applicable to chlorophenol concentrations of 10-6 to 10-7 mol l-1. Using CuDP after a single complete extraction into 10 ml of nitrobenzene, the lowest determinable concentration giving rise to absorbance A = 0.010 is 0.3 mg of pentachlorophenol in a litre; using CuPH after a single extraction into 10 ml of methyl isobutyl ketone, it is 0.2 mg of chlorophenol in a litre.
Evaluation of adsorption and retention models for separation of polychlorinated biphenyls by HPLC on reversed phases
Authors: Jakuš Vladimír
Published: August 2009

Adsorption model for separation of polychlorinated biphenyls (PCB) in HPLC on reversed phases (chemically bonded C18) was applied to a series of 15 PCB. The values for adsorption interaction energy were computed employing the method of empirical potential functions according to Dashevskii. The model of interphase partitioning and the partition model of separation are also presented with respect to the optimized geometry of the PCB molecule with an optimal torsion angle. The Gibbs solvation energies in the stationary (octanol) and mobile (water) phases for 15 PCB were computed by means of continuum models. The energy values were correlated with capacity factors and partition coefficients. Correlation analysis indicated the dominant role in PCB separations to be partition processes of the solute in mobile phase; adsorption on these surfaces does not influence considerably the separation process.
Dependence between calculated flexibility of lamellas of layered materials and their ability to undergo intercalation reactions
Authors: Votinský Jiří , Beneš Ludvík
Published: August 2009

A computational procedure has been suggested enabling estimates of the flexibility of individual layered materials from their crystallographical structure. The data about flexibility of layers have been obtained by calculation for compounds of the type Q2Y3 (Q = SbIII, BiIII; Y = Se-II, Te-II; space group of symmetry R3m), MPS3 (M = MnII, FeII, CoII, NiII, CdII,C2/m), TX2 (T = NbIV, TaIV, MoV; X = S-II, Se-II; P63/mmc), FeOCl (Pmnm), Zr(HPO4)2 (P21/n) and ROPO4 (R = VV, NbV, Mo; P4/n). The flexibility of the layers of these compounds increases in the order: Q2Y3 << MPS3 < TX2 < FeOCl = Zr(HPO4)2 < ROPO4. The same trend is observed for the ability of these compounds to form intercalates. In most of the structures given a distinct anisotropy of flexibility has been found by the calculation.
Synthesis of triphenylarsine oxide by oxidation of triphenylarsine by oxygen under the catalytic effect of iron compounds
Authors: Vančová Vlasta , Ondrejkovičová Iveta
Published: August 2009

Triphenylarsine oxide can be prepared conveniently by reacting triphenylarsine with dioxygen in the presence of iron compounds of the type of FeX3. [FeX3(OAsPh3)2] and [Fe(OAsPh3)4].(I3)2 (X = Br, SCN; Ph = C6H5), which act as catalysts. The last-mentioned compound was found most catalytically active. Conducted in acetonitrile solution at slightly elevated temperatures (60 to 70°C) and atmospheric pressure of dioxygen, the oxidation is selective and quantitative.
3-Acetoxy-2-cycloalken-1-ones by acetylation of cyclic 1,3-diketones with ketene
Authors: Boháč Andrej , Hrnčiar Pavel
Published: August 2009

Acetylation of lower 1,3-cycloalkenediones with ketene takes place exclusively at oxygen in contrast to acyclic β-diketones. Thus, 1,3-cyclopentanedione (I), 1,3-cyclohexanedione (II) and 5,5-dimethyl-1,3-cyclohexanedione (III) afforded the corresponding 3-acetoxy-2-cycloalken-1-ones VI - VIII in quantitative yields. 1,3-Cycloheptanedione (IV) and 1,3-cyclooctanedione (V) differed considerably from the preceding diketones by low reactivities.
Correlation of structural parameters with antituberculotic activity in a group of 2-benzamidobenzothiazoles
Authors: Waisser Karel , Kuneš Jiří , Odlerová Želmíra
Published: August 2009

Fourteen 2-benzamidobenzothiazole derivatives substituted in the benzoyl group and 2-cinnamamidobenzothiazole have been synthesized. The prediction of active structures by the method by Topliss gives incorrect results but, as shown on the basis of the Hansch QSAR analysis, the 2-(4-dimethylaminobenzamido)benzothiazole synthesized on the basis of the QSAR procedure by Topliss behaves anomalously also in the procedure by Hansch. Regression equations of the Hansch type have been found in which the antituberculotic activity is interpreted by lipophilicity and electronic effects of substituents. When tested in vitro, the most active compounds are comparable with ethionamide.
6-(ω-Guanidinoalkyl)- and 6-(ω-imidazolinaminoalkyl)-5,6,7,8-tetrahydrodibenz[c,e]azocines
Authors: Szemes Fridrich , Rybár Alfonz , Solčániová Eva
Published: August 2009

Guanidine derivatives of 5,6,7,8-tetrahydrodibenz[c,e]azocine IV and V were prepared by a three-step synthesis starting from 5,6,7,8-tetrahydrodibenz[c,e]azocine (I) via the corresponding 6-(ω-cyanoalkyl) II and 6-(ω-aminoalkyl) derivatives III; finaly, compounds III were treated with either methylisothiuronium halide or methylthioimidazolinium halide.
Contracts to devolve health services in fragile states and developing countries: do ethics matter?
Authors: Jayasinghe S
Published: August 2009

Fragile states and developing countries increasingly contract out health services to non-state providers (NSPs) (such as non-governmental organisations, voluntary sector and private sector). The paper identifies ethical issues when contracts involve devolution of health services to NSPs and proposes procedures to prevent or resolve these ethical dilemmas. Ethical issues were identified by examining processes of contracting out. Health needs could be used to select areas to be contracted out and to identify service needs. Health needs comprise “disease-burden-related needs”, “health-service needs”, and “urgency of health-service needs”. The mix of services should include an analysis of cost-effectiveness. NSPs should be selected fairly, without bias, and conflicts of interest during their work must be avoided. The population’s views must be respected and accountability structures established. Devolved health services should ensure equity of access to healthcare. The services ought to be sustainable and evaluated objectively. Of these issues, conflicts of interest among NSPs and sustainability of health services have not attracted attention in the literature on ethics of health policy. Fair procedures could address these ethical issues—for example, public consultation on issues; decisions based on the public consultation and made on evidence; principles of decisions stated and reasonable; decisions given adequate publicity; a mechanism established to challenge decisions; assurance that mechanisms meet the above conditions; and regular review of the policies. These procedures are complemented by improving self-governance of NSPs, countries’ development of guidelines for devolving health services, and measures to educate the public of the client countries on these issues.
Performance-based readability testing of participant materials for a phase I trial: TGN1412: Table 1
Authors: Knapp P , Raynor D K , Silcock J , Parkinson B
Published: August 2009

Background:

Concern has been expressed about the process of consent to clinical trials, particularly in phase I “first-in-man” trials. Trial participant information sheets are often lengthy and technical. Content-based readability testing of sheets, which is often required to obtain research ethics approval for trials in the USA, is limited and cannot indicate how information will perform.

Methods:

An independent-groups design was used to study the user-testing performance of the participant information sheet from the phase I TGN1412 trial. Members of the public were asked to read it, then find and demonstrate understanding of 21 key aspects of the trial. The participant information sheet was then rewritten, redesigned and tested on 20 members of the public, using the same 21-item questionnaire.

Results:

On the original TGN1412 participant information sheet, participants could not find answers and some of the found information was not understood. Six of 21 questions, including those relating to placebo, follow-up visits and the emergency phone number, were found by eight or fewer of 10 participants. The revised information sheet performed better, with the answers to 17 of 21 questions found and understood by all 20 participants.

Conclusions:

Tests showed that the TGN1412 participant information sheet may not inform participants adequately for consent. Revising its content and design led to significant improvements. Writers of materials for trial participants should take account of good practice in information design. Performance-based user testing may be a useful method to indicate strengths and weaknesses in trial materials.
Top-down and bottom-up forces in mammalian herbivore – vegetation systems: an essay review
Authors: Turkington Roy
Published: August 2009

For almost 50 years ecologists have debated why herbivores generally don’t increase in numbers to such levels as to deplete or devastate vegetation. One hypothesis is that herbivore populations are regulated at low densities by predators, and a second hypotheses is that plants are fundamentally poor food for herbivores. This has lead to two main hypotheses about the role of herbivores in structuring vegetation: the “bottom-up” and “top-down” hypotheses. Here I survey the literature, with a focus on field experiments designed to investigate the soil resource – vegetation – mammalian herbivore system, specifically asking five questions about how each trophic level responds to (i) resource addition, (ii) vegetation removal, (iii) herbivore removal or reduction, (iv) herbivore addition, and (v) the interaction of resource levels and herbivory? I use these to develop 12 testable predictions. I document the major areas of research as they relate to these 12 predictions, and use these to evaluate weaknesses and limitations in field methods. There are surprisingly few terrestrial studies that conduct factorial manipulations of multiple nutrients or herbivores, even though it is clear that these are essential. Specifically, I argue that a manipulative experimental approach is the most valuable way to advance our theory and understanding, and I advocate the continued use of long-term factorial field experiments that simultaneously manipulate soil resources levels and herbivory (preferably at multiple levels), repeated in a range of environments in which individual species or functional groups are monitored.
Ethylene and programmed cell death in plants
Authors: Trobacher Christopher P.
Published: August 2009

Plants produce and utilize the gaseous hydrocarbon ethylene as a phytohormone throughout their life cycle. Ethylene is notoriously associated with fruit ripening and this aspect of its biology, along with its biosynthesis and mechanisms of signal transduction, has received a great deal of study. Many plants also employ ethylene signalling during instances of programmed cell death (PCD), including aerenchyma formation, epidermal PCD above emerging adventitious roots, senescence of petals, leaves, and reproductive structures, and endosperm death in developing cereal seeds. Ethylene-signalling during PCD is both spatially and temporally regulated, and is selective in that it induces PCD only in sensitized cells or tissues. This review examines instances of ethylene-regulated plant PCD, proposes a general model, and suggests avenues for future research that might improve our understanding of both PCD and ethylene signal transduction.
Assessing Juvenile Salmonid Response to Gas Supersaturation Using a General Multivariate Dose–Response Model
Authors: Jensen J. O. T. , Schnute J. , Alderdice D. F.
Published: August 2009

Based on data compiled from the literature, we investigate the effects of excess total gas pressure (TGP%) on juvenile salmonids (chinook, Oncorhynchus tshawytscha; coho, O. kisutch; sockeye, O. nerka; and steelhead, Salmo gairdneri). Our study relates exposure time to 50% mortality (ET50) to TGP%, component levels of dissolved oxygen (O2%) and nitrogen (N2%), water depth, temperature, barometric pressure (BP), and fish size. We employ a new device, called a tabular histogram, for exploratory data analysis. We also formulate and test statistical hypotheses by applying the general multivariate dose–response model described in a companion paper (Can. J. Fish. Aquat. Sci. 43: 1684–1693). When modeled in response to TGP%, ET50 follows a typical exponential dose–response relationship. Based on our full data set, two ancillary factors, water depth and fish length, significantly improve the model's ability to explain variations in ET50. Furthermore, based on a smaller subset of the data, either of the factors O2% or N2% also improve the model fit significantly. For 50-d exposures, apparently "safe" levels of TGP% range from 103.8 to 114.8%, depending on associated factor levels of water depth and fish size.
Dependence of Exploitation Rates for Maximum Yield and Stock Collapse on Age and Sex Structure of Chinook Salmon (Oncorhynchus tshawytscha) Stocks
Authors: Hankin David G. , Healey M. C.
Published: August 2009

In this paper we investigate the equilibrium behavior of an age- and sex-structured version of the Ricker stock–recruitment model specifically tailored to the complex nature of chinook salmon (Oncorhynchus tshawytscha) biology and fisheries. Conclusions from our analysis include the following. (1) Exploitation rates for maximum yield (umsy) and stock collapse (umax) depend strongly on a stock's maturity schedule, being lowest for a late-maturing stock and greatest for an early maturing stock. (2) Values of exploitation rates for umax overlap considerably with those for umsy, emphasizing the probability of stock collapse in fully exploited mixed stock fisheries. (3) Values of umsy and umax are independent of the value of the Ricker β parameter but depend directly on the Ricker α parameter, indicating that management research should focus on obtaining better estimates of α, contrary to recent suggestions in the literature. (4) Because they mature at older ages, female chinook suffer greater cumulative fishery removal rates than males and decline in abundance more rapidly as exploitation increases. Consequently, the use of sex-independent maturity schedules can give misleading estimates for umsy and umax. (5) Maximum changes in mean age of stocks that can be attributed to fishing up effects ranged from 0.32 to 0.81 yr. Many stocks appear already to have declined in mean age by this amount, further emphasizing the probability of impending collapse of some stocks.
Hypersaline Gradients in Two Canadian High Arctic Lakes
Authors: Stewart Kenton M. , Platford Robert F.
Published: August 2009

The meromictic Sophia and Garrow lakes are probably saline relicts of cutoff fjords on the uplifted Cornwallis and Little Cornwallis islands in the High Arctic of the Canadian Archipelago. Sophia and Garrow have brackish (S = 2–4) upper and hypersaline (S = 55–90) lower waters with ion ratios (especially the lower waters) similar to that of the sea. Substantial oxygen extends well below the chemocline in Sophia. The stability of these lakes is among the highest known. Because of their size, depth, and unusually warm lower waters, it seems likely that an unfrozen "thermal chimney" extends beneath the lakes through the surrounding permafrost. We feel that the hypersaline gradients evolved primarily by descent of "salt fingers" during freeze out from above, and not by solute rejection from the ground during uplift and permafrost growth, or through taliks connected to the sea, as proposed by Page et al. (1984. Limnol. Oceanogr. 29: 564–573).
Iodine-catalyzed efficient synthesis of chalcones by grinding under solvent-free conditions
Authors: Wang Hongshe , Zeng June
Published: August 2009

Chalcones are useful intermediates in organic synthesis and exhibit a large number of different biological activities. Chalcones have been synthesized in high yields by Claisen–Schmidt condensation of substituted acetophenones with various aromatic aldehydes in the presence of 10 mol% of iodine at room temperature by grinding under solvent-free conditions.
ON NONCOMMUTATIVE MINISUPERSPACE, COSMOLOGY AND Λ
Authors: OBREGÓN O. , SABIDO M. , MENA E.
Published: August 2009

In this letter we study the effects of a noncommutative minisuperspace, including matter degrees of freedom on a toy model for FRW universe with cosmological constant. In this simple model the vacuum energy density is modified by the presence of the noncommutative minisuperspace parameter, from which we conjecture on the discrepancy between the calculated and observed vacuum energy density associated to Λ.
MONSTERS, BLACK HOLES AND THE STATISTICAL MECHANICS OF GRAVITY
Authors: HSU STEPHEN D. H. , REEB DAVID
Published: August 2009

We review the construction of monsters in classical general relativity. Monsters have finite ADM mass and surface area, but potentially unbounded entropy. From the curved space perspective, they are objects with large proper volume that can be glued on to an asymptotically flat space. At no point is the curvature or energy density required to be large in Planck units, and quantum gravitational effects are, in the conventional effective field theory framework, small everywhere. Since they can have more entropy than a black hole of equal mass, monsters are problematic for certain interpretations of black hole entropy and the AdS/CFT duality.

In the second part of the paper we review recent developments in the foundations of statistical mechanics which make use of properties of high-dimensional (Hilbert) spaces. These results primarily depend on kinematics — essentially, the geometry of Hilbert space — and are relatively insensitive to dynamics. We discuss how this approach might be adopted as a basis for the statistical mechanics of gravity. Interestingly, monsters and other highly entropic configurations play an important role.
ANALYTICAL SOLUTION OF THE MAGNETO-HYDRODYNAMIC FLOW OVER A NONLINEAR STRETCHING SHEET
Authors: GANJI D. D. , BARARNIA H. , SOLEIMANI S. , GHASEMI E.
Published: August 2009

In this paper, the homotopy perturbation method (HPM) and the Padé approximation are employed to investigate the magneto-hydrodynamic (MHD) boundary layer flow over a nonlinear stretching sheet, which occurs in many important engineering applications, such as the power generator, the cooling of reactors and the design of heat exchangers. The validity of results is verified by comparison with exact results and is shown in tables and graphs. It is found that the HPM is a user-friendly, powerful tool for solving complicated problems in physics and mathematics, and that in particular it has good accuracy as compared with exact results.
AUGMENTED FIFO CACHE REPLACEMENT POLICIES FOR LOW-POWER EMBEDDED PROCESSORS
Authors: CHO SANGYEUN , MOAKAR LORY AL
Published: August 2009

This paper explores a family of augmented FIFO replacement policies for highly setassociative caches that are common in low-power embedded processors. In such processors, the implementation cost and complexity of the replacement policy is as important as the cache hit rate. By exploiting the cache hit way information between two replacements, the proposed replacement schemes reduce cache misses by 1% to 18% on average depending on the cache configuration, compared with the conventional FIFO policy. The proposed schemes come at a small implementation cost of additional state bits and control logic. The reduction in cache misses directly translates into data access energy savings of 1% to 15% on average, depending on the cache configuration. Our work suggests that there is room for improving the popular FIFO policy at a small cost.
FLOATING-POINT ARITHMETIC FOR COMPUTATIONAL GEOMETRY PROBLEMS WITH UNCERTAIN DATA
Authors: JIANG D. , STEWART N. F.
Published: August 2009

It has been suggested in the literature that ordinary finite-precision floating-point arithmetic is inadequate for geometric computation, and that researchers in numerical analysis may believe that the difficulties of error in geometric computation can be overcome by simple approaches. It is the purpose of this paper to show that these suggestions, based on an example showing failure of a certain algorithm for computing planar convex hulls, are misleading, and why this is so.

It is first shown how the now-classical backward error analysis can be applied in the area of computational geometry. This analysis is relevant in the context of uncertain data, which may well be the practical context for computational-geometry algorithms such as, say, those for computing convex hulls. The exposition will illustrate the fact that the backward error analysis does not pretend to overcome the problem of finite precision: it merely provides a way to distinguish those algorithms that overcome the problem to whatever extent it is possible to do so.

It is then shown that often the situation in computational geometry is exactly parallel to other areas, such as the numerical solution of linear equations, or the algebraic eigenvalue problem. Indeed, the example mentioned can be viewed simply as an example of the use of an unstable algorithm, for a problem for which computational geometry has already discovered provably stable algorithms.

Finally, the paper discusses the implications of these analyses for applications in three-dimensional solid modeling. This is done by considering a problem defined in terms of a simple extension of the planar convex-hull algorithm, namely, the verification of the well-formedness of extruded objects. A brief discussion concerning more difficult problems in solid modeling is also included.
Schistosoma Genomics: New Perspectives on Schistosome Biology and Host-Parasite Interaction
Authors: Han Ze-Guang , Brindley Paul J. , Wang Sheng-Yue , Chen Zhu
Published: August 2009

Schistosomiasis, caused mainly by Schistosoma japonicum, S. mansoni, and S. hematobium, remains one of the most prevalent and serious parasitic diseases worldwide. The blood flukes have a complex life cycle requiring adaptation for survival in fresh water as free-living forms and as parasites in snail intermediate and vertebrate definitive hosts. Functional genomics analyses, including transcriptomic and proteomic approaches, have been performed on schistosomes, in particular S. mansoni and S. japonicum, using powerful high-throughput methodologies. These investigations have not only chartered gene expression profiles across genders and developmental stages within mammalian and snail hosts, but have also characterized the features of the surface tegument, the eggshell and excretory–secretory proteomes of schistosomes. The integration of the genomic, transcriptomic, and proteomic information, together with genetic manipulation on individual genes, will provide a global insight into the molecular architecture of the biology, pathogenesis, and host-parasite interactions of the human blood flukes. Importantly, these functional genomics analyses lay a foundation on which to develop new antischistosome vaccines as well as drug targets and diagnostic markers for treatment and control of schistosomiasis.
Syndromes of Telomere Shortening
Authors: Armanios Mary
Published: August 2009

Telomeres and telomerase were initially discovered in pursuit of questions about how the ends of chromosomes are maintained. The implications of these discoveries to age-related disease have emerged in recent years with the recognition of a group of telomere-mediated syndromes. Telomere-mediated disease was initially identified in the context of dyskeratosis congenita, a rare syndrome of premature aging. More recently, mutations in telomerase components were identified in adults with idiopathic pulmonary fibrosis. These findings have revealed that the spectrum of telomere-mediated disease is broad and includes clinical presentations in both children and adults. We have previously proposed that these disorders be collectively considered as syndromes of telomere shortening. Here, the spectrum of these disorders and the unique telomere genetics that underlies them are reviewed. I also propose broader clinical criteria for defining telomere-mediated syndromes outside of dyskeratosis congenita, with the goal of facilitating their diagnosis and highlighting their pathophysiology.
Inherited Variation in Gene Expression
Authors: Skelly Daniel A. , Ronald James , Akey Joshua M.
Published: August 2009

Variation in gene expression constitutes an important source of biological variability within and between populations that is likely to contribute significantly to phenotypic diversity. Recent conceptual, technical, and methodological advances have enabled the genome-scale dissection of transcriptional variation. Here, we outline common approaches for detecting gene expression quantitative trait loci, and summarize the insights gleaned from these studies regarding the genetic architecture of transcriptional variation and the nature of regulatory alleles. Particular emphasis is placed on human studies, and we discuss experimental designs that ensure that increasingly large and complex studies continue to advance our understanding of gene expression variation. We conclude by discussing the evolution of gene expression levels, and we explore prospects for leveraging new technological developments to investigate inherited variation in gene expression in even greater depth.
The Importance of Ecological and Phylogenetic Conditions for the Occurrence and Frequency of Sexual Cannibalism
Authors: Wilder Shawn M. , Rypstra Ann L. , Elgar Mark A.
Published: August 2009

Sexual cannibalism, the consumption of the male by the female before, during, or after mating, can be a striking example of sexual conflict with potentially large fitness consequences for males and females. In this review, we examine how ecological and phylogenetic factors may affect the occurrence and frequency of sexual cannibalism within and among species. Ecological factors such as food and mate availability may primarily influence cannibalism by affecting the benefit of cannibalism for females. Phylogenetic factors such as feeding mode, sexual size dimorphism, certain mating behaviors, and genetic constraints may influence the vulnerability of the male to the female or the propensity of females to attack males. Although in some cases it may be difficult to separate the effects of co-occurring factors, in other cases comparative and phylogenetic approaches may aid in determining the influence of ecological and phylogenetic factors for the evolution of sexual cannibalism.
Consumer Finance
Authors: Tufano Peter
Published: August 2009

Although consumer finance is a substantial element of the economy, it has had a smaller footprint within financial economics. In this review, I suggest a functional definition of the subfield of consumer finance, focusing on four key functions: payments, risk management, moving funds from today to tomorrow (saving/investing), and from tomorrow to today (borrowing). I provide data showing the economic importance of consumer finance in the American economy. I propose a historical explanation for its relative lack of attention by financial economists and in business school curricula based on historic geographic and gender splits between business and consumer studies. I review the literature in consumer finance, organized by its focus on the consumer, financial institutions, and the government. This work is spread out between economics, marketing, psychology, sociology, technology, and public policy. Finally, I suggest a number of open research questions.
Copy Number Variation in Human Health, Disease, and Evolution
Authors: Zhang Feng , Gu Wenli , Hurles Matthew E. , Lupski James R.
Published: August 2009

Copy number variation (CNV) is a source of genetic diversity in humans. Numerous CNVs are being identified with various genome analysis platforms, including array comparative genomic hybridization (aCGH), single nucleotide polymorphism (SNP) genotyping platforms, and next-generation sequencing. CNV formation occurs by both recombination-based and replication-based mechanisms and de novo locus-specific mutation rates appear much higher for CNVs than for SNPs. By various molecular mechanisms, including gene dosage, gene disruption, gene fusion, position effects, etc., CNVs can cause Mendelian or sporadic traits, or be associated with complex diseases. However, CNV can also represent benign polymorphic variants. CNVs, especially gene duplication and exon shuffling, can be a predominant mechanism driving gene and genome evolution.
Unraveling a Multifactorial Late-Onset Disease: From Genetic Susceptibility to Disease Mechanisms for Age-Related Macular Degeneration
Authors: Swaroop Anand , Chew Emily Y. , Bowes Rickman Catherine , Abecasis Gonçalo R.
Published: August 2009

Aging-associated neurodegenerative diseases significantly influence the quality of life of affected individuals. Genetic approaches, combined with genomic technology, have provided powerful insights into common late-onset diseases, such as age-related macular degeneration (AMD). Here, we discuss current findings on the genetics of AMD to highlight areas of rapid progress and new challenges. We also attempt to integrate available genetic and biochemical data with cellular pathways involved in aging to formulate an integrated model of AMD pathogenesis.
Sequencing Primate Genomes: What Have We Learned?
Authors: Marques-Bonet Tomas , Ryder Oliver A. , Eichler Evan E.
Published: August 2009

We summarize the progress in whole-genome sequencing and analyses of primate genomes. These emerging genome datasets have broadened our understanding of primate genome evolution revealing unexpected and complex patterns of evolutionary change. This includes the characterization of genome structural variation, episodic changes in the repeat landscape, differences in gene expression, new models regarding speciation, and the ephemeral nature of the recombination landscape. The functional characterization of genomic differences important in primate speciation and adaptation remains a significant challenge. Limited access to biological materials, the lack of detailed phenotypic data and the endangered status of many critical primate species have significantly attenuated research into the genetic basis of primate evolution. Next-generation sequencing technologies promise to greatly expand the number of available primate genome sequences; however, such draft genome sequences will likely miss critical genetic differences within complex genomic regions unless dedicated efforts are put forward to understand the full spectrum of genetic variation.
Transforming growth factor-β1 downregulates caveolin-1 expression and enhances sphingosine 1-phosphate signaling in cultured vascular endothelial cells
Authors: Igarashi Junsuke , Shoji Kazuyo , Hashimoto Takeshi , Moriue Tetsuya , Yoneda Kozo , Takamura Tomoko , Yamashita Tetsuo , Kubota Yasuo , Kosaka Hiroaki
Published: August 2009

In vascular endothelial cells, specialized microdomains of plasma membrane termed caveolae modulate various receptor signal transduction pathways regulated by caveolin-1, a resident protein of caveolae. We examined whether transforming growth factor-β1 (TGF-β1), a multifunctional cytokine, alters expression levels of caveolin-1 and influences heterologous receptor signaling. Treatment of cultured bovine aortic endothelial cells (BAEC) with TGF-β1 induces marked decreases in caveolin-1 expression in a time- and dose-dependent fashion at both levels of protein and mRNA. A pharmacological inhibitor of activin receptor-like kinase 5 (ALK-5) counteracts caveolin-1 downregulation by TGF-β1, indicating the involvement of ALK-5 receptor subtype for TGF-β1. Sphingosine 1-phosphate (S1P) is a serum-borne angiogenic lipid growth factor that exerts a wide variety of biological actions. S1P modulates G protein-coupled S1P receptors, activating downstream molecules kinases AMP-activated protein kinase (AMPK), and Akt as well as a small G protein Rac1, ultimately to promote migration. Because S1P receptor signaling is associated with caveolae/caveolin-1, we examined whether pretreatment with TGF-β1 enhances effects of S1P on BAEC. Whereas S1P alone evokes robust BAEC responses to S1P, pretreatment with TGF-β1 leads to even higher magnitudes of S1P-elicited signaling responses and cell migration. Conversely, genetic knockdown of caveolin-1 using small interfering RNA mimics TGF-β1-induced promotion of BAEC responses to S1P. Collectively, these data demonstrate that TGF-β1 downregulates caveolin-1 of cultured endothelial cells, involving ALK-5 receptor subtype. Because downregulation of caveolin-1 by TGF-β1 promotes subsequent heterologous receptor signaling by S1P, these results may also identify novel point of cross-talk between cytokines and sphingolipids within endothelial signal transduction machineries.
Mechanisms of gastric emptying disturbances in chronic and acute inflammation of the distal gastrointestinal tract
Authors: Keller Jutta , Beglinger Christoph , Holst Jens Juul , Andresen Viola , Layer Peter
Published: August 2009

It is unclear why patients with inflammation of the distal bowel complain of symptoms referable to the upper gastrointestinal tract, specifically to gastric emptying (GE) disturbances. Thus we aimed to determine occurrence and putative pathomechanisms of gastric motor disorders in such patients. Thirteen healthy subjects (CON), 13 patients with Crohn's disease (CD), 10 with ulcerative colitis (UC), and 7 with diverticulitis (DIV) underwent a standardized13C-octanoic acid gastric emptying breath test. Plasma glucose, CCK, peptide YY, and glucagon-like peptide-1 (GLP-1) were measured periodically and correlated with GE parameters. Results were given in means ± SD. Compared with CON, GE half time (T) was prolonged by 50% in CD (115 ± 55 vs. 182 ± 95 min, P = 0.037). Six CD, 2 DIV, and 2 UC patients had pathological T (>200 min). Postprandial plasma glucose was increased in all patients but was highest in DIV and correlated with T ( r = 0.90, P = 0.006). In CD, mean postprandial CCK levels were increased threefold compared with CON (6.5 ± 6.7 vs. 2.1 ± 0.6 pmol/l, P = 0.027) and were correlated with T ( r = 0.60, P = 0.041). Compared with CON, GLP-1 levels were increased in UC (25.1 ± 5.2 vs. 33.5 ± 13.0 pmol/l, P = 0.046) but markedly decreased in DIV (9.6 ± 5.2 pmol/l, P < 0.0001). We concluded that a subset of patients with CD, UC, or DIV has delayed GE. GE disturbances are most pronounced in CD and might partly be caused by excessive CCK release. In DIV there might be a pathophysiological link between decreased GLP-1 release, postprandial hyperglycemia, and delayed GE. These explorative data encourage further studies in larger patient groups.