bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of rRNA transcription in Escherichia coli
Authors: Condon C , Squires C , Squires C L
Published: December 2020

The control of rRNA synthesis in response to both extra- and intracellular signals has been a subject of interest to microbial physiologists for nearly four decades, beginning with the observations that Salmonella typhimurium cells grown on rich medium are larger and contain more RNA than those grown on poor medium. This was followed shortly by the discovery of the stringent response in Escherichia coli, which has continued to be the organism of choice for the study of rRNA synthesis. In this review, we summarize four general areas of E. coli rRNA transcription control: stringent control, growth rate regulation, upstream activation, and anti-termination. We also cite similar mechanisms in other bacteria and eukaryotes. The separation of growth rate-dependent control of rRNA synthesis from stringent control continues to be a subject of controversy. One model holds that the nucleotide ppGpp is the key effector for both mechanisms, while another school holds that it is unlikely that ppGpp or any other single effector is solely responsible for growth rate-dependent control. Recent studies on activation of rRNA synthesis by cis-acting upstream sequences has led to the discovery of a new class of promoters that make contact with RNA polymerase at a third position, called the UP element, in addition to the well-known -10 and -35 regions. Lastly, clues as to the role of antitermination in rRNA operons have begun to appear. Transcription complexes modified at the antiterminator site appear to elongate faster and are resistant to the inhibitory effects of ppGpp during the stringent response.
Production and function of cytokines in natural and acquired immunity to Candida albicans infection
Authors: Ashman R B , Papadimitriou J M
Published: December 2020

Host resistance against infections caused by the yeast Candida albicans is mediated predominantly by polymorphonuclear leukocytes and macrophages. Antigens of Candida stimulate lymphocyte proliferation and cytokine synthesis, and in both humans and mice, these cytokines enhance the candidacidal functions of the phagocytic cells. In systemic candidiasis in mice, cytokine production has been found to be a function of the CD4+ T helper (Th) cells. The Th1 subset of these cells, characterized by the production of gamma interferon and interleukin-2, is associated with macrophage activation and enhanced resistance against reinfection, whereas the Th2 subset, which produces interleukins-4, -6, and -10, is linked to the development of chronic disease. However, other models have generated divergent data. Mucosal infection generally elicits Th1-type cytokine responses and protection from systemic challenge, and identification of cytokine mRNA present in infected tissues of mice that develop mild or severe lesions does not show pure Th1- or Th2-type responses. Furthermore, antigens of C. albicans, mannan in particular, can induce suppressor cells that modulate both specific and nonspecific cellular and humoral immune responses, and there is an emerging body of evidence that molecular mimicry may affect the efficiency of anti-Candida responses within defined genetic contexts.
Natural plasmids of filamentous fungi
Authors: Griffiths A J
Published: December 2020

Among eukaryotes, plasmids have been found in fungi and plants but not in animals. Most plasmids are mitochondrial. In filamentous fungi, plasmids are commonly encountered in isolates from natural populations. Individual populations may show a predominance of one type, but some plasmids have a global distribution, often crossing species boundaries. Surveys have shown that strains can contain more than one type of plasmid and that different types appear to be distributed independently. In crosses, plasmids are generally inherited maternally. Horizontal transmission is by cell contact. Circular plasmids are common only in Neurospora spp., but linear plasmids have been found in many fungi. Circular plasmids have one open reading frame (ORF) coding for a DNA polymerase or a reverse transcriptase. Linear plasmids generally have two ORFs, coding for presumptive DNA and RNA polymerases with amino acid motifs showing homology to viral polymerases. Plasmids often attain a high copy number, in excess of that of mitochondrial DNA. Linear plasmids have a protein attached to their 5' end, and this is presumed to act as a replication primer. Most plasmids are neutral passengers, but several linear plasmids integrate into mitochondrial DNA, causing death of the host culture. Inferred amino acid sequences of linear plasmid ORFs have been used to plot phylogenetic trees, which show a fair concordance with conventional trees. The circular Neurospora plasmids have replication systems that seem to be evolutionary intermediates between the RNA and the DNA worlds.
Molecular and industrial aspects of glucose isomerase
Authors: Bhosale S H , Rao M B , Deshpande V V
Published: December 2020

Glucose isomerase (GI) (D-xylose ketol-isomerase; EC. 5.3.1.5) catalyzes the reversible isomerization of D-glucose and D-xylose to D-fructose and D-xylulose, respectively. The enzyme has the largest market in the food industry because of its application in the production of high-fructose corn syrup (HFCS). HFCS, an equilibrium mixture of glucose and fructose, is 1.3 times sweeter than sucrose and serves as a sweetener for use by diabetics. Interconversion of xylose to xylulose by GI serves a nutritional requirement in saprophytic bacteria and has a potential application in the bioconversion of hemicellulose to ethanol. The enzyme is widely distributed in prokaryotes. Intensive research efforts are directed toward improving its suitability for industrial application. Development of microbial strains capable of utilizing xylan-containing raw materials for growth or screening for constitutive mutants of GI is expected to lead to discontinuation of the use of xylose as an inducer for the production of the enzyme. Elimination of Co2+ from the fermentation medium is desirable for avoiding health problems arising from human consumption of HFCS. Immobilization of GI provides an efficient means for its easy recovery and reuse and lowers the cost of its use. X-ray crystallographic and genetic engineering studies support a hydride shift mechanism for the action of GI. Cloning of GI in homologous as well as heterologous hosts has been carried out, with the prime aim of overproducing the enzyme and deciphering the genetic organization of individual genes (xylA, xylB, and xylR) in the xyl operon of different microorganisms. The organization of xylA and xylB seems to be highly conserved in all bacteria. The two genes are transcribed from the same strand in Escherichia coli and Bacillus and Lactobacillus species, whereas they are transcribed divergently on different strands in Streptomyces species. A comparison of the xylA sequences from several bacterial sources revealed the presence of two signature sequences, VXW(GP)GREG(YSTAE)E and (LIVM)EPKPX(EQ)P. The use of an inexpensive inducer in the fermentation medium devoid of Co2+ and redesigning of a tailor-made GI with increased thermostability, higher affinity for glucose, and lower pH optimum will contribute significantly to the development of an economically feasible commercial process for enzymatic isomerization of glucose to fructose. Manipulation of the GI gene by site-directed mutagenesis holds promise that a GI suitable for biotechnological applications will be produced in the foreseeable future.
Bacterial modulins: a novel class of virulence factors which cause host tissue pathology by inducing cytokine synthesis
Authors: Henderson B , Poole S , Wilson M
Published: December 2020

Cytokines are a diverse group of proteins and glycoproteins which have potent and wide-ranging effects on eukaryotic cell function and are now recognized as important mediators of tissue pathology in infectious diseases. It is increasingly recognized that for many bacterial species, cytokine induction is a major virulence mechanism. Until recent years, the only bacterial component known to stimulate cytokine synthesis was lipopolysaccharide (LPS). It is only within the past decade that it has been clearly shown that many components associated with the bacterial cell wall, including proteins, glycoproteins, lipoproteins, carbohydrates, and lipids, have the capacity to stimulate mammalian cells to produce a diverse array of cytokines. It has been established that many of these cytokine-inducing molecules act by mechanisms distinct from that of LPS, and thus their activities are not due to LPS contamination. Bacteria produce a wide range of virulence factors which cause host tissue pathology, and these diverse factors have been grouped into four families: adhesins, aggressins, impedins, and invasins. We suggest that the array of bacterial cytokine-inducing molecules represents a new class of bacterial virulence factor, and, by analogy with the known virulence families, we suggest the term "modulin" to describe these molecules, because the action of cytokines is to modulate eukaryotic cell behavior. This review summarizes our current understanding of cytokine biology in relation to tissue homeostasis and disease and concisely reviews the current literature on the cytokine-inducing molecules produced by gram-negative and gram-positive bacteria, with an emphasis on the cellular mechanisms responsible for cytokine induction. We propose that modulins, by controlling the host immune and inflammatory responses, maintain the large commensal flora that all multicellular organisms support.
Field evaluations of marine oil spill bioremediation
Authors: Swannell R P , Lee K , McDonagh M
Published: December 2020

Bioremediation is defined as the act of adding or improving the availability of materials (e.g., nutrients, microorganisms, or oxygen) to contaminated environments to cause an acceleration of natural biodegradative processes. The results of field experiments and trials following actual spill incidents have been reviewed to evaluate the feasibility of this approach as a treatment for oil contamination in the marine environment. The ubiquity of oil-degrading microorganisms in the marine environment is well established, and research has demonstrated the capability of the indigenous microflora to degrade many components of petroleum shortly after exposure. Studies have identified numerous factors which affect the natural biodegradation rates of oil, such as the origin and concentration of oil, the availability of oil-degrading microorganisms, nutrient concentrations, oxygen levels, climatic conditions, and sediment characteristics. Bioremediation strategies based on the application of fertilizers have been shown to stimulate the biodegradation rates of oil in aerobic intertidal sediments such as sand and cobble. The ratio of oil loading to nitrogen concentration within the interstitial water has been identified to be the principal controlling factor influencing the success of this bioremediation strategy. However, the need for the seeding of natural environments with hydrocarbon-degrading bacteria has not been clearly demonstrated under natural environmental conditions. It is suggested that bioremediation should now take its place among the many techniques available for the treatment of oil spills, although there is still a clear need to set operational limits for its use. On the basis of the available evidence, we have proposed preliminary operational guidelines for bioremediation on shoreline environments.
Ribosome regulation by the nascent peptide
Authors: Lovett P S , Rogers E J
Published: December 2020

Studies of bacterial and eukaryotic systems have identified two-gene operons in which the translation product of the upstream gene influences translation of the downstream gene. The upstream gene, referred to as a leader (gene) in bacterial systems or an upstream open reading frame (uORF) in eukaryotes, encodes a peptide that interferes with a function(s) of its translating ribosome. The peptides are therefore cis-acting negative regulators of translation. The inhibitory peptides typically consist of fewer than 25 residues and function prior to emergence from the ribosome. A biological role for this class of translation inhibitor is demonstrated in translation attenuation, a form or regulation that controls the inducible translation of the chloramphenicol resistance genes cat and cmlA in bacteria. Induction of cat or cmlA requires ribosome stalling at a particular codon in the leader region of the mRNA. Stalling destabilizes an adjacent, downstream mRNA secondary structure that normally sequesters the ribosome-binding site for the cat or cmlA coding regions. Genetic studies indicate that the nascent, leader-encoded peptide is the selector of the site of ribosome stalling in leader mRNA by cis interference with translation. Synthetic leader peptides inhibit ribosomal peptidyltransferase in vitro, leading to the prediction that this activity is the basis for stall site selection. Recent studies have shown that the leader peptides are rRNA-binding peptides with targets at the peptidyl transferase center of 23S rRNA. uORFs associated with several eukaryotic genes inhibit downstream translation. When inhibition depends on the specific codon sequence of the uORF, it has been proposed that the uORF-encoded nascent peptide prevents ribosome release from the mRNA at the uORF stop codon. This sets up a blockade to ribosome scanning which minimizes downstream translation. Segments within large proteins also appear to regulate ribosome activity in cis, although in most of the known examples the active amino acid sequences function after their emergence from the ribosome, cis control of translation by the nascent peptide is gene specific; nearly all such regulatory peptides exert no obvious trans effects in cells. The in vitro biochemical activities of the cat/cmla leader peptides on ribosomes and rRNA suggest a mechanism through which the nascent peptide can modify ribosome behavior. Other cis-acting regulatory peptides may involve more complex ribosomal interactions.
Virus-encoded superantigens
Authors: Huber B T , Hsu P N , Sutkowski N
Published: December 2020

Superantigens are microbial agents that have a strong effect on the immune response of the host. Their initial target is the T lymphocyte, but a whole cascade of immunological reactions ensues. It is thought that the microbe engages the immune system of the host to its own advantage, to facilitate persistent infection and/or transmission. In this review, we discuss in detail the structure and function of the superantigen encoded by the murine mammary tumor virus, a B-type retrovirus which is the causative agent of mammary carcinoma. We will also outline what has more recently become known about superantigen activity associated with two human herpesviruses, cytomegalovirus and Epstein-Barr virus. It is likely that we have only uncovered the tip of the iceberg in our discovery of microbial superantigens, and we predict a flood of new information on this topic shortly.
Microbial metabolism of pyridine, quinoline, acridine, and their derivatives under aerobic and anaerobic conditions
Authors: Kaiser J P , Feng Y , Bollag J M
Published: December 2020

Our review of the metabolic pathways of pyridines and aza-arenes showed that biodegradation of heterocyclic aromatic compounds occurs under both aerobic and anaerobic conditions. Depending upon the environmental conditions, different types of bacteria, fungi, and enzymes are involved in the degradation process of these compounds. Our review indicated that different organisms are using different pathways to biotransform a substrate. Our review also showed that the transformation rate of the pyridine derivatives is dependent on the substituents. For example, pyridine carboxylic acids have the highest transformation rate followed by mono-hydroxypyridines, methylpyridines, aminopyridines, and halogenated pyridines. Through the isolation of metabolites, it was possible to demonstrate the mineralization pathway of various heterocyclic aromatic compounds. By using 14C-labeled substrates, it was possible to show that ring fission of a specific heterocyclic compound occurs at a specific position of the ring. Furthermore, many researchers have been able to isolate and characterize the microorganisms or even the enzymes involved in the transformation of these compounds or their derivatives. In studies involving 18O labeling as well as the use of cofactors and coenzymes, it was possible to prove that specific enzymes (e.g., mono- or dioxygenases) are involved in a particular degradation step. By using H2 18O, it could be shown that in certain transformation reactions, the oxygen was derived from water and that therefore these reactions might also occur under anaerobic conditions.
RNA-protein interactions in regulation of picornavirus RNA translation
Authors: Belsham G J , Sonenberg N
Published: December 2020

The translation of picornavirus RNA occurs by a cap-independent mechanism directed by a region of about 450 nucleotides from the 5' untranslated region, termed an internal ribosome entry site (IRES). Internal initiation of protein synthesis occurs without any requirement for viral proteins. Furthermore, it is maintained when host cell protein synthesis is almost abolished. By using in vitro translation systems, two distinct families of IRES elements which have very different predicted RNA secondary structures have been defined. The cardiovirus and aphthovirus elements function very efficiently in rabbit reticulocyte lysate, whereas the enterovirus and rhinovirus elements function poorly in this system. However, supplementation of this translation system with additional cellular proteins can stimulate translation directed by the enterovirus and rhinovirus RNAs and reduce production of aberrant initiation products. The characterization of cellular proteins interacting with the picornavirus IRES is a major focus of research. Many different protein species can be observed to interact with regions of the IRES by in vitro analyses, e.g., UV cross-linking. However, the function and significance of many of these interactions are not always known. For two proteins, La and the polypyrimidine tract-binding protein, evidence has been obtained for a functional role of their interaction with IRES elements.
Microbial pathogenesis in cystic fibrosis: mucoid Pseudomonas aeruginosa and Burkholderia cepacia
Authors: Govan J R , Deretic V
Published: December 2020

Respiratory infections with Pseudomonas aeruginosa and Burkholderia cepacia play a major role in the pathogenesis of cystic fibrosis (CF). This review summarizes the latest advances in understanding host-pathogen interactions in CF with an emphasis on the role and control of conversion to mucoidy in P. aeruginosa, a phenomenon epitomizing the adaptation of this opportunistic pathogen to the chronic chourse of infection in CF, and on the innate resistance to antibiotics of B. cepacia, person-to-person spread, and sometimes rapidly fatal disease caused by this organism. While understanding the mechanism of conversion to mucoidy in P. aeruginosa has progressed to the point where this phenomenon has evolved into a model system for studying bacterial stress response in microbial pathogenesis, the more recent challenge with B. cepacia, which has emerged as a potent bona fide CF pathogen, is discussed in the context of clinical issues, taxonomy, transmission, and potential modes of pathogenicity.
Proton-dependent multidrug efflux systems
Authors: Paulsen I T , Brown M H , Skurray R A
Published: December 2020

Multidrug efflux systems display the ability to transport a variety of structurally unrelated drugs from a cell and consequently are capable of conferring resistance to a diverse range of chemotherapeutic agents. This review examines multidrug efflux systems which use the proton motive force to drive drug transport. These proteins are likely to operate as multidrug/proton antiporters and have been identified in both prokaryotes and eukaryotes. Such proton-dependent multidrug efflux proteins belong to three distinct families or superfamilies of transport proteins: the major facilitator superfamily (MFS), the small multidrug resistance (SMR) family, and the resistance/ nodulation/cell division (RND) family. The MFS consists of symporters, antiporters, and uniporters with either 12 or 14 transmembrane-spanning segments (TMS), and we show that within the MFS, three separate families include various multidrug/proton antiport proteins. The SMR family consists of proteins with four TMS, and the multidrug efflux proteins within this family are the smallest known secondary transporters. The RND family consists of 12-TMS transport proteins and includes a number of multidrug efflux proteins with particularly broad substrate specificity. In gram-negative bacteria, some multidrug efflux systems require two auxiliary constituents, which might enable drug transport to occur across both membranes of the cell envelope. These auxiliary constituents belong to the membrane fusion protein and the outer membrane factor families, respectively. This review examines in detail each of the characterized proton-linked multidrug efflux systems. The molecular basis of the broad substrate specificity of these transporters is discussed. The surprisingly wide distribution of multidrug efflux systems and their multiplicity in single organisms, with Escherichia coli, for instance, possessing at least nine proton-dependent multidrug efflux systems with overlapping specificities, is examined. We also discuss whether the normal physiological role of the multidrug efflux systems is to protect the cell from toxic compounds or whether they fulfil primary functions unrelated to drug resistance and only efflux multiple drugs fortuitously or opportunistically.
The secretory pathway of protists: spatial and functional organization and evolution
Authors: Becker B , Melkonian M
Published: December 2020

All cells secrete a diversity of macromolecules to modify their environment or to protect themselves. Eukaryotic cells have evolved a complex secretory pathway consisting of several membrane-bound compartments which contain specific sets of proteins. Experimental work on the secretory pathway has focused mainly on mammalian cell lines or on yeasts. Now, some general principles of the secretory pathway have become clear, and most components of the secretory pathway are conserved between yeast cells and mammalian cells. However, the structure and function of the secretory system in protists have been less extensively studied. In this review, we summarize the current knowledge about the secretory pathway of five different groups of protists: Giardia lamblia, one of the earliest lines of eukaryotic evolution, kinetoplastids, the slime mold Dictyostelium discoideum, and two lineages within the "crown" of eukaryotic cell evolution, the alveolates (ciliates and Plasmodium species) and the green algae. Comparison of these systems with the mammalian and yeast system shows that most elements of the secretory pathway were presumably present in the earliest eukaryotic organisms. However, one element of the secretory pathway shows considerable variation: the presence of a Golgi stack and the number of cisternae within a stack. We suggest that the functional separation of the plasma membrane from the nucleus-endoplasmic reticulum system during evolution required a sorting compartment, which became the Golgi apparatus. Once a Golgi apparatus was established, it was adapted to the various needs of the different organisms.
T helper cell activation and human retroviral pathogenesis
Authors: Copeland K F , Heeney J L
Published: December 2020

T helper (Th) cells are of central importance in regulating many critical immune effector mechanisms. The profile of cytokines produced by Th cells correlates with the type of effector cells induced during the immune response to foreign antigen. Th1 cells induce the cell-mediated immune response, while Th2 cells drive antibody production. Th cells are the preferential targets of human retroviruses. Infections with human T-cell leukemia virus (HTLV) or human immunodeficiency virus (HIV) result in the expansion of Th cells by the action of HTLV (adult T-cell leukemia) or the progressive loss of T cells by the action of HIV (AIDS). Both retrovirus infections impart a high-level activation state in the host immune cells as well as systemically. However, diverging responses to this activation state have contrasting effects on the Th-cell population. In HIV infection, Th-cell loss has been attributed to several mechanisms, including a selective elimination of cells by apoptosis. The induction of apoptosis in HIV infection is complex, with many different pathways able to induce cell death. In contrast, infection of Th cells with HTLV-1 affords the cell a protective advantage against apoptosis. This advantage may allow the cell to escape immune surveillance, providing the opportunity for the development of Th-cell cancer. In this review, we will discuss the impact of Th-cell activation and general immune activation on human retrovirus expression with a focus upon Th-cell function and the progression to disease.
Person-ness of voices in lived experience accounts of psychosis: combining literary linguistics and clinical psychology
Authors: Semino Elena , Demjén Zsófia , Collins Luke
Published: December 2020

In this paper, we use concepts and insights from the literary linguistic study of story-world characters to shed new light on the nature of voices as social agents in the context of lived experience accounts of voice-hearing. We demonstrate a considerable overlap between approaches to voices as social agents in clinical psychology and the perception of characters in the linguistic study of fiction, but argue that the literary linguistic approach facilitates a much more nuanced account of the different degrees of person-ness voices might be perceived to possess. We propose a scalar Characterisation Model of Voices and demonstrate its explanatory potential by comparing two lived experience descriptions of voices in interviews with voice-hearers in a psychosis intervention. The new insights into the phenomenology of voice-hearing achieved by applying the model are relevant to the understanding of voice-hearing as well as to therapeutic interventions.
Household transmission and incidence of positive SARS-CoV-2 RT-PCR in symptomatic healthcare workers, clinical course and outcome: a French hospital experience
Authors: Krastinova Evguenia , Garrait Valérie , Lecam Marie-Thérèse , Coste André , Varon Emmanuelle , Delacroix Isabelle , Si Ali Amine , Jung Camille , Smati Mounira , Cherbit Muriel , Maître Bernard , Pairon Jean-Claude , Andujar Pascal
Published: December 2020

Objectives

Although healthcare workers (HCWs) have been particularly affected by SARS-CoV-2, detailed data remain scarce. In this study, we investigated infection rates, clinical characteristics, occupational exposure and household transmission among all symptomatic HCWs screened by SARS-CoV-2 RT-PCR between 17 March (French lockdown) and 20 April.

Methods

SARS-CoV-2 RT-PCR was proposed to symptomatic (new cough or dyspnoea) HCWs at Creteil Hospital in one of the Parisian suburbs most severely affected by COVID-19. Data on occupational profile, living situation and household, together with self–isolation and mask use at home were collected, as well as the number of cases in the household.

Results

The incidence rate of symptomatic SARS-CoV-2 was estimated to be 5% (110/2188). A total of 110 (35%) of the 314 HCWs tested positive and 9 (8%) were hospitalised. On multivariate analysis, factors independently associated with positive RT-PCR were occupational profile with direct patient facing (OR 3.1, 95% CI 1.1 to 8.8), p<0.03), and presence of anosmia (OR 5.7, 95% CI 3.1 to 10.6), p<0.0001). Being a current smoker was associated with negative RT-PCR (OR 0.3, 95% CI 0.1 to 0.7), p=0.005). Transmission from HCWs to household members was reported in 9 (14%) cases, and 2 deaths occurred. Overall, self-isolation was possible in 52% of cases, but only 31% of HCWs were able to wear a mask at home.

Conclusion

This is the first study to report infection rates among HCWs during the peak of the SARS-CoV-2 epidemic in France and the lockdown period, highlighting the risk related to occupational profile and household transmission.
Top 10 research priorities for people living with pulmonary fibrosis, their caregivers, healthcare professionals and researchers
Authors: Tikellis Gabriella , Tong Allison , Lee Joanna Y T , Corte Tamera J. , Hey-Cunningham Alison J , Bartlett Michael , Crawford Tonia , Glaspole Ian , Price John , Maloney Jamie , Holland Anne E
Published: December 2020

Introduction

People with pulmonary fibrosis (PF) experience a high symptom burden, reduced quality of life and a shortened lifespan. Treatment options are limited and little is known about what patients, caregivers and healthcare professionals (HCPs)/researchers consider as the most important research priorities. This study aimed to identify the top 10 research priorities for PF across all stakeholders.

Methods

Participants included people with PF, caregivers and HCPs/researchers involved with PF. The research priority setting exercise involved three stages: (1) identifying priorities using an open-ended questionnaire and thematic analysis, (2) development of specific research questions at a face-to-face workshop, and (3) online ranking of research questions to identify the top 10 research priorities using nominal group ranking method.

Results

196 participants completed stage 1 generating 560 questions and 14 research themes were identified. Stage 2 involved 32 participants and generated 53 indicative questions from which 39 were used for the final ranking. Stage 3 was completed by 270 participants. The top ranked priorities focussed on medications to reverse scarring in the lungs (ranked 1
st
), improving lung function (ranked 2
nd
, 6
th
and 8
th
), interventions aimed at alleviating symptoms (ranked 5
th
and 7
th
), prevention of PF (ranked 3
rd
and 4
th
) and the best exercise programme for PF (ranked 10
th
). There was good consensus among patients/carers and HCPs/researchers on the top 10 priorities, however, causes of acute exacerbations and early diagnosis for improving survival, was ranked higher by HCPs/researchers.

Conclusion

Interventions for preserving lung health and alleviation of symptom burden were top research priorities for PF stakeholders.
Short- and long-term effects of fire and vegetation cover on four lizard species in Amazonian savannas
Authors: Souza E. , Lima A.P. , Magnusson W.E. , Kawashita-Ribeiro R. , Fadini R. , Ghizoni I.R. , Ganança P. , Fraga R.
Published: December 2020

Ecological succession in tropical savannas is limited by seasonal fire, which affects habitat quality. Although fire may cause negligible or positive effects on animals occupying savannas, most short-term studies (months to a few years) are based on a single temporal sampling snapshot, and long-term studies (decades) are rare. We sampled four lizard species (Rainbow Whiptail, Cnemidophorus lemniscatus (Linnaeus, 1758); Striped Whiptail, Kentropyx striata (Daudin, 1802); Grass Anole, Norops auratus Duméril and Bibron, 1837 = Anolis auratus Daudin, 1802; Amazon Racerunner, Ameiva ameiva (Linnaeus, 1758)) in Amazonian savannas to test the effects of fire and vegetation cover on lizard densities at two temporal scales. In the short term, we use three sampling snapshots to test the effects of fire and vegetation cover on estimated lizard densities over the subsequent 1–5 years. In the long term, we test the effects of fire and changes in vegetation cover over 21 years on current lizard density differences. In the short term, species responses were usually consistent with foraging and thermoregulation modes. However, the results were not consistent among species and years, although the variances in species density explained by year as a random factor were generally low. In the long term, the main effects of fire and vegetation cover show that lizard densities may change spatially, but not necessarily temporarily. Wildfire is a natural resource of savannas and apparently have little impact on resident lizards of that ecosystem.
Sum rule for the Compton amplitude and implications for the proton–neutron mass difference
Authors: Gasser J. , Leutwyler H. , Rusetsky A.
Published: December 2020

The Cottingham formula expresses the leading contribution of the electromagnetic interaction to the proton-neutron mass difference as an integral over the forward Compton amplitude. Since quarks and gluons reggeize, the dispersive representation of this amplitude requires a subtraction. We assume that the asymptotic behaviour is dominated by Reggeon exchange. This leads to a sum rule that expresses the subtraction function in terms of measurable quantities. The evaluation of this sum rule leads to $$m_{\mathrm{QED}}^{p-n}=0.58\pm 0.16\,\text {MeV}$$

m

QED

p
-
n

=
0.58
±
0.16

MeV

.
Freeze-in Dirac neutrinogenesis: thermal leptonic CP asymmetry
Authors: Li Shao-Ping , Li Xin-Qiang , Yan Xin-Shuai , Yang Ya-Dong
Published: December 2020

We present a freeze-in realization of the Dirac neutrinogenesis in which the decaying particle that generates the lepton-number asymmetry is in thermal equilibrium. As the right-handed Dirac neutrinos are produced non-thermally, the lepton-number asymmetry is accumulated and partially converted to the baryon-number asymmetry via the rapid sphaleron transitions. The necessary CP-violating condition can be fulfilled by a purely thermal kinetic phase from the wavefunction correction in the lepton-doublet sector, which has been neglected in most leptogenesis-based setup. Furthermore, this condition necessitates a preferred flavor basis in which both the charged-lepton and neutrino Yukawa matrices are non-diagonal. To protect such a proper Yukawa structure from the basis transformations in flavor space prior to the electroweak gauge symmetry breaking, we can resort to a plethora of model buildings aimed at deciphering the non-trivial Yukawa structures. Interestingly, based on the well-known tri-bimaximal mixing with a minimal correction from the charged-lepton or neutrino sector, we find that a simultaneous explanation of the baryon-number asymmetry in the Universe and the low-energy neutrino oscillation observables can be attributed to the mixing angle and the CP-violating phase introduced in the minimal correction.
Deep Learning Networks-Based Action Videos Classification and Search
Authors: Wang Wenshi , Huang Zhangqin , Tian Rui
Published: December 2020

This work presents the deep learning networks-based method using fine-tuning for classification and search of a diversity of action videos. First, a 3D convolutional neural networks (3D CNN) model which performs pre-training operation and fine-tuning strategy is employed to extract the spatiotemporal features of videos. It is first pre-trained on UCF-101 datasets to train model with initial parameters. Then, a small new dataset is employed to fine-tune the initial model for the training of the new model. Once features are extracted by the final CNNs model, distance measure can be adopted to calculate the similarities between the query video and the test dataset for the video search. The searched video is returned and ranked according to the priority when it has higher similarity with the query video. The comparison results in the experiment shows that the search method using fine-tuning obtains better performance than the method without using fine-tuning. Second, the classification results based on the 3D CNN model using fine-tuning are also presented for the consideration of a query by keyword. Accuracy result obtained using the model with the help of fine-tuning is approximately 2.8% higher than that without using fine-tuning.
Time Optimization for Workflow Scheduling by Incorporating Level Strategy into Out-Degree
Authors: Jiang Junqiang , Zhu Chenyan , Cai Hailin , Pan Li , Li Wenbin , Yan Quanfeng , Yang Zhihe , Yang Bo
Published: December 2020

Efficient workflow scheduling plays a critical role in achieving high performance in heterogeneous distributed computing systems. Given its key importance, workflow scheduling has been extensively studied, and various algorithms have been proposed in the literature mainly for systems with homogeneous or heterogeneous processors. Most of the algorithms leverage the average computation cost to prioritize tasks, and few focus on the combination of the level and out-degree of tasks, which both have a considerable impact on scheduling. A new list scheduling algorithm called level and out-degree earliest finish time (LOEFT) is proposed in this paper to address the problem of static workflow scheduling in a heterogeneous computing environment to reduce the workflow execution time. This algorithm has three major phases: task leveling, task prioritization and processor selection. In the task leveling phase, tasks are categorized into different groups based on depth value to ensure data transmission completeness. In the task prioritizing phase, the upward rank value is combined with the out-degree of every task to calculate the heterogeneous priority rank value on different processors and leverage the value to sort all tasks. In the processor selection phase, the selected task is assigned to the processor, which minimizes the former’s earliest finish time. The experimental simulation of randomly generated DAG and real-world application workflows proves that the LOEFT algorithm can significantly reduce the workflow execution time.
An Efficient Hardware Approach for Approximate Logarithmic Computation
Authors: Ahmed Syed Ershad , Sri Krishna Yerasuri Mohana
Published: December 2020

In this work, we present a technique that combines piecewise linear interpolation technique with a look-up table-based method in a novel way resulting in a logarithmic converter with higher accuracy. The piecewise linear interpolation function is obtained using a new algorithm, which aids in reducing the interpolation error. The algorithm helps in obtaining an optimized interpolation function which tracks the slope of log[Formula: see text] function more accurately. As a consequence, the size of the look-up table used to correct this interpolation error reduces significantly. Further, precision of the logarithmic converter can be improved by adding additional memory without changing the overall hardware. The method of combining linear interpolation with look-up results in high accuracy with less hardware complexity compared to similar existing techniques. The proposed and existing logarithmic converter designs are synthesized on FPGA and compared for their performance. Results indicate that the proposed approach achieves an improvement of 12% to 22% in memory for accuracies ranging from 10-bit to 20-bit.
MEAN–VARIANCE PORTFOLIO MANAGEMENT WITH FUNCTIONAL OPTIMIZATION
Authors: TSANG KA WAI , HE ZHAOYI
Published: December 2020

This paper introduces a new functional optimization approach to portfolio optimization problems by treating the unknown weight vector as a function of past values instead of treating them as fixed unknown coefficients in the majority of studies. We first show that the optimal solution, in general, is not a constant function. We give the optimal conditions for a vector function to be the solution, and hence give the conditions for a plug-in solution (replacing the unknown mean and variance by certain estimates based on past values) to be optimal. After showing that the plug-in solutions are sub-optimal in general, we propose gradient-ascent algorithms to solve the functional optimization for mean–variance portfolio management with theorems for convergence provided. Simulations and empirical studies show that our approach can perform significantly better than the plug-in approach.
Theory of Robot Communication: II. Befriending a Robot Over Time
Authors: Hoorn Johan F.
Published: December 2020

In building on theories of Computer-Mediated Communication (CMC), Human–Robot Interaction, and Media Psychology (M[Formula: see text]; i.e., Theory of Affective Bonding), this paper proposes an explanation of how over time, people experience the mediated or simulated aspects of the interaction with a social robot. In two simultaneously running loops, a more reflective process is balanced with a more affective process. If human interference is detected behind the machine, Robot-Mediated Communication commences, which basically follows CMC assumptions; if human interference remains undetected, Human–Robot Communication (HRC) comes into play, holding the robot for an autonomous social actor. The more emotionally aroused a robot user is, the more likely they develop an affective relationship with what actually is a machine. The main contribution of this paper is an integration of CMC, HRC, and M[Formula: see text], outlining a full-blown theory of robot communication connected to friendship formation, accounting for communicative features, modes of processing, as well as psychophysiology.
The transmission of dengue virus with Aedes aegypti mosquito in a heterogeneous environment
Authors: Zhang Mengyun , Lin Zhigui , Zhu Huaiping
Published: December 2020

This paper deals with dengue virus transmitted by the mosquito Aedes aegypti. A reaction–diffusion model is proposed incorporating both human and the A. aegypti population, where we divided mosquitoes into two sub-populations: the winged population and an aquatic form, with the winged mosquito population divided into the susceptible and infected classes. The threshold [Formula: see text] depending on spatial heterogeneity is introduced for the mosquito population. Moreover, we introduce the basic reproduction number [Formula: see text] for the infected classes, as well as its analytical properties. [Formula: see text] and [Formula: see text] are utilized to investigate the stability of the mosquito-established equilibriums. Our results show that the mosquitoes persist if [Formula: see text], while the transmission of dengue virus depends on the condition whether [Formula: see text] or [Formula: see text].
A measurement of epidermal thickness of fingertip skin from OCT images using convolutional neural network
Authors: Lin Yongping , Li Dezi , Liu Wang , Zhong Zhaowei , Li Zhifang , He Youwu , Wu Shulian
Published: December 2020

In this study, we proposed a method to measure the epidermal thickness (ET) of skin based on deep convolutional neural network, which was used to determine the boundaries of skin surface and the ridge portion in dermal–epidermis junction (DEJ) in cross-section optical coherence tomography (OCT) images of fingertip skin. The ET was calculated based on the row difference between the surface and the ridge top, which is determined by search the local maxima of boundary of the ridge portion. The results demonstrated that the region of ridge portion in DEJ was well determined and the ET measurement in this work can reduce the effect of the papillae valley in DEJ by 9.85%. It can be used for quantitative characterization of skin to differentiate the skin diseases.
Role of Institutional Investors: Evidence from the Foreign Rule-144A Debt Market
Authors: Huang Alan G. , Kalimipalli Madhu , Nayak Subhankar , Ramchand Latha
Published: December 2020

We examine the unique role played by institutional investors in the private corporate debt market for Rule 144A debt. We use the recent global financial crisis as a quasi-natural experiment to study how qualified institutional buyers (QIBs) facilitated funding to the foreign debt issuers in U.S. Using an exhaustive sample of foreign bond issuances in the U.S. from over 65 countries between 1990 and 2013, we examine (a) corporate decisions involving debt choice and market timing, and (b) determination of offer spreads. Our findings collectively support the notion that QIBs enabled funding in the foreign 144A debt market despite the financial crisis.
Electronic Structure and Thermoelectric Properties of Semiconductors K2GeSiX6 (X=F, Cl, Br and I) Compounds: Ab-Initio Investigation
Authors: Houari M. , Bouadjemi B. , Lantri T. , Matougui M. , Haid S. , Mesbah S. , Zitouni A. , Bentata S. , Aziz Z. , Bouhafs B.
Published: December 2020

In this work, we have studied the structural, optoelectronic, elastic and thermoelectric properties for halides doubles perovskites compounds K2GeSiX6 ([Formula: see text], Cl, Br and I). Based on the linearized augmented plane wave method with full potential (FP-LAPW) method, the previous properties are treated within GGA-PBE and the modified Beck–Johnson correction (mBJ-GGA) approximations. The results show that these compounds are stable in the nonmagnetic phase (NM). Due to the electronic properties, our results indicate that all these compounds have a semiconductor behavior with a direct bandgap at [Formula: see text]-[Formula: see text] direction with values of 2.30[Formula: see text]eV, 0.632[Formula: see text]eV, 0.259[Formula: see text]eV and 0.124[Formula: see text]eV for K2GeSiF6, K2GeSiCl6, K2GeSiBr6 and K2GeSiI6, respectively. In addition, the high dielectric constant, high absorption coefficient and high optical conductivity suggest that the materials have the potential for a wide absorption range that starts from the visible to the ultraviolet of optoelectronic applications, including solar or photovoltaic cells. Finally, the thermoelectric properties, through the calculation of the various related parameters (Seebeck coefficient, electrical conductivity, thermal conductivity, power factor and figure of merit), show that the materials K2GeSiBr6 and K2GeSiI6 can be promising for predispositions thermoelectric and by comparing the thermoelectric parameters of the two materials mentioned above, at room temperature, the material K2GeSiI6 has better performance than the material K2GeSiBr6, due to a significantly higher Seebeck coefficient (234.32[Formula: see text][Formula: see text]V/°K), a fairly substantial power factor ([Formula: see text][Formula: see text]Wk[Formula: see text]m[Formula: see text]s[Formula: see text]) and a fairly low thermal conductivity ([Formula: see text][Formula: see text]WK[Formula: see text]m[Formula: see text]s[Formula: see text]).
China in an Evolving Northeast Asia
Authors: Gong Keyu
Published: December 2020

The Northeast Asian security landscape is fast evolving amid intensifying China-U.S. strategic competition and a still raging coronavirus pandemic. Frequent summit meetings among regional leaders, including the historic meetings between Donald Trump and Kim Jong-un, have not translated into broader security dialogues and joint efforts to build a robust and durable regional security architecture. Divergent security perceptions, America’s dominant security role, and a mosaic pattern of regional security arrangements and mechanisms are the major factors shaping Northeast Asian security dynamics. Beijing remains committed to the declared path of peaceful development amid growing suspicion and concern over its strategic intention and capabilities; with strategic patience and perseverance, it is determined to play a larger role in forging consensus, building institutions, advancing cooperation, and coordinating relations in regional security matters.