bluuebunny/crossref_metadata_2025 huggingface dataset:
Pedicle distraction increases intervertebral and spinal canal area in a cadaver and bone model
Authors: Hughes Matthew , Papadakos Nikolaos , Bishop Tim , Bernard Jason
Published: May 2018

Introduction: Lumbar spinal stenosis is degenerative narrowing of the spinal canal and/or intervertebral foramen causing compression of the spinal cord and nerve roots. Traditional decompression techniques can often cause significant trauma and vertebral instability. This paper evaluates a method of increasing pedicle length to decompress the spinal and intervertebral foramen, which could be done minimally invasive.

Methods: Three Sawbone (Sawbones Europe, Sweden) and 1 cadaveric lumbar spine underwent bilateral pedicle distraction at L4. A pedicle channel was drilled between the superior articular process and transverse process into the vertebral body. The pedicles underwent osteotomy at the midpoint. Screws were inserted bilaterally and fixated distraction of 0 mm, 2 mm, 4 mm and 6 mm. CT images were taken at each level of distraction. Foramen area was measured in the sagittal plane at L3/4. Spinal canal area was measured at L4 in the axial images. The cadaver was used to evaluate safety of osteotomy and soft tissue interactions preventing distraction. Statistical analysis was by student paired t-test and Pearson rank test.

Results: Increasing distraction led to greater Spinal canal area. From 4.27 cm2 to 5.72 cm2 (p = 0.002) with 6 mm distraction. A Maximal increase of 34.1%. Vertebral foramen area also increased with increasing pedicle distraction. From 2.43 cm2 to 3.22 cm2 (p = 0.022) with 6 mm distraction. A maximal increase of 32.3%. The cadaver spinal canal increased in area by 21.7%. The vertebral foramen increased in area by 36.2% (left) and 22.6% (right).

Discussion: For each increase in pedicle distraction the area of the spinal and vertebral foramen increases. Pedicle distraction could potentially be used to alleviate spinal stenosis and root impingement. A potential osteotomy plane could be at the midpoint of the pedicle with minimal risk to nerve roots and soft tissue restrictions to prevent distraction.
ACTIVDISPENS – Bewegung trotz Sportdispens
Authors: Perrot Guido , Runge Lisa
Published: May 2018

Mit dem Fortschritt der Medizin und den besseren Hygienestandards hat sich die Haupttodesursache in den westlichen Ländern in Vergleich zum Mittelalter
verändert. Heutzutage zählen die nicht übertragbaren Krankheiten (auch bekannt als chronische Krankheiten oder noncommunicable diseases, NCD) zu den häufigsten
Todesursachen der Schweizer Bevölkerung. Laut Bundesamt für Gesundheit (BAG) leiden 2,2 Millionen Menschen in der Schweiz an NCDs 2; das entspricht einem Viertel der Bevölkerung. Aufgrund von aufwendigen, teuren und vor allem zeitlich unbestimmt langen Therapien stellen
chronische Krankheiten eine große Herausforderung für die Ökonomie und Gesundheit der westlichen Gesellschaft dar. Das BAG berichtet des Weiteren, dass allein
2011 die Behandlung der fünf häufigsten NCDs 25,6 Milliarden Franken kostete, was rund 40 % der direkten Schweizer Gesundheitskosten entspricht 2. Neben Herz-Kreislauf-Erkrankungen, Krebs, Diabetes mellitus und chronischen Atemwegserkrankungen zählen auch die
Erkrankungen des Bewegungsapparates dazu. Bestimmte Risikofaktoren verstärken und beschleunigen diese Zustände. Ein ungesunder Lebensstil und mangelnde Bewegung
gehören zu den größten Risikofaktoren 2.

Anmerkung: ACTIVDISPENS® ist eine geschützte Marke.
Kolumne – Feierabend-Wahnsinn
Authors: Schiewack Michael
Published: May 2018

Michael Schiewack wähnte sich schon im Feierabend, als eine Ärztin empört bei ihm in der Praxis anrief. Es sei ausgeschlossen, eine Verordnung zu ändern! Gut, dass Ergotherapeuten beraten können und Ärzte auch nur Menschen sind.
Kein Roboter kann die Pflege ersetzen
Authors: Schmidt Maximilian
Published: May 2018

Längst hat die Technik Einzug in die Krankenhäuser gehalten – elektronische Datenverarbeitung und Überwachungssysteme sind aus dem Klinikalltag nicht mehr
wegzudenken. Und die Entwicklung schreitet weiter voran. Sind technische Assistenzsysteme denkbar, die in der Lage sind, Pflegeaufgaben zu übernehmen? Was würde
das für die Pflege bedeuten?
Detection of clinically relevant serrated polyps during screening colonoscopy: results from seven cooperating centers within the German colorectal screening program
Authors: Schramm Christoph , Janhsen Katharina , Hofer Jan-Hinnerk , Toermer Hans , Stelzer Annette , Stenschke Frank , Stollenwerk Michael , Scheller Ingo , Lang Sonja , Goeser Tobias , Steffen Hans-Michael
Published: May 2018

Background Serrated polyps have been recognized as precursors of colorectal cancer (CRC) via the serrated pathway. Endoscopic detection and histopathological evaluation of serrated polyps are challenging. The aims of this study were to determine detection rates of the recently proposed entity of clinically relevant serrated polyps (crSPs) and to identify factors that influence their detection in a primary colonoscopy screening cohort.

Methods We retrospectively analyzed average-risk screening colonoscopies performed at a tertiary academic hospital and six community-based private practices in Germany between 01/01/2012 and 14/12/2016. Exclusion criteria were age < 50 years, conditions with increased risk for CRC (e. g. inflammatory bowel disease, history of CRC, hereditary cancer syndromes), and incomplete procedures. CrSPs were defined as serrated polyps ≥ 10 mm and/or > 5 mm located proximally to the splenic flexure. Conventional adenomas were defined as adenomas excluding serrated polyps.

Results A total of 4161 colonoscopies from average-risk individuals were included (median age 62 years [interquartile range 56 – 69]; 48.6 % male). CrSPs were detected in 6.9 %, with a mean detection rate of 4.7 % (95 % confidence interval 2.3 % – 7.2 %). Detection rates ranged from 0 % to 16.2 %. In multivariate analysis, simultaneous detection of conventional adenomas and an endoscopist adenoma detection rate of ≥ 25 % were significantly associated with increased detection of crSPs, with odds ratios of 1.43 (95 %CI 1.11 – 1.85; P = 0.01) and 7.35 (95 %CI 4.43 – 12.19; P < 0.001). The individual endoscopist’s detection rate for conventional adenomas and crSPs were significantly correlated (r = 0.54, P = 0.02).

Conclusion Detection rates for crSPs differed between participating endoscopists. However, individual skills to detect polypoid lesions have a relevant bearing on the detection rate of crSPs.
An Efficient One-Pot Multicomponent Synthesis of Tetracyclic Quinazolino[4,3-b]quinazolines by Sequential C–N Bond Formation and Copper-Mediated Aerobic Oxidative Cyclization
Authors: Alla Manjula , Potuganti Gal , Indukuri Divakar
Published: May 2018

An efficient one-pot synthesis of quinazolino[4,3-b]quinazoline derivatives has been accomplished, starting from 2-(2-bromo­phenyl)quinazolin-4(3H)-one, aldehydes, and various nitrogen sources under aerobic conditions. The multicomponent protocol is mediated by copper(I) salts and involves amination of 2-(2-bromophenyl)quinazolin-4(3H)-one, followed by condensation with the aldehyde and an oxidative cyclization to give the target compounds in moderate to good yields.
Evaluating Central Aortic Blood Pressures in a Tertiary South Indian Hospital
Authors: Kavirayani Hemamalini
Published: May 2018

Background Of late, central aortic blood pressure (CABP) has emerged as a better parameter than peripheral blood pressure (BP) in the diagnosis of cardiovascular events. Advent of new technologies has facilitated the calculation of CABP from machine-derived peripheral BP. In this study, the author determined the differences between peripheral BP measured manually or by machine and machine-derived CABP and examined whether this difference is stable even after categorizing the sample pool based on sex, hypertension, diabetes status, and β-blocker use.

Materials and Methods A total of 83 patients (both male and female) who attended the cardiology outpatient department were enrolled in the study. BP was recorded both manually and using Mobil-O-Graph pulse wave analyzer (ARC Solver) in the patient's sitting posture. The author compared the derived central, manual, and device-measured BP among the patient samples and assessed whether sex, hypertension, diabetes, and β-blocker use influence these differences.

Results Among the study population, 28 were females and 55 were males; patients’ mean age was 59.97 ± 12.15 years. The mean peripheral systolic BP (SBP) and diastolic BP (DBP) measured manually were127.55 ± 20.15 and 79.73 ± 9.57 mm Hg, respectively. Similar measurements recorded by the device were 129.68 ± 19.93 and 78.92 ± 13.48, respectively. The derived mean central aortic SBP and DBP was 117.69 ± 17.78 and 80.15 ± 13.71, respectively. Statistically significant difference in the manual and central aortic SBP (9.85 ± 11.16; p < 0.0001) was observed. This difference was significant irrespective of sex, hypertension, diabetes status, and β-blocker use. Similarly, difference between machine-derived peripheral SBP and central aortic SBP was statistically significant (p < 0.0001). However, the difference in manual and central aortic DBP was nonsignificant (p = 0.6976). Interestingly, a small (−1.34 ± 2.28) but statistically significant difference (p < 0.0001) between machine-derived peripheral DBP and central aortic DBP was observed. Further analysis to find out effect of β-blocker use on CABP revealed that the central aortic SBP is slightly, but statistically significantly, lower in β-blocker users (117.7 ± 17.71; p < 0.0001) than that of β-blocker nonusers (118.9 ± 18.37; p< 0.0001).

Conclusion Central aortic systolic pressure is statistically significantly lower than the manually recorded peripheral SBP irrespective of sex, hypertension, diabetes status, and β-blocker use. A small but significant difference was observed between machine-derived peripheral DBP and central aortic DBP. Patients using β-blockers were observed to have marginally lower CABP values than those who are not using them.
Mammographically Detected Breast Arterial Calcification—A Marker of Coronary Artery Disease in Women
Authors: Gorantla Padmasri , Kapoor Anu , Maddury Jyotsna
Published: May 2018

Background and Aim Coronary artery disease (CAD) resulting from atherosclerosis is one of the major causes of mortality and morbidity worldwide and is still a leading cause of death in women older than 40 years. The gold standard for diagnosis of CAD is by coronary angiography (CAG). However, this procedure is both invasive and expensive and thus is not suitable as a screening tool in asymptomatic individuals. Like coronary calcification, atherosclerotic vascular calcification involving small-to-medium–sized arteries is also observed in the breast. Modern mammographic equipment is very sensitive in the detection of microcalcifications. The aim of this study is to study the relationship between mammographically detected breast arterial calcification (BAC) and CAD and to evaluate the role of BAC as a marker for CAD.

Methods Twenty female patients older than 40 years who had undergone CAG for suspected CAD were included in the study. Screening mammograms were performed and analyzed for the presence of BAC. The results were analyzed for correlation between severity of BAC and CAD.

Results Twenty patients with mean age of 56.45 (age range: 40–68) were evaluated. BACs were found in 60% of these cases with a peak age group of 56 to 60 years. BAC was bilateral (92%) in most cases. CAG reports were positive for CAD in 45% of patients. The sensitivity of BAC in predicting CAD was 77.7% with a specificity of 54.5%, positive predictive value (PPV) of 58.3%, and negative predictive value (NPV) of 75%. Conclusion Screening mammography has a potential to serve as a noninvasive tool for early detection of CAD in asymptomatic women. Larger population-based studies with controls will be required to establish the utility of this screening tool.
Neonatal Thyrotoxicosis with Tricuspid Valve Regurgitation and Hydrops in a Preterm Infant Born to a Mother with Graves' Disease
Authors: Doucette Stefani , Tierney Anne , Roggensack Anne , Yusuf Kamran
Published: May 2018

Neonatal hyperthyroidism is rare disorder due to the passage of thyroid receptor antibodies (TRBs) from the mother to the fetus. Neonatal thyrotoxicosis can present in several ways and if unrecognized, can be fatal. We present a preterm neonate who developed fetal hydrops and tricuspid regurgitation in utero. The mother had a history of treated Grave's disease. The infant responded to maternal treatment antenatally and postnatal anti-thyroid treatment, with resolution of both the tricuspid regurgitation and hydrops. To our knowledge, this is the first case report of tricuspid regurgitation associated with fetal and neonatal thyrotoxicosis. Our case also highlights the importance of obtaining a detailed and accurate history in a mother with previous Grave's disease, even if treated.
Polypharmakologie als ein neuer Ansatz zur Präzisionsmedizin in der Adipositas- und Diabetestherapie
Authors: Jall S. , Götz A. , Tschöp M. H. , Müller T. D.
Published: May 2018

Die weltweite Prävalenz von morbid gesteigertem Körpergewicht hat im 21. Jahrhundert epidemische Ausmaße angenommen. Adipositas gehört zu den wichtigsten Risikofaktoren für die Entstehung von Diabetes mellitus Typ 2, kardiovaskulären Erkrankungen und bestimmten Tumorleiden. Die Entwicklung neuer individueller pharmakologischer Therapieoptionen ist von größtem gesellschaftlichen Interesse, um der wachsenden Belastung unserer Gesundheitssysteme wirksam zu begegnen. Konservative Behandlungen, die beispielsweise auf eine Lebensstiländerung abzielen, sind nur unzureichend erfolgreich und derzeit verfügbare pharmakologische Therapieoptionen sind bislang nur wenig effektiv und/oder haben gravierende Nebenwirkungen. Einzelne Wirkstoffe, wie etwa Orlistat, waren bislang nicht in der Lage der steigenden Adipositaspandemie entgegenzuwirken. Ein vielversprechender neuer Ansatz ist es, die Wirkung verschiedener Schlüsselhormone in einem einzigen hochwirksamen Biomolekül zu vereinen. Verschiedene solcher Polyagonisten mit Multihormonwirkung befinden sich derzeit in klinischer Evaluation. Dazu gehört u.a. ein dualer Agonist mit Aktivität an den Rezeptoren für das Glukagon-ähnliche Peptid 1 (GLP-1) und Glukagon, ein dualer Agonist an den Rezeptoren für GLP-1 und das glukoseabhängige insulinotrope Polypeptid (GIP) sowie ein Triagonist mit Aktivität an den Rezeptoren für GLP-1, GIP und Glukagon. erfolgreich und derzeit verfügbare pharmakologische Therapieoptionen sind bislang nur wenig effektiv und/oder haben gravierende Nebenwirkungen. Einzelne Wirkstoffe, wie etwa Orlistat, waren bislang nicht in der Lage der steigenden Adipositaspandemie entgegenzuwirken. Ein vielversprechender neuer Ansatz ist es, die Wirkung verschiedener Schlüsselhormone in einem einzigen hochwirksamen Biomolekül zu vereinen. Verschiedene solcher Polyagonisten mit Multihormonwirkung befinden sich derzeit in klinischer Evaluation. Dazu gehört u.a. ein dualer Agonist mit Aktivität an den Rezeptoren für das Glukagon-ähnliche Peptid 1 (GLP-1) und Glukagon, ein dualer Agonist an den Rezeptoren für GLP-1 und das glukoseabhängige insulinotrope Polypeptid (GIP) sowie ein Triagonist mit Aktivität an den Rezeptoren für GLP-1, GIP und Glukagon.
Fortschritte in der Demenztherapie – Was ist bereits praxisrelevant?
Authors: Roeben Benjamin , Zieschang Tania , Maetzler Walter
Published: May 2018

Due to the aging population, dementias represent a growing challenge for the health systems and for the society. This overview summarizes the current state of already practice-relevant therapies and management of dementias. Non-pharmacological approaches have a greater impact than pharmacological treatment. Increasing evidence underlines that consistent management of cardiovascular risk factors has beneficial effects on the progression of at least some, possibly almost all types of dementias. The main pharmacological agents for symptomatic treatment of cognitive deficits in Alzheimer’s and Parkinson’s disease-associated dementias are cholinesterase inhibitors and memantine. In most other dementias, no specific pharmacological treatment is currently available. There is an urgent need for further research on the effective management of dementias.
Occupational Therapy Intervention Process Model (OTIPM) – Betätigungsbasiert von Aufnahme bis Abschluss
Authors: Senn Daniela , Yvonne Indermühle , Eberhard Clara , Aegler Barbara
Published: May 2018

Prozessmodelle begleiten Therapeuten und Klienten durch den Therapieprozess und zeigen, wann welche Schritte anstehen. Damit können Ergotherapeuten das Vorgehen leichter planen und Entscheidungen begründeter treffen. Durchlaufen Sie diese strukturelle Hilfe des OTIPM zusammen mit Ergotherapeut Gabriel und seinem Klienten Herrn Tanner.
Structures and dynamics in a two-dimensional dipolar dust particle system
Authors: Hou X. N. , Liu Y. H. , Kravchenko O. V. , Lapushkina T. A. , Azarova O. A. , Chen Z. Y. , Huang F.
Published: May 2018

The effects of electric dipole moment, the number of dipolar particles, and system temperature on the structures and dynamics of a dipolar dust particle system are studied by molecular dynamics simulations. The results show that the larger electric dipole moment is favorable for the formation of a long-chain structure, the larger number of dipolar dust particles promotes the formation of the multi-chain structure, and the higher system temperature can cause higher rotation frequency. The trajectories, mean square displacement (MSD), and the corresponding spectrum functions of the MSDs are also calculated to illustrate the dynamics of the dipolar dust particle system, which is also closely related to the growth of dust particles. Some simulations are qualitatively in agreement with our experiments and can provide a guide for the study on dust growth, especially on the large-sized particles.
Common-path conoscopic interferometry for enhanced picosecond ultrasound detection
Authors: Liu Liwang , Guillet Yannick , Audoin Bertrand
Published: May 2018

We report on a common-path implementation of conoscopic interferometry in picosecond pump-probe reflectometry for simple and efficient detection of picosecond ultrasounds. The interferometric configuration proposed here is greatly simplified, involving only the insertion of a birefringent crystal in a standard reflectometry setup. Our approach is demonstrated by the optical detection of coherent acoustic phonons propagating through thin metal films under two representative geometries, one a particular case where the crystal slab is part of a sample as substrate of a metal film, and the other a more general case where the crystal slab is independent of the sample as part of the detection system. We first illustrate the former with a 300 nm thin film of polycrystalline titanium, deposited by physical vapor deposition on top of a 1 mm-thick uniaxial (0001) sapphire crystal. A signal-to-noise ratio (SNR) enhancement of more than 15 dB is achieved compared to conventional reflectometry. Next, the general case is demonstrated with a 900 nm-tungsten film sputtered on a silicon wafer substrate. More echoes can be discriminated by using the reported approach compared to standard reflectometry, which confirms the improvement in SNR and suggests broad applications for the reported method.
Atomistic modeling trap-assisted tunneling in hole tunnel field effect transistors
Authors: Long Pengyu , Huang Jun Z. , Povolotskyi Michael , Sarangapani Prasad , Valencia-Zapata Gustavo A. , Kubis Tillmann , Rodwell Mark J. W. , Klimeck Gerhard
Published: May 2018

Tunnel Field Effect Transistors (FETs) have the potential to achieve steep Subthreshold Swing (S.S.) below 60 mV/dec, but their S.S. could be limited by trap-assisted tunneling (TAT) due to interface traps. In this paper, the effect of trap energy and location on OFF-current (IOFF) of tunnel FETs is evaluated systematically using an atomistic trap level representation in a full quantum transport simulation. Trap energy levels close to band edges cause the highest leakage. Wave function penetration into the surrounding oxide increases the TAT current. To estimate the effects of multiple traps, we assume that the traps themselves do not interact with each other and as a whole do not modify the electrostatic potential dramatically. Within that model limitation, this numerical metrology study points to the critical importance of TAT in the IOFF in tunnel FETs. The model shows that for Dit higher than 1012/(cm2 eV) IOFF is critically increased with a degraded ION/IOFF ratio of the tunnel FET. In order to have an ION/IOFF ratio higher than 104, the acceptable Dit near Ev should be controlled to no larger than 1012/(cm2 eV).
The optical lens coupled X-ray in-line phase contrast imaging system for the characterization of low Z materials
Authors: Wang Kai , Lin Wei , Dai Fei , Li Jun , Qi Xiaobo , Lei Haile , Liu Yuanqiong
Published: May 2018

Due to the high spatial resolution and contrast, the optical lens coupled X-ray in-line phase contrast imaging system with the secondary optical magnification is more suitable for the characterization of the low Z materials. The influence of the source to object distance and the object to scintillator distance on the image resolution and contrast is studied experimentally. A phase correlation algorithm is used for the image mosaic of a serial of X-ray phase contrast images acquired with high resolution, the resulting resolution is less than 1.0 μm, and the whole field of view is larger than 1.4 mm. Finally, the geometric morphology and the inner structure of various weakly absorbing samples and the evaporation of water in the plastic micro-shell are in situ characterized by the optical lens coupled X-ray in-line phase contrast imaging system.
Remarks on the thermal stability of an Ohmic-heated nanowire
Authors: Timsit Roland S.
Published: May 2018

The rise in temperature of a wire made from specific materials, due to ohmic heating by a DC electrical current, may lead to uncontrollable thermal runaway with ensuing melting. Thermal runaway stems from a steep decrease with increasing temperature of the thermal conductivity of the conducting material and subsequent trapping of the ohmic heat in the wire, i.e., from the inability of the wire to dissipate the heat sufficiently quickly by conduction to the cooler ends of the wire. In this paper, we show that the theory used to evaluate the temperature of contacting surfaces in a bulk electrical contact may be applied to calculate the conditions for thermal runaway in a nanowire. Implications of this effect for electrical contacts are addressed. A possible implication for memory devices using ohmic-heated nanofilms or nanowires is also discussed.
Shock compression behavior of a mixture of cubic and hexagonal boron nitride
Authors: Hu Xiaojun , Yang Gang , Zhao Bin , Li Peiyun , Yang Jun , Leng Chunwei , Liu Hanyu , Huang Haijun , Fei Yingwei
Published: May 2018

We report Hugoniot measurements on a mixture of cubic boron nitride (cBN) and hexagonal boron nitride (hBN, ∼10% in weight) to investigate the shock compression behavior of BN at Hugoniot stresses up to 110 GPa. We observed a discontinuity at ∼77 GPa along the Hugoniot and interpreted it as the manifestation of the shock-induced phase transition of hBN to cBN. The experimental stress at 77–110 GPa shows significant deviation from the hydrodynamic Hugoniot of cBN calculated using the Mie-Grüneisen model coupled with the reported 300 K-isotherms of cBN. Our investigation reveals that material strength in cBN increases with the experimental stress at least up to 110 GPa. The material strength might be preserved at higher stress if we consider the previously reported high stress data.
Cyclic trimer of human cystatin C, an amyloidogenic protein - molecular dynamics and experimental studies
Authors: Chrabąszczewska Magdalena , Maszota-Zieleniak Martyna , Pietralik Zuzanna , Taube Michał , Rodziewicz-Motowidło Sylwia , Szymańska Aneta , Szutkowski Kosma , Clemens Daniel , Grubb Anders , Kozak Maciej
Published: May 2018

Human cystatin C (HCC) is a cysteine protease inhibitor that takes a series of oligomeric forms in solution (e.g., dimers, trimers, tetramers, decamers, dodecamers, and other higher oligomers). The best-known form of cystatin C is the dimer, which arises as a result of a domain swapping mechanism. The formation of the HCC oligomeric forms, which is most likely due to this domain swapping mechanism, is associated with the aggregation of HCC into amyloid fibrils and deposits. To investigate the structure of a specific HCC oligomer, we developed a covalently stabilized trimer of HCC. An atomic model of this HCC trimer was proposed on the basis of molecular docking and molecular dynamics simulations. The most stable model of the HCC trimer obtained from the molecular dynamics simulations is characterized by a well-preserved secondary structure. The molecular size and structural parameters of the HCC trimer in solution were also confirmed by Small Angle Neutron Scattering and Nuclear Magnetic Resonance Diffusometry.
Positron induced scattering cross sections for hydrocarbons relevant to plasma
Authors: Singh Suvam , Antony Bobby
Published: May 2018

This article explores positron scattering cross sections by simple hydrocarbons such as ethane, ethene, ethyne, propane, and propyne. Chemical erosion processes occurring on the surface due to plasma–wall interactions are an abundant source of hydrocarbon molecules which contaminate the hydrogenic plasma. These hydrocarbons play an important role in the edge plasma region of Tokamak and ITER. In addition to this, they are also one of the major components in the planetary atmospheres and astrophysical mediums. The present work focuses on calculation of different positron impact interactions with simple hydrocarbons in terms of the total cross section (Qtot), elastic cross section (Qel), direct ionization cross section (Qion), positronium formation cross section (Qps), and total ionization cross section (Qtion). Knowing that the positron-plasma study is one of the trending fields, the calculated data have diverse plasma and astrophysical modeling applications. A comprehensive study of Qtot has been provided where the inelastic cross sections have been reported for the first time. Comparisons are made with those available from the literature, and a good agreement is obtained with the measurements.
Tribo-electric charging of dielectric solids of identical composition
Authors: Angus John C. , Greber Isaac
Published: May 2018

Despite its long history and importance in many areas of science and technology, there is no agreement on the mechanisms responsible for tribo-electric charging, including especially the tribo-charging of chemically identical dielectric solids. Modeling of the excitation, diffusional transport, and de-excitation of electrons from hot spots shows that a difference in local surface roughness of otherwise identical solid dielectric objects leads to different transient excited electron concentrations during tribo-processes. The model predicts that excited electron concentrations are lower and concentration gradients higher in solids with rougher rather than smoother surfaces. Consequently, during contact, the flux of charge carriers (electrons or holes) from hot spots will be greater into the rougher solid than into the smoother solid. These predictions are in agreement with current and historical observations of tribo-electric charge transfer between solids of the same composition. This effect can take place in parallel with other processes and may also play a role in the charging of solids of different composition.
The nonlocal electron kinetics for a low-pressure glow discharge dusty plasma
Authors: Liang Yonggan , Wang Ying , Li Hui , Tian Ruihuan , Yuan Chengxun , Kudryavtsev A. A. , Rabadanov K. M. , Wu Jian , Zhou Zhongxiang , Tian Hao
Published: May 2018

The nonlocal electron kinetic model based on the Boltzmann equation is developed in low-pressure argon glow discharge dusty plasmas. The additional electron-dust elastic and inelastic collision processes are considered when solving the kinetic equation numerically. The orbital motion limited theory and collision enhanced collection approximation are employed to calculate the dust surface potential. The electron energy distribution function (EEDF), effective electron temperature Teff, and dust surface potential are investigated under different plasma and dust conditions by solving the Boltzmann and the dust charging current balance equations self-consistently. A comparison of the calculation results obtained from nonlocal and local kinetic models is made. It is shown that the appearance of dust particles leads to a deviation of the EEDF from its original profile for both nonlocal and local kinetic models. With the increase in dust density and size, the effective electron temperature and dust surface potential decrease due to the high-energy electron loss on the dust surface. Meanwhile, the nonlocal and local results differ much from each other under the same calculation condition. It is concluded that, for low-pressure (PR ≤ 1 cm*Torr) glow discharge dusty plasmas, the existence of dust particles will amplify the difference of local and nonlocal EEDFs, which makes the local kinetic model more improper to determine the main parameters of the positive column. The nonlocal kinetic model should be used for the calculation of the EEDFs and dusty plasma parameters.
Reweighted autoencoded variational Bayes for enhanced sampling (RAVE)
Authors: Ribeiro João Marcelo Lamim , Bravo Pablo , Wang Yihang , Tiwary Pratyush
Published: May 2018

Here we propose the reweighted autoencoded variational Bayes for enhanced sampling (RAVE) method, a new iterative scheme that uses the deep learning framework of variational autoencoders to enhance sampling in molecular simulations. RAVE involves iterations between molecular simulations and deep learning in order to produce an increasingly accurate probability distribution along a low-dimensional latent space that captures the key features of the molecular simulation trajectory. Using the Kullback-Leibler divergence between this latent space distribution and the distribution of various trial reaction coordinates sampled from the molecular simulation, RAVE determines an optimum, yet nonetheless physically interpretable, reaction coordinate and optimum probability distribution. Both then directly serve as the biasing protocol for a new biased simulation, which is once again fed into the deep learning module with appropriate weights accounting for the bias, the procedure continuing until estimates of desirable thermodynamic observables are converged. Unlike recent methods using deep learning for enhanced sampling purposes, RAVE stands out in that (a) it naturally produces a physically interpretable reaction coordinate, (b) is independent of existing enhanced sampling protocols to enhance the fluctuations along the latent space identified via deep learning, and (c) it provides the ability to easily filter out spurious solutions learned by the deep learning procedure. The usefulness and reliability of RAVE is demonstrated by applying it to model potentials of increasing complexity, including computation of the binding free energy profile for a hydrophobic ligand–substrate system in explicit water with dissociation time of more than 3 min, in computer time at least twenty times less than that needed for umbrella sampling or metadynamics.
Intradomain phase transitions in flexible block copolymers with self-aligning segments
Authors: Burke Christopher J. , Grason Gregory M.
Published: May 2018

We study a model of flexible block copolymers (BCPs) in which there is an enlthalpic preference for orientational order, or local alignment, among like-block segments. We describe a generalization of the self-consistent field theory of flexible BCPs to include inter-segment orientational interactions via a Landau-de Gennes free energy associated with a polar or nematic order parameter for segments of one component of a diblock copolymer. We study the equilibrium states of this model numerically, using a pseudo-spectral approach to solve for chain conformation statistics in the presence of a self-consistent torque generated by inter-segment alignment forces. Applying this theory to the structure of lamellar domains composed of symmetric diblocks possessing a single block of “self-aligning” polar segments, we show the emergence of spatially complex segment order parameters (segment director fields) within a given lamellar domain. Because BCP phase separation gives rise to spatially inhomogeneous orientation order of segments even in the absence of explicit intra-segment aligning forces, the director fields of BCPs, as well as thermodynamics of lamellar domain formation, exhibit a highly non-linear dependence on both the inter-block segregation (χN) and the enthalpy of alignment (ε). Specifically, we predict the stability of new phases of lamellar order in which distinct regions of alignment coexist within the single mesodomain and spontaneously break the symmetries of the lamella (or smectic) pattern of composition in the melt via in-plane tilt of the director in the centers of the like-composition domains. We further show that, in analogy to Freedericksz transition confined nematics, the elastic costs to reorient segments within the domain, as described by the Frank elasticity of the director, increase the threshold value ε needed to induce this intra-domain phase transition.
A 2 × 2 quantum dot array with controllable inter-dot tunnel couplings
Authors: Mukhopadhyay Uditendu , Dehollain Juan Pablo , Reichl Christian , Wegscheider Werner , Vandersypen Lieven M. K.
Published: May 2018

The interaction between electrons in arrays of electrostatically defined quantum dots is naturally described by a Fermi-Hubbard Hamiltonian. Moreover, the high degree of tunability of these systems makes them a powerful platform to simulate different regimes of the Hubbard model. However, most quantum dot array implementations have been limited to one-dimensional linear arrays. In this letter, we present a square lattice unit cell of 2 × 2 quantum dots defined electrostatically in an AlGaAs/GaAs heterostructure using a double-layer gate technique. We probe the properties of the array using nearby quantum dots operated as charge sensors. We show that we can deterministically and dynamically control the charge occupation in each quantum dot in the single- to few-electron regime. Additionally, we achieve simultaneous individual control of the nearest-neighbor tunnel couplings over a range of 0–40 μeV. Finally, we demonstrate fast (∼1 μs) single-shot readout of the spin state of electrons in the dots through spin-to-charge conversion via Pauli spin blockade. These advances pave the way for analog quantum simulations in two dimensions, not previously accessible in quantum dot systems.
Measuring the complex admittance and tunneling rate of a germanium hut wire hole quantum dot
Authors: Li Yan , Li Shu-Xiao , Gao Fei , Li Hai-Ou , Xu Gang , Wang Ke , Liu He , Cao Gang , Xiao Ming , Wang Ting , Zhang Jian-Jun , Guo Guo-Ping
Published: May 2018

We investigate the microwave reflectometry of an on-chip reflection line cavity coupled to a Ge hut wire hole quantum dot. The amplitude and phase responses of the cavity can be used to measure the complex admittance and evaluate the tunneling rate of the quantum dot, even in the region where transport signal through the quantum dot is too small to be measured by conventional direct transport means. The experimental observations are found to be in good agreement with a theoretical model of the hybrid system based on cavity frequency shift and linewidth shift. Our experimental results take the first step towards fast and sensitive readout of charge and spin states in Ge hut wire hole quantum dot.
Equation of state, phase stability, and phase transformations of uranium-6 wt. % niobium under high pressure and temperature
Authors: Zhang Jianzhong , Vogel Sven , Brown Donald , Clausen Bjorn , Hackenberg Robert
Published: May 2018

In-situ time-of-flight neutron diffraction experiments were conducted on the uranium-niobium alloy with 6 wt. % Nb (U–6Nb) at pressures up to 4.7 GPa and temperatures up to 1073 K. Upon static compression at room temperature, the monoclinic structure of U–6Nb (α″ U–6Nb) remains stable up to the highest experimental pressure. Based on the pressure-volume measurements at room temperature, the least-squares fit using the finite-strain equation of state (EOS) yields an isothermal bulk modulus of B0 = 127 ± 2 GPa for the α″-phase of U–6Nb. The calculated zero-pressure bulk sound speed from this EOS is 2.706 ± 0.022 km/s, which is in good agreement with the linear extrapolation of the previous Hugoniot data above 12 GPa for α″ U–6Nb, indicating that the dynamic response under those shock-loading conditions is consistent with the stabilization of the initial monoclinic phase of U-6Nb. Upon heating at ambient and high pressures, the metastable α″ U–6Nb exhibits complex transformation paths leading to the diffusional phase decomposition, which are sensitive to applied pressure, stress state, and temperature-time path. These findings provide new insight into the behavior of atypical systems such as U-Nb and suggest that the different U-Nb phases are separated by rather small energies and hence highly sensitive to compositional, thermal, and mechanical perturbations.
Seasonal variation in the profile of sex steroids and histological testicular development of brook trout (Salvelinus fontinalis Mitchill) during the annual reproductive cycle in Tasmania
Authors: Fatima Shafaq , Adams Mark , Wilkinson Ryan
Published: May 2018

Early maturation in brook trout males has been a constraint for commercial production of this species in Tasmania. However, control of maturation in males can be achieved by manipulating photoperiod (duration of light phase). To design an appropriate light treatment regime, an assessment of the annual reproductive cycle was initially required under ambient photoperiod as the annual reproductive cycle of male brook trout under ambient Tasmanian conditions of light and temperature was unknown. Here we describe the seasonal variations in testicular development and plasma profiles of testosterone (T), 11-ketotestosterone (11-KT) and oestradiol-17β (E2) during the second year in a male brook trout cohort held under ambient light conditions. Brook trout males were recruited for maturation in December when a reduction in daylength presumably stimulated testicular development. Increases in levels of T, 11-KT and gonadosomatic index (GSI) values were observed soon after the summer solstice, corresponding with maturation. The highest GSI mean value (3.44 ± 0.11%) was observed in April when mature males could be manually stripped of milt and such males were present until July. Profiles of sex steroids and histological development observed in this study were finely synchronised with variations in seasonal photoperiod changes. Photoperiod before recruitment during December should be controlled to manipulate maturation in brook trout males during their second year.
Aspects of reproduction, and morphology of the penis, of Pseudantechinus woolleyae (Marsupialia : Dasyuridae)
Authors: Woolley P. A.
Published: May 2018

Woolley’s Pseudantechinus, P. woolleyae, has remained virtually unstudied in the 30 years since its recognition in 1988 as a species distinct from P. macdonnellensis. It has a wide distribution in arid regions of Western Australia. What little is known of its biology comes largely from studies carried out over the years 1988–91 on one wild-caught female and her offspring, and a few specimens held in the collection of the Western Australian Museum. P. woolleyae is a seasonal breeder and young are born from late July to early October. They mature when ~7 months old. Both males and females are potentially capable of breeding in more than one year. Males have accessory erectile tissue that does not form an appendage on the penis.
Risk and safety challenges facing religious tourism - an introduction.
Authors: Raj R. , Griffin K. , Korstanje M. E.
Published: May 2018

This chapter offers an introduction to the risk and safety challenges facing religious tourism. It presents an overview of tourism-related research on (1) risk associated with individual or collective demographic assets; (2) risk associated with personality traits; and (3) risk as a disciplinary mechanism of control. An overview of the book's chapters is also presented.
Risk of terrorism and crime on the tourism industry.
Authors: Ayesha Chowdhury Ayesha Chowdhury , Raj R.
Published: May 2018

This chapter discusses the conceptual differences between crime, hate crime and terrorism. In addition, it evaluates the risks faced by travellers due to the recent phenomenon of terrorism, which has impacted the tourism industry greatly. Finally, the chapter illustrates that terrorism is an extraordinary type of crime that needs extraordinary legal protection.
Religious risk perceptions for medical travellers.
Authors: Bİlİm Y. , Bİrsen A. G.
Published: May 2018

Focusing on medical tourism, this chapter presents a discussion of the relationship between tourism and aspects of compulsory consumption. Religious factors and risk perceptions in consumer decision making in medical travel are examined.
Risk assessment and the religious event space: the context for the risk assessment.
Authors: Theodore B.
Published: May 2018

This chapter provides a specific contextual examination of the use of religious sites. Furthermore, it interrogates events, while providing a practical and logical approach to key areas that require risk assessment within the religious event space. The chapter identifies general risk factors and provides samples of risk documentation that may be used. It is anticipated that this will provide a practical guide explaining how to maximize opportunities to ensure the safety of attendees within the religious event space through the use of effective and comprehensive risk assessment practices.
Risk management or the right to ritual: attempting to control the masses at the Kumbh Mela.
Authors: Griffin D. , Radhakrishnan Y. P. , Griffin K.
Published: May 2018

This chapter introduces the Hindu festival Kumbh Mela as a motivating factor driving religious tourism and pilgrimage. Specific attention is given here to risk management at the 2013 Kumbh Mela in Allahabad, a mega-event in which over 100 million pilgrims attended and bathed in the river Ganga. Environmental and health concerns regarding the polluted water of the river Ganga are noted. The chapter addresses the fundamental question of how authorities can balance the needs, wants and requirements of the many stakeholders of this event, i.e. whether health and safety professionals can implement their water risk management plans while ensuring that pilgrims are allowed to attend and to perform a rite of passage that is a fundamental element of their faith.
The experience of medieval pilgrims on the route to Santiago de Compostela, Spain: evidence from the 12th-century Pilgrim's Guide.
Authors: Garton T.
Published: May 2018

The dramatic rise in popularity of the pilgrimage to Santiago de Compostela in the 11th and 12th centuries is reflected in the 12th-century Pilgrim's Guide, which provides information about shrines to visit and the experiences of pilgrims along the four main routes through France and northern Spain - routes which are used by pilgrims to this day. This chapter examines the information provided in the Pilgrim's Guide with an emphasis on the physical, visual and spiritual experiences of pilgrims along the route. The Guide describes the characteristics of the lands, peoples, local customs and food and drink experienced on the journey, as well as the miraculous qualities of saints whose shrines should be visited on the way, and in some cases the visual imagery of their shrines. Scholars have tended to emphasize the typical 'pilgrimage church' plan exemplified by the churches at Santiago, Toulouse or Conques, but a study of both the guide and the surviving churches reveals a rich variety of architectural forms and imagery that would have been experienced by 12th-century pilgrims along the pilgrimage routes. Each shrine emphasized the validity and significance of its relics, and the arrangement of the sacred space and visual imagery was frequently designed to demonstrate the miraculous powers or qualities of the local saint, as well as to encourage, warn and influence the behaviour and beliefs of devotees visiting the shrine. Methods of communication about the experiences of pilgrims have changed in recent times, as well as the religious emphasis; modern pilgrims have easy access to information about the journey and place less emphasis on the power of holy relics and more on the inner spiritual experience, but many aspects of walking the Camino remain the same.
Children's processions to Glasnevin: contestation, education, recreation.
Authors: Keely V.
Published: May 2018

Throughout the ages children participated in processions which were an integrated element of pilgrimage. Some processions included children as part of the general population of participants or spectators while other pilgrimage processions were designed specifically for them. Drawing on insights from the philosophy of place, emotional geography and anthropology, this chapter is a case study of a late 19th-century procession for schoolchildren in Dublin which reveals a fledging network of schools established to counter proselytism in the inner city. Tickets to a procession in the leafy suburb of Glasnevin were a coveted reward for impoverished inner-city schoolchildren enabling them to have a day out in an area of the city where the natural beauty of the pilgrimage site contrasted sharply with the squalid conditions of the slums of the Coombe. The pilgrimage to Glasnevin represents a temporary exodus from the contested spaces of the Coombe to a place where the Roman Catholic affiliation of the child pilgrims could be celebrated in tranquillity and enjoyment. Indeed enjoyment was an intended outcome rather than an unanticipated result of the procession, which is all the more remarkable given the Jansenist tendencies of the prevailing spirituality of the period. The procession functioned as a medium of socialization, enfolding the children in the relatedness of place, which served to reinforce their Roman Catholic identity in a highly charged climate of proselytism. Ordered in hierarchical ranks, the procession both reflected and imposed order within an ecclesial framework. Dialogue with other contributors in this volume shows the conceptual congruence between certain philosophies of place and the anthropological understanding of meshworks. The pronounced sensory elements of the Glasnevin procession - sight, hearing, smell and touch - were deployed to engage the whole person in the religious experience. Thus we are enabled to expand the notion of dreamscape to include knowledge mediated by sensory experience.