bluuebunny/crossref_metadata_2025 huggingface dataset:
On linear concentration dependences of K'm, V' and 1/νi enzyme kinetic parameters
Authors: Krupyanko Vladimír I.
Published: February 2010

The most frequently occurring incorrect uses of the plots of intercepts, slopes and other coordinates for the determination of constants of enzyme activation Ka and of nontrivial inhibition K(IIi), K(Vi), K(Ii), were analyzed. The correct plots are shown. Calculations of the K(Ii) and K(IIi) constants of nontrivial types of enzyme inhibition using the corrected plots of the intercepts are given.
Unusual (zig-zag) temperature dependence of the rate constant for irreversible thermoinactivation of hydrophilized enzymes
Authors: Šikšnis Virginius , Mozhaev Vadim V. , Galkantaite Nina , Melik-Nubarov Nikolai S. , Denis Genadii , Martinek Karel
Published: February 2010

Hydrophilized preparations of α-chymotrypsin and trypsin obtained by covalent modification of the enzymes with anhydrides of aromatic carboxylic acids (trimellitic, pyromellitic and mellitic) or with glyoxylic acid display an unusual temperature dependence of the rate constants of irreversible thermoinactivation: the linear plots (with positive and negative values of an effective activation energy) alternate in a zig-zag manner. A formal kinetic scheme describing this behaviour is suggested, involving the temperature-dependent conformational transition of modified α-chymotrypsin into a more stable conformation.
Vibronic constants for tetrahedral complexes with triple degenerate electron terms
Authors: Breza Martin , Pelikán Peter
Published: February 2010

Ti - (a1 + e + t2) vibronic coupling (i = 1,2) in tetrahedral systems is analysed. Using a non-linear regression analysis the potential (vibration and vibronic) constants in derived analytic formula of adiabatic potential surface are evaluated from numerical maps calculated by CNDO-UHF method for transition metals. The obtained results are in agreement with the correct understanding of the Jahn-Teller theorem: not the degeneracy of molecular orbitals, but the orbital degeneracy of electronic state is of deciding importance.
Kinetics of hydrogen peroxide decomposition on a Fe2O3-MoO3
Authors: Wassel Magdy A. , Zidan Farok I. , El-Wardani Mohamed
Published: February 2010

Kinetics of H2O2 decomposition on a Fe2O3-MoO3 (wt. ratio 2:3.8) catalyst was investigated at two concentrations of H2O2 (1.2 and 2.4 wt.%) and in the temperature range 25-45 °C. Also the effect of catalyst concentration was studied. An induction period was observed which duration depended on the temperature used.
Modified syntheses of 2-(methylthio)-10-(2-(1-methyl-2-piperidinyl)ethyl)phenothiazine (thioridazine) and 1-(3-(2-(methylsulfonyl)-10-phenothiazinyl)propyl)-piperidine-4-carboxamide (metopimazine)
Authors: Šindelář Karel , Holubek Jiří , Koruna Ivan , Hrubantová Marta , Protiva Miroslav
Published: February 2010

Modified syntheses of the title compounds used the enhanced reactivity of the aromatic fluorine atom in exchange reactions and proceeded via fluorinated intermediates. 2-(2-Fluorophenylthio)-5-(methylthio)nitrobenzene (III) was synthesized, reduced to the amine IV which was alkylated with 2-(2-chloroethyl)-1-methylpiperidine to compound VI. This was cyclized with sodium hydride in dimethyl sulfoxide to thioridazine (I) in excellent yield. The last two steps could be combined and thioridazine resulted from IV in one step. Synthesis of metopimazine (II) started similarly from 4-(2-fluorophenylthio)-3-nitrophenyl methyl sulfone (XII) which was reduced to the amine XIV and cyclized to 2-(methylsulfonyl)phenothiazine (XVII). Alkylation of XIV with 1-(3-chloropropyl)piperidine-4-carboxamide (X) proceeded with simultaneous cyclization and afforded metopimazine (II).
Reactions of N-tricyanovinylamines with thiols in aqueous solutions
Authors: Podhradský Dušan , Paulíková Helena , Imrich Ján
Published: February 2010

Kinetics of reactions between N-substituted tricyanovinylamines and thiols, where primarily reduction of the C=C double bond takes place, was investigated under conditions adequate to physiological ones. The reaction rates did not depend either on the type of the reacting thiol, or on the pH of the medium, but they decreased with the increasing pKa value of the imino group. A quantitative conversion of the thiol peptide glutathione to its oxidized form was evidenced.
Synthesis of piperidine derivatives as potential analgetic agents
Authors: Jílek Jiří , Rajšner Miroslav , Valenta Vladimír , Borovička Miloš , Holubek Jiří , Ryska Miroslav , Svátek Emil , Metyš Jan , Protiva Miroslav
Published: February 2010

Reaction of N-(1-(2-phenylethyl)-4-piperidinyl)propionanilide (I) with phosphorus pentasulfide gave the thioamide VI. Acylation of N-(1-(2-phenylethyl)-4-piperidinyl)aniline with 2-(methoxy)acetic and 2-(methylthio)acetic anhydrides afforded the amides II and III. Treatment of 4-anilino-1-benzylpiperidine-4-methanol with thionyl chloride gave the spirocyclic sulfurous acid ester amide XIV. Reduction of the hydrochloride of ethyl 3-(1-ethoxycarbonyl-4-phenylimino-3-piperidinyl)propionate (XXII) with sodium cyanoborohydride gave the perhydro-1,6-naphthyridine derivative XIX, a model compound in the synthesis of the cyclic analogue of fentanyl (I). Ethyl 4-anilino-1-(2-phenylethyl)-1,2,3,6-tetrahydropyridine-3-carboxylate (XXIX) hydrochloride, obtained by reaction of ethyl 4-oxo-1-(2-phenylethyl)piperidine-3-carboxylate hydrochloride with aniline, was reduced with lithium aluminium hydride to 4-anilino-1-(2-phenylethyl)piperidine-3-methanol (XXXI). 1-Methyl- and 1-benzyl-4-piperidone were reacted with 4-cyclopropylphenylmagnesium bromide and the tertiary alcohols XXXVII and XXXVIII obtained were acylated with propionyl chloride to give the esters XXXIX and XL. The piperidine derivatives XLI, XLVI and XLVIII were prepared as potential neurotropic agents. Alkylation of 8-hydroxy-6,11-dimethyl-1,2,3,4,5,6-hexahydro-2,6-methano-3-benzazocine (XLIX) with 2-(2-chloroethyl)-1,3-dioxane and -1,3-dioxolane resulted in the 6,7-benzomorphan derivatives L and LI. Out of the compounds prepared, only the closest fentanyl analogues II, III, and VI showed very strong analgetic activity.
Preparation and properties of 2-(dialkylaminomethyl)cyclohexyl and 2-(dialkylaminomethyl)phenyl carbanilates
Authors: Brádlerová Alena , Prónayová Nadežda , Mišíková Eva , Ďurinda Ján
Published: February 2010

A series of 2-(dialkylaminomethyl)cyclohexyl and 2-(dialkylaminomethyl)phenyl esters of substituted carbanilic acid have been prepared and their identity verified by elemental analysis and evaluation of IR and 13C NMR spectra. The spectral results have been used also for determination of isomerism of the starting 2-dialkylaminomethylcyclohexanols and final carbanilates. Local anaesthetic activity and acute toxicity have been tested with some of the substances.
Papain-catalyzed fragment synthesis of protected cholecystokinin derivatives
Authors: Čeřovský Václav , Pírková Jana , Majer Pavel , Slaninová Jiřina , Hlaváček Jan
Published: February 2010

Sodium salts of methyl esters of N-tert-butyloxycarbonyl-β-tert-butylaspartyl-O4-sulfotyrosine (II) or N-tert-butyloxycarbonyl-O4-sulfotyrosine (III) were condensed with amino components derived from peptide amides IVb-IVe and IVg (simulating the carboxy-terminal part of cholecystokinin) under catalysis with papain. Rates and yields of conversion of these peptides to the corresponding derivatives Ib-If were compared with the results reported previously for analogous papain-catalyzed fragment synthesis of the protected carboxy-terminal octapeptide of cholecystokinin Ia. In the condensation reactions with the individual amino components quantitative changes were observed in the ability of papain to catalyze the peptide bond synthesis which appeared as differences in the maximum yield (and the time required for achieving it) of the condensation reaction, monitored by HPLC. The observed differences are related not only with the distance of the amino acid substitution from the P'1 subsite in the given amino component but also with the side-chain structure of the substituting amino acid.
A topological quantum-chemical study of the chemisorption of carbon monoxide on the fcc (112) surfaces of Ni, Pt, Pd, Rh, and Ir
Authors: Pancíř Jiří , Haslingerová Ivana
Published: February 2010

A semiempirical quantum-chemical topological method is applied to the study of the fcc (112) surfaces of Ni, Pt, Pd, Rh, and Ir and the nondissociative as well as dissociative chemisorption of carbon monoxide on them. On Ni, dissociative chemisorption is preferred to linear capture, whereas on Pd and Pt, linear capture is preferred although dissociative chemisorption is also feasible. On Rh and, in particular, on Ir, dissociative chemisorption is energetically prohibited. The high dissociative ability of the Ni surface can be ascribed to a rather unusual charge alteration and to the degeneracy of the frontier orbitals. Negative charges at the surface level are only found on the Ni and Pt surfaces whereas concentration of positive charges is established on the Rh and Ir surfaces; the Pd surface is nearly uncharged. Metals with negatively charged surfaces seem to be able to dissociate molecules of carbon monoxide. It is demonstrated that CO adsorption can take place on all metal surface sites, most effectively in the valley of the step. In all the cases studied, the attachment to the surface is found to be energetically more favourable for the carbon than for the oxygen.
Oxidation of carbon monoxide by oxygen over pure and platinum-doped LaMnO3 perovskites
Authors: Bartoň Jaroslav , Pour Vladimír
Published: February 2010

The properties of pure and platinum-doped LaMnO3 perovskites, including their catalytic activities for the reaction of CO with oxygen, have been determined. Perovskite samples were prepared by decomposition of lanthanum and manganese citrates. The surface areas were 12.2 m2/g for pure LaMnO3 and 9.8 m2/g for the platinum-doped sample. The doping with a small amount of platinum markedly enhances the catalytic activity of LaMnO3 perovskite. The (CO + O2) reaction starts at 200 °C over LaMnO3 and at temperatures below 100 °C over a sample doped with Pt. The reaction kinetics for both the pure and platinum-doped LaMnO3 can be described by empirical equation (4). When Pt-doped perovskite is used, an increase in the apparent activation energy occurs at about 150 °C. This fact is attributed to a change in the mechanism of CO oxidation.
29Si and 13C NMR spectra of (E)-β-substituted 3-methoxy-4-trimethylsiloxystyrenes
Authors: Schraml Jan , Brežný Robert , Kvíčalová Magdalena , Čermák Jan
Published: February 2010

NMR spectra of eleven (E)-β-substituted 3-methoxy-4-trimethylsiloxy-styrenes were measured under standard conditions that approach those of infinite dilution. The sensitivity of 29Si chemical shifts to the nature of (E)-β-substituent is high, in comparison with 4-substituted 2-methoxytrimethylsiloxybenzenes the insertion of a CH=CH bridge between the substituent and the benzene ring reduces the sensitivity by a factor of 1.5 only.
A complete classification of stable symmetries of the Jahn-Teller systems
Authors: Breza Martin
Published: February 2010

The classification of stable symmetries of the Jahn-Teller systems for common symmetry groups with degenerate relativistic and non-relativistic electronic states is elaborated. The results obtained by epikernel principle and by the method of step-by-step symmetry descent are compared. The deficiency of the epikernel principle is demonstrated on some examples of the Jahn-Teller phase transitions.
NADH oxidation during peroxidase catalyzed metabolism of carcinogenic non-aminoazo dye 1-phenylazo-2-hydroxynaphthalene (Sudan I)
Authors: Stiborová Marie , Anzenbacher Pavel
Published: February 2010

The peroxidase catalyzed oxidation of 1-phenylazo-2-hydroxynaphthalene (Sudan I) in the presence of NADH results in oxidation to oxidized NAD+. This oxidation is supposed to be caused by the reduction of reactive Sudan I metabolite(s). Under certain conditions NADH acts as the agent protecting the cellular nucleophilic compounds such as nucleic acids (DNA, tRNA) against modification caused by reactive metabolite(s) formed from carcinogenic Sudan I by the peroxidase/H2O2 system. The results are discussed from the point of view of the physiological significance of NADH in the initiation of chemical carcinogenesis.
Use of 4-chlorobutyl esters in peptide synthesis
Authors: Amaral Trigo M. Joaquina S. A. , Oliveira Santos M. Isabel A.
Published: February 2010

Article without abstract
Differential pulse polarographic studies on simple and mixed ligand complexes of Cd(II) with diaminopropane and adipate ligands
Authors: Killa Hamada M. , Mabrouk El-Sayed M. , Abdel Fattah Abdel Fattah A.
Published: February 2010

The composition, stability and equilibria of ternary complexes of Cd(II) with adipate (Adp) as primary ligand and 1,3-diaminopropane (DAMP) as secondary ligand have been studied using differential pulse (d.p.) polarography. The results reveal the presence of three ternary complexes with stoichiometries 1:1:1, 1:1:2, and 1:2:1. Also, the composition and stability of binary species have been determined. The reduction of simple and mixed ligand complexes is reversible and diffusion controlled. The formation constants of mixed complexes were calculated and compared with the observed values.
IR laser induced decomposition of trifluoroacetic, pentafluoropropionic and heptafluorobutyric anhydrides
Authors: Kubát Pavel , Pola Josef
Published: February 2010

The continuous-wave CO2 laser induced gas-phase decomposition of trifluoroacetic, pentafluoropropionic and heptafluorobutyric anhydride, sensitized by sulfur hexafluoride was studied in order to determine the course of the reactions in the absence of wall effects. The decompositions of all the compounds are assumed to involve cleavage of parent compound into acyl fluoride F(CF2)nCOF and .(CF2)nCO2. biradical, the latter undergoing decay into CO and F(CF2)n-1COF compounds. The theoretical treatment of the biradical by MNDO calculations as well as trapping with ethene are presented.
Holdup and holdup profiles in the reciprocating plate extractor VPE
Authors: Sovová Helena , Bízek Vladislav , Procházka Jaroslav
Published: February 2010

In this work measurements of mean holdup of dispersed phase, of axial holdup profiles and of flooding points in a reciprocating plate contactor with both the VPE-type plates and the sieve plates were carried out. The experimental results were compared with a monodisperse model of steady-state column hydrodynamics and the model parameters were evaluated. Important differences in the behaviour of the two plate types could be identified. Comparison was also made between two reciprocating drives of different pulse form.
The change in the standard gibbs energy ΔG° during the formation of the double selenates M2Mg(SeO4)2.6 H2O (m = K, NH4, Rb, Cs)
Authors: Vojtíšek Pavel , Ebert Miroslav
Published: February 2010

The energy conditions for the formation of the compounds under the conditions of heterogeneous equilibrium were studied using the Filippov eutonic method, permitting the ΔG° values for the reactions leading to the formation of the above double selenates to be obtained directly. The values obtained, which varied in the range -17.8 to -24.4 kJ mol-1, were correlated with the solubilities of the compounds formed and the selenates M2SeO4. The interaction M2SeO4-MgSeO4 in the liquid phase was also studied.
The use of polymer sorbents in radioimmunoassay
Authors: Mikan Antonín , Čoupek Jiří
Published: February 2010

Several polymer sorbents were tested for use in radioimmunoassay. Separon EDMA, particle size 5-12 μm was found to have optimal properties. Its suspension behaves almost as a solution, pipette fouling never occurs. It can be centrifuged within one minute, thus eliminating the need for a refrigerated centrifuge. Assay results are the same as its Norit A, but more reliable.
Triethylamine borane - a stable, efficient and safe reductant for transforming carboxylic acids to primary alcohols
Authors: Kříž Otomar , Plzák Zbyněk , Plešek Jaromír
Published: February 2010

Triethylamine borane, (C2H5)3N.BH3, is a stable, safe and readily available reagent which at 80 °C reduces carboxylic acids to primary alcohols in high yields; functional derivatives of carboxylic acids such as esters, nitriles or amides are virtually nonreactive with this reagent under the same conditions. Aldehydes, ketones and acid chlorides, however, react readily. No solvent is required for the process.
Does a home-based strength and balance programme in people aged ≥80 years provide the best value for money to prevent falls? A systematic review of economic evaluations of falls prevention interventions
Authors: Davis J C , Robertson M C , Ashe M C , Liu-Ambrose T , Khan K M , Marra C A
Published: February 2010

Objectives

To investigate the value for money of strategies to prevent falls in older adults living in the community.

Design

Systematic review of peer reviewed journal articles reporting an economic evaluation of a falls prevention intervention as part of a randomised controlled trial or a controlled trial, or using an analytical model. MEDLINE, PUBMED, EMBASE and NHS EED databases were searched to identify cost-effectiveness, cost–utility and cost–benefit studies from 1945 through July 2008.

Main outcome measures

The primary outcome measure was incremental cost-effectiveness, cost–utility and cost–benefit ratios in the reported currency and in pounds sterling at 2008 prices. The quality of the studies was assessed using two instruments: (1) an economic evaluation checklist developed by Drummond and colleagues and (2) the Quality of Health Economic Studies instrument.

Results

Nine studies meeting our inclusion criteria included eight cost-effectiveness analyses, one cost–utility and one cost–benefit analysis. Three effective falls prevention strategies were cost saving in a subgroup of participants: (1) an individually customised multifactorial programme in those with four or more of the eight targeted fall risk factors, (2) the home-based Otago Exercise Programme in people ≥80 years and (3) a home safety programme in the subgroup with a previous fall. These three findings were from six studies that scored ≥75% on the Quality of Health Economic Studies instrument.

Conclusions

Best value for money came from effective single factor interventions such as the Otago Exercise Programme which was cost saving in adults 80 years and older. This programme has broad applicability thus warranting warrants health policy decision-makers’ close scrutiny.
A meningeal myofibroblastic neoplasm related to solitary fibrous tumour and associated with a malignant neuroblastic element
Authors: Bracey T S , Hilton D A , Sulkin T , Smith M E F
Published: February 2010

Background

Solitary fibrous tumour (SFT) is a rare mesenchymal tumour now described at many locations, including the meninges. Intracranial SFT closely resembles meningioma clinically and radiologically, and, like meningioma, reports of meningeal SFT suggest a relatively benign behaviour after complete resection. Histopathological features distinguishing SFT from meningioma include variable cellularity, spindle cells arranged in fascicles, staghorn blood vessels and immunopositivity for CD34.

Clinical presentation

The case is reported of a 60-year-old man with an anterior cranial fossa meningeal-based mass, which was resected. Histology showed some features in common with SFT (variable cellularity, spindled morphology, CD34 expression), but included an epithelioid element with cytokeratin and desmin immunopositivity, and lacked the characteristic vascular pattern of SFT. Histological features of meningioma were lacking. Recurrence of the tumour with extracranial extension 9 years later resulted in death of the patient. Histological examination revealed similar biphasic epithelioid and spindled CD34-immunopositive appearance to the earlier tumour, but in addition showed a high-grade element resembling olfactory neuroblastoma.

Conclusion

This case report is of a meningeal-based mesenchymal neoplasm with histological similarities to SFT. Its morphology and immunophenotype, however, are distinct from SFT and hence it is proposed that it is a newly described entity. In addition, recurrence of the tumour with a high-grade neuroblastic element has, to our knowledge, not previously been described in SFT.
The role of fine-needle aspiration in the diagnosis of thyroid lymphoma: a retrospective study of nine cases and review of published series
Authors: Morgen Eric K , Geddie William , Boerner Scott , Bailey Denis , Santos Gilda da Cunha
Published: February 2010

Aims

To review the clinicopathological, cytomorphological and immunophenotyping data from new cases and published series of thyroid lymphoma diagnosed by fine-needle aspiration (FNA), in order to identify useful diagnostic features.

Methods

Cases from 1988 to 2009 with an FNA diagnosis of thyroid lymphoma were selected from hospital records. An electronic MEDLINE(R) and EMBASE search retrieved published series from 1980 to 2009. Available clinical, cytomorphological and immunophenotyping data from all cases were collected. In our cases, cytology slides and available surgical specimens were also reviewed.

Results

There were nine cases from eight of our patients, and 70 reviewed cases from eight series with at least four patients each. The most common presentation was a rapidly enlarging thyroid mass. Average patient age was 61 years in reviewed cases and 72 years in our cases. Large-cell lymphoma was the predominant subtype, revealing relatively monotonous populations of large, abnormal lymphoid cells. One of our cases, later diagnosed as marginal zone lymphoma, showed small lymphocytes with plasmacytoid features. Immunoprofiling information was available in five of our cases (three by immunocytochemistry and two by laser scanning cytometry) and in 34 reviewed cases (22 by immunocytochemistry, six by flow cytometry, and six by flow cytometry or immunocytochemistry).

Conclusions

Cytological diagnosis of thyroid lymphoma requires careful analysis of morphological, clinical and immunophenotypic information. The presented data suggest certain helpful features: a fast-growing nodule in an elderly patient, a monotonous population of large abnormal cells in a background of lymphoglandular bodies, a predominant population of plasmacytoid lymphocytes, and immunophenotyping demonstrating light chain restriction.
Serum CA19.9 levels are commonly elevated in primary ovarian mucinous tumours but cannot be used to predict the histological subtype
Authors: Kelly Paul J , Archbold Pooler , Price John H , Cardwell Chris , McCluggage W Glenn
Published: February 2010

Aims

CA19.9 is a monosialoganglioside secreted by mucinous tumours of the gastrointestinal tract, including the pancreas and biliary tree. Limited studies have shown that this tumour marker may also be elevated in primary ovarian mucinous neoplasms, but no study has assessed whether serum CA19.9 levels can be used to predict if a primary ovarian mucinous tumour is benign, borderline or malignant. The aim of this study was to correlate the serum CA19.9 level with the histological features in a large series of primary ovarian mucinous neoplasms.

Methods

144 cases of primary ovarian mucinous neoplasm (79 benign, 45 borderline and 20 malignant) were identified in which a preoperative serum CA19.9 level had been performed. The association between the serum levels and the histological subtype and a variety of other parameters was investigated. In a subset of cases, immunohistochemical staining for CA19.9 was performed on tumour blocks.

Results

Serum CA19.9 levels were elevated in 27%, 38% and 40% of mucinous cystadenomas, borderline mucinous tumours and mucinous carcinomas, respectively. Markedly elevated levels of serum CA19.9 were observed in each group, with the highest serum CA19.9 measurements being noted in borderline mucinous tumours. There was no relationship between the serum CA19.9 level and whether the tumours were benign, borderline or malignant (Kruskal–Wallis test p value=0.32). A weak but statistically significant correlation was found between tumour maximum dimension and CA19.9 level (Spearman's rank correlation coefficient=0.17, p=0.04). In those cases in which CA19.9 immunohistochemistry was performed, all tumours showed positive staining for CA19.9, with 60% of these cases being associated with an elevated serum CA19.9 level.

Conclusion

Preoperative CA19.9 levels cannot be used to predict whether a suspected ovarian mucinous tumour is benign, borderline or malignant. Markedly elevated serum levels (>1000 U/ml) may be found in benign mucinous neoplasms as well as in borderline and malignant tumours.
Lower Silurian (Aeronian) megafaunal and conodont biofacies of the northwestern Michigan Basin
Authors: Watkins Rodney , Kuglitsch Jeffrey J.
Published: February 2010

Lower Silurian (Llandovery: Aeronian) carbonates of the Burnt Bluff Group, northwestern Michigan Basin, represent a transect along a southward-dipping ramp that extends from tidal-flat to basin environments. Benthic megafaunas include an ostracod biofacies (tidal flat), stromatoporoid–coral biofacies (very shallow subtidal), pentamerid, crinozoan, and crinozoan–stromatoporoid biofacies (deeper subtidal), and a crinozoan–sponge biofacies (distal ramp and basin). The crinozoan–sponge biofacies, which includes diverse, small crinozoan ossicles, 19 types of siliceous sponge spicules, and at least 65 other taxa, has a biota that is similar to those of Silurian continental margins. Megafaunal biofacies indicate an Early Silurian gradient going from a shoreline in the north to water depths of perhaps 60 m in the south. The Burnt Bluff Group contains conodonts of the Icriodella discreta – Icriodella deflecta zone as an onshore biofacies with Panderodus, Kockelella, Ozarkodina, Icriodella, and Oulodus, and an offshore biofacies with Panderodus, Walliserodus, and Aspelundia.
Controls on aragonite and calcite precipitation in hot spring travertines at Chemurkeu, Lake Bogoria, Kenya
Authors: Renaut Rubin W. , Jones Brian
Published: February 2010

Subfossil travertines precipitated around hot spring orifices at Chemurkeu on the western shore of Lake Bogoria, Kenya, are composed of calcite, aragonite, and minor dolomite. Aragonite crystal beds, which form 5–10% of the travertine by volume, are formed of large pseudohexagonal prisms, whereas the calcite crystal beds are composed mainly of feather dendrites. Dolomite is only found between aragonite crystals. Boundaries between aragonite and calcite crystals commonly display evidence of dissolution, but there is no evidence to indicate that calcite formed by inversion of aragonite or that the dolomite replaced the aragonite. Thus, the aragonite, calcite, and dolomite are each treated as primary precipitates. Reticulate gelatinous coatings, with a high Si and Mg content, cover most external and internal surfaces of the aragonite and calcite crystals. The travertines may have formed under more humid conditions than today, when the spring waters contained more Ca2+. The physiochemical conditions at the modern springs provide a context for interpreting the factors that controlled the precipitation of the aragonite and calcite. Today, the hot (T > 85 °C) Na–HCO3–Cl spring waters at Chemurkeu, which have a salinity of ~6 g∙L−1 total dissolved solids, a pH of 8.1–9.1, and contain < 2 mg∙L−1 of Ca2+ and < 0.7 mg∙L−1 of Mg2+, are fed by a shallow aquifer [Formula: see text] and a deeper aquifer (T = 170 °C). Modern spring waters, derived from meteoric groundwater, lake water, and condensed steam, are fed mainly from the shallow thermal aquifer. Field, petrographic, and scanning electron microscope evidence obtained from the travertines, coupled with knowledge of the modern springs, indicates that the progressive and cyclic alternation from calcite precipitation to aragonite precipitation to aragonite dissolution which characterizes many travertine successions may have been caused by changes in [Formula: see text] of the spring waters under high temperatures (> 90 °C). The textures in the travertines show that precipitation of the aragonite and calcite crystals was probably abiotic, and episodic rather than continuous. Rapid degassing of CO2 associated with shallow boiling was probably a major factor in crystal growth.
Late Paleozoic small foraminifers (endothyrids) from South America (Ecuador and Bolivia)
Authors: Mamet Bernard L.
Published: February 2010

In the Pangea, small foraminifers (endothyrids) are useful tools for studying the stratigraphy of the late Paleozoic. However, they have been largely ignored in South America. This article reports for the first time their widespread occurrence in the subcontinent and illustrates representatives of 21 families encountered from the Early Pennsylvanian (Bashkirian) to the Early Permian (Artinskian). Fifty-five foraminiferal genera are recognized in three basins of Ecuador–Bolivia and enable us to establish a crude zonation. The fauna is nonendemic, all genera being previously known from Eurasia and North America. There are also a number of taxa derived from the Arctic Realm (Sverdrup Basin and Arctic Alaska). In association with the microflora of green and red algae, the microfauna suggests temperate warm conditions. This indicates that since the Middle Carboniferous, warm climatic oscillations affected the South American part of Gondwana.
ON ALTERNATING PHRASE-STRUCTURE GRAMMARS
Authors: MORIYA ETSURO , OTTO FRIEDRICH
Published: February 2010

The concepts of alternation and of state alternation are extended from context-free grammars to context-sensitive and arbitrary phrase-structure grammars. For the resulting classes of alternating grammars the expressive power is investigated with respect to the leftmost derivation mode and with respect to the unrestricted derivation mode. In particular new grammatical characterizations for the class of languages that are accepted by alternating pushdown automata are obtained in this way.
APPROXIMATION SCHEMES FOR SCHEDULING JOBS WITH CHAIN PRECEDENCE CONSTRAINTS
Authors: JANSEN KLAUS , SOLIS-OBA ROBERTO
Published: February 2010

We study the problem of scheduling jobs with precedence constraints and present two polynomial time approximation schemes for it. The first one is for the case when the machines are identical and the precedence graph partitions the jobs into groups of fixed size. As an interesting particular case, this yields a polynomial time approximation scheme for scheduling jobs with chain or tree precedence constraints on identical machines, when each chain or tree is of constant size. The second approximation scheme is for scheduling jobs with arbitrarily long chain precedence constraints on uniformly related machines when the number of machines is fixed.
AN ALGORITHM AND APPLICATIONS TO SEQUENCE ALIGNMENT WITH WEIGHTED CONSTRAINTS
Authors: PENG YUNG-HSING , YANG CHANG-BIAU , TSENG KUO-TSUNG , HUANG KUO-SI
Published: February 2010

Given two sequences S1, S2, and a constrained sequence C, a longest common subsequence of S1, S2 with restriction to C is called a constrained longest common subsequence of S1 and S2 with C. At the same time, an optimal alignment of S1, S2 with restriction to C is called a constrained pairwise sequence alignment of S1 and S2 with C. Previous algorithms have shown that the constrained longest common subsequence problem is a special case of the constrained pairwise sequence alignment problem, and that both of them can be solved in O(rnm) time, where r, n, and m represent the lengths of C, S1, and S2, respectively. In this paper, we extend the definition of constrained pairwise sequence alignment to a more flexible version, called weighted constrained pairwise sequence alignment, in which some constraints might be ignored. We first give an O(rnm)-time algorithm for solving the weighted constrained pairwise sequence alignment problem, then show that our extension can be adopted to solve some constraint-related problems that cannot be solved by previous algorithms for the constrained longest common subsequence problem or the constrained pairwise sequence alignment problem. Therefore, in contrast to previous results, our extension is a new and suitable model for sequence analysis.
THE CLIFFORD SPACE GEOMETRY BEHIND THE PIONEER AND FLYBY ANOMALIES
Authors: CASTRO CARLOS
Published: February 2010

It is rigorously shown how the extended relativity theory in Clifford spaces (C-spaces) can explain the variable radial dependence ap(r) of the Pioneer anomaly; its sign (pointing towards the Sun); why planets do not experience the anomalous acceleration and why the present day value of the Hubble scale RH appears. It is the curvature–spin coupling of the planetary motions that hold the key. The difference in the rate at which clocks tick in C-space translates into the C-space analog of Doppler shifts which may explain the anomalous redshifts in cosmology, where objects which are not that far apart from each other exhibit very different redshifts. We conclude by showing how the empirical formula for the flybys anomalies obtained by Anderson et al.17 can be derived within the framework of Clifford geometry.
NONLINEAR DYNAMICS OF SOFT FERMION EXCITATIONS IN HOT QCD PLASMA: SOFT-QUARK BREMSSTRAHLUNG AND ENERGY LOSSES
Authors: MARKOV YU. A. , MARKOVA M. A. , VALL A. N.
Published: February 2010

Within the framework of a semiclassical approximation the general theory of calculation of effective currents and sources generating bremsstrahlung of an arbitrary number of soft quarks and soft gluons at collision of a high-energy color-charged particle with thermal partons in a hot quark–gluon plasma is developed. For the case of one- and two-scattering thermal partons with radiation of one or two soft excitations, the effective currents and sources are calculated in an explicit form. In the model case of "frozen" medium, approximate expressions for energy losses induced by the most simple processes of bremsstrahlung of soft quark and soft gluon are derived. On the basis of a conception of the mutual cancellation of singularities in the sum of so-called "diagonal" and "off-diagonal" contributions to the energy losses, an effective method of determining color factors in scattering probabilities containing the initial values of Grassmann color charges is suggested. The dynamical equations for Grassmann color charges of hard particle used by us earlier on are proved to be insufficient for investigation of the higher radiative processes. It is shown that for correct description of these processes the given equations should be supplemented successively with the higher-order terms in powers of the soft fermionic field.
RENAISSANCE OF THE ~1 TeV FIXED-TARGET PROGRAM
Authors: ADAMS T. , APPEL J. A. , ARMS K. E. , BALANTEKIN A. B. , CONRAD J. M. , COOPER P. S. , DJURCIC Z. , DUNWOODIE W. , ENGELFRIED J. , FISHER P. H. , GOTTSCHALK E. , DE GOUVEA A. , HELLER K. , IGNARRA C. M. , KARAGIORGI G. , KWAN S. , LOINAZ W. A. , MEADOWS B. , MOORE R. , MORFÍN J. G. , NAPLES D. , NIENABER P. , PATE S. F. , PAPAVASSILIOU V. , PETROV A. A. , PUROHIT M. V. , RAY H. , RUSS J. , SCHWARTZ A. J. , SELIGMAN W. G. , SHAEVITZ M. H. , SCHELLMAN H. , SPITZ J. , SYPHERS M. J. , TAIT T. M. P. , VANNUCCI F.
Published: February 2010

This document describes the physics potential of a new fixed-target program based on a ~1 TeV proton source. Two proton sources are potentially available in the future: the existing Tevatron at Fermilab, which can provide 800 GeV protons for fixed-target physics, and a possible upgrade to the SPS at CERN, called SPS+, which would produce 1 TeV protons on target. In this paper we use an example Tevatron fixed-target program to illustrate the high discovery potential possible in the charm and neutrino sectors. We highlight examples which are either unique to the program or difficult to accomplish at other venues.
ON KERR–DE SITTER METRIC
Authors: ABBASSI AMIR H. , KHOSRAVI SH. , ABBASSI AMIR M.
Published: February 2010

We present our derivations for Kerr–de Sitter metric in a proper comoving coordinate system. It asymptotically approaches to the de Sitter metric in Robertson–Walker form. This has been done by considering the stationary axially-symmetric space–time in which motion of particle is integrable. That is the Hamilton–Jacobi and Klein–Gordon equations are separable. In this form it is asymptotically consistent with comoving frame.
BROADBAND RESONANT MASS GRAVITATIONAL WAVE DETECTION
Authors: AGUIAR ODYLIO D. , BARROSO JOAQUIM J. , MARINHO RUBENS M. , PIMENTEL GUILHERME L. , TOBAR MICHAEL E.
Published: February 2010

By changing from a resonant multimode paradigm to a free mass paradigm for transducers in resonant mass gravitational wave detection, an array of six spheres can achieve a sensitivity response curve competitive with interferometers, being as sensitive as GEO600 and TAMA300 in the 3–6 kHz band and more sensitive than LIGO for 50% of the 6–10 kHz band. This approach has additional benefits. First, due to the relatively inexpensive nature of this technology (~US$1 million), it is accessible to a broader part of the world's scientific community. Additionally, spherical resonant mass detectors have the ability to discern both the direction and polarization resolutions.
THE COSMOLOGICAL CONSTANT PROBLEM: A USER'S GUIDE
Authors: BERTOLAMI ORFEU
Published: February 2010

We discuss the validity of general relativity at low energy and relate the threshold below which the theory breaks down to the observed value of the cosmological constant. This suggests the existence of a mass scale of [Formula: see text] and a putative violation of the equivalence principle at about the 10−14 level.
THE FORCE OF GRAVITY IN SCHWARZSCHILD AND GULLSTRAND–PAINLEVÉ COORDINATES
Authors: BRANNEN CARL
Published: February 2010

We derive the exact equations of motion (in Newtonian, F = ma, form) for test masses in Schwarzschild and Gullstrand–Painlevé coordinates. These equations of motion are simpler than the usual geodesic equations obtained from Christoffel tensors, in that the affine parameter is eliminated. The various terms can be compared against tests of gravity. In force form, gravity can be interpreted as resulting from a flux of superluminal particles (gravitons). We show that the first order relativistic correction to Newton's gravity results from a two-graviton interaction.
CONSTRAINTS ON EMERGENT GRAVITY
Authors: JENKINS ALEJANDRO
Published: February 2010

In this essay we review the central difficulty in formulating a viable quantum field theory in which gravity is emergent at low energies rather than being mediated by a fundamental gauge field. The Weinberg–Witten theorem forbids spin 2, massless modes from carrying Lorentz-covariant stress–energy. In general relativity the stress–energy is not covariant because it violates a gauge invariance, but a gravitational theory without fundamental spin 2 gauge invariance must either lack a stress–energy operator or have a nonrelativistic graviton. The latter option is incompatible with the principle of equivalence, though such theories are not necessarily ruled out at low energies.
THE RETURN OF THE PHOENIX UNIVERSE
Authors: LEHNERS JEAN-LUC , STEINHARDT PAUL J. , TUROK NEIL
Published: February 2010

Georges Lemaitre introduced the term "phoenix universe" to describe an oscillatory cosmology with alternating periods of gravitational collapse and expansion. This model is ruled out observationally, because it requires a supercritical mass density and cannot accommodate dark energy. However, a new cyclic theory of the universe has been proposed that evades these problems. In a recent elaboration of this picture, almost the entire universe observed today is fated to become entrapped inside black holes, but a tiny region will emerge from these ashes like a phoenix to form an even larger smooth, flat universe filled with galaxies, stars, planets, and, presumably, life. Survival depends crucially on dark energy and suggests a reason why its density is small and positive today.
SEMICLASSICAL VIOLATION OF THE EQUIVALENCE PRINCIPLE IN THE GRAVITATIONAL LENSES REALM
Authors: ACCIOLY ANTONIO , PASZKO RICARDO
Published: February 2010

An expression for the gravitational deflection angle of a high-energy massless scalar boson is computed using the JWKB method. The resulting expression depends on the energy of the scalar boson or, equivalently, on its wavelength, even to first order in [Formula: see text], where G is Newton's constant, M is the mass of the gravitational source, and b is the impact parameter. On the other hand, combining the expressions for the magnification of two images obtained from a gravitational lens with the classical expression for the cross section, it is found that for purely gravitational scatterings the gravitational cross sections are proportional to the relative intensities. As a consequence of this remarkable proportionality and of the fact that the deflection angle obtained via the JWKB method is energy dependent, we come to the conclusion that chromatic effects in the gravitational lenses at the semiclassical level are possible, which violates the classical equivalence principle. The probability of detecting this tiny effect in the foreseeable future is discussed.
CAN WE SEE NAKED SINGULARITIES?
Authors: DESHINGKAR SHRIRANG S.
Published: February 2010

We study singularities which can form in a spherically symmetric gravitational collapse of a general matter field obeying weak energy condition. We show that null naked singularities that form in such a collapse can never be observed. No energy can come out of these singularities; thus they will have no physical consequences outside. As this happens for any null singularity, we do not need to assume specific form of matter and establish role of initial data. Hence our result is very general.
QUANTUM-GRAVITATIONAL RUNNING/REDUCTION OF THE SPACE–TIME DIMENSION
Authors: MAZIASHVILI MICHAEL
Published: February 2010

Quantum gravity causes the space–time dimension to depend on the size of the region; it monotonically increases with the size of the region and asymptotically approaches 4 for large distances. This effect was discovered in numerical simulations of lattice quantum gravity in the framework of causal dynamical triangulation (arXiv:hep-th/0505113), as well as in the renormalization group approach to quantum gravity (arXiv:hep-th/0508202). However, in these approaches the interpretation and physical meaning of the effective change of dimension at shorter scales is not clear. Without invoking particular models in this paper, we show that the box-counting dimension in the face of finite resolution of space–time (generally implied by quantum gravity) indicates a simple way in which both the qualitative and the quantitative features of this effect can be understood. In this way we derive a simple analytic expression of space–time dimension running, which implies the modification of Newton's inverse square law in perfect agreement with the modification coming from one-loop gravitational radiative corrections.
k-MOUFLAGE GRAVITY
Authors: BABICHEV E. , DEFFAYET C. , ZIOUR R.
Published: February 2010

We introduce a large class of scalar–tensor theories where gravity becomes stronger at large distances via the exchange of a scalar that mixes with the graviton. At small distances, i.e. large curvature, the scalar is screened via an analog of the Vainshtein mechanism of massive gravity. The crossover distance between the two regimes can be made cosmological by an appropriate choice of the parameters.
WARM TACHYONIC INFLATION IN A WARPED BACKGROUND
Authors: DESHAMUKHYA ATRI , PANDA SUDHAKAR
Published: February 2010

We analyze warm tachyonic inflation, proposed in the literature, from the viewpoint of four-dimensional effective action for the tachyon field on a non-BPS D3-brane. We find that consistency with observational data on density perturbation and validity of effective action requires warped compactification. The number of background branes which source the flux is found to be of the order of 10, in contrast to the order of 1014 in the standard cold inflationary scenario.
WHAT IF THE INFLATON IS A SPINOR CONDENSATE?
Authors: SHANKARANARAYANAN S.
Published: February 2010

In the usual cosmological inflationary scenarios, the scalar field — the inflaton — is usually assumed to be an elementary field. In this essay, we ask: What are the observational signatures if the scalar field is a spinor condensate? And is there a way to distinguish between the canonical scalar field and the spinor-condensate-driven models? In the homogeneous and isotropic background, we show that — although the dark-spinor (Elko) condensate leads to an acceleration equation identical to that of the canonical-scalar-field-driven inflation — the dynamics of the two models are different. In the slow-roll limit, we show that the model predicts a running of the scalar spectral index consistent with the WMAP data. We show that the consistency relations between the spinor condensate and the canonical-scalar-field-driven model are different, which we will be able to test using the future CMB and gravitational wave missions.
FROM TIME TO TIMESCAPE — EINSTEIN'S UNFINISHED REVOLUTION
Authors: WILTSHIRE DAVID L.
Published: February 2010

I argue that Einstein overlooked an important aspect of the relativity of time in never quite realizing his quest to embody Mach's principle in his theory of gravity. As a step towards that goal, I broaden the strong equivalence principle to a new principle of physics, the cosmological equivalence principle, to account for the role of the evolving average regional density of the universe in the synchronisation of clocks and the relative calibration of inertial frames. In a universe dominated by voids of the size observed in large-scale structure surveys, the density contrasts of expanding regions are strong enough that a relative deceleration of the background between voids and the environment of galaxies, typically of order 10−10 ms−2, must be accounted for. As a result one finds a universe whose present age varies by billions of years according to the position of the observer: a timescape. This model universe is observationally viable: it passes three critical independent tests, and makes additional predictions. Dark energy is revealed as a mis-identification of gravitational energy gradients and the resulting variance in clock rates. Understanding the biggest mystery in cosmology therefore involves a paradigm shift, but in an unexpected direction: the conceptual understanding of time and energy in Einstein's own theory is incomplete.
NEUTRINO AND ANTINEUTRINO ENERGY LOSS RATES IN MASSIVE STARS DUE TO ISOTOPES OF TITANIUM
Authors: NABI JAMEEL-UN
Published: February 2010

Weak interaction rates on titanium isotopes are important during the late phases of evolution of massive stars. A search was made for key titanium isotopes from available literature and a microscopic calculation of weak rates of these nuclei were performed using the proton-neutron quasiparticle random phase approximation (pn-QRPA) theory. Earlier the author presented the stellar electron capture rates on titanium isotopes. In this paper I present the neutrino and antineutrino energy loss rates due to capture and decay rates on isotopes of titanium in stellar environment. Accurate estimate of neutrino energy loss rates are needed for the study of the late stages of the stellar evolution, in particular for cooling of neutron stars and white dwarfs. The results are also compared against previous calculations. At high stellar temperatures the calculated neutrino and antineutrino energy loss rates are bigger by more than two orders of magnitude as compared to the large scale shell model results and favor stellar cores with lower entropies. This study can prove useful for core-collapse simulators.