bluuebunny/crossref_metadata_2025 huggingface dataset:
False-Positive Xpert MTB/RIF Results in Retested Patients with Previous Tuberculosis: Frequency, Profile, and Prospective Clinical Outcomes
Authors: Theron Grant , Venter Rouxjeane , Smith Liezel , Esmail Aliasgar , Randall Philippa , Sood Vishesh , Oelfese Suzette , Calligaro Greg , Warren Robin , Dheda Keertan
Published: January 2018

Globally, Xpert MTB/RIF (Xpert) is the most widely used PCR test for the diagnosis of tuberculosis (TB). Positive results in previously treated patients, which are due to old DNA or active disease, are a diagnostic dilemma. We prospectively retested sputum from 238 patients, irrespective of current symptoms, who were previously diagnosed to be Xpert positive and treated successfully. Patients who retested as Xpert positive and culture negative were exhaustively investigated (repeat culture, chest radiography, bronchoscopy with bronchoalveolar lavage, long-term clinical follow-up). We evaluated whether the duration since previous treatment completion, mycobacterial burden (the Xpert cycle threshold [

C
T

] value), and reclassification of Xpert-positive results with a very low semiquantitation level to Xpert-negative results reduced the rate of false positivity. A total of 229/238 (96%) of patients were culture negative. Sixteen of 229 (7%) were Xpert positive a median of 11 months (interquartile range, 5 to 19 months) after treatment completion. The specificity was 93% (95% confidence interval [CI], 89 to 96%). Nine of 15 (40%) Xpert-positive, culture-negative patients reverted to Xpert negative after 2 to 3 months (1 patient declined further participation). Patients with false-positive Xpert results had a lower mycobacterial burden than patients with true-positive Xpert results (

C
T

, 28.7 [95% CI, 27.2 to 30.4] versus 17.6 [95% CI, 16.9 to 18.2];
P
< 0.001), an increased likelihood of a chest radiograph not compatible with active TB (5/15 patients versus 0/5 patients;
P
= 0.026), and less-viscous sputum (15/16 patients versus 2/5 patients whose sputum was graded as mucoid or less;
P
= 0.038). All patients who initially retested as Xpert positive and culture negative (“Xpert false positive”) were clinically well without treatment after follow-up. The duration since the previous treatment poorly predicted false-positive results (a duration of ≤2 years identified only 66% of patients with false-positive results). Reclassifying Xpert-positive results with a very low semiquantitation level to Xpert negative improved the specificity (+3% [95% CI, +2 to +5%]) but reduced the sensitivity (−10% [95% CI, −4 to −15%]). Patients with previous TB retested with Xpert can have false-positive results and thus not require treatment. These data inform clinical practice by highlighting the challenges in interpreting Xpert-positive results, underscore the need for culture, and have implications for next-generation ultrasensitive tests.
Assessing the Burden of Clostridium difficile Infection in Low- and Middle-Income Countries
Authors: Roldan G. A. , Cui A. X. , Pollock N. R.
Published: January 2018

In contrast to the significant resources invested in the diagnosis and prevention of
Clostridium difficile
infection (CDI) in resource-rich settings, in resource-limited settings patients with community- and hospital-acquired diarrhea may not routinely be tested for CDI. Is CDI actually less frequent or severe in resource-limited settings, or might we be missing an important opportunity to prevent CDI-related morbidity and mortality (and to promote antibiotic stewardship) in these settings? Here, we review the literature to assess the overall burden of CDI in low- and middle-income countries.
A Specialized Peptidoglycan Synthase Promotes
Salmonella
Cell Division inside Host Cells
Authors: Castanheira Sónia , Cestero Juan J. , Rico-Pérez Gadea , García Pablo , Cava Felipe , Ayala Juan A. , Pucciarelli M. Graciela , García-del Portillo Francisco
Published: January 2018

Bacterial cell division has been studied extensively under laboratory conditions. Despite being a key event in the bacterial cell cycle, cell division has not been explored
in vivo
in bacterial pathogens interacting with their hosts. We discovered in
Salmonella enterica
serovar Typhimurium a gene absent in nonpathogenic bacteria and encoding a peptidoglycan synthase with 63% identity to penicillin-binding protein 3 (PBP3). PBP3 is an essential cell division-specific peptidoglycan synthase that builds the septum required to separate daughter cells. Since
S
. Typhimurium carries genes that encode a PBP3 paralog—which we named PBP3
SAL
—and PBP3, we hypothesized that there are different cell division events in host and nonhost environments. To test this, we generated
S
. Typhimurium isogenic mutants lacking PBP3
SAL
or the hitherto considered essential PBP3. While PBP3 alone promotes cell division under all conditions tested, the mutant producing only PBP3
SAL
proliferates under acidic conditions (pH ≤ 5.8) but does not divide at neutral pH. PBP3
SAL
production is tightly regulated with increased levels as bacteria grow in media acidified up to pH 4.0 and in intracellular bacteria infecting eukaryotic cells. PBP3
SAL
activity is also strictly dependent on acidic pH, as shown by beta-lactam antibiotic binding assays. Live-cell imaging microscopy revealed that PBP3
SAL
alone is sufficient for
S
. Typhimurium to divide within phagosomes of the eukaryotic cell. Additionally, we detected much larger amounts of PBP3
SAL
than those of PBP3
in vivo
in bacteria colonizing mouse target organs. Therefore, PBP3
SAL
evolved in
S
. Typhimurium as a specialized peptidoglycan synthase promoting cell division in the acidic intraphagosomal environment.

IMPORTANCE
During bacterial cell division, daughter cells separate by a transversal structure known as the division septum. The septum is a continuum of the cell wall and therefore is composed of membrane(s) and a peptidoglycan layer. To date, actively growing bacteria were reported to have only a “cell division-specific” peptidoglycan synthase required for the last steps of septum formation and consequently, essential for bacterial life. Here, we discovered that
Salmonella enterica
has two peptidoglycan synthases capable of synthesizing the division septum. One of these enzymes, PBP3
SAL
, is present only in bacterial pathogens and evolved in
Salmonella
to function exclusively in acidic environments. PBP3
SAL
is used preferentially by
Salmonella
to promote cell division
in vivo
in mouse target organs and inside acidified phagosomes. Our data challenge the concept of only one essential cell division-specific peptidoglycan synthase and demonstrate that pathogens can divide in defined host locations using alternative mechanisms.
Homoacetogenesis in Deep-Sea
Chloroflexi
, as Inferred by Single-Cell Genomics, Provides a Link to Reductive Dehalogenation in Terrestrial
Dehalococcoidetes
Authors: Sewell Holly L. , Kaster Anne-Kristin , Spormann Alfred M.
Published: January 2018

The deep marine subsurface is one of the largest unexplored biospheres on Earth and is widely inhabited by members of the phylum
Chloroflexi
. In this report, we investigated genomes of single cells obtained from deep-sea sediments of the Peruvian Margin, which are enriched in such
Chloroflexi
. 16S rRNA gene sequence analysis placed two of these single-cell-derived genomes (DscP3 and Dsc4) in a clade of subphylum I
Chloroflexi
which were previously recovered from deep-sea sediment in the Okinawa Trough and a third (DscP2-2) as a member of the previously reported DscP2 population from Peruvian Margin site 1230. The presence of genes encoding enzymes of a complete Wood-Ljungdahl pathway, glycolysis/gluconeogenesis, a
Rhodobacter
nitrogen fixation (Rnf) complex, glyosyltransferases, and formate dehydrogenases in the single-cell genomes of DscP3 and Dsc4 and the presence of an NADH-dependent reduced ferredoxin:NADP oxidoreductase (Nfn) and Rnf in the genome of DscP2-2 imply a homoacetogenic lifestyle of these abundant marine
Chloroflexi
. We also report here the first complete pathway for anaerobic benzoate oxidation to acetyl coenzyme A (CoA) in the phylum
Chloroflexi
(DscP3 and Dsc4), including a class I benzoyl-CoA reductase. Of remarkable evolutionary significance, we discovered a gene encoding a formate dehydrogenase (FdnI) with reciprocal closest identity to the formate dehydrogenase-like protein (complex iron-sulfur molybdoenzyme [CISM], DET0187) of terrestrial
Dehalococcoides/Dehalogenimonas
spp. This formate dehydrogenase-like protein has been shown to lack formate dehydrogenase activity in
Dehalococcoides/Dehalogenimonas
spp. and is instead hypothesized to couple HupL hydrogenase to a reductive dehalogenase in the catabolic reductive dehalogenation pathway. This finding of a close functional homologue provides an important missing link for understanding the origin and the metabolic core of terrestrial
Dehalococcoides/Dehalogenimonas
spp. and of reductive dehalogenation, as well as the biology of abundant deep-sea
Chloroflexi
.

IMPORTANCE
The deep marine subsurface is one of the largest unexplored biospheres on Earth and is widely inhabited by members of the phylum
Chloroflexi
. In this report, we investigated genomes of single cells obtained from deep-sea sediments and provide evidence for a homacetogenic lifestyle of these abundant marine
Chloroflexi
. Moreover, genome signature and key metabolic genes indicate an evolutionary relationship between these deep-sea sediment microbes and terrestrial, reductively dehalogenating
Dehalococcoides
.
Effect of Environmental Factors and an Emerging Parasitic Disease on Gut Microbiome of Wild Salmonid Fish
Authors: Vasemägi Anti , Visse Marko , Kisand Veljo
Published: January 2018

Cohabiting microorganisms play diverse and important roles in the biology of multicellular hosts, but their diversity and interactions with abiotic and biotic factors remain largely unsurveyed. Nevertheless, it is becoming increasingly clear that many properties of host phenotypes reflect contributions from the associated microbiome. We focus on a question of how parasites, the host genetic background, and abiotic factors influence the microbiome in salmonid hosts by using a host-parasite model consisting of wild brown trout (
Salmo trutta
) and the myxozoan
Tetracapsuloides bryosalmonae
, which causes widely distributed proliferative kidney disease. We show that parasite infection increases the frequency of bacteria from the surrounding river water community, reflecting impaired homeostasis in the fish gut. Our results also demonstrate the importance of abiotic environmental factors and host size in the assemblage of the gut microbiome of fish and the relative insignificance of the host genotype and gender.
Corneal endothelial alterations in alcohol dependence syndrome
Authors: Sati Alok , Moulick Parthasarathi , Shankar Sandeep , Chatterjee Kaushik , Dwivedi Arun Kumar , Vazirani Jayesh
Published: January 2018

Background/aims

To evaluate the corneal endothelial changes in patients with alcohol dependence syndrome (ADS).

Methods

A total of 322 corneas of 322 subjects were studied, and two groups were formed. The first, the ADS group, included 161 corneas of 161 patients and the second, the age-matched control group, was composed of 161 corneas of 161 healthy subjects. Both the groups were examined by specular microscope and the endothelial parameters were compared. The endothelial parameters were also compared before and after the abstinence of alcohol in the former group. The ADS group was further analysed to assess the influence of life time alcohol consumption, years/pattern of drinking, levels of Liver enzymes, levels of mean corpuscular volume, screening questionnaires and stages of fatty liver on corneal endothelium.

Results

On comparing the two groups using Mann-Whitney U test, a significant difference was found in central corneal thickness (CCT) and endothelial cell density (CD) between the ADS (CCT: 529±29 µm, CD: 2571±236 cells/mm2) and control groups (CCT: 510±32 µm, CD: 2752±291 cells/mm2) (P<0.001 (CCT); P<0.001 (CD)). Using Wilcoxon sign-rank test, a significant difference was found in CCT (P<0.001) and CD (P<0.001) with abstinence of alcohol. Kruskal-Wallis test was used to compare the endothelial parameters in four stages of fatty liver and found a significant difference in terms of CCT (P<0.001) and CD (P<0.001).

Conclusions

Corneal endothelial alteration is present in patients with ADS, more marked in patients with an increase in stage of fatty liver.
Improving the wait time to consultation at the emergency department
Authors: Shen Yuzeng , Lee Lin Hui
Published: January 2018

Prolonged wait times at the emergency department (ED) are associated with increased morbidity and mortality, and decreased patient satisfaction. Reducing wait times at the ED is challenging. The objective of this study is to determine if the implementation of a series of interventions would help decrease the wait time to consultation (WTC) for patients at the ED within 6 months. Interventions include creation of a common board detailing work output, matching manpower to patient arrivals and adopting a team-based model of care. A retrospective analysis of the period from January 2015 to May 2016 was undertaken to define baseline duration for WTC. Rapid PDSA (Plan, Do, Study, Act) cycles were used to implement a series of interventions, and changes in wait time were tracked, with concurrent patient load, rostered manpower and number of admissions from ED. Results of the interventions were tracked from 1 October 2016 to 30 April 2017. There was improvement in WTC within 6 months of initiation of interventions. The improvements demonstrated appeared consistent and sustained. The average 95th centile WTC decreased by 38 min to 124 min, from the baseline duration of 162 min. The median WTC improved to 21 min, compared with a baseline timing of 24 min. The improvements occurred despite greater patient load of 4317 patients per month, compared with baseline monthly average of 4053 patients. There was no increase in admissions from ED and no change in the amount of ED manpower over the same period. We demonstrate how implementation of low-cost interventions, enabling transparency, equitable workload and use of a team-based care model can help to bring down wait times for patients. Quality improvement efforts were sustained by employing a data-driven approach, support from senior clinicians and providing constant feedback on outcomes.
Beyond prognostication: ambulance personnel’s lived experiences of cardiac arrest decision-making
Authors: Anderson Natalie Elizabeth , Gott Merryn , Slark Julia
Published: January 2018

Introduction

The purpose of this study was to explore ambulance personnel’s decisions to commence, continue, withhold or terminate resuscitation efforts for patients with out-of-hospital cardiac arrest.

Method

Semistructured interviews with a purposive sample of 16 demographically diverse ambulance personnel, currently employed in a variety of emergency ambulance response roles, around New Zealand.

Results

Participants sought and integrated numerous factors, beyond established prognostic indicators, when making resuscitation decisions. Factors appeared to be integrated in four distinct phases, described under four main identified themes: prearrival impressions, immediate on-scene impressions, piecing together the big picture and transition to termination of resuscitation. Commencing or continuing resuscitation was sometimes a default action, particularly where ambulance personnel felt the context was uncertain, unfamiliar or overwhelming. Managing the impact of termination of resuscitation and resulting scene of a death required significant confidence, psychosocial skills and experience.

Conclusion

This unique, exploratory study provides new insights into ambulance personnel’s experiences of prehospital resuscitation decision-making. Prognostication in out-of-hospital cardiac arrest is known to be challenging, but results from this study suggest that confidence in a poor prognosis for the cardiac arrested patient is only part of the resuscitation decision-making picture. Results suggest ambulance personnel may benefit from greater educational preparation and mentoring in managing the scene of a death to avoid inappropriate or prolonged resuscitation efforts.
Heart failure with preserved ejection fraction: controversies, challenges and future directions
Authors: Zakeri Rosita , Cowie Martin R
Published: January 2018

Heart failure with preserved ejection fraction (HFpEF) comprises almost half of the population burden of HF. Because HFpEF likely includes a range of cardiac and non-cardiac abnormalities, typically in elderly patients, obtaining an accurate diagnosis may be challenging, not least due to the existence of multiple HFpEF mimics and a newly identified subset of patients with HFpEF and normal plasma natriuretic peptide concentrations. The lack of effective treatment for these patients represents a major unmet clinical need. Heterogeneity within the patient population has triggered debate over the aetiology and pathophysiology of HFpEF, and the neutrality of randomised clinical trials suggests that we do not fully understand the syndrome(s). Dysregulated nitric oxide–cyclic guanosine monophosphate–protein kinase G signalling, driven by comorbidities and ageing, may be the fundamental abnormality in HFpEF, resulting in a systemic inflammatory state and microvascular endothelial dysfunction. Novel informatics platforms are also being used to classify HFpEF into subphenotypes, based on statistically clustered clinical and biological characteristics: whether such subclassification will lead to more targeted therapies remains to be seen. In this review, we summarise current concepts and controversies, and highlight the diagnostic and therapeutic challenges in clinical practice. Novel treatments and disease management strategies are discussed, and the large gaps in our knowledge identified.
Possible relationship between antiphospholipid antibodies and embolic events in infective endocarditis
Authors: Selton-Suty Christine , Maigrat Charles-Henry , Devignes Jean , Goehringer François , Erpelding Marie-Line , Alla François , Thivilier Carine , Huttin Olivier , Venner Clément , Juilliere Yves , Doco-Lecompte Thanh , Lecompte Thomas
Published: January 2018

Objective

Antiphospholipid (aPL) antibodies may activate platelets and contribute to vegetation growth and embolisation in infective endocarditis (IE). We aimed to determine the value of aPL as predictors of embolic events (EE) in IE.

Methods

We studied 186 patients with definite IE (Duke-Li criteria, all types of IE) from the Nanc-IE prospective registry (2007–2012) who all had a frozen blood sample and at least one imaging procedure to detect asymptomatic or confirm symptomatic EE. Anticardiolipin (aCL) and anti-β2-glycoprotein I (β2GPI) antibodies (IgG and IgM) were assessed after the end of patients’ inclusion. The relationship between antibodies and the detection of EE after IE diagnosis were studied with Kaplan-Meier and Cox multivariate analyses.

Results

At least one EE was detected in 118 (63%) patients (52 cerebral, 95 other locations) after IE diagnosis in 80 (time interval between IE and EE diagnosis: 5.9±11.3 days). At least one aPL antibody was found in 31 patients (17%).

Detection of EE over time after IE diagnosis was more frequent among patients with anti-β2GPI IgM (log-rank P=0.0036) and that of cerebral embolisms, among patients with aCL IgM and anti-β2GPI IgM (log-rank P=0.002 and P<0.0001, respectively).

Factors predictive of EE were anti-β2GPI IgM (HR=3.45 (1.47–8.08), P=0.0045), creatinine (2.74 (1.55–4.84), P=0.0005) and vegetation size (2.41 (1.41–4.12), P=0.0014). Those of cerebral embolism were aCL IgM (2.84 (1.22–6.62), P=0.016) and anti-β2GPI IgM (4.77 (1.79–12.74), P=0.0018).

Conclusion

The presence of aCL and anti-β2GPI IgM was associated with EE, particularly cerebral ones, and could contribute to assess the embolic risk of IE.
Trends in cardiovascular risk factor and disease prevalence in patients undergoing non-cardiac surgery
Authors: Smilowitz Nathaniel R , Gupta Navdeep , Guo Yu , Beckman Joshua A , Bangalore Sripal , Berger Jeffrey S
Published: January 2018

Objectives

Cardiovascular risk factors are prevalent in the population undergoing non-cardiac surgery. Changes in perioperative cardiovascular risk factor profiles over time are unknown. The objective of this study was to evaluate national trends in cardiovascular risk factors and atherosclerotic cardiovascular disease (ASCVD) among patients undergoing non-cardiac surgery.

Methods

Adults aged ≥45 years old who underwent non-cardiac surgery were identified using the US National Inpatient Sample from 2004 to 2013. The prevalence of traditional cardiovascular risk factors (hypertension, dyslipidaemia, diabetes mellitus, obesity and chronic kidney disease) and ASCVD (coronary artery disease, peripheral artery disease and prior stroke] were evaluated over time.

Results

A total of 10 581 621 hospitalisations for major non-cardiac surgery were identified. Between 2008 and 2013, ≥2 cardiovascular risk factors and ASCVD were present in 44.5% and 24.3% of cases, respectively. Over time, the prevalence of multiple (≥2) cardiovascular risk factors increased from 40.5% in 2008–2009 to 48.2% in 2012–2013, P<0.001. The proportion of patients with coronary artery disease (17.2% in 2004–2005 vs 18.2% in 2012–2013, P<0.001), peripheral artery disease (6.3% in 2004–2005 vs 7.4% in 2012–2013, P<0.001) and prior stroke (3.5% in 2008–2009 vs 4.7% 2012–2013, P<0.001) also increased over time. The proportion of patients with a modified Revised Cardiac Risk Index score ≥3 increased from 6.6% in 2008–2009 to 7.7% in 2012–2013 (P<0.001).

Conclusions

Among patients undergoing major non-cardiac surgery, the burden of cardiovascular risk factors and the prevalence of ASCVD increased over time. Adverse trends in risk profiles require continued attention to improve perioperative cardiovascular outcomes.
Allergy teaching is suboptimal and heterogeneous in the undergraduate medical curriculum in the UK
Authors: Reid Emily Frances , Krishna Mamidipudi Thirumala , Bethune Claire
Published: January 2018

Aim

To record the level of allergy teaching occurring in UK medical schools. The UK has experienced an ‘allergy epidemic’ during the last 3–4 decades. Previous government reviews have emphasised the importance of allergy education and training, treating common allergies in primary care with referral pathways to a specialist and the creation of regional networks. It is acknowledged that the delivery of allergy teaching in UK medical schools is variable, despite the well-recognised need.

Methods

All consultant members of the British Society for Allergy and Clinical Immunology involved in teaching medical students were invited to partake in qualitative research, employing an online questionnaire for data collection. Participants were asked to comment on the format of the allergy teaching delivered, the student participation and the clinical opportunities provided. Students were recruited to complete a similar survey as supporting evidence.

Results

44 responses were collected, representing 64.7% of medical schools in the UK. Clinical allergy placements were compulsory in 31.8% of medical schools that responded. In 36.4%, it was reported that less than 10% of students had an opportunity to take an independent history from a patient with allergic disease, or practise using an epinephrine autoinjector. 90.9% responded that an allergy rotation was not offered to final year students.

Conclusions

Allergy undergraduate teaching is suboptimal and heterogeneous in UK medical schools and there is a real need for standardisation as a means to enhance quality of care.
Triage and the Modified Physiological Triage Tool-24 (MPTT-24)
Authors: Vassallo James , Horne S , Smith J E
Published: January 2018

Major incidents occur on a regular basis. So far in 2017, England has witnessed five terrorism-related major incidents, resulting in approximately 40 fatalities and 400 injured. Triage is a key principle in the effective management of a major incident and involves prioritising patients on the basis of their clinical acuity. This paper describes the limitations associated with existing methods of primary major incident triage and the process of developing a new and improved triage tool—the Modified Physiological Triage Tool-24 (MPTT-24). Whilst the MPTT-24 is likely to be the optimum physiological method for primary major incident triage, it needs to be accompanied by an appropriate secondary triage process. The existing UK military and civilian secondary triage tool, the Triage Sort, is described, which offers little advantage over primary methods for identifying patients who require life-saving intervention. Further research is required to identify the optimum method of secondary triage.
Clinical outcomes and costs of cardiac revascularisation in England and New York state
Authors: Leyva Francisco , Qiu Tian , Evison Felicity , Christoforou Christopher , McNulty David , Ludman Peter , Ray Daniel
Published: January 2018

Objectives

Healthcare expenditure per-capita in the USA is higher than in England. We hypothesised that clinical outcomes after cardiac revascularisation are better in the USA. We compared costs and outcomes of patients undergoing coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) in England and New York State (NYS).

Methods

Costs and total mortality were assessed using the Hospital Episode Statistics for England and the Statewide Planning and Research Cooperative System for NYS. Outcomes after a first CABG or PCI were assessed in patients undergoing a first CABG (n=142 969) or PCI (n=431 416).

Results

After CABG, crude total mortality in England was 0.72% lower at 30 days and 3.68% lower at 1 year (both P<0.001). After PCI, crude total mortality was 0.35% lower at 30 days and 3.55% lower at 1 year (both P<0.001). No differences emerged in total mortality at 30 days after either CABG (England: HR 1.02,95% CI 0.94 to 1.10) or PCI (HR 1.04, 95% CI 0.99 to 1.09) after covariate adjustment. At 1 year, adjusted total mortality was lower in England after both CABG (HR 0.74, 95% CI 0.71 to 0.78) and PCI (HR 0.66, 95% CI 0.65 to 0.68). After adjustment for cost-to-charge ratios and purchasing power parities, costs in NYS amounted to uplifts of 3.8-fold for CABG and 3.6-fold for PCI.

Conclusions

Total mortality after CABG and PCI was similar at 30 days and lower in England at 1 year. Costs were approximately fourfold higher in NYS.
Analytical and experimental studies on a new linear energy harvester
Authors: Kurt Erol , Kale Mustafa Melih , Akbaba Sinan , Bizon Nicu
Published: January 2018

A new electromagnetic energy harvester has been designed to generate electricity from mechanical vibrations. The new system operates with two springs attached to two ends of a linear-laminated core and a winding circulated on the core directs the electrical energy to the output. Initially an electromagnetic model has been developed for the Halbach-oriented magnets at the ends of core. That orientation has been used to deviate the magnetic field at the tips of the core unit. Some preliminary studies prove that the output peak voltage U = 0.75 V and maximal peak power P = 14 mW can be achieved experimentally, thereby a power density of p = 0.3684 mW/cm3 is obtained with the new system. The efficiency of that new designed linear harvester reaches 36% at its optimum frequency and electrical load conditions.
Two sodium pumps in the hepatopancreas of the intertidal euryhaline crab Neohelice granulata: biochemical characteristics and differential modulation after feeding
Authors: Méndez E. , Caruso Neves C. , López Mañanes A.A.
Published: January 2018

No study has been done on the existence, biochemical characteristics, and modulation of K+-independent ouabain-insensitive Na+ ATPase activity (the second sodium pump) in the digestive tract of intertidal euryhaline crabs and moreover on the coexistence and modulation under distinct physiological and (or) environmental conditions of different sodium pumps. We determined the occurrence, characteristics, and responses at different times (0, 1, 24, 48, and 120 h) after feeding upon distinct salinities of Na+ ATPase activity and Na+/K+ ATPase in the hepatopancreas of Neohelice granulata (Dana, 1851), which is a model species. The stimulation by Na+ under total inhibition of Na+/K+ ATPase activity revealed the occurrence of Na+ ATPase activity that was totally inhibited by 2 mmol·L–1 furosemide, exhibits Michaelis–Menten kinetics for ATP (apparent Km = 0.52 ± 0.16 mmol·L–1), and highest activity at around pH 7.4. In crabs acclimated to 35 psu (osmoconforming conditions), Na+ ATPase activity was highly increased (about 15-fold) (532 ± 58 nmol Pi·mg protein−1·min−1) in the hepatopancreas 48 h after feeding. In 10 psu (hyper-regulating conditions), Na+ ATPase activity decreased in the hepatopancreas 24 h after feeding (7 ± 9 nmol Pi·mg protein−1·min−1) and recovered initial values after 48 h (24 ± 35 nmol Pi·mg protein−1·min−1). Unlike Na+ ATPase, Na+/K+ ATPase activity did not change after feeding at any salinity, suggesting the specific modulation of the second sodium pump and its role in postprandial adjustments in the hepatopancreas.
Simplicial Palatini action
Authors: Khatsymovsky V. M.
Published: January 2018

We consider the piecewise flat spacetime and a simplicial analog of the Palatini form of the general relativity (GR) action where the discrete Christoffel symbols are given on the tetrahedra as variables that are independent of the metric. Excluding these variables with the help of the equations of motion gives exactly the Regge action.

This paper continues our previous work. Now, we include the parity violation term and the analog of the Barbero–Immirzi parameter introduced in the orthogonal connection form of GR. We consider the path integral and the functional integration over the connection. The result of the latter (for certain limiting cases of some parameters) is compared with the earlier found result of the functional integration over the connection for the analogous orthogonal connection representation of Regge action.

These results, mainly as some measures on the lengths/areas, are discussed for the possibility of the diagram technique where the perturbative diagrams for the Regge action calculated using the measure obtained are finite. This finiteness is due to these measures providing elementary lengths being mostly bounded and separated from zero, just as the finiteness of a theory on a lattice with an analogous probability distribution of spacings.
Particle physics today, tomorrow and beyond
Authors: Ellis John
Published: January 2018

The most important discovery in particle physics in recent years was that of the Higgs boson, and much effort is continuing to measure its properties, which agree obstinately with the Standard Model, so far. However, there are many reasons to expect physics beyond the Standard Model, motivated by the stability of the electroweak vacuum, the existence of dark matter and the origin of the visible matter in the Universe, neutrino physics, the hierarchy of mass scales in physics, cosmological inflation and the need for a quantum theory for gravity. Most of these issues are being addressed by the experiments during Run 2 of the LHC, and supersymmetry could help resolve many of them. In addition to the prospects for the LHC, I also review briefly those for direct searches for dark matter and possible future colliders.
Suppression of Bekenstein–Hawking radiation in f(T)-gravity
Authors: Addazi Andrea
Published: January 2018

We discuss semiclassical Nariai black holes in the framework of f(T)-gravity. For a diagonal choice of tetrads, stable Nariai metrics can be found, emitting Bekenstein–Hawking radiation in semiclassical limit. However, for a nondiagonal choice of tetrads, evaporation and anti-evaporation instabilities are turned on. In turn, this causes a backreaction effect suppressing the Bekenstein–Hawking radiation. In particular, evaporation instabilities produce a new radiation — different by Bekenstein–Hawking emission — nonviolating unitarity in particle physics sector.
Holographic helical superconductor with higher curvature corrections
Authors: Mukhopadhyay Subir , Paul Chandrima
Published: January 2018

We study [Formula: see text] gauge theory with Chern–Simons term, coupled to scalar field in adjoint, in Einstein–Gauss–Bonnet gravity. We explore phases of holographic superconductor in terms of the condensates and free energies in the background of AdS black hole and AdS soliton. In the case of black hole, we find with increasing strength of higher curvature terms, transition temperature decreases. For AdS soliton, the critical value of chemical potential increases as the higher curvature terms dominate.
Knot invariants with multiple skein relations
Authors: Yang Zhiqing
Published: January 2018

Given any oriented link diagram, one can construct knot invariants using skein relations. Usually such a skein relation contains three or four terms. In this paper, the author introduces several new ways to smooth a crossings, and uses a system of skein equations to construct link invariants. This invariant can also be modified by writhe to get a more powerful invariant. The modified invariant is a generalization of both the HOMFLYPT polynomial and the two-variable Kauffman polynomial. Using the diamond lemma, a simplified version of the modified invariant is given. It is easy to compute and is a generalization of the two-variable Kauffman polynomial.
A new invariant and decompositions of manifolds
Authors: Ogasa Eiji
Published: January 2018

We introduce a new topological invariant [Formula: see text] of compact manifolds-with-boundaries [Formula: see text] which is much connected with boundary-unions. A boundary-union is a kind of decomposition of compact manifolds-with-boundaries. See the body of the paper for the precise definition. Let [Formula: see text] and [Formula: see text] be [Formula: see text]-dimensional compact manifolds-with-boundaries. Let [Formula: see text] be a boundary-union of [Formula: see text] and [Formula: see text]. Then we have [Formula: see text] We define [Formula: see text] as follows: First, define an invariant of [Formula: see text]-closed manifolds. Take the maximum of the invariant of all connected-components of the boundary of each handle-body of an ordered-handle-decomposition with a fixed base [Formula: see text], where we impose the condition that the base [Formula: see text] is a (not necessarily connected) closed manifold. Take the minimum of the maximum for all ordered-handle-decompositions with the base [Formula: see text]. It is our another invariant [Formula: see text]. Take the maximum of the minimum, [Formula: see text], for all basis to satisfy the above condition. It is [Formula: see text]. See the body of the paper for the precise definition.
Modeling of Nanofluid-Fluid Two-Phase Flow and Heat Transfer
Authors: Guan Qiangshun , Yap Yit Fatt , Li Hongying , Che Zhizhao
Published: January 2018

This paper presents a model for two-phase nanofluid-fluid flow and heat transfer. The nonuniform nanoparticles are transported using Buongiorno model by convection, Brownian diffusion and thermophoresis. This is the first attempt to employ Buongiorno model for two-phase nanofluid-fluid flow. The moving interface between the nanofluid and the immiscible fluid is captured using the level-set method. The model is first verified and then demonstrated for coupled flow and heat transfer in (1) a water–alumina nanofluid-filled cavity with a rising silicone oil drop and (2) stratified flow of water–alumina nanofluid, pure water and silicone oil in a channel.
Einstein static universe, GUP, and natural IR and UV cut-offs
Authors: Darabi F. , Atazadeh K.
Published: January 2018

We study the Einstein static universe (ESU) in the framework of Generalized Uncertainty Principle (GUP) constructed by the Snyder non-commutative space. It is shown that the deformation parameter can induce an effective energy density subject to GUP which obeys the holographic principle (HP) and plays the role of a cosmological constant. Using the holographic feature of this effective energy density, we introduce natural IR and UV cut-offs which depend on the GUP-based effective equation of state. Moreover, we propose a solution to the cosmological constant problem (CCP). This solution is based on the result that the Einstein equations just couple to the tiny holographic-based surface energy density (cosmological constant) induced by the deformation parameter, rather than the large quantum gravitational-based volume energy density (vacuum energy) having contributions of order [Formula: see text].
Porphyrins for olfaction mimic: The Rome Tor Vergata approach
Authors: Di Natale Corrado , Martinelli Eugenio , Magna Gabriele , Mandoj Federica , Monti Donato , Nardis Sara , Stefanelli Manuela , Paolesse Roberto
Published: January 2018

The impressive chemistry shown by porphyrins in natural systems is particularly attractive for exploitation in chemical sensors. In these devices the sensing mechanisms can mimic most of the porphyrin biological reactivity, such as reversible binding, activation of small molecules, redox activity, and photoactivated processes. The simultaneous presence of multiple binding mechanisms allows porphyrins to interact with a large variety of analytes. This feature reduces the selectivity, but prompts the development of sensor arrays, where the cross-selectivity of more sensors is used to classify and identify samples characterized by a complex composition. Since 1995 the Sensors Group of the University of Rome Tor Vergata has exploited these features to prepare sensor arrays based on different transducers and aimed at several applications. These kinds of devices have been reported as electronic noses (gaseous phase analytes) and electronic tongues (liquid phase analytes) to underline that their working mechanisms are tentatively similar to that of biological senses. We report here some of the results obtained.
Sorption and catalysis by robust microporous metalloporphyrin framework solids
Authors: Smithenry Dennis W. , Wilson Scott R. , Nakagaki Shirley , Suslick Kenneth S.
Published: January 2018

Two isostructural metalloporphyrin framework solids have been synthesized. Both frameworks contains manganese(III) metal complexes of trans-dicarboxylateporphyrins whose peripheralcarboxylates coordinate the edges of tetrahedral Zn4O[Formula: see text] clusters; the two metalloporphyrins explored are Mn(III) and Co(II). The cubic interpenetrated frameworks have 72% free volume and 4 × 7 Å averaged size pores. The evacuated frameworks are robust and retain a structure open to the sorption of substrates with medium polarity. The manganese porphyrin framework catalyzes the hydroxylation of cyclic and linear alkanes with iodosylbenzene as oxidant in a size- and polarity-selective manner. In addition, the catalysis was found to occur within the pores, making this a rare case of porphyrin framework solid with interior catalysis.
On the k-matchings of the complements of bicyclic graphs
Authors: Li Hong-Hai , Liang Yi-Ping
Published: January 2018

A matching of a graph [Formula: see text] is a set of pairwise nonadjacent edges of [Formula: see text], and a [Formula: see text]-matching is a matching consisting of [Formula: see text] edges. In this paper, we characterize the bicyclic graphs whose complements have the extremal number of [Formula: see text]-matchings for all [Formula: see text].
A Hirota bilinear equation for Painlevé transcendents PIV, PII and PI
Authors: Hone A. N. W. , Zullo F.
Published: January 2018

We present some observations on the tau-function for the fourth Painlevé equation. By considering a Hirota bilinear equation of order four for this tau-function, we describe the general form of the Taylor expansion around an arbitrary movable zero. The corresponding Taylor series for the tau-functions of the first and second Painlevé equations, as well as that for the Weierstrass sigma function, arise naturally as special cases, by setting certain parameters to zero.
Evaluating the susceptibility to anthropogenic sinkholes in Apulian calcarenites, southern Italy
Authors: Fiore A. , Fazio N. L. , Lollino P. , Luisi M. , Miccoli M. N. , Pagliarulo R. , Perrotti M. , Pisano L. , Spalluto L. , Vennari C. , Vessia G. , Parise M.
Published: January 2018

Sinkholes are the main hazard related to underground voids of both natural and anthropogenic origin. Instabilities developing underground may propagate upwards in a dramatic manner and reach the surface in the form of a sinkhole. The Apulia region in southern Italy is an interesting case study due to the outcropping of soluble rocks throughout the region. These rocks are affected by karst processes and have a high number of anthropogenic cavities. The latter were excavated by humans at different times for a variety of purposes. The worrying recent increase in the number of sinkhole events registered in Apulia led us to collect information on natural and anthropogenic sinkholes in Apulia. We focused on anthropogenic cavities, mostly excavated in Plio-Pleistocene calcarenites, and characterized the rock masses before using two- and three-dimensional parametric numerical analyses to model the instability processes, with the aim of exploring the failure mechanisms that lead to the occurrence of sinkholes. The parametric studies allowed us to carry out a preliminary evaluation of the stability conditions through simple charts designed for use in the field.
Lower Cretaceous reservoir development in the North Sea Central Graben, and potential analogue settings in the Southern Permian Basin and South Viking Graben
Authors: Zwaan Frank
Published: January 2018

Much of the future hydrocarbon exploration potential in the North Sea lies in locating stratigraphic traps and discrete reservoir intervals. This study assesses the potential for Lower Cretaceous reservoirs, with particular focus on the Norwegian Central Graben and methods to identify future prospects over a wider area. Seismic interpretation and well data reveal the structure and sedimentology of the study area. Although the region was isolated from a large hinterland in the Early Cretaceous, potential local sediment sources, sediment transport routes and areas with possible reservoir development are identified. The greater Mandal High area, where Lower Cretaceous shoreface deposits and submarine fan systems are postulated, is suggested for primary focus. Similar deposits may have developed around the other exposed highs in the region, although several were drowned towards the end of the Early Cretaceous. Detailed seismic and stratigraphic analysis will be necessary to identify individual reservoir units. Since comparable settings may have occurred in the adjacent South Viking Graben and Southern Permian Basin regions during the Early Cretaceous, further reservoir assessment is recommended for the North Sea in general.
Wall-Modeled Large-Eddy Simulation for Complex Turbulent Flows
Authors: Bose Sanjeeb T. , Park George Ilhwan
Published: January 2018

Large-eddy simulation (LES) has proven to be a computationally tractable approach to simulate unsteady turbulent flows. However, prohibitive resolution requirements induced by near-wall eddies in high–Reynolds number boundary layers necessitate the use of wall models or approximate wall boundary conditions. We review recent investigations in wall-modeled LES, including the development of novel approximate boundary conditions and the application of wall models to complex flows (e.g., boundary-layer separation, shock/boundary-layer interactions, transition). We also assess the validity of underlying assumptions in wall-model derivations to elucidate the accuracy of these investigations, and offer suggestions for future studies.
Lymphatic System Flows
Authors: Moore James E. , Bertram Christopher D.
Published: January 2018

The supply of oxygen and nutrients to tissues is performed by the blood system and involves a net leakage of fluid outward at the capillary level. One of the principal functions of the lymphatic system is to gather this fluid and return it to the blood system to maintain overall fluid balance. Fluid in the interstitial spaces is often at subatmospheric pressure, and the return points into the venous system are at pressures of approximately 20 cmH2O. This adverse pressure difference is overcome by the active pumping of collecting lymphatic vessels, which feature closely spaced one-way valves and contractile muscle cells in their walls. Passive vessel squeezing causes further pumping. The dynamics of lymphatic pumping have been investigated experimentally and mathematically, revealing complex behaviors that indicate that the system performance is robust against minor perturbations in pressure and flow. More serious disruptions can lead to incurable swelling of tissues called lymphedema.
Diffuse-Interface Capturing Methods for Compressible Two-Phase Flows
Authors: Saurel Richard , Pantano Carlos
Published: January 2018

Simulation of compressible flows became a routine activity with the appearance of shock-/contact-capturing methods. These methods can determine all waves, particularly discontinuous ones. However, additional difficulties may appear in two-phase and multimaterial flows due to the abrupt variation of thermodynamic properties across the interfacial region, with discontinuous thermodynamical representations at the interfaces. To overcome this difficulty, researchers have developed augmented systems of governing equations to extend the capturing strategy. These extended systems, reviewed here, are termed diffuse-interface models, because they are designed to compute flow variables correctly in numerically diffused zones surrounding interfaces. In particular, they facilitate coupling the dynamics on both sides of the (diffuse) interfaces and tend to the proper pure fluid–governing equations far from the interfaces. This strategy has become efficient for contact interfaces separating fluids that are governed by different equations of state, in the presence or absence of capillary effects, and with phase change. More sophisticated materials than fluids (e.g., elastic–plastic materials) have been considered as well.
Cyclic-GMP–Elevating Agents Suppress Polyposis in ApcMin Mice by Targeting the Preneoplastic Epithelium
Authors: Sharman Sarah K. , Islam Bianca N. , Hou Yali , Singh Nagendra , Berger Franklin G. , Sridhar Subbaramiah , Yoo Wonsuk , Browning Darren D.
Published: January 2018

The cGMP signaling axis has been implicated in the suppression of intestinal cancers, but the inhibitory mechanism and the extent to which this pathway can be targeted remains poorly understood. This study has tested the effect of cGMP-elevating agents on tumorigenesis in the ApcMin/+ mouse model of intestinal cancer. Treatment of ApcMin/+ mice with the receptor guanylyl-cyclase C (GCC) agonist linaclotide, or the phosphodiesterase-5 (PDE5) inhibitor sildenafil, significantly reduced the number of polyps per mouse (67% and 50%, respectively). Neither of the drugs affected mean polyp size, or the rates of apoptosis and proliferation. This was possibly due to increased PDE10 expression, as endogenous GCC ligands were not deficient in established polyps. These results indicated that the ability of these drugs to reduce polyp multiplicity was primarily due to an effect on nonneoplastic tissues. In support of this idea, ApcMin/+ mice exhibited reduced levels of endogenous GCC agonists in the nonneoplastic intestinal mucosa compared with wild-type animals, and this was associated with crypt hyperplasia and a loss of goblet cells. Administration of either sildenafil or linaclotide suppressed proliferation, and increased both goblet cell numbers and luminal apoptosis in the intestinal mucosa. Taken together, the results demonstrate that targeting cGMP with either PDE5 inhibitors or GCC agonists alters epithelial homeostasis in a manner that reduces neoplasia, and suggests that this could be a viable chemoprevention strategy for patients at high risk of developing colorectal cancer. Cancer Prev Res; 11(2); 81–92. ©2018 AACR.