Showing papers by "Free University of Berlin published in 2005"

Towards complete cofactor arrangement in the 3.0 Å resolution structure of photosystem II

Abstract: Oxygenic photosynthesis in plants, algae and cyanobacteria is initiated at photosystem II, a homodimeric multisubunit protein-cofactor complex embedded in the thylakoid membrane. Photosystem II captures sunlight and powers the unique photo-induced oxidation of water to atmospheric oxygen. Crystallographic investigations of cyanobacterial photosystem II have provided several medium-resolution structures (3.8 to 3.2 A) that explain the general arrangement of the protein matrix and cofactors, but do not give a full picture of the complex. Here we describe the most complete cyanobacterial photosystem II structure obtained so far, showing locations of and interactions between 20 protein subunits and 77 cofactors per monomer. Assignment of 11 beta-carotenes yields insights into electron and energy transfer and photo-protection mechanisms in the reaction centre and antenna subunits. The high number of 14 integrally bound lipids reflects the structural and functional importance of these molecules for flexibility within and assembly of photosystem II. A lipophilic pathway is proposed for the diffusion of secondary plastoquinone that transfers redox equivalents from photosystem II to the photosynthetic chain. The structure provides information about the Mn4Ca cluster, where oxidation of water takes place. Our study uncovers near-atomic details necessary to understand the processes that convert light to chemical energy.

The general self-efficacy scale: multicultural validation studies.

Abstract: General self-efficacy is the belief in one's competence to cope with a broad range of stressful or challenging demands, whereas specific self-efficacy is constrained to a particular task at hand. Relations between general self-efficacy and social cognitive variables (intention, implementation intentions, outcome expectancies, and self-regulation), behavior-specific self-efficacy, health behaviors, well-being, and coping strategies were examined among 1,933 respondents in 3 countries: Germany (n = 633), Poland (n = 359), and South Korea (n = 941). Participants were between 16 and 86 years old, and some were dealing with stressful situations such as recovery from myocardial events or tumor surgery. Perceived self-efficacy was measured by means of the General Self-Efficacy Scale (R. Schwarzer & M. Jerusalem, 1995). Meta-analysis was used to determine population effect sizes for four sets of variables. Across countries and samples, there is consistent evidence for associations between perceived self-efficacy and the variables under study confirming the validity of the psychometric scale. General self-efficacy appears to be a universal construct that yields meaningful relations with other psychological constructs.

Bridging the intention–behaviour gap: Planning, self-efficacy, and action control in the adoption and maintenance of physical exercise

Abstract: Although some people may develop an intention to change their health behaviour, they might not take any action. This discrepancy has been labelled the “intention–behaviour gap.” Detailed action planning, perceived self-efficacy, and self-regulatory strategies (action control) may mediate between intentions and behaviour. This was examined in a longitudinal sample of 307 cardiac rehabilitation patients who were encouraged to adopt or maintain regular exercise. At the first time point, the predictors of intention and intention itself were assessed. Two months and four months later, the mediators and outcomes were measured. Results confirmed that all the three factors (planning, maintenance self-efficacy, and action control) served to mediate between earlier exercise intentions and later physical activity, each of them making a unique contribution. The results have implications for research on the “intention–behaviour gap,” and indicate that planning, maintenance self-efficacy and action control may be impor...

Arabidopsis Cytokinin Receptor Mutants Reveal Functions in Shoot Growth, Leaf Senescence, Seed Size, Germination, Root Development, and Cytokinin Metabolism

Abstract: We used loss-of-function mutants to study three Arabidopsis thaliana sensor histidine kinases, AHK2, AHK3, and CRE1/ AHK4, known to be cytokinin receptors. Mutant seeds had more rapid germination, reduced requirement for light, and decreased far-red light sensitivity, unraveling cytokinin functions in seed germination control. Triple mutant seeds were more than twice as large as wild-type seeds. Genetic analysis indicated a cytokinin-dependent endospermal and/or maternal control of embryo size. Unchanged red light sensitivity of mutant hypocotyl elongation suggests that previously reported modulation of red light signaling by A-type response regulators may not depend on cytokinin. Combined loss of AHK2 and AHK3 led to the most prominent changes during vegetative development. Leaves of ahk2 ahk3 mutants formed fewer cells, had reduced chlorophyll content, and lacked the cytokinin-dependent inhibition of dark-induced chlorophyll loss, indicating a prominent role of AHK2 and, particularly, AHK3 in the control of leaf development. ahk2 ahk3 double mutants developed a strongly enhanced root system through faster growth of the primary root and, more importantly, increased branching. This result supports a negative regulatory role for cytokinin in root growth regulation. Increased cytokinin content of receptor mutants indicates a homeostatic control of steady state cytokinin levels through signaling. Together, the analyses reveal partially redundant functions of the cytokinin receptors and prominent roles for the AHK2/ AHK3 receptor combination in quantitative control of organ growth in plants, with opposite regulatory functions in roots and shoots.

Short term benefits for laparoscopic colorectal resection.

Abstract: Background Colorectal resections are common surgical procedures all over the world. Laparoscopic colorectal surgery is technically feasible in a considerable amount of patients under elective conditions. Several short-term benefits of the laparoscopic approach to colorectal resection (less pain, less morbidity, improved reconvalescence and better quality of life) have been proposed. Objectives This review compares laparoscopic and conventional colorectal resection with regards to possible benefits of the laparoscopic method in the short-term postoperative period (up to 3 months post surgery). Search methods We searched MEDLINE, EMBASE, CancerLit, and the Cochrane Central Register of Controlled Trials for the years 1991 to 2004. We also handsearched the following journals from 1991 to 2004: British Journal of Surgery, Archives of Surgery, Annals of Surgery, Surgery, World Journal of Surgery, Disease of Colon and Rectum, Surgical Endoscopy, International Journal of Colorectal Disease, Langenbeck's Archives of Surgery, Der Chirurg, Zentralblatt fur Chirurgie, Aktuelle Chirurgie/Viszeralchirurgie. Handsearch of abstracts from the following society meetings from 1991 to 2004: American College of Surgeons, American Society of Colorectal Surgeons, Royal Society of Surgeons, British Assocation of Coloproctology, Surgical Association of Endoscopic Surgeons, European Association of Endoscopic Surgeons, Asian Society of Endoscopic Surgeons. Selection criteria All randomised-controlled trial were included regardless of the language of publication. No- or pseudorandomised trials as well as studies that followed patient's preferences towards one of the two interventions were excluded, but listed separately. RCT presented as only an abstract were excluded. Data collection and analysis Results were extracted from papers by three observers independently on a predefined data sheet. Disagreements were solved by discussion. 'REVMAN 4.2' was used for statistical analysis. Mean differences (95% confidence intervals) were used for analysing continuous variables. If studies reported medians and ranges instead of means and standard deviations, we assumed the difference of medians to be equal to the difference of means. If no measure of dispersion was given, we tried to obtain these data from the authors or estimated SD as the mean or median. Data were pooled and rate differences as well as weighted mean differences with their 95% confidence intervals were calculated using random effects models. Main results 25 RCT were included and analysed. Methodological quality of most of these trials was only moderate and perioperative treatment was very traditional in most studies. Operative time was longer in laparscopic surgery, but intraoperative blood was less than in conventional surgery. Intensity of postoperative pain and duration of postoperative ileus was shorter after laparoscopic colorectal resection and pulmonary function was improved after a laparoscopic approach. Total morbidity and local (surgical) morbidity was decreased in the laparoscopic groups. General morbidity and mortality was not different between both groups. Until the 30th postoperative day, quality of life was better in laparoscopic patients. Postoperative hospital stay was less in laparoscopic patients. Authors' conclusions Under traditional perioperative treatment, lapararoscopic colonic resections show clinically relevant advantages in selected patients. If the long-term oncological results of laparoscopic and conventional resection of colonic carcinoma show equivalent results, the laparoscopic approach should be preferred in patients suitable for this approach to colectomy.

Receptor and viral determinants of SARS-coronavirus adaptation to human ACE2

Abstract: Human angiotensin-converting enzyme 2 (ACE2) is a functional receptor for SARS coronavirus (SARS-CoV) Here we identify the SARS-CoV spike (S)-protein-binding site on ACE2 We also compare S proteins of SARS-CoV isolated during the 2002-2003 SARS outbreak and during the much less severe 2003-2004 outbreak, and from palm civets, a possible source of SARS-CoV found in humans All three S proteins bound to and utilized palm-civet ACE2 efficiently, but the latter two S proteins utilized human ACE2 markedly less efficiently than did the S protein obtained during the earlier human outbreak The lower affinity of these S proteins could be complemented by altering specific residues within the S-protein-binding site of human ACE2 to those of civet ACE2, or by altering S-protein residues 479 and 487 to residues conserved during the 2002-2003 outbreak Collectively, these data describe molecular interactions important to the adaptation of SARS-CoV to human cells, and provide insight into the severity of the 2002-2003 SARS epidemic

A Customer Relationship Management Roadmap: What Is Known, Potential Pitfalls, and Where to Go

Abstract: The goal of this preface is to describe how the special section on customer relationship management (CRM) was developed. In May 2003, Richard Staelin, Executive Director of the Teradata Center for Customer Relationship Management at Duke University, proposed that Journal of Marketing (JM) publish a special section. The proposal included activities that were designed to promote interactions among marketing academics and practitioners; the goal was to stimulate dialogue and new research on CRM. I found the proposal attractive because CRM is a broad-based topic that interests many marketers. After extensive discussion, the American Marketing Association (AMA) and the Teradata Center formally agreed to cosponsor the special section. Subsequently, there was a conference on Relationship Marketing and Customer Relationship Management (cochaired by Michael Ehret, Wesley Johnston, Michael Kleinaltenkamp, and Lou Pelton) that took place at Freie Universitat Berlin in the summer of 2003; a conference on Cus...

Acoustic Communication in Noise

Abstract: Publisher Summary Environmental noise can affect acoustic communication through limiting the broadcast area, or active space, of a signal by decreasing signal-to-noise ratios at the position of the receiver. At the same time, noise is ubiquitous in all habitats and is, therefore, likely to disturb animals, as well as humans, under many circumstances. However, both animals and humans have evolved diverse solutions to the background noise problem, and this chapter reviews recent advancements in studies of vocal adaptations to interference by background noise and relate these to fundamental issues in sound perception. The chapter starts with the discussion of sender's side by considering potential evolutionary shaping of species-specific signal characteristics and individual short‐term adjustments of signal features. Subsequently, it focuses on the receivers of signals and reviews their sensory capacities for signal detection, recognition, and discrimination and relates these issues to auditory scene analysis and the ecological concept of signal space. The data from studies on insects, anurans, birds, and mammals, including humans, and to a lesser extent available work on fish and reptiles is also discussed in the chapter.

Individual Risk Attitudes: New Evidence from a Large, Representative, Experimentally-Validated Survey

Abstract: This paper presents new evidence on the distribution of risk attitudes in the population, using a novel set of survey questions and a representative sample of roughly 22,000 individuals living in Germany. Using a question that asks about willingness to take risks in general, on an 11-point scale, we find evidence of heterogeneity across individuals, and show that willingness to take risks is negatively related to age and being female, and positively related to height and parental education. We test the behavioral relevance of this survey measure by conducting a complementary field experiment, based on a representative sample of 450 subjects, and find that the general risk question is a good predictor of actual risk-taking behavior. We then use a more standard lottery question to measure risk preferences in our sample of 22,000, and find similar results regarding heterogeneity and determinants of risk preferences, compared to the general risk question. The lottery question also makes it possible to estimate the coefficient of relative risk aversion for each individual in the sample. Using five questions about willingness to take risks in specific domains - car driving, financial matters, sports and leisure, career, and health - the paper also studies the impact of context on risk attitudes, finding a strong but imperfect correlation across contexts. Using data on a collection of risky behaviors from different contexts, including traffic offences, portfolio choice, smoking, occupational choice, participation in sports, and migration, the paper compares the predictive power of all of the risk measures. Strikingly, the general risk question predicts all behaviors whereas the standard lottery measure does not. The best predictor for any specific behavior is typically the corresponding context-specific measure.

Action planning and coping planning for long-term lifestyle change: Theory and assessment

Abstract: Planning is regarded as highly valuable in the process of health behaviour change. It bridges the gap between behavioural intentions and health behaviour. To further develop this concept, a distinction is made between action planning and coping planning. The latter refers to the mental simulation of overcoming anticipated barriers to action. Action planning and coping planning for physical exercise were examined in a longitudinal study with 352 cardiac patients. They were approached during rehabilitation treatment and followed up at two and four months after discharge. Both planning cognitions were psychometrically identified, and it was found that they operated differently in the behavioural change process. Action plans were more influential early in the rehabilitation process, whereas coping plans were more instrumental later on. Participants with higher levels of coping planning after discharge were more likely to report higher levels of exercise four months after discharge. It is suggested to include both kinds of planning in interventions at different stages in health behaviour change.

Genome-Wide Analysis of the General Stress Response Network in Escherichia coli: σS-Dependent Genes, Promoters, and Sigma Factor Selectivity

Abstract: The σS (or RpoS) subunit of RNA polymerase is the master regulator of the general stress response in Escherichia coli. While nearly absent in rapidly growing cells, σS is strongly induced during entry into stationary phase and/or many other stress conditions and is essential for the expression of multiple stress resistances. Genome-wide expression profiling data presented here indicate that up to 10% of the E. coli genes are under direct or indirect control of σS and that σS should be considered a second vegetative sigma factor with a major impact not only on stress tolerance but on the entire cell physiology under nonoptimal growth conditions. This large data set allowed us to unequivocally identify a σS consensus promoter in silico. Moreover, our results suggest that σS-dependent genes represent a regulatory network with complex internal control (as exemplified by the acid resistance genes). This network also exhibits extensive regulatory overlaps with other global regulons (e.g., the cyclic AMP receptor protein regulon). In addition, the global regulatory protein Lrp was found to affect σS and/or σ70 selectivity of many promoters. These observations indicate that certain modules of the σS-dependent general stress response can be temporarily recruited by stress-specific regulons, which are controlled by other stress-responsive regulators that act together with σ70 RNA polymerase. Thus, not only the expression of genes within a regulatory network but also the architecture of the network itself can be subject to regulation.

Efficacy and safety of infliximab in patients with ankylosing spondylitis: results of a randomized, placebo-controlled trial (ASSERT).

Abstract: Objective The signs and symptoms of ankylosing spondylitis (AS) respond inadequately to nonsteroidal antiinflammatory drugs, corticosteroids, and disease-modifying antirheumatic drugs in quite a number of patients. Tumor necrosis factor inhibitors have demonstrated success in reducing AS disease activity in a limited number of clinical trials. The objective of this multicenter, randomized, placebo-controlled study was to evaluate the efficacy and safety of infliximab in patients with AS. Methods Patients were randomly assigned to receive infusions of placebo or 5 mg/kg infliximab at weeks 0, 2, 6, 12, and 18. Efficacy was assessed using the ASsessment in Ankylosing Spondylitis (ASAS) International Working Group criteria, the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), night pain, patient's global assessment, the Bath Ankylosing Spondylitis Functional Index (BASFI), the Bath Ankylosing Spondylitis Metrology Index (BASMI), chest expansion, the Mander enthesis index, the total swollen joint index, the C-reactive protein level, and the Short Form 36 (SF-36) health survey questionnaire. The primary end point in this study was the proportion of patients with a 20% improvement response according to the ASAS International Working Group criteria (ASAS20 responders) at week 24. Results Of the 357 patients screened, 201 were assigned to receive 5 mg/kg infliximab and 78 were assigned to receive placebo. After 24 weeks, 61.2% of patients in the infliximab group were ASAS20 responders compared with 19.2% of patients in the placebo group (P < 0.001). Clinical benefit was observed in patients receiving infliximab as early as week 2 and was maintained over the 24-week study period. Patients receiving infliximab also showed significant improvements in the BASDAI, BASFI, BASMI, chest expansion, and physical component summary score of the SF-36. Adverse events were reported by 82.2% of patients receiving infliximab and by 72.0% of patients receiving placebo; however, most adverse events in both treatment groups were mild or moderate in severity. Conclusion Infliximab was well tolerated and effective in a large cohort of patients with AS during a 24-week study period.

Experimental deformation of partially melted granite revisited: implications for the continental crust

Abstract: A review and reinterpretation of previous experimental data on the deformation of partially melted crustal rocks reveals that the relationship of aggregate strength to melt fraction is non-linear, even if plotted on a linear ordinate and abscissa. At melt fractions, Φ 0.07. This melt fraction (Φ = 0.07) marks the transition from a significant increase in the proportion of melt-bearing grain boundaries up to this point to a minor increase thereafter. Therefore, we suggest that it is the increase of melt-interconnectivity that causes the dramatic strength drop between the solidus and a melt fraction of 0.07. We term this drop the ‘melt connectivity transition’ (MCT). A second, less-pronounced strength drop occurs at higher melt fractions and corresponds to the breakdown of the solid (crystal) framework. This is the ‘solid-to-liquid transition’ (SLT), corresponding to the well known ‘rheologically critical melt percentage’. Although the strength drop at the SLT is about four orders of magnitude, the absolute value of this drop is small compared with the absolute strength of the unmelted aggregate, rendering the SLT invisible in a linear aggregate strength v. melt-fraction diagram. On the other hand, the more important MCT has been overlooked in previous work because experimental data usually are plotted in logarithmic strength v. melt-fraction diagrams, obscuring large strength drops at high absolute strength values. We propose that crustal-scale localization of deformation effectively coincides with the onset of melting, pre-empting attainment of the SLT in most geological settings. The SLT may be restricted to controlling flow localization within magmatic bodies, especially where melt accumulates.

The active NPC converter and its loss-balancing control

Abstract: The three-level neutral-point-clamped voltage-source converter (NPC VSC) is widely used in high-power medium-voltage applications. The unequal loss distribution among the semiconductors is one major disadvantage of this popular topology. This paper studies the loss distribution problem of the NPC VSC and proposes the active NPC VSC to overcome this drawback. The switch states and commutations of the converter are analyzed. A loss-balancing scheme is introduced, enabling a substantially increased output power and an improved performance at zero speed, compared to the conventional NPC VSC.

Named graphs, provenance and trust

Abstract: The Semantic Web consists of many RDF graphs nameable by URIs. This paper extends the syntax and semantics of RDF to cover such Named Graphs. This enables RDF statements that describe graphs, which is beneficial in many Semantic Web application areas. As a case study, we explore the application area of Semantic Web publishing: Named Graphs allow publishers to communicate assertional intent, and to sign their graphs; information consumers can evaluate specific graphs using task-specific trust policies, and act on information from those Named Graphs that they accept. Graphs are trusted depending on: their content; information about the graph; and the task the user is performing. The extension of RDF to Named Graphs provides a formally defined framework to be a foundation for the Semantic Web trust layer.

Photosynthetic O2 Formation Tracked by Time-Resolved X-ray Experiments

Abstract: Plants and cyanobacteria produce atmospheric dioxygen from water, powered by sunlight and catalyzed by a manganese complex in photosystem II. A classic S-cycle model for oxygen evolution involves five states, but only four have been identified. The missing S4 state is particularly important because it is directly involved in dioxygen formation. Now progress comes from an x-ray technique that can monitor redox and structural changes in metal centers in real time with 10-microsecond resolution. We show that in the O2-formation step, an intermediate is formed—the enigmatic S4 state. Its creation is identified with a deprotonation process rather than the expected electron-transfer mechanism. Subsequent electron transfer would give an additional S4′ state, thus extending the fundamental S-state cycle of dioxygen formation.

Imaging of Titan from the Cassini spacecraft

Abstract: Titan, the largest moon of Saturn, is the only satellite in the Solar System with a substantial atmosphere. The atmosphere is poorly understood and obscures the surface, leading to intense speculation about Titan's nature. Here we present observations of Titan from the imaging science experiment onboard the Cassini spacecraft that address some of these issues. The images reveal intricate surface albedo features that suggest aeolian, tectonic and fluvial processes; they also show a few circular features that could be impact structures. These observations imply that substantial surface modification has occurred over Titan's history. We have not directly detected liquids on the surface to date. Convective clouds are found to be common near the south pole, and the motion of mid-latitude clouds consistently indicates eastward winds, from which we infer that the troposphere is rotating faster than the surface. A detached haze at an altitude of 500 km is 150–200 km higher than that observed by Voyager, and more tenuous haze layers are also resolved.

Franck-Condon blockade and giant Fano factors in transport through single molecules.

Abstract: We show that Franck-Condon physics leads to a significant current suppression at low bias voltages (termed Franck-Condon blockade) in transport through single molecules with strong coupling between electronic and vibrational degrees of freedom. Transport in this regime is characterized by remarkably large Fano factors (10(2)-10(3) for realistic parameters), which arise due to avalanchelike transport of electrons. Avalanches occur in a self-similar manner over a wide range of time scales, leading to power-law dependences of the current noise on frequency and vibrational relaxation rate.

Immediate-early and delayed cytokinin response genes of Arabidopsis thaliana identified by genome-wide expression profiling reveal novel cytokinin-sensitive processes and suggest cytokinin action through transcriptional cascades.

Abstract: Cytokinins are hormones that regulate many developmental and physiological processes in plants. Recent work has revealed that the cytokinin signal is transduced by two-component systems to the nucleus where target genes are activated. Most of the rapid transcriptional responses are unknown. We measured immediate-early and delayed cytokinin responses through genome-wide expression profiling with the Affymetrix ATH1 full genome array (Affymetrix Inc., Santa Clara, CA, USA). Fifteen minutes after cytokinin treatment of 5-day-old Arabidopsis seedlings, 71 genes were upregulated and 11 genes were downregulated. Immediate-early cytokinin response genes include a high portion of transcriptional regulators, among them six transcription factors that had previously not been linked to cytokinin. Five plastid transcripts were rapidly regulated as well, indicating a rapid transfer of the signal to plastids or direct perception of the cytokinin signal by plastids. After 2 h of cytokinin treatment genes coding for transcriptional regulators, signaling proteins, developmental and hormonal regulators, primary and secondary metabolism, energy generation and stress reactions were over-represented. A significant number of the responding genes are known to regulate light (PHYA, PSK1, CIP8, PAT1, APRR), auxin (Aux/IAA), ethylene (ETR2, EIN3, ERFs/EREBPs), gibberellin (GAI, RGA1, GA20 oxidase), nitrate (NTR2, NIA) and sugar (STP1, SUS1) dependent processes, indicating intense crosstalk with environmental cues, other hormones and metabolites. Analysis of cytokinin-deficient 35S:AtCKX1 transgenic seedlings has revealed additional, long-lasting cytokinin-sensitive changes of transcript abundance. Comparative overlay-analysis with the software tool mapman identified previously unknown cytokinin-sensitive metabolic genes, for example in the metabolism of trehalose-6-phosphate. Taken together, we present a genome-wide view of changes in cytokinin-responsive transcript abundance of genes that might be functionally relevant for the many biological processes that are governed by cytokinins.

The flight paths of honeybees recruited by the waggle dance

Abstract: In the 'dance language' of honeybees, the dancer generates a specific, coded message that describes the direction and distance from the hive of a new food source, and this message is displaced in both space and time from the dancer's discovery of that source. Karl von Frisch concluded that bees 'recruited' by this dance used the information encoded in it to guide them directly to the remote food source, and this Nobel Prize-winning discovery revealed the most sophisticated example of non-primate communication that we know of. In spite of some initial scepticism, almost all biologists are now convinced that von Frisch was correct, but what has hitherto been lacking is a quantitative description of how effectively recruits translate the code in the dance into flight to their destinations. Using harmonic radar to record the actual flight paths of recruited bees, we now provide that description.

Strongly coupled optical phonons in the ultrafast dynamics of the electronic energy and current relaxation in graphite

Abstract: Ultrafast charge carrier dynamics in graphite has been investigated by time-resolved terahertz spectroscopy Analysis of the transient dielectric function and model calculations show that more than 90% of the initially deposited excitation energy is transferred to a few strongly coupled lattice vibrations within 500 fs These hot optical phonons also substantially contribute to the striking increase of the Drude relaxation rate observed during the first picosecond after photoexcitation The subsequent cooling of the hot phonons yields a lifetime estimate of 7 ps for these modes Graphite has attracted continuous attention in research over the past decades [1] Recently, a strong ambipolar electric field effect was found in thin films of this semimetal, thereby demonstrating its potential for future electronics [2] Moreover, graphite is closely related to carbon nanotubes, which are the focus of nanotechnology research [3] The latest experimental and theoretical efforts revealed that optical phonons in graphite strongly interact with the electrons [4,5] These strongly coupled optical phonons (SCOPs) have high quantum energies of up to 02 eV and can be excited only by electrons of elevated energy The scattering of electrons by SCOPsis believed to increase the dc resistivity of carbon nanotubes when high electric fields are applied [3] In view of possible applications in electronics, further investigations are required on how SCOPs influence the transport and energy relaxation of electrons Time-resolved terahertz spectroscopy (TRTS) is a promising experimental approach to this question Avisible pump pulse excites charge carriers in the sample and thus enables them to generate optical phonons A subsequent terahertz (THz) pulse probes the low-energy response of the system

Isotope Effects In Chemistry and Biology

Abstract: Editorial Biography Theoretical Basis of Isotope Effects from an Autobiographical Perspective J. Bigeleisen Enrichment of Isotopes T. Ishida and Y. Fujii Comments on Selected Topics in Isotope Theoretical Chemistry M. Wolfsberg Condensed Matter Isotope Effects W.A. Van Hook Anharmonicities, Isotopes, and IR and NMR Properties of Hydrogen-Bonded Complexes J.E. Del Bene Isotope Effects on Hydrogen-Bond Symmetrization in Ice and Strong Acids at High Pressure K. Aoki Hydrogen Bond Isotope Effects Studied by NMR H-H. Limbach, G.S. Denisov and N.S. Golubev Isotope Effects and Symmetry of Hydrogen Bonds in Solution: Single- and Double-Well Potential J.S. Lau and C.L. Perrin NMR Studies of Isotope Effects of Compounds with Intramolecular Hydrogen Bonds P.E. Hansen Vibrational Isotope Effects in Hydrogen Bonds Z. Mielke and L. Sobczyk Isotope Selective Infrared Spectroscopy and Intramolecular Dynamics M. Hippler and M. Quack Nonmass-Dependent Isotope Effects R.E. Weston, Jr. Isotope Effects in the Atmosphere E. Roth, R. Letolle, C. M. Stevens, and F. Robert Isotope Effects for Exotic Nuclei O. Matsson Muonium - An Ultra-Light Isotope of Hydrogen E. Roduner The Kinetic Isotope Effect in the Photo-Dissociation Reaction of Excited-State Acids in Aqueous Solutions E. Pines The Role of an Internal-Return Mechanism on Measured Isotope Effects H.F. Koch Vibrationally Enhanced Tunneling and Kinetic Isotope Effects in Enzymatic Reactions S.D. Schwartz Kinetic Isotope Effects for Proton-Coupled Electron Transfer Reactions S. Hammes-Schiffer Kinetic Isotope Effects in Multiple Proton Transfer Z. Smedarchina, W. Siebrand, and A. Fernandez-Ramos Interpretation of Primary Kinetic Isotope Effects for Adiabatic and Nonadiabatic Proton-Transfer Reactions in a Polar Environment P.M. Kiefer and J.T. Hynes Variational Transition-State Theory and Multidimensional Tunneling for Simple and Complex Reactions in the Gas Phase, Solids, Liquids, and Enzymes D.G. Truhlar Computer Simulations of Isotope Effects in Enzyme Catalysis A. Warshel, Mats H. M. Olsson, and J. Villa-Freixa Chapter 24 Oxygen-18 Isotope Effects as a Probe of Enzymatic Activation of Molecular Oxygen Justine P. Roth and Judith P. Klinman Chapter 25 Solution and Computational Studies of Kinetic Isotope Effects in Flavoprotein and Quinoprotein Catalyzed Substrate Oxidations as Probes of Enzymic Hydrogen Tunneling and Mechanism J. Basran, L. Masgrau, M.J. Sutcliffe, and N.S. Scrutton Proton Transfer and Proton Conductivity in Condensed Matter Environment A.M. Kuznetsov and J. Ulstrup Mechanisms of CH-Bond Cleavage Catalyzed by Enzymes W. Siebrand and Z. Smedarchina Kinetic Isotope Effects as Probes for Hydrogen Tunneling in Enzyme Catalysis A. Kohen Hydrogen Bonds, Transition-State Stabilization, and Enzyme Catalysis R.L. Schowen Substrate and pH Dependence of Isotope Effects in Enzyme Catalyzed Reactions W.E. Karsten and P.F. Cook Catalysis by Alcohol Dehydrogenases B.V. Plapp Effects of High Hydrostatic Pressure on Isotope Effects D.B. Northrop Solvent Hydrogen Isotope Effects in Catalysis by Carbonic Anhydrase: Proton Transfer through Intervening Water Molecules D.N. Silverman and I. Elder Isotope Effects from Partitioning of Intermediates in Enzyme-Catalyzed Hydroxylation Reactions Paul F. Fitzpatrick Chlorine Kinetic Isotope Effects on Biological Systems P. Paneth Nucleophile Isotope Effects V.E. Anderson, A.G. Cassano, and M.E. Harris Enzyme Mechanisms from Isotope Effects W. W. Cleland Catalysis and Regulation in the Soluble Methane Monooxygenase System: Applications of Isotopes and Isotope Effects J.D. Lipscomb Secondary Isotope Effects A.C. Hengge Isotope Effects in the Characterization of Low Barrier Hydrogen Bonds P.A. Frey Theory and Practice of Solvent Isotope Effects D.M. Quinn Enzymatic Binding Isotope Effects and the Interaction of Glucose with Hexokinase B.E. Lewis and V.L. Schramm Index

Honey bees navigate according to a map-like spatial memory

Abstract: By using harmonic radar, we report the complete flight paths of displaced bees. Test bees forage at a feeder or are recruited by a waggle dance indicating the feeder. The flights are recorded after the bees are captured when leaving the hive or the feeder and are released at an unexpected release site. A sequence of behavioral routines become apparent: (i) initial straight flights in which they fly the course that they were on when captured (foraging bees) or that they learned during dance communication (recruited bees); (ii) slow search flights with frequent changes of direction in which they attempt to “get their bearings”; and (iii) straight and rapid flights directed either to the hive or first to the feeding station and then to the hive. These straight homing flights start at locations all around the hive and at distances far out of the visual catchment area around the hive or the feeding station. Two essential criteria of a map-like spatial memory are met by these results: bees can set course at any arbitrary location in their familiar area, and they can choose between at least two goals. This finding suggests a rich, map-like organization of spatial memory in navigating honey bees.

Myeloablative megatherapy with autologous stem-cell rescue versus oral maintenance chemotherapy as consolidation treatment in patients with high-risk neuroblastoma: a randomised controlled trial.

Abstract: Summary Background Myeloablative megatherapy is commonly used to improve the poor outlook of children with high-risk neuroblastoma, yet its role is poorly defined. We aimed to assess whether megatherapy with autologous stem-cell transplantation could increase event-free survival and overall survival compared with maintenance chemotherapy. Methods 295 patients with high-risk neuroblastoma (ie, patients with stage 4 disease aged older than 1 year or those with MYCN -amplified tumours and stage 1, 2, 3, or 4S disease or stage 4 disease and Findings Intention-to-treat analysis showed that patients allocated megatherapy had increased 3-year event-free survival compared with those allocated maintenance therapy (47% [95% CI 38–55] vs 31% [95% CI 23–39]; hazard ratio 1·404 [95% CI 1·048–1·881], p=0·0221), but did not have significantly increased 3-year overall survival (62% [95% CI 54–70] vs 53% [95% CI 45–62]; 1·329 [0·958–1·843], p=0·0875). Improved 3-year event-free survival and 3-year overall survival were also recorded for patients given megatherapy in the as-treated group (n=212) and in the treated-as-randomised group (n=145). Two patients died from therapy-related complications during induction treatment. No patients given maintenance therapy died from acute treatment-related toxic effects. Five patients given megatherapy died from acute complications related to megatherapy. Interpretation Myeloablative chemotherapy with autologous stem-cell transplantation improves the outcome for children with high-risk neuroblastoma despite the raised risk of treatment-associated death.

The institutionalization of private governance: How business and nonprofit organizations agree on transnational rules

Abstract: This article assesses the recent trend of cooperation among antagonistic private actors that results in the creation and implementation of issue-specific transnational norms and rules and the subsequent shift from public to private forms of governance. Many political scientists agree that authority also exists outside of formal political structures. Private actors increasingly begin to make their own rules and standards that acquire authority beyond the international system. This observation is often referred to as private transnational governance as opposed to public or international governance. Although the concept of private governance gains prominence in academic debates, it is not clear how private governance on the global scale is constructed and maintained or what specific or general conditions are necessary for private governance to emerge. Based on the review of common theoretical propositions, this article develops an integrated model along which the necessary conditions for the emergence of private governance can be assessed and understood. As most research has hitherto focused on institutionalized cooperation between business actors (self-regulation), this article takes a closer look at those transnational systems of rule that result out of the enhanced cooperation between profit and nonprofit actors (coregulation).

Tropical to mid-latitude snow and ice accumulation, flow and glaciation on Mars

Abstract: Images from the Mars Express HRSC (High-Resolution Stereo Camera) of debris aprons at the base of massifs in eastern Hellas reveal numerous concentrically ridged lobate and pitted features and related evidence of extremely ice-rich glacier-like viscous flow and sublimation. Together with new evidence for recent ice-rich rock glaciers at the base of the Olympus Mons scarp superposed on larger Late Amazonian debris-covered piedmont glaciers, we interpret these deposits as evidence for geologically recent and recurring glacial activity in tropical and mid-latitude regions of Mars during periods of increased spin-axis obliquity when polar ice was mobilized and redeposited in microenvironments at lower latitudes. The data indicate that abundant residual ice probably remains in these deposits and that these records of geologically recent climate changes are accessible to future automated and human surface exploration.