bluuebunny/crossref_metadata_2025 huggingface dataset:
Lukians Podagra und die Beichtinschriften Kleinasiens
Authors: Petzl Georg
Published: September 2009

Lukians Podagra und die Beichtinschriften Kleinasiens (pp. 131-145)

On connaît en Asie Mineure occidentale un groupe d'inscriptions grecques du IIème et IIIème s. apr. J.-C, appelées "confessions". Les stèles qui les portent étaient érigées dans de petits sanctuaires paysans, consacrés à des divinités locales. Celles-ci punissaient les personnes coupables d'un délit sacré, en les frappant de maladies (et même de mort). C'est ce que racontent les inscriptions; parce que, pour retrouver une bonne relation avec le dieu, il était nécessaire de faire connaître la faute, la punition et la reconnaissance, après la réconciliation. La petite parodie tragique "Podagra" de Lucien présente la "Goutte" comme une déesse suprême qui exige une obéissance absolue; il y a aussi une scène de confession publique. La pièce comporte certains traits et termes qui se retrouvent dans les inscriptions, comme le montre une analyse détaillée. L'auteur présente une conception religieuse qui a son origine dans l'Ancien Orient et qui est aussi à la base des confessions de l'Asie Mineure.
Erodoto, VI, 137 e la schiavitù minorile
Authors: Paradiso Annalisa
Published: September 2009

Erodoto, VI, 137e la schiavitu minorile (pp. 21-27)

Dans Hérodote VI, 137, 3 ce sont les filles -et non pas les fils- des Athéniens qui allaient puiser l'eau à la source Ennéacrounos, car c'étaient elles que les Pélasges violaient. Te kaî toùspaîdas est donc à rayer, rien que pour des raisons grammaticales, mais pas du tout historiques. Chercher l'eau n'était pas un travail réservé aux femmes: des témoignages iconographiques nous montrent qu'il était pratiqué aussi par des adolescents.
De la poésie chorale au stasimon tragique [Pragmatique de voix féminines]
Authors: Calame Claude
Published: September 2009

De la poésie chorale au stasimon tragique (pp. 1 8 1 -203)

Transférées sur la scène attique et insérées dans l'intrigue narrative qui y est dramatisée, les formes de la poésie chorale traditionnelle acquièrent dans le théâtre tragique des fonctions nouvelles tout en maintenant leur dimension pragmatique forte. Une analyse comparative d'un Parthénée de Pindare avec la parodos des Sept contre Thèbes d'Eschyle et avec le chant choral correspondant des Phéniciennes d'Euripide peut montrer qu'à côte de sa fonction rituelle et performative, la voix du chœur féminin de la tragédie classique peut assumer à la fois l'expression des émotions suscitées par l'action jouée sur la scène et un rôle herméneutique de commentaire de cette action. L'intervention chorale se situe ainsi, par mimésis interposée, entre intrigue scénique et réaction du public.
Les brocards de Loki et la toile d'Arachné
Authors: Mezzadri Bernard
Published: September 2009

Les brocards de Loki et la toile d'Arachné (pp. 439-450)

Le nom suédois de l'araignée évoque celui du dieu Loki, le pernicieux meurtrier de Baldr. Plusieurs arguments plaident contre la thèse d'une simple coïncidence : non seulement le comportement cruel du trickster nordique s'accorde avec celui de l'insecte, mais ils possèdent le même type d'intelligence rusée, très comparable à la métis des Grecs et qui se cristallise dans les mailles du filet inventé par Loki ou de la toile que tissent les araignées. Plus singulière cependant est l'articulation dans les deux cultures de représentations a priori hétérogènes ; un animal habile à tendre des pièges ; une poésie satirique qui prend les dieux pour cibles de ses brocards. Le mythe d'Arachné les conjoint et permet ainsi de conforter l'hypothèse d'une liaison parallèle entre le railleur de la Lokasenna et l'araignée en pays Scandinave. La structure ainsi révélée éclaire peut-être aussi certains aspects de l'épisode des « Amours d'Ares et Aphrodite » dans l'Odyssée.
Deux publicains et leur tombeau
Authors: Gawlikowski M.
Published: September 2009

A new displaced inscription found in Palmyra, in Latin, Greek and Palmyrene, gives the names of two freedmen who have built together a tomb in AD 56/57. They were C. Virius Alcimus and T. Statilius Hermes. The former is also known from his likeness in the British Museum (WA 125036), where he is shown with his wife Viria Phoibe. The same man is also mentioned in the Tariff as a publican, together with his partner (as restored by I.S. Shifman), during or before the governorship of Licinius Mucianus (AD 67-69). Accordingly, the BM sculpture cannot be later than the second half of the 1st cent., being thus one of the earliest funerary sculptures on record from Palmyra.
Monuments du culte "dolichénien" en Cyrrhestique
Authors: Gatier Pierre-Louis
Published: September 2009

Several reliefs discovered in the territories of Cyrrhus, Beroia and Hierapolis, in Northern Syria, display a typical dolichenian iconography. They are directly linked to the cult of Jupiter-Zeus from Dolichè. Others, in the same region are testimonies of Jovian cults. All together they prove the extension of the devotion to the great god of the mountain and storm — either Hadad or Jupiter Dolichenus — in rural communities of Northern Syria during Roman times. A Latin inscription from the Euphrates bank (Khirbet Khalid) has to be connected with the cult of Jupiter Dolichenus among Roman soldiers.
Nouvelles recherches sur l'Obsidienne de Cheikh Hassan (Vallée de l'Euphrate, Syrie) au néolithique : PPNA et PPNB Ancien
Authors: Abbès Frédéric
Published: September 2009

Jt\y~^\ pUil tJL» OllJu Jjli «tti
La réutilisation des éléments d'architecture du temple haut du sanctuaire de Zeus à Gerasa à la période byzantine
Authors: March Chrystelle
Published: September 2009

À travers l'exemple du temple haut du sanctuaire de Zeus, on examine ici les conditions de la réutilisation des éléments d'architecture des sanctuaires romains de Gerasa à la période byzantine, en s'appuyant sur les données archéologiques issues de la fouille menée de 1996 à 2001 et sur l'observation des monuments byzantins de la cité. Cette étude apporte tout d'abord des éléments pour la restitution architecturale du temple et la reconstitution de son histoire aux périodes tardives. Elle offre en outre des informations sur le type de réutilisation des blocs et l'influence de l'architecture d'origine dans la composition des constructions byzantines. Elle met surtout en évidence le fait que le remploi des blocs ne procède pas ici du pillage sauvage et désordonné longtemps évoqué, mais plutôt d'une opération de démontage réfléchie et organisée. Des lots de blocs semblent en effet avoir été constitués sur le site de provenance et attribués pour la construction de chacun des édifices byzantins étudiés.
Palladium-catalyzed cross coupling reactions of 4-bromo-6H-1,2-oxazines
Authors: Zimmer Reinhold , Schmidt Elmar , Andrä Michal , Duhs Marcel-Antoine , Linder Igor , Reissig Hans-Ulrich
Published: September 2009

A number of 4-aryl- and 4-alkynyl-substituted 6H-1,2-oxazines 8 and 9 have been prepared in good yields via cross coupling reactions of halogenated precursors 2, which in turn are easily accessible by bromination of 6H-1,2-oxazines 1. Lewis-acid promoted reaction of 1,2-oxazine 9c with 1-hexyne provided alkynyl-substituted pyridine derivative 12 thus demonstrating the potential of this approach for the synthesis of pyridines.
NANOTECHNOLOGY AND SOCIOPOLITICAL MODERNITY IN DEVELOPING COUNTRIES; CASE STUDY OF IRAN
Authors: Ghazinoory Sepehr , Ghazinouri Reza
Published: September 2009

What we must keep in mind is that although nanotechnology is an emerging and high technology, it is still technology or, in other words, it has an instrumental nature and in order to study its effect on societies we have to consider the role of instruments’ evolution in societies and study nanotechnology as the most recent part of this trend. In this article we study the nature of modern technologies, role of technology based economy on different social and political aspects of developing countries; we have a review on the concept of social and political modernity and describe how development of nanotechnology will accelerate those countries’ modernization from social and political point of view in addition to modernizing their economy. So this paper is a cross‐disciplinary study between nanotechnology and social sciences. There are two different scenarios about the future of nanotechnology. One is the proof of radical nanotechnology and the other is the acceptance of the claim that nanotechnology is only an enabling technology. In the present paper, we studied the effects of both scenarios. The obstacles to modernity in Iran and potential effect of nanotechnology on them are studied as a case study. Santrauka Nors nanotechnologija yra nauja ir pažangi technologija, ji tėra tik instrumentas. Norint įvertinti jos reikšmę visuomenei, reikia išnagrinėti panašių instrumentų raidą visuomenėse ir vertinti nanotechnologiją kaip naujausią tendenciją. Šiame straipsnyje ištirta šiuolaikinių technologijų prigimtis, technologijos vaidmuo žinių ekonomikoje skirtingais besivystančių šalių socialiniais ir politiniais periodais, apžvelgtos socialinio ir politinio šiuolaikiškumo sąvokos, apibūdinta, kaip išsivysčiusios nanotechnologijos pagreitins šalių modernizaciją socialiniu ir politiniu požiūriu be jų ekonomikos modernizavimą. Šis straipsnis yra nanotechnologijos ir socialinių mokslų tarpdisciplininė studija. Yra du skirtingi nanotechnologijos ateities scenarijai: pirmasis teigia, kad nanotechnologija sukels radikalių pokyčių; antrasis skelbia, kad nanotechnologija yra tiktai galimybių suteikimo technologija. Šiame straipsnyje tyrinėti abiejų scenarijų padariniai, tirtos kliūtys šiuolaikiškumui Irane įsitvirtinti ir nanotechnologijos poveikis šaliai.
INVESTIGATION OF HUMAN FACTORS WHILE SOLVING MULTIPLE CRITERIA OPTIMIZATION PROBLEMS IN COMPUTER NETWORK
Authors: Petkus Tomas , Filatovas Ernestas , Kurasova Olga
Published: September 2009

The aim of this investigation is to analyze a class of multiple criteria optimization problems that are solved by human‐computer interaction, using a computer network. A multiple criteria problem is iterated by interactively selecting different weight coefficients of the criteria. Several parallel solution strategies for solving this optimization problem have been developed and analyzed. The experiments have shown the importance of human assistance in solving this multiple criteria problem. New experimental investigations have been carried out with a different number of computers and different strategies where the human factors are analyzed. We have investigated the time necessary for human's training to solve this multiple criteria optimization problem, the dependence of human factors on the strategy of parallel solution and on the number of computers in a computer network. Santrauka Tyrimo tikslas – ištirti daugiakriterinių optimizavimo uždavinių klasę, kai uždaviniai sprendžiami kompiuterio ir žmogaus sąveikai naudojant kompiuterių tinklą. Daugiakriterinio optimizavimo uždavinys sprendžiamas interaktyviai, kiekvienam kriterijui parenkami skirtingi svoriniai koeficientai. Šiam uždaviniui spręsti buvo sukurtos ir ištirtos kelios lygiagretaus sprendimo strategijos. Eksperimentai parodė žmogaus, dalyvaujančio sprendžiant šį uždavinį, svarbą. Tiriant žmogiškąjį faktorių buvo atlikti eksperimentiniai tyrimai naudojant skirtingą kompiuterių skaičių pagal skirtingas strategijas. Ištirtas laikas, reikalingas žmogui išmokti spręsti šį daugiakriterinį optimizavimo uždavinį, nustatyta žmogiškojo faktoriaus priklausomybė nuo pasirinktos lygiagretaus sprendimo strategijos ir kompiuterių skaičiaus kompiuterių tinkle.
INFLUENCE OF THE OUTSIDE CLIMATE PARAMETERS ON THE SELECTION OF THE OPTIMUM COMBINATION OF THE ENERGY SAVING MEASURES
Authors: Samarin Oleg , Lushin Kirill , Paulauskaitė Sabina , Valančius Kęstutis
Published: September 2009

In this paper the influence of climatic parameters of building region on expedient depth of implementation of different ways of energy consumption decrease in civil buildings is reviewed. The data of multivariate calculations of power and technological efficiency of an adopted complex of energy saving measures for reference climatic zones of the terrain of Russia in modern economic conditions with allowance for discounting of costs are adduced. The analysis of the obtained outcomes is given and the guidelines are also offered at the choice of optimum combination of the solutions on a decrease of power inputs at exploitation of a building depending on the number of degree‐days of the heating season, as well as on established prices for stuffs both equipment and fares on power supplies. Santrauka Straipsnyje išnagrinėta statybos rajono klimato parametrų įtaka tikslingam įvairių energijos taupymo būdų taikymui visuomeninės paskirties pastatuose. Pateikiami energetinio ir techninio-ekonominio skirtingų energijos taupymo priemonių komplekso variantų, charakteringų Rusijos teritorijos klimato zonoms šiuolaikinėmis ekonominėms sąlygoms, įvertinant sąnaudų diskontavimą, skaičiavimo duomenys. Atlikta gautų rezultatų analizė ir pasiūlytos rekomendacijos, kaip pasirinkti optimalų energijos sąnaudų mažinimo derinį eksploatuojant pastatus, priklausomai nuo šildymo periodo dienolaipsnių ir galiojančių medžiagų, įrengimų ir šilumos tiekimo tarifų kainų.
ENVIRONMENT FACTORS OF ENERGY COMPANIES AND THEIR EFFECT ON VALUE: ANALYSIS MODEL AND APPLIED METHOD
Authors: Šliogerienė Juratė , Kaklauskas Artūras , Zavadskas Edmundas Kazimieras , Bivainis Juozas , Seniut Mark
Published: September 2009

Practical tasks related to property management and disposal in energy companies can be solved only if the actual property value of these companies is known. Traditional practical property valuation methods are based on the analysis of incurred property development costs or financial indicators of activities and are inadequate to account for the influence of environment factors on corporate activities and, in turn, on the value of companies. An analysis model for environment factors affecting energy companies was developed to improve objectiveness of valuation; through analysis of the model's components it is possible to analyse external macro, meso and microenviron‐ment of a particular company and to assess efficiency of such environment, as well as the impact of separate factors on value. A criteria system developed using the Analysis Model for Environment Factors and the Decision Support System for Measurement of Effect of Environment Factors on Value of Energy Companies, which was developed by the authors, were used to solve a practical task, which helped to evaluate the effectiveness of the Model of Environment Factors. The practical task included measurement of the utility degree and market value of the selected electricity companies and assessment of the impact of the criteria, which affect the environment, on the value of the selected energy companies. Santrauka Energetikos įmonių turto valdymo, disponavimo turtu praktiniams uždaviniams spręsti reikalinga tikroji šių įmonių turto vertė. Tradiciniai praktikoje taikomi turto vertinimo metodai pagrįsti turto sukūrimo sąnaudų ar veiklos finansinių rodiklių analize, jie neįvertina daugelio vertę veikiančių aplinkos veiksnių įtakos. Siekiant padidinti vertės nustatymo objektyvumą, pasiūlytas taikyti energetikos įmonių aplinkos veiksnių tyrimo modelis, kurio elementų analizė leidžia įvairiais aspektais pažvelgti į šių įmonių turto vertę ir įvertinti vertės kitimo priežastis. Sukurtas modelis leidžia analizuoti įmonės aplinką, vertinti jos efektyvumą, aplinką ir suinteresuotas grupes veikiančią išorinę makro-, mezo- ir mikroaplinką kaip visumą. Naudojantis rodiklių, apibūdinančių analizuojamo sektoriaus aplinką, sistema, pasiūlyta infrastruktūros įmonėms vertinti, taikyti daugiakriterine analize paremtus metodus. Siekiant nustatyti aplinkos veiksnių tyrimo modelio veiksmingumą, išspręstas praktinis uždavinys – taikant modelį ir remiantis daugiakriterinės analizės metodais nustatytas pasirinktų elektros energetikos įmonių naudingumo laipsnis ir rinkos vertė.
Phagocyte-specific S100A8/A9 Protein Levels During Disease Exacerbations and Infections in Systemic Lupus Erythematosus
Authors: SOYFOO MUHAMMAD S. , ROTH JOHANNES , VOGL THOMAS , POCHET ROLAND , DECAUX GUY
Published: September 2009

Objective:

S100A8 and S100A9 are calcium binding proteins of the S100 family highly expressed in neutrophils and monocytes. S100 proteins are novel ligands of TLR4 important in modulating inflammation. High levels of S100A8/A9 found in human inflammatory diseases are a marker of disease activity in rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA). We determined levels of S100A8/A9 in sera of patients with systemic lupus erythematosus (SLE) and analyzed their relation to clinical variables of disease activity.

Methods.

A group of 93 patients with SLE were studied over a period of 3 years, and 143 serum samples were analyzed. S100A8/A9 serum concentrations were determined by a sandwich ELISA. Sera from 10 primary Sjögren’s syndrome (pSS) patients and 50 healthy volunteers were used as controls. Correlations to SLEDAI, ANA, anti-dsDNA, WBC, CH50, C4, and CRP were made. In addition, infections were recorded in all SLE patients.

Results.

Serum levels of S100A8/A9 were significantly (p = 0.04) higher in SLE patients (1412 ± 664 ng/ml) versus healthy controls (339 ± 35 ng/ml) and pSS patients (400 ± 85 ng/ml). The only significant correlation (r = 0.219; p = 0.015) was found was between S100A8/A9 and SLEDAI. Further, SLE patients with concomitant infections had higher serum levels of S100A8/A9 (39300 ± 13375 ng/ml) than those without infections (1150 ± 422 ng/ml).

Conclusion.

Serum levels of S100A8/A9 are significantly raised in SLE versus pSS patients and healthy controls and can be correlated to a disease activity index. S100A8/A9 is a more relevant marker of infection in SLE patients.
Determining Transition States in Bioinorganic Reactions
Authors: Lundberg Marcus , Morokuma Keiji
Published: September 2009

This article summarizes basic aspects of time‐dependent density functional theory (TD‐DFT) and its applications in inorganic chemistry. Sections titled TD‐DFT and Spectroscopic Properties outline some of the theoretical formalism and explain how excitation energies can be obtained from TD‐DFT linear response theory. Common approximations in density functional theory (DFT) exchange‐correlation (XC) potentials that might have adverse effects on the accuracy of computed results are explained. Sections titled Benchmark Data and Some Case Studies discuss a number of case studies, with emphasis on TD‐DFT excitation spectra computations in coordination chemistry. Computations of spectra and other properties of metals clusters are also discussed. Apart from excitation spectra, this section also describes TD‐DFT computations of Raman intensities (including resonance Raman and surface‐enhanced Raman spectra (SERS)), magnetic circular dichroism, optical rotatory dispersion (CD and ORD), and concludes with some comments on relativistic effects.
Approximate Density Functionals: Which Should I Choose?
Authors: Rappoport Dmitrij , Crawford Nathan R. M. , Furche Filipp , Burke Kieron
Published: September 2009

Density functional methods have a long tradition in inorganic and bioinorganic chemistry. We introduce the density functional machinery and give an overview of most popular approximate exchange‐correlation (XC) functionals. We present comparisons of density functionals for energies, structures, and reaction barriers of inorganic and bioinorganic systems, giving guidance on the title question. New development directions and current trends in density functional theory (DFT) are reviewed.
Water Oxidation by the Manganese Cluster in Photosynthesis
Authors: Siegbahn Per E. M.
Published: September 2009

Almost all quantum chemical studies performed on enzyme mechanisms have relied on high‐resolution X‐ray structures as starting points. Since no such structure yet exists for photosystem II, a model study of this enzyme is unusually difficult. In this chapter, the approach adopted to obtain the mechanism for OO bond formation in this enzyme is described. Another difficulty, in common with many other enzymatic mechanisms, is that electrons and protons are stepwise removed from the active complex. A method is outlined in which accurate redox potentials and pKavalues can be obtained from rather small models. In this approach, the main effects of the enzyme, homogeneous and inhomogeneous, are included. The most important result is that the OO bond is formed between an oxygen radical and an oxo group. In the S2to S3transition a reconstruction of the oxygen evolving complex takes place due to insertion of a water molecule. Good agreement with most experimental observations is obtained.
Modeling Metalloenzymes with Density Functional and Mixed Quantum Mechanical/Molecular Mechanical (QM/MM) Calculations: Progress and Challenges
Authors: Friesner Richard A.
Published: September 2009

We discuss the application of density functional theory (DFT)‐based quantum chemical and mixed quantum mechanics/molecular mechanics (QM/MM) methods to the modeling of metalloenzyme chemistry. The state of the art of current approaches in terms of accuracy and reliability is considered, primarily in the context of two example systems, methane monooxygenase (MMO) and cytochrome P450. Key issues include the intrinsic accuracy of current DFT functionals for metal‐containing systems, modeling of conformational changes in protein structure, treatment of environmental electrostatic effects, use of spectroscopic calculations to help in identifying the structures of intermediates, and the validity of standard transition state theory approximations using a small number of optimized structures, as opposed to performing full statistical mechanical sampling with methods such as free energy perturbation theory. Considerable insight into the catalytic cycles of both MMO and P450 have been obtained over the past decade using existing computational methods, in close coupling with experimental efforts. However, significant challenges remain, both for the two systems that we consider here and for the modeling of metalloenzyme chemistry in the general case. A number of the most important of these challenges are identified and prospects for addressing them via improvements of the theoretical methodology are discussed.
Computational Studies: Cisplatin
Authors: Mantri Yogita , Baik Mu‐Hyun
Published: September 2009

Cisplatin is one of the most successful anticancer drugs currently in use. Since the discovery of its antitumor activity over three decades ago, intense research has been carried out to uncover the details of its cytotoxic activity and to design analogs with fewer side effects. Computational studies have complemented experimental studies in this research effort. Much of the early computational effort was dedicated to understanding the details of the hydrolysis process of cisplatin that leads to the activated drug. With mounting evidence that DNA was the primary target of the drug and a simultaneous increase in computing power, later theoretical studies aimed to explore the atomistic details of cisplatin–DNA interactions. Currently, both quantum mechanical and molecular mechanical methods are being used to study the thermodynamics and kinetics of not only cisplatin–DNA complexes, but also of other complexes such as Pt(II)‐based cisplatin analogs, other transition metal complexes, and DNA binding organic molecules. Despite these remarkable achievements, much work still remains to be done, both experimentally and computationally, especially in elucidating the role of repair enzymes in modulating the cytotoxic activity of DNA binding agents.
Computational Studies:B12Cofactors and their Interaction with Enzyme Active Sites
Authors: Brunold Thomas C.
Published: September 2009

Cyanocobalamin, commonly known asvitamin B12, and its biologically active derivatives, 5′‐deoxyadenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl), have long fascinated scientists with their elaborate structures and intriguing reactivities in enzymatic systems. While the large size and complex electronic structures of these cofactors have posed a major challenge for theoretical chemists, recent insights gained from kinetic, spectroscopic, and X‐ray crystallographic studies have established an excellent foundation for validating computational investigations of the geometric, electronic, and reactivity properties of the isolated cofactors and the molecular details of the catalytic cycles of B12‐dependent enzymes. This review—which is by no means exhaustive—summarizes salient information that has been obtained from experimentally validated computational studies of the following: (i) the free B12cofactors in their Co3+, Co2+, and Co1+oxidation states; (ii) the mechanism by which enzymes involved in the biosynthesis of AdoCbl overcome the large thermodynamic barrier associated with the Co2+ → Co1+reduction; (iii) plausible strategies by which AdoCbl‐dependent enzymes achieve a trillion‐fold rate of acceleration for thehomolyticcleavage of the cofactor's CoC(Ado) bond; and (iv) the means by which MeCbl‐dependent methyltransferases regenerate the active MeCbl cofactor and accelerate the rate of methyl transfer viaheterolyticCoC(Me) bond cleavage by as many as 6 orders of magnitude.
Electronic Structure Calculations: Transition Metal—
NO
Complexes
Authors: Ghosh Abhik , Hopmann Kathrin H. , Conradie Jeanet
Published: September 2009

The advent of density functional theory led to a major exploration (and, in some cases, a reexploration) of key aspects of transition metal nitrosyls. Many of these developments are reviewed here for the first time, with comparable emphasis placed on both heme/metalloporphyrin and nonheme systems. The latter exhibit diverse electronic structures, which we have described in some depth. Several of the open‐shell species described exhibit broken‐symmetry electronic structures, with significant spatial separation of majority and minority spin densities.
Multiple Aromaticity, Multiple Antiaromaticity, and Conflicting Aromaticity in Inorganic Systems
Authors: Zubarev Dmitry Yu. , Boldyrev Alexander I.
Published: September 2009

In recent years there have been significant advances in extending the concepts of aromaticity and antiaromaticity into the realm of inorganic chemistry. These new developments have shown that aromaticity and antiaromaticity in metal systems are frequently multiple in nature. Two new types of aromaticity, namely, δ‐ and ϕ‐aromaticity, were found in transition metal and f‐element cyclic systems in addition to the σ‐ and π‐types already known in organic chemistry. There are also now many examples of inorganic systems with conflicting aromaticity, which refers to the systems with simultaneous presence of aromaticity and antiaromaticity in different electronic (σ‐, π‐, δ‐, or ϕ‐) subsystems. It was shown that the antiaromaticity in any electronic subsystem could be interpreted in terms of formation of small areas of aromaticity leading to the island aromaticity.
Computational Studies: Boranes
Authors: Shameema Oottikkal , Jemmis Eluvathingal D.
Published: September 2009

Computational studies on boranes, in recent years, are summarized with the special emphasis on the macropolyhedral boranes. Computational studies to understand the energetics, geometry, aromaticity, and reactivity of boranes and substituted boranes are reviewed. There is a recent interest in macropolyhedral boranes because of their uses in boron neutron capture therapy (BNCT) of cancer, ionic liquids, weakly coordinating ions, and materials chemistry. The
mno
rule, which is the electronic counting rule for the macropolyhedral boranes, is explained. Even though the electron counting rule explains the electronic structure of macropolyhedra, it cannot explain the relative stability of isomers since different structures are possible with the same electron count. There have been many computational studies to explain the relative stability of various structural patterns in macropolyhedral boranes. We have used the concept of orbital compatibility to explain the relative energies of different macropolyhedral structural patterns. Computations on the
closo
‐
closo
macropolyhedral boranes show that a large polyhedral borane prefers to condense with a smaller polyhedron owing orbital compatibility. Even though only a few
closo
‐
closo
macropolyhedral structures have been synthesized experimentally, calculations suggest optimism for the synthesis of many condensation products. A brief discussion about the use of the computational methods for the rearrangement of the B
20
H
16
skeleton reacting with ligands is also provided.
Nuclear Magnetic Resonance (NMR) Parameters of Transition Metal Complexes: Methods and Applications
Authors: Kaupp Martin , Bühl Michael
Published: September 2009

This article provides an overview of first‐principle computations targeted at nuclear magnetic resonance (NMR) properties of transition‐metal complexes. Recent methodological developments and illustrative applications are highlighted, all of which are rooted in density functional theory (DFT). Special attention is called to chemical applications of such NMR computations, ranging from structure elucidation of metalloenzymes to detailed interpretation of NMR spectra of paramagnetic compounds.
Computational Methods: Transition Metal Clusters
Authors: Gautier Régis , Halet Jean‐François , Saillard Jean‐Yves
Published: September 2009

Cluster chemistry is dominated by structural aspects. Indeed, structure and bonding are strongly related to stability and properties, and cluster structures are particularly diverse and often complex. Thus, electron‐counting rules, which relate structure to electron count, have been the key to the development of cluster chemistry as a distinct area of chemistry. These rules have been set up progressively along time with the help of quantum chemistry. This article deals with the recent progress on transition metal and mixed main group/transition metal cluster chemistry arising from the contribution of modern computational theory to the rationalization of structures. This article focuses on “viable” species, i.e., molecules that are isolable under reasonable conditions and deals with the exploration of the limitations of the classical electron‐counting rules as well as the establishment of new rules for new structural types with the help of quantum chemical calculations.
Computational Studies: Chemical Evolution of Metal Sites
Authors: Jensen Kasper P.
Published: September 2009

The structures of naturally occurring metal sites have evolved over hundreds of millions of years to perform complex functions under very specific biological and nonbiological constraints. Modern computational chemistry has now reached a level of accuracy that allows us to study the full significance of molecular evolution by systematically altering the components of the native metal sites and by monitoring the resulting effects on relevant computed properties. This procedure, referred to as
computational chemical evolution
, not only explains the use of certain metal ions as opposed to others in metalloproteins, but also lends promise to the design of new multifunctional metal sites that are no longer restricted by biological constraints, to be used in medicine and catalysis.
Theoretical Aspects of Main Group Multiple Bonded Systems
Authors: Silaghi‐Dumitrescu Ioan , Petrar Petronela , Nemeş Gabriela , Bruce King R.
Published: September 2009

Computational data on homonuclear multiple bonding between elements of group 13 and heavier elements of group 14 are reviewed. For R

n

EER

n

, there is an increased tendency of bending the RER planes (
n
 = 2) or the RE bonds (
n
 = 1) toward the EE axis upon descending a group. This is related to the mixing of the valence σ–π orbitals reflecting the tendency of the heavier elements to retain nonbonding character for their
n
s
2
orbital. As a result, the bond orders are also reduced and the EE interaction weakened.
Basal Ganglia and The Regulation of Movement
Authors: Turner Robert S
Published: September 2009

The basal ganglia (BG) is composed of several heavily interconnected nuclei at the base of the cerebrum. A series of anatomically distinct parallel circuits through the BG receive afferent projections from and project back to cortical regions that mediate skeletomotor, oculomotor, frontal associative, and limbic functions. All circuits share a common intrinsic organization captured largely by the heuristic model of direct and indirect pathways that link BG input stations to outputs. Activation of the direct pathway may facilitate movement whereas the indirect pathway may suppress movement. Neuromodulators such as dopamine have different effects on activity and synaptic plasticity in the two pathways. Clinical disorders that involve the BG are often associated with movement disorders. Although the actual roles of the BG in the control of movement are still actively debated, growing evidence suggests it acts as a reinforcement‐driven tutor for learning automatic behavioural routines.

Key concepts

The BG is organized as anatomically segregated loop circuits that contribute to the control of movement, cognition and motivation.

All BG circuits share a common basic organization.

Input projections from cortex and thalamus terminate as excitatory synapses in the striatum and subthalamic nucleus.

Output projections tonically inhibit target neurons in thalamic and brainstem nuclei.

Direct and indirect pathways connect input and output nuclei of the BG.

Activation of the direct pathway facilitates movement whereas activation of the indirect pathway suppresses movement.

A variety of neuromodulators, such as dopamine, affect the activity of neurons in the direct and indirect pathways differently.

Most BG‐related clinical conditions (e.g. Parkinson disease) arise from imbalanced activation of direct and indirect pathways and involve abnormal discharge patterns in BG output neurons.

BG circuits may regulate how an animal allocates time and effort to movements and actions and act as a tutor for new skill learning.
Oncogenic Viruses
Authors: McCance Dennis John
Published: September 2009

Infectious agents account for appropriately 25% of cancers worldwide and viruses in particular have been useful in elucidating many of the cellular pathways that can be deregulated in cancer. Therefore, the more that is known about how viral proteins disrupt the normal cell the more we will learn about important regulatory pathways that when altered or abrogated, lead to a transformed cell.
Phylogeny Based on 16
S
r
RNA
/
DNA
Authors: Stackebrandt Erko
Published: September 2009

Polyphasic systematics of prokaryotes is guided by the results of comparative analysis of the evolutionary conservative 16S ribosomal
ribonucleic acid
(RNA) genes. Certain genes coding for ‘housekeeping’ proteins support the phylogenetic outline but most of these genes are either not ubiquitous or they are evolving too rapidly to embrace all higher taxa. Dendrograms of phylogenetic relatedness show the order at which organisms evolved in time, thus providing the frame for their classification. The delineation and circumscription of taxa should not be solely based on the topology of dendrograms but it is advised to include a wide range of molecular, chemical and metabolic properties, which need to be assessed and evaluated in the light of novel taxonomic information.

Key concepts:

The results of comparative 16S ribosomal
ribonucleic acid
(rRNA) gene sequence analysis shattered the dogma of the bifurcation of higher life form categories, that is prokaryotes versus eukaryotes.

The advantage of rRNA genes over genes coding for proteins is a combination of properties: universal presence, easy accessibility and polymerase chain reaction (PCR) amplification, rare lateral gene transfer and broad coverage of taxa between domain and species.

The only taxonomic category where the 16S rRNA gene sequence fails to unravel detailed evolutionary insights into the structure of its members is the taxon ‘species’.

Taxonomy of a strain is more than the analysis of a few sequences: it is a pragmatic concept that takes into account the results of its evolutionary history leading to changes at the genomic, epigenetic and phenotypic levels.

Classification is a process in which the database of a strain is compared to the network of strains already classified. Its place in the system is found when this dataset matches most closely the dataset of an already classified taxon. In this process the 16S rRNA sequence guides the affiliation to the genus level.
Antigens: Thymus‐dependent
Authors: Bachmann Martin F
Published: September 2009

B cells secrete antibodies that mediate protection against a great variety of pathogens. There are two classes of antigens for B cells, T cell‐dependent (thymus‐dependent, TD) and T cell‐independent (TI) antigens. The former require the presence of cognate T‐helper (TH) cells to trigger a B‐cell response, whereas the TI antigens can mount an antibody response in the absence of TH. A large class of antigens, namely proteins on pathogen surfaces, are both TI and TD: They are able to induce a TI IgM (immunoglobulin M) antibody response, since they are highly repetitive and linked to toll‐like receptor (TLR) ligands and they induce a TD response, since they are proteins. Epitope repetitiveness, presence of TLR‐ligands and T help together shape the quantity, quality and duration of an antibody response.

Key Concepts:

TI antigens induce antibody responses in the absence of TH.

TI antibody responses are mostly of the IgM isotype and short‐lived.

TD antigens require THcells to induce an antibody responses.

TD antibody responses are usually of the IgG isotype and more long‐lived.

Pathogens are complex antigens and are both TI (they are repetitive and contain TLR ligands) and TD (they contain proteins and induce TH).

This combination of TI and TD makes pathogens such strong immunogens for B cells.

Antigen‐repetitiveness and presence of TLR ligands modulate the overall magnitude of the antibody responses.

Presence of THimprints memory into the antibody responses by allowing the formation of long‐lived plasma cells as well as memory B cells.
Epitopes
Authors: Muller Claude P , Jacoby Monique
Published: September 2009

T‐ and B‐cell epitopes differ fundamentally in the way they are recognized by the immune system. B‐cell epitopes are recognized as three‐dimensional structures on the surface of native antigens. T‐cell epitopes are parts of internalized and processed antigens that are presented to T lymphocytes in association with molecules of the major histocompatibility complex. Since in a biological system T‐ and B‐cell receptors or antibody molecules face a virtual infinite number of structures, cognate interactions with epitopes are the basis of the primordial intelligence that drives the teleological choices of the immune system. Although theoretically any antigen comprises a myriad of potential epitopes, the immune response will focus only on a few of them by a phenomenon termed immunodominance. Understanding the mechanisms that govern epitope selection is important for epitope prediction and vaccine design.

Key concepts

Surface immunoglobulins of B cells and antibodies recognize the B‐cell epitope of an antigen in its native conformation.

The main common feature of B‐cell epitopes (BCEs) is accessibility on the surface of the antigen.

T‐cell receptors (TCRs) recognize the T‐cell epitopes (TCEs) only after intracellular processing of the antigen, and in association with major histocompatibility complex (MHC) molecules, a concept termed MHC restriction.

TCEs presented by MHC class II molecules are longer and more variable in size than those presented by MHC class I molecules.

TCE peptides that bind to the same allele of MHC class I molecules share common ‘anchor’ residues that contact the MHC molecule. In MHC class II‐restricted TCEs, the anchor residues are less well defined.

High affinity of the TCR–MHC–peptide tripartite interaction as well as coreceptors and other signalling modules are needed for T‐cell activation.

Immunodominance refers to the concept that only a small subset of the potential epitopes (TCEs or BCEs) present in a given antigen elicit an immune response.

The immunodominance of a TCE depends on its accessibility within the antigen, the specificity of processing enzymes and its affinity to transporter proteins, chaperons, MHC and TCRs.

Mimotopes are small molecules that mimic the structure of complex conformational epitopes without any sequence homology.
Transfer
RNA
Recognition by Synthetases
Authors: Giegé Richard , Eriani Gilbert
Published: September 2009

Fidelity of transfer
ribonucleic acid
(tRNA) charging by amino acids ensures correct translation of the genetic code into proteins. Charging is catalysed by a set of enzymes known as aminoacyl‐tRNA synthetases. Owing to the degeneracy of the genetic code, some of the different tRNAs have the same amino acid attached to them. Specificity of the charging reaction is ensured by positive elements, the identity determinants unique to each tRNA and responsible for its recognition by the cognate synthetase, and negative elements, the antideterminants that prevent false recognitions. To fulfil the aminoacylation specificity and prevent noncognate aminoacyl‐tRNA delivery to the ribosome, some synthetases also mediate proofreading reactions that increase fidelity of the tRNA charging. In such reactions, misactivated amino acids or mischarged tRNAs are checked in specific sites and noncognate products are hydrolysed.
Translation Initiation Models in Prokaryotes and Eukaryotes
Authors: Londei Paola
Published: September 2009

Translation is one stage of protein synthesis in which messenger
ribonucleic acid
(mRNA) acts as a template for the synthesis of a polypeptide chain; it consists of four phases: initiation, elongation, termination and ribosome recycling. Initiation of protein synthesis, entailing ribosomal recognition of the mRNA start codon and the setting of the correct reading frame, is the rate‐limiting step of translation and the main target of translation regulation in all cells. However, the mechanism and molecular machinery for initiation have diverged in the primary domains of life: the Bacteria, the Archaea and the Eukarya (eukaryotes). In bacteria, translation initiation is relatively simple, while in eukaryotes is complex and requires more components. In archaea, despite their prokaryotic phenotype, the machinery for protein synthesis initiation is much more elaborated than in bacteria and presents intriguing similarities with the corresponding eukaryotic process. The features of translational initiation in archaea, bacteria and eukaryotes are reviewed, highlighting the divergent and common aspects of this important cellular process in the three domains of life.

Key concepts

Initiation is the first of four steps of the translation cycle. During initiation the small ribosomal subunit interacts with the messenger
ribonucleic acid
(mRNA) and finds the right start codon, thereby setting the correct reading frame for decoding.

In all cells, translation initiation is assisted and modulated by several proteins called translation initiation factors (IFs). The most important roles of the IFs are to select the proper initiator transfer RNA, to adjust it correctly in the ribosomal P site, to ensure the accurate selection of the start codon and to prevent the premature joining of the large ribosomal subunit to the pre‐initiation complex.

Initiation is the rate‐limiting step of translation. It is the efficiency whereby an mRNA is decoded and the amount of final product is largely determined at the initiation level.

In all cells, the principal mechanisms of translational control act at the level of initiation, usually targeting certain IFs that play essential roles in the initiation process.

The initiation step of translation has incurred a marked evolutionary divergence. The mechanism and components of initiation differ in several aspects in the three primary domains of life, that is the Bacteria, the Archaea and the Eukaryotes.

The Bacteria have the simplest machinery for translation initiation. However, this is not because they are prokaryotes. The other prokaryotic domain, the Archaea, has a fairly complex machinery for initiation, resembling that of eukaryotes, which have the most complex initiation process.
Inhibitors of the Elongation Cycle of Protein Synthesis
Authors: Wilson Daniel N , Starosta Agata L , Yamamoto Hiroshi , Nierhaus Knud H
Published: September 2009

The protein synthetic machinery is a highly complex apparatus that offers many potential sites for functional interference and represents a major target in the cell for antibiotics. The knowledge of ribosomal structure and function has progressed enormously in recent years, which has, in turn, accelerated our understanding of the mechanism of drug action. Conversely, drugs have been used as tools to probe the translation cycle, thus providing a means to further dissect the multitude of steps involved in protein synthesis. In an era where bacteria are showing an ever‐increasing resistance to many clinically relevant antibiotics, the importance of understanding their mechanism of inhibition is essential to the development of novel and more effective replacements.

Key concept:

A large number of antibiotics target the ribosome and inhibit specific steps during the elongation cycle.
Ribosomal Proteins: Role in Ribosomal Functions
Authors: Wilson Daniel N , Gupta Romi , Mikolajka Aleksandra , Nierhaus Knud H
Published: September 2009

The assignment of specific ribosomal functions to individual ribosomal proteins is difficult due to the enormous cooperativity of the ribosome; however, important roles for distinct ribosomal proteins are becoming evident. Although ribosomal
ribonucleic acid
(rRNA) has the major claim to certain aspects of ribosome function, such as decoding and
peptidyltransferase
activity, there are also protein‐dominated functional hot‐spots on the ribosome such as the messenger RNA (mRNA) entry pore, the translation factor‐binding site and the exit of the ribosomal tunnel. The latter is binding site for both chaperones and complexes associated with protein transport through membranes. Furthermore, the contribution of ribosomal proteins is essential for the assembly and optimal functioning of the ribosome.

Key concepts:

Both the 16S and 23S rRNAs and a subset of r‐proteins are essential for assembly, structure and function of ribosomes; the ribosomal interface, the place where the three tRNA‐binding sites A, P and E are located and thus where protein synthesis occurs, is preferentially composed of rRNA; functional hot‐spots such as mRNA entry pore, elongation factor‐binding site (L7/L12 stalk), the L1 protuberance and the tunnel exit are dominated by r‐proteins; many r‐proteins have a globular domain and long extensions protruding deep into the ribosome; the globular domains of r‐proteins are located at or near the ribosomal surface; antibiotic resistance can be mediated by mutations in either rRNA or r‐protein genes; some r‐proteins are essential for assembly but play no role in structure or function of the ribosome; accuracy of proteins is tuned and balanced by r‐proteins (S4, S5 and S12); r‐proteins at the tunnel exit can function as a docking station for factors important for protein folding or for attaching the ribosome to membranes.