bluuebunny/crossref_metadata_2025 huggingface dataset:
An appraisal of survival strategies
Authors: Mitchison N. A.
Published: August 2011

Only a few years ago parasite immunology looked an unattractive subject better left to the dogged specialists. Parasites and hosts had been playing chess together for a million years, and there seemed little prospect of perturbing matters in favour of the host immune system. All that has changed, for three reasons. Firstly, we have learned how to grow at least some parasitesin vitro, and prospects of doing so with others are encouraging. Secondly, progress in cellular immunology has revealed the sort of loopholes in the host defence system which parasites are likely to exploit: we are learning the questions which matter about parasites as antigens. Thirdly, and most importantly, molecular genetics is being brought to bear on parasites: we can now see a real, though long-term, prospect of manufacturing practicable vaccines through bio-engineering, and more immediately it gives us the tools needed to probe the host immune responses in the form of cloned antigens.
Sequestration – beneficial to both host and parasite
Authors: Mackenzie C.D.
Published: August 2011

The interaction between host and infecting organism plays an important role in the survival of both of these components. The mechanisms whereby survival of one, or both, is achieved can be considered at various anatomical levels and degrees of complexity; those involving whole tissues together with events occurring at the cellular and subcellular levels. The involvement of sequestration, or the ‘standing apart’ of an invading organism from the host, as a mechanism of survival can also be examined at these various levels.
Stage-specific antigens ofTrichinella spiralis
Authors: Parkhouse R. M. E. , Ortega-Pierres Guadalupe
Published: August 2011

Infective larvae, adults and newborn larvae ofTrichinella spiraliswere surface labelled with radioactive iodine, and the surface material was solubilized in the mild detergent sodium deoxycholate. The radio-isotope labelled products were stage-specific glycoproteins that were few in number (2–4 components) and antigenic in infected mice and rats. Antibodies synthesized in infected animals against these biochemically defined surface antigens may or may not interact with the surface of the living worm. The latter type of antibody is unlikely to be involved in the initial phase of parasite rejection and is therefore another example of a non-protective host antibody response. The stimulus for its synthesis must be the observed release of surface antigen. A monoclonal antibody to a surface glycoprotein of newborn larvae protected against infection, and also promoted eosinophil killingin vitro. This observation emphasizes the importance of surface antigens in protection against infection, suggests a role for granulocytesin vivo, and provides encouragement for the possible use of nematode surface antigens in protection. An example of regional specialization of the nematode cuticle was given by a monoclonal antibody reactive with only the surface of the male intromittent organ and not the female or remainder of the male. The same stages were labelledin vitrowith radioactive methionine, and the secreted proteins were also found to be stage-specific. Some, but not all, were antigenic in infected mice. The total concanavalin A-binding somatic glycoproteins of each stage exhibited considerable individuality, and hence stage specificity, when resolved by two-dimensional gel electrophoresis. These results extend our knowledge of stage-specific components ofT. spiralis, and allow a rational approach towards protection and the construction of diagnostic procedures.
Variation in ‘target’ antigens between appropriate and inappropriate hosts of Taenia saginata metacestodes
Authors: Harrison L. J. S. , Parkhouse R. M. E. , Sewell M. M. H.
Published: August 2011

The antibody response of the appropriate hosts (cattle) to Taenia saginata larvae was compared with that of an inappropriate host (Balb/c mice) using gel electrophoresis followed by immunoelectrotransfer blot techniques (Western blotting). Three groups of cattle were included, those known to be resistant to challenge infection because of repeated oral challenge with T. saginata eggs over a 1-year period, a previously infected but known susceptible group and a group of uninfected controls. Serum from the mice and the two groups of infected cattle contained antibodies recognizing different ‘target’ antigens, some of which may be related to host resistance. The potential value of the technique of Western blotting in dissecting the humoral response of a particular host species to parasitic infection and in the identification of those antigens suitable for the production of effective vaccines is discussed.
Manipulation of the immune response in parasitic infections
Authors: Howard J.G.
Published: August 2011

The following brief survey considers various manoeuvres which can be applied to manipulate the immune response to parasitic infectionsin vivo. The examples quoted largely concern malaria, babesiosis, schistosomiasis and leishmaniasis, predominantly in inbred mouse strains. Since my own relevant research experience has been restricted to leishmaniasis, this will receive undue emphasis, although it does illustrate particularly well points I wish to stress. The types of intervention described do not all provide the precision of interpretation with which they are sometimes credited. Thus, effects of immunosuppression or T-cell depletion alone can usually only implicate the specific immune response (in its broad sense) in shaping the natural history and outcome of an infection or in underlying the effect of prophylactic immunization. Nevertheless, more precise delineation of lymphocyte subset involvement can be obtained by cell replacement studies in some of these models or by exclusion of antibody. The outcomes of these approaches have been (or are) predictable in most cases. More fascinating, however, are the various instances which will be stressed where totally unpredicted and contrary observations have been made which led (or may lead) to fresh insight into the disease. These serendipitous findings illustrate at the same time the value of applying the manoeuvres, even though they imply that the logical immunologist cannot yet always outsmart the parasite by design.
Molecular characterization of antigens of lymphatic filarial parasites
Authors: Selkirk M. E. , Denham D. A. , Partono F. , Sutanto I. , Maizels R. M.
Published: August 2011

Three species of filarial worms,Wuchereria bancrofti, Brugia malayiandBrugia timori, are the causative agents of lymphatic filariasis in man, defined by the characteristic tropism of adult worms of each species for the afferent lymphatics. Reproductive activity leads to the release of large numbers of microfilariae, which circulate in the vascular system, and upon ingestion by an appropriate mosquito vector, develop through to infective third-stage larvae (L3) within 10–14 days. After a subsequent bloodmeal, the infective larvae enter the definitive host via the wound and mature to the adult stage over several months, involving two moults, during which the entire nematode exoskeleton (cuticle) is replaced.
The cloning of schistosome genes encoding antigenic and maturation-linked polypeptides
Authors: Knight M. , Simpson A. J. G. , Kelly C. , Smithers S. R.
Published: August 2011

Schistosomiasis is a chronic debilitating disease which accounts for considerable human mortality and morbidity and is second only to malaria in its prevalence and severity. Despite several years of concentrated effort to combat the disease with molluscicides and chemotherapy, schistosomiasis is still spreading, and it is thought that 500 million people are currently exposed to infection (larotski & Davis, 1981).
Vaccinia virus: an expression vector for genes from parasites
Authors: Smith G. L. , Cheng K.-C. , Moss B.
Published: August 2011

Smallpox has been eradicated by immunization with live vaccinia virus. Now, using genetic engineering, infectious vaccinia virus recombinants are being constructed which express genes from other pathogens. These viruses can stimulate specific immunological responses against the foreign antigen in vaccinated animals and can protect against disease caused by the corresponding pathogen. In this paper we describe how recombinant vaccinia viruses are constructed and illustrate the potential of this vector system for expression of genes from parasitic pathogens.
Antigens ofPlasmodiwn falciparumblood stages with clinical interest cloned and expressed inE. coli
Authors: Scaife J. , Bone N. , Goman M. , Hall R. , Hope I. A. , Hyde J. E. , Langsley G. , Mackay M. , Oquendo P. , Simmons D.
Published: August 2011

The human malaria parasite,Plasmodium falciparum, is currently being actively studied by molecular biologists. It is hoped that the use of recombinant DNA techniques in this area will give new insights into the biology of the organism and, at the same time, provide new approaches to diagnosis and vaccine development.

Our own studies employ the blood stages of the parasite and cover three main areas: enzymes of importance in parasite metabolism; antigens of potential use in a subunit vaccine; and repetitive DNA as a probe able to distinguish genetically different isolates ofP. falciparumand as a species-specific diagnostic tool in human and mosquito infections.
The potential of using recombinant DNA species-specific probes for the identification of tropicalLeishmania
Authors: Barker D. C. , Gibson Lorna J. , Kennedy W. P. K. , Nasser A.A.A.A , Williams R. H.
Published: August 2011

Human leishmaniasis is a world-wide public health problem with more than 400000 new reported cases/year (Anon, 1984) in the tropics and subtropics. Were (1985) has estimated that Leishmaniases affect about 20 million people in the Third World. In hospitals where treatment is available, initially all positive cases are treated equally; it is the prognosis and follow-up that varies according to the causative organism. A wide variety of species or subspecies ofLeishmaniamay be present in a small verrucose lesion developing after an infected sandfly bite or appear in lesions as the disease progresses. Depending on whichLeishmaniais present a clinial decision must be made whether to treat with drugs of varying toxicity or not.
Inflammatory responses to parasites
Authors: Mackenzie C. D. , Gatrill A. J. , Luty A. J. , Manyasi D. G. , Moore C. , Sayers G. , Sulaiman S.
Published: August 2011

The patients we are concerned about in tropical medicine are unfortunately affected by a wide range of conditions, not only those seen and studied extensively in the West, such as cancer, cardiovascular diseases and viral or bacterial infections, but also the major protozoan and metazoan conditions – the parasitic diseases. It is with this spectrum of pathophysiological changes that occurs in this last group that we are presently concerned and this communication is intended to present an overview of the subject.
Pathophysiology of severe falciparum malaria in man
Authors: Warrell D. A.
Published: August 2011

The term severe falciparum malaria implies an infection with manifestations and complications which are potentially fatal in man, the natural host for this parasite. Much that has been written on the pathophysiology of animal malarias is of doubtful relevance to the understanding of the mechanism ofPlasmodium falciparuminfection in man. The clinical picture of severeP. falciparuminfection differs in several respects from severe animal malarias, even those of non-human primates. Cerebral dysfunction is the most common severe manifestation of falciparum malaria in man. Coma develops suddenly after a generalized convulsion or gradually towards the end of the first week of illness. There are signs of a symmetrical upper motor neurone lesion and brain-stem dysfunction, but only about 5% of survivors show persisting neurological deficit after 2 or 3 days of unconsciousness. The mortality of cerebral malaria depends on how it is defined and on the predominant age group and other factors. In patients with proved acuteP. falciparuminfection with unrousable coma, in whom other causes of encephalopathy have been excluded, the mortality is between 15 and 50% despite treatment with antimalarial drugs (Warrell, Looareesuwan, Warrell, Kasemsarn, Intaraprasert, Bunnag & Harinasuta, 1982).
Some general characteristics of the transport of nutrients and toxic compounds in yeasts and fungi
Authors: Eddy A. A.
Published: August 2011

This essay deals in turn with the six main mechanisms that are believed to be involved in the passage of small molecules across the cell membrane of yeasts and fungi. Such solutes include amino acids, carbohydrates, purines and pyrimidines and other nutrients, among which are the ions K+,,or. The subject has been reviewed extensively (see, for example, Eddy, 1982; Cooper, 1982; Serrano, 1984; Harold, 1986). Transport systems relate to chemotherapy in two ways. First, they may themselves be potential targets for drug action. Second, they may deliver a drug to its intracellular target, the drug being an illicit passenger in a transport system with a different primary role. Most of our knowledge about yeast and fungal transport is currently based on studies with relatively few species selected because they are known to be amenable to genetic and biochemical analysis. The organisms include representative strains ofNeurospora crassaor ofSaccharomyces cerevisiaeand selected species ofRhodotorulaandSchizosaccharomyces. Fungal organisms pathogenic to man, such asCandida albicans, those causing either systemic fungal infections (see Kerridge, 1986; Shepherd, Poulter & Sullivan, 1985), or the numerous fungal diseases of plants have been little used as models of nutrient transport, despite their clinical or economic importance. Whether all these ecologically diverse organisms, which in evolutionary terms are only distantly related, employ only the transport mechanisms so far discovered inSaccharomyces cerevisiaeis an open question.
Global warming: Trends and effects
Authors: Tickell Crispin
Published: August 2011

As animals we have been a remarkably successful species; but also as animals we are vulnerable to environmental, in particular climate change. Such change is accelerating as a result of human activity, and global warming may already be taking place. Although we can foresee the trends, we cannot yet be specific about the results. Change usually proceeds by steps rather than gradients. But warming would probably include new risks to human health and contribute to an increase in human displacement. Of course climate change is only one among other complex problems facing human society, but it is closely related to them all, including population increase, environmental degradation and loss of biodiversity. We cannot prevent global warming but we can anticipate and mitigate some of its worst effects. Peoples and governments still need persuading of the need for action and of the magnitude of the issue at stake.
Transmission and control in an institutional pandemic influenza A(H1N1) 2009 outbreak
Authors: ARINAMINPATHY N. , RAPHAELY N. , SALDANA L. , HODGEKISS C. , DANDRIDGE J. , KNOX K. , McCARTHY N. D.
Published: August 2011

A pandemic influenza A(H1N1) 2009 outbreak in a summer school affected 117/276 (42%) students. Residential social contact was associated with risk of infection, and there was no evidence for transmission associated with the classroom setting. Although the summer school had new admissions each week, which provided susceptible students the outbreak was controlled using routine infection control measures (isolation of cases, basic hygiene measures and avoidance of particularly high-risk social events) and prompt treatment of cases. This was in the absence of chemoprophylaxis or vaccination and without altering the basic educational activities of the school. Modelling of the outbreak allowed estimation of the impact of interventions on transmission. These models and follow-up surveillance supported the effectiveness of routine infection control measures to stop the spread of influenza even in this high-risk setting for transmission.
The prevalence, detection and intervention for depression and anxiety in oncology
Authors: Boothroyd David Andrew , Hodgson Denyse
Published: August 2011

Clinical depression is the most prevalent psychiatric disorder amongst cancer patients and is associated with significant functional impairment, although often under-diagnosed and untreated. In one study, only 6% of patients with clinical depression were identified by their oncologists. The detection of and intervention for anxiety and depression in oncology is widely debated in the literature. Diagnosing clinically significant distress amongst cancer patients requires sensitivity as many symptoms of depression are very similar to those of some cancers themselves. The two detection methods discussed in the literature are either self report questionnaires (i.e., HADS) and diagnostic clinical interviews. There are several techniques described in the literature that have shown to be effective in reducing anxiety and depression in oncology. These can be broken down into four main categories, namely, cognitive behavioural therapy (CBT), counselling, drug therapy and complementary therapies, and it is acknowledged that patients receiving any type of intervention generally cope better than those who receive none at all. The effective management of anxiety and depression is dependent on the ability of health professionals to establish a rapport with patients and pick up on cues, regardless of whether intervention is necessary. However, an obvious lack of time and resources within the NHS can be a limiting factor, thus all health care professionals must take more responsibility for the detection of anxiety and depression, followed by the appropriate referral.
Coupled nitrification‐denitrification in sediment of the eastern Bering Sea shelf leads to 15N enrichment of fixed N in shelf waters
Authors: Granger J. , Prokopenko M. G. , Sigman D. M. , Mordy C. W. , Morse Z. M. , Morales L. V. , Sambrotto R. N. , Plessen B.
Published: August 2011

We studied the nitrogen biogeochemistry of the ice‐covered eastern Bering Sea shelf using the isotope ratios (15N/14N and 18O/16O) of NO3− and other N species. The 15N/14N of late winter NO3− on the shelf decreases inshore and is inversely correlated with bottom water [NH4+], consistent with an input of low‐15N/14N NO3− from partial nitrification of NH4+ remineralized from the sediments. An inshore 15N/14N increase in total dissolved N (TDN) suggests that (1) the sediment‐derived NH4+ is elevated in 15N due to the same partial nitrification that yields the low‐15N/14N NO3−, and (2) 15N‐deplete NO3− from partial nitrification within the sediments is denitrified to N2. The proportion of newly nitrified NO3− on the shelf, evidenced by an inshore decrease in NO3− 18O/16O, is correlated with the N deficit, further implicating nitrification coupled to denitrification; however, a simple N isotope budget indicates a comparable rate of denitrification supported by diffusion of NO3− into the sediments. The isotopic impact of benthic N loss is further demonstrated by a correlation between the 15N/14N of shelf surface sediment and the N deficit of the overlying water column, both of which increase inshore and northward, as well as by Arctic NO3− isotope data indicating that the fixed N transported through Bering Strait has a 15N/14N higher than is found in the open Bering Sea. The significant net isotope effect of benthic N loss on the Bering shelf, 6–8 ‰, is at odds with previous assumptions regarding the global ocean's N isotope budget.
Expression of γ‐chain cytokine receptors on CD8+ T cells in HIV infection with a focus on IL‐7Rα (CD127)
Authors: Crawley Angela M , Angel Jonathan B
Published: August 2011

When interleukin‐2 (IL‐2) receptor γ‐chain (γC)‐sharing cytokine receptors on T cells bind their specific ligands (IL‐2, ‐4, ‐7, ‐9, ‐15 or ‐21), they initiate a variety of cell signals that promote survival, differentiation or antiviral or antitumor cytolytic functions. Although expression of the γC is constitutive across T‐cell subsets, the varying expression of other receptor complex components can regulate cytokine signalling and function. Impaired γC cytokine activity in HIV infection, and the role of γC cytokines in CD8+ T‐cell function and homeostasis, implicates these molecules among potential contributors to the observed decline of cytolytic activity (CTL) in HIV disease. In particular, this review will be highlighting information about the IL‐7 receptor (IL‐7R) complex, which is composed of the γC and the IL‐7Rα (CD127) chains. There has been an abundance of HIV‐related CD127 research and its important role in CD8+ T‐cell survival and function. The expression of CD127 undergoes dramatic changes throughout the course of T‐cell responses in HIV infection. The expression of CD127 is significantly decreased in progressive HIV disease, whereas effective antiretroviral therapy results in its recovery. Observations of impaired IL‐7 activity in HIV+ individuals have suggested that CD127 has an important role in HIV immunopathogenesis. In addition, a soluble form of CD127 (sCD127) is upregulated in the plasma of HIV+ individuals. Hence, CD127 is being increasingly considered as a marker of disease prognosis, and related information may provide insight into understanding the expression and role of other γC receptors in HIV disease and contribute to the development of novel cytokine‐based therapeutics.
Prediction of specific virus outbreaks made from the increased concentration of a new class of virus genomic peptides, replikins.
Authors: Bogoch Samuel , Bogoch Elenore
Published: August 2011

Advance warning of pathogen outbreaks has not been possible heretofore. A new class of genomic peptides associated with rapid replication was discovered and named replikins. Software was designed to analyze replikins quantitatively. Replikin concentration changes were measured annually prior to, and “real time” every few days during, the 2009 H1N1 influenza pandemic. Replikins were seen by both linear sequence representation and three-dimensional X-ray diffraction, and found to expand on the virus hemagglutinin surface prior to and during the H1N1 pandemic.A highly significant increased concentration of virus replikins was found a) retrospectively in three pandemics from 1918 to 1999 (14,227 sequences)(p<0.001), and b) prospectively before the H1N1 2009 pandemic (12,806 sequences) (in the hemagglutinin gene (N=8,046), p values by t-test = 1/10130, by linear regression = 1/1024 and 1/1029, by Spearman correlation < 2/1016, by Wilcoxon rank sum<1/1016, by multiple regression adjusting for correlation between consecutive years = 2/1022. Rising replikin concentration in H1N1 from 2006 to 2008, predicted one year in advance the H1N1 outbreak of 2009; and in H5N1, predicted the lethal outbreaks of H5N1 1997-2010.The possible combination of influenza strains H1N1 (high infectivity) and H5N1 (high lethality) is a matter of global concern (1,2). The risk of a combined H1N1 (high infectivity) - H5N1 (high lethality) outbreak may have increased because first, the Replikin Counts of the two virus strains have risen simultaneously, not seen previously; second, the rise is to the highest levels recorded since 1918 for H1N1, in Mexico (16.7), and since 1957 for H5N1, in Egypt (23.3); and third, clinical outbreaks of each strain are occurring in 2011. These simultaneous conditions may increase the risk that the two virus strains might come into contact with each other more frequently, facilitating transfer of genomic material to form a hybrid.
Endothelin-Induced Sarcoplasmic Reticulum Calcium Depletion Waves in Vascular Smooth Muscle Cells
Authors: Esfandiarei Mitra , Choi Yohan , Tehrani Arash , Hoskins Jeremy , Fameli Nicola , van Breemen Cornelis
Published: August 2011

Agonist-stimulated waves of elevated cytoplasmic Ca2+ concentration ([Ca2+]i ) regulate blood vessel tone and vasomotion in vascular smooth muscle. Previous studies employing cytoplasmic Ca2+ indicators revealed that these Ca2+ waves were generated by a combination of inositol 1,4,5-trisphosphate (IP3) and Ca2+ induced Ca2+ release (CICR) from the sarcoplasmic reticulum (SR); although, some of the mechanistic details remain uncertain. However, these findings were derived indirectly from observing agonist-induced [Ca2+]i fluctuations in the cytoplasm.Here, for the first time, we have recorded Endothelin-1 (ET-1) induced waves of Ca2+ depletion from the SR lumen in vascular smooth muscle cells (VSMCs) using a calsequestrin-targeted Ca2+ indicator. Our findings show that these waves: (1) are due to regenerative CICR by the receptors for IP3 (IP3R), (2) have a marked latency period, (3) are characterized by a transient increase in SR Ca2+ ([Ca2+]SR ) both at the point of origin and at the wave front, (4) proceed with diminishing velocity, and (5) are arrested by the nuclear envelope. Our quantitative model indicates that the gradual decrease in the velocity of the SR depletion wave, in the absence of external Ca2+, results from continuity of the SR luminal network.
Acute Orbital Hemorrhage as a Presentation of a Lytic Bony Lesion
Authors: Almousa Radwan , Shuen Chao , Sundar Gangadhara
Published: August 2011

A 61-year-old Chinese man presented to the emergency department with a 1-day history of painful swelling of the right eyelid with loss of vision. He had been treated earlier for an isolated pathological fracture of the T7 vertebra from plasmacytoma. Computed tomography was suggestive of superior orbital hematoma with bony erosion of the inner and outer tables of an isolated frontal cell, and urgent drainage of the hematoma resulted in relief of the pain and improvement of the vision. A formal orbitotomy was performed to evacuate the hematoma, followed by combined endoscopic sinus surgery and external anterior frontal table trephine to connect the isolated cell to the frontal sinus. The histology did not show evidence of myeloma, and the orbital hematoma was probably a result of an acute hemorrhage into the mucocele of an isolated cell in the frontal bone. However, in patients with a history of multiple myeloma, it is important to consider lytic bony involvement as the cause of an orbital hemorrhage.
Self-Ordering of Misfit Dislocation Segments in Epitaxial SiGe Islands on Si(001)
Authors: Boioli F. , Zinovyev V. A. , Gatti R. , Marzegalli A. , Montalenti F. , Stoffel M. , Merdzhanova T. , Wang L. , Pezzoli F. , Rastelli A. , Schmidt O. G. , Miglio Leo
Published: August 2011

Ordering of misfit dislocation segments in concentric polygons at the base of SiGe epitaxial islands on Si(001) has been recently indicated by in situ Transmission Electron Microscope observation. In this paper we confirm the very regular spacing by Atomic Force Microscope and He-ion Microscope measurements of the footprint carved in the Si substrate by the plastic events. We explain the intriguing ordering, as obtained with no gliding rearrangements, by cyclic occurrence of the thermodynamic critical conditions for plastic events. Quantitative predictions by a fully analytical model, which includes the dependence on island shape and composition in the generation of misfit dislocations, matched very well experimental measurements.
CCSD-PCM: Improving upon the reference reaction field approximation at no cost
Authors: Caricato Marco
Published: August 2011

The combination of the coupled cluster (CC) method with the polarizable continuum model (PCM) of solvation requires a much larger computational effort than gas phase CC calculations, since the PCM contribution depends nonlinearly on the CC reduced density: perturbation theory energy and density (PTED) scheme. An approximation can be introduced that neglects the “correlation” PCM contribution and only considers the “reference” PCM contribution to the free energy: PTE scheme. The PTE scheme is a computationally efficient strategy, since the cost is comparable to gas phase CC, but the difference in the free energy with respect to the PTED scheme can be significant. In this work, two intermediate approximations are presented, PTE(S) and PTES (where S stands for singles), which retain the computational efficiency of the PTE scheme while reducing the energy gap with the PTED scheme. PTE(S) only introduces an energy correction to the PTE free energy, while PTES introduces explicit PCM terms in the iterative solution of the CC equations. PTE(S) improves the PTE free energy, although such correction is small. PTES recovers 50%–80% of the PTE-PTED difference and represents a promising approach to perform calculations in solution of CC quality at a cost comparable to gas phase CC. The expressions for the CC-PTE(S) and -PTES wave functions, free energy, and free energy analytical gradients are presented, and the methods are tested with numerical examples.
Real-time observation of CO oxidation reaction on Ir(111) surface at 33 ms resolution by means of wavelength-dispersive near-edge x-ray absorption fine structure spectroscopy
Authors: Amemiya Kenta , Kousa Yuka , Nakamoto Shuichi , Harada Taiga , Kozai Shogo , Yoshida Masaaki , Abe Hitoshi , Sumii Ryohei , Sakamaki Masako , Kondoh Hiroshi
Published: August 2011

The CO oxidation reaction on Ir(111) is observed by the near-edge x-ray absorption fine structure (NEXAFS) spectroscopy in the soft x-ray region. A continuous data acquisition at 33 ms real-time resolution is realized for a single event of the reaction without the repetition, by adopting the wavelength-dispersive NEXAFS technique. The time evolution of the coverages for atomic O and molecular CO is quantitatively estimated during the reaction. The obtained activation energy is significantly larger than that on Pt(111).
Studying the force characteristics of a high temperature superconducting linear synchronous motor
Authors: Zheng Luhai , Jin Jianxun
Published: August 2011

A single-sided high temperature superconducting (HTS) linear synchronous motor (HTSLSM) with an HTS bulk magnet array as its secondary has been developed. A field-cooled magnetization system has also been developed to obtain the magnet array with alternate magnetic poles. In order to identify the performance and force characteristics of the HTSLSM, an equivalent 3D finite element analysis (FEA) model has been built up to analyze its field distributions and cogging force characteristics, and an experimental system has been constructed to measure its thrust and normal force characteristics. The traits of the thrust and the normal force have been extracted by comprehensive experiments, including the trends versus different exciting currents, different air gap lengths and variable magnetic poles. The analysis and experimental results are fundamental to the electromagnetic optimum design and control scheme evaluation for the HTSLSM.
Thermophysical properties for shock compressed polystyrene
Authors: Wang Cong , He Xian-Tu , Zhang Ping
Published: August 2011

We have performed quantum molecular dynamic simulations for warm dense polystyrene at high pressures. The principal Hugoniot up to 770 GPa is derived from wide range equation of states. The optical conductivity is calculated via the Kubo-Greenwood formula, from which the dc electrical conductivity and optical reflectivity are determined. The nonmetal-to-metal transition is identified by gradual decomposition of the polymer. Our results show good agreement with recent high precision laser-driven experiments.
Detailed investigation of the influence of the process parameters on the nano-morphology of Ag deposited on SiC by radio-frequency sputtering
Authors: Ruffino F. , Grimaldi M. G.
Published: August 2011

In this work, a detailed study of the influence of the synthesis parameters (deposition time t and emission current I) on the morphological properties of Ag nanoparticles sputter-deposited on silicon carbide is carried out. Using the atomic force microscopy technique, we analyzed the evolution of several structural characteristics as a function both of t and I: the length and width of the Ag nanoparticles, the number of nanoparticles per unit area, the nanoparticles’ fraction of the covered area, and the roughness of the resulting Ag film. Using consolidated theoretical frameworks and fitting approaches, the relations between such quantities and the process parameters t and I were established. In particular, the application of the interrupted coalescence model allowed us to evaluate the critical mean island diameter for the partial coalescence process; the dynamic scaling theories of growing interfaces lead, instead, to the determination of the dynamic scaling, growth, and roughness exponents (the values of which suggest a conservative growth process of the islands in which the atomic surface diffusion plays a key role). Finally, the Avrami approach to the study of the evolution of the fraction of area covered by the Ag islands allowed us to evaluate the Avrami exponent.
Molecular dynamics simulation of cation dynamics in bis-thiourea pyridinium nitrate inclusion compound
Authors: Pajzderska A. , Gonzalez M. A. , Wąsicki J.
Published: August 2011

Molecular dynamics simulations have been performed on the high temperature phase of the bis-thiourea pyridinium nitrate inclusion compound. Three different potential models have been tested. In the three cases, the analysis of the centre of mass motion of pyridium cations indicates that they do not diffuse along the channels. However, only the potential including a specific hydrogen bonding interaction provides a description of the in-plane cation reorientation in reasonable agreement with the experimental results deduced from quasielastic neutron scattering (QENS) measurements. This model shows that the pyridinium cation reorients among three non-equivalent positions and gives reorientational correlation times comparable to those extracted from the QENS data. We conclude that the particular geometry of this reorientation is due to the formation of hydrogen bonds of different strength between the pyridinium cation of the guest sublattice and the host sublattice.
Tunable high-energy soliton pulse generation from a large-mode-area fiber and its application to third harmonic generation microscopy
Authors: Wang Ke , Xu Chris
Published: August 2011

We demonstrate high-energy soliton generation from 1580 nm to 2130 nm by using soliton self-frequency shift in a large-mode-area fiber, pumped by a femtosecond fiber laser source. Transformed-limited soliton pulses with 70 fs pulse width and up to 45 nJ pulse energy are obtained. The broad wavelength tuning range and the high soliton pulse energy, together with the robust fiber-based excitation source, offer unprecedented performance, flexibility, and practicality. To demonstrate the application of the soliton pulses, we image the myelin in mouse brain using third harmonic generation microscopy.
Note: Piezoelectric strain voltage sensing at ultra-low frequencies
Authors: Laskovski A. , Moheimani S. O. R. , Yuce M. R.
Published: August 2011

Piezoelectric sensors have emerged as a versatile tool for measurement of various quantities such as pressure, acceleration, strain, or force across many industrial applications. When mechanically strained, electric charges are produced inside a piezoelectric transducer. These charges result in an electric field that may be measured as a voltage difference between two electrodes, from which the strain can be inferred. To measure this voltage the sensor must be interfaced with an external device that would typically have a finite input impedance. This, together with the capacitive nature of the piezoelectric sensor, results in an inability to measure strain at low frequencies. We propose a method, based on using a varactor diode in an oscillator circuit, which can result in accurate measurements of the piezoelectric voltage at ultra-low frequencies. We demonstrate successful measurements at 1 mHz.
Enhanced emission and light control with tapered plasmonic nanoantennas
Authors: Maksymov Ivan S. , Davoyan Arthur R. , Kivshar Yuri S.
Published: August 2011

We introduce a design of Yagi-Uda plasmonic nanoantennas for enhancing the directive gain and achieving control over the angular emission of light. We demonstrate that tapering of nanoantenna elements allows to decrease the inter-element spacing tenfold also enhancing the emission directivity. We find the optimal tapering angle that provides the maximum directivity enhancement and the minimum end-fire beamwidth.
Relationship between topological order and glass forming ability in densely packed enstatite and forsterite composition glasses
Authors: Kohara S. , Akola J. , Morita H. , Suzuya K. , Weber J. K. R. , Wilding M. C. , Benmore C. J.
Published: August 2011

The atomic structures of magnesium silicate melts are key to understanding processes related to the evolution of the Earth’s mantle and represent precursors to the formation of most igneous rocks. Magnesium silicate compositions also represent a major component of many glass ceramics, and depending on their composition can span the entire fragility range of glass formation. The silica rich enstatite (MgSiO
3
) composition is a good glass former, whereas the forsterite (Mg
2
SiO
4
) composition is at the limit of glass formation. Here, the structure of MgSiO
3
and Mg
2
SiO
4
composition glasses obtained from levitated liquids have been modeled using Reverse Monte Carlo fits to diffraction data and by density functional theory. A ring statistics analysis suggests that the lower glass forming ability of the Mg
2
SiO
4
glass is associated with a topologically ordered and very narrow ring distribution. The MgO

x

polyhedra have a variety of irregular shapes in MgSiO
3
and Mg
2
SiO
4
glasses and a cavity analysis demonstrates that both glasses have almost no free volume due to a large contribution from edge sharing of MgO

x

-MgO

x

polyhedra. It is found that while the atomic volume of Mg cations in the glasses increases compared to that of the crystalline phases, the number of Mg-O contacts is reduced, although the effective chemical interaction of Mg
2+
remains similar. This unusual structure-property relation of Mg
2
SiO
4
glass demonstrates that by using containerless processing it may be possible to synthesize new families of dense glasses and glass ceramics with zero porosity.
Malt1-dependent RelB cleavage promotes canonical NF-κB activation in lymphocytes and lymphoma cell lines
Authors: Hailfinger Stephan , Nogai Hendrik , Pelzer Christiane , Jaworski Maike , Cabalzar Katrin , Charton Jean-Enno , Guzzardi Montserrat , Décaillet Chantal , Grau Michael , Dörken Bernd , Lenz Peter , Lenz Georg , Thome Margot
Published: August 2011

The protease activity of the paracaspase Malt1 contributes to antigen receptor-mediated lymphocyte activation and lymphomagenesis. Malt1 activity is required for optimal NF-κB activation, but little is known about the responsible substrate(s). Here we report that Malt1 cleaved the NF-κB family member RelB after Arg-85. RelB cleavage induced its proteasomal degradation and specifically controlled DNA binding of RelA- or c-Rel–containing NF-κB complexes. Overexpression of RelB inhibited expression of canonical NF-κB target genes and led to impaired survival of diffuse large B-cell lymphoma cell lines characterized by constitutive Malt1 activity. These findings identify a central role for Malt1-dependent RelB cleavage in canonical NF-κB activation and thereby provide a rationale for the targeting of Malt1 in immunomodulation and cancer treatment.
Microbe domestication and the identification of the wild genetic stock of lager-brewing yeast
Authors: Libkind Diego , Hittinger Chris Todd , Valério Elisabete , Gonçalves Carla , Dover Jim , Johnston Mark , Gonçalves Paula , Sampaio José Paulo
Published: August 2011

Domestication of plants and animals promoted humanity's transition from nomadic to sedentary lifestyles, demographic expansion, and the emergence of civilizations. In contrast to the well-documented successes of crop and livestock breeding, processes of microbe domestication remain obscure, despite the importance of microbes to the production of food, beverages, and biofuels. Lager-beer, first brewed in the 15th century, employs an allotetraploid hybrid yeast,
Saccharomyces pastorianus
(syn.
Saccharomyces carlsbergensis
), a domesticated species created by the fusion of a
Saccharomyces cerevisiae
ale-yeast with an unknown cryotolerant
Saccharomyces
species. We report the isolation of that species and designate it
Saccharomyces eubayanus
sp. nov. because of its resemblance to
Saccharomyces bayanus
(a complex hybrid of
S. eubayanus
,
Saccharomyces uvarum
, and
S. cerevisiae
found only in the brewing environment). Individuals from populations of
S. eubayanus
and its sister species,
S. uvarum
, exist in apparent sympatry in
Nothofagus
(Southern beech) forests in Patagonia, but are isolated genetically through intrinsic postzygotic barriers, and ecologically through host-preference. The draft genome sequence of
S. eubayanus
is 99.5% identical to the non-
S. cerevisiae
portion of the
S. pastorianus
genome sequence and suggests specific changes in sugar and sulfite metabolism that were crucial for domestication in the lager-brewing environment. This study shows that combining microbial ecology with comparative genomics facilitates the discovery and preservation of wild genetic stocks of domesticated microbes to trace their history, identify genetic changes, and suggest paths to further industrial improvement.
Booming markets for Moroccan argan oil appear to benefit some rural households while threatening the endemic argan forest
Authors: Lybbert Travis J. , Aboudrare Abdellah , Chaloud Deborah , Magnan Nicholas , Nash Maliha
Published: August 2011

Morocco's argan oil is now the most expensive edible oil in the world. High-value argan markets have sparked a bonanza of argan activity. Nongovernmental organizations, international and domestic development agencies, and argan oil cooperatives aggressively promote the win–win aim of simultaneously benefiting local people and the health of the argan forest. This paper tests some of these win–win claims. Analysis of a panel of detailed household data suggests that the boom has enabled some rural households to increase consumption, increase their goat herds (which bodes poorly for the argan forest), and send their girls to secondary school. The boom has predictably made households vigilant guardians of fruit on the tree, but it has not incited investments in longer term tree and forest health. We evaluate landscape-level impacts of these changes using commune-level data on educational enrollment and normalized difference vegetation index data over the period from 1981 to 2009. The results of the mesoanalysis of enrollment are consistent with the microanalysis: the argan boom seems to have improved educational outcomes, especially for girls. Our normalized difference vegetation index analysis, however, suggests that booming argan prices have not improved the forest and may have even induced degradation. We conclude by exploring the dynamic interactions between argan markets, local institutions, rural household welfare, and forest conservation and sustainability.
Racemization as a stereochemical measure of dynamics and robustness in shape-shifting organic molecules
Authors: He Maggie , Bode Jeffrey W.
Published: August 2011

Bullvalene is a structurally unique dynamic molecule thought to interconvert among 1.2 million degenerate isomers. The incorporation of different chemical substituents onto the bullvalene core should lead to a “shape-shifting” molecule that can interconvert among thousands of discrete structural isomers. Previous NMR spectroscopy and HPLC studies on substituted bullvalenes ascertained the fact that these compounds are dynamic, but they could not attest to whether the molecules are only interconverting among only a few isomers or if a multitude of structures are being accessed. Here we confirm the remarkable shape-shifting property of a tetrasubstituted bullvalene by means of a racemization experiment. We show that a single, though fleeting, chiral, enantioenriched tetrasubstituted bullvalene isomer can spontaneously equilibrate to a racemic population of dynamic compounds. Despite the fact that conversion from one enantiomer of a bullvalene isomer to the other may require dozens or even hundreds of rearrangements and involve many potential pathways, CD spectroscopy and HPLC analysis of different bullvalene populations showed that multiple pathways exist and result in the complete racemization of an initial enantioenriched chiral bullvalene. These oligosubstituted bullvalenes represent a very rare example of an entity that can spontaneously transform itself into different discrete structures using ambient thermal energy. The confirmation that these shape-shifting organic molecules are chemically robust yet structurally dynamic is an important step toward their further use as materials, sensors, and biologically active compounds.
A quorum-sensing molecule acts as a morphogen controlling gas vesicle organelle biogenesis and adaptive flotation in an enterobacterium
Authors: Ramsay Joshua P. , Williamson Neil R. , Spring David R. , Salmond George P. C.
Published: August 2011

Gas vesicles are hollow intracellular proteinaceous organelles produced by aquatic Eubacteria and Archaea, including cyanobacteria and halobacteria. Gas vesicles increase buoyancy and allow taxis toward air–liquid interfaces, enabling subsequent niche colonization. Here we report a unique example of gas vesicle-mediated flotation in an enterobacterium;
Serratia
sp. strain ATCC39006. This strain is a member of the
Enterobacteriaceae
previously studied for its production of prodigiosin and carbapenem antibiotics. Genes required for gas vesicle synthesis mapped to a 16.6-kb gene cluster encoding three distinct homologs of the main structural protein, GvpA. Heterologous expression of this locus in
Escherichia coli
induced copious vesicle production and efficient cell buoyancy. Gas vesicle morphogenesis in
Serratia
enabled formation of a pellicle-like layer of highly vacuolated cells, which was dependent on oxygen limitation and the expression of
ntrB
/
C
and
cheY
-like regulatory genes within the gas-vesicle gene cluster. Gas vesicle biogenesis was strictly controlled by intercellular chemical signaling, through an
N
-acyl homoserine lactone, indicating that in this system the quorum-sensing molecule acts as a morphogen initiating organelle development. Flagella-based motility and gas vesicle morphogenesis were also oppositely regulated by the small RNA-binding protein, RsmA, suggesting environmental adaptation through physiological control of the choice between motility and flotation as alternative taxis modes. We propose that gas vesicle biogenesis in this strain represents a distinct mechanism of mobility, regulated by oxygen availability, nutritional status, the RsmA global regulatory system, and the quorum-sensing morphogen.