bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil-Geopolymer Mixtures Using Recycled Concrete Aggregates for Base and Subbase Layers
Authors: Odion Daniel , Khattak Mohammed J , Abader Makarios , Heim Nathan
Published: April 2019

The recycling of concrete aggregates has become a viable venture to investigate particularly its application in road construction. This study was conducted to proffer the feasibility of using recycled concrete aggregate (RCA) mixed with soil, flyash and alkali activator as an alternative to soil-cement in road base or subbase applications. The resulting product known as Soil-RCA geopolymer was made by varied mix constituents of flyash, RCA, sodium silicate, and sodium hydroxide. The influence of mixture variables on the mechanical properties of Soil-RCA geopolymer was investigated through an experiment design using two different flyash. Models to predict the unconfined compressive strengths based on mixture parameters were also established for the sensitivity analysis and selection of final mixtures. The results and analysis showed that the Soil-RCA geopolymer mixture exhibited sound strength, stiffness and durability characteristics.
An Overview of Corrosion Risk of Metal Culverts in Arkansas
Authors: Hasan Mdariful , Hossain Zahid
Published: April 2019

Metal culverts or pipes used in cross-drains along or across the Arkansas highway system are susceptible to corrode over time. Catastrophic incidents such as a complete washout of metal culverts along with roadway can be prevented if proper metals can be selected during the construction project. At present, the Arkansas Department of Transportation (ArDOT) does not have enough information about corrosion effects on metal culverts. The main objective of this study is to develop a user-friendly corrosion map for Arkansas by analyzing soil properties, water properties, and environmental data collected from the public domain as well as those gathered from laboratory experiments. Experimental data will be used to develop mathematical models to predict the resistivity and corrosive nature of soils. In this paper, relevant literature has been reviewed to narrow down the specific gaps in the available data and limitations in using methods to analyze the risk, challenges in developing regression and neural network models and risk mapping. Findings of this study have helped the research team to design the experimental plan and appropriate metrics need to be considered for developing the predictive models for this study.
Karst Sinkhole Detecting and Mapping Using Airborne LiDAR - A Conceptual Framework
Authors: Zhang Su , Bogus Susan , Baros Shirley , Neville Paul , Dow Ryan
Published: April 2019

Sinkholes cause subsidence and collapse problems for many transportation infrastructure assets. Subsequently, transportation infrastructure management agencies dedicate a considerable amount of time and money to detect and map sinkholes as part of their asset management programs. Traditionally, sinkholes are detected through area reconnaissance, which includes visual inspection of a site to locate existing sinkholes or device inspection of a site to locate potential sinkholes or previously filled sinkholes. Another method for sinkhole detection is through a review of maps such as geological maps. These methods are expensive, time-consuming, and labor-intensive. Recent advances in remote sensing, especially airborne light detection and ranging (LiDAR), allows for the examination of the change in the Earth's surface elevation accurately and rapidly. The focus of this study is to develop a conceptual framework for sinkhole detection and mapping with airborne LiDAR. This conceptual framework lays the foundation for the future application of airborne LiDAR for sinkhole detection and mapping.
Evaluation of Selected Performance Properties of Nanoclay-Modified Asphalt Binders
Authors: Hassan Mohammad N. , Tariq Morshed M M , Hossain Zahid
Published: April 2019

Asphalt binders are often modified with additives such as acid, polymer, or a combination of multiple additives to achieve improved performance to sustain heavy loads and adverse weather conditions. According to some previous researches, nanoclay can be a good alternative of currently practiced Styrene-Butadiene-Styrene (SBS) modification, and the former is expected to reduce the overall cost of the asphalt binder. Three types of nanoclay (Cloisite 10A, 11B, and 15A) were blended with asphalt binders prepared from two different sources (Arabian Crude and Canadian Crude). A blending protocol has been developed to blend nanoclay with the base binders. Mechanical properties including viscosity, rutting parameter have undergone significant changes after the nanoclay modification. It was also observed that nanoclay modified binders offer different moisture susceptibility while bonding with different aggregates; the nanoclay modified asphalt binder exhibits better bonding with gravel than sandstone. Mechanistic properties such as viscosity and rutting parameter are found to be highly correlated with the chemical compositions. Binders from the Canadian crude showed more colloidal stability than binders from the Arabian crude after nanoclay modification.
Investigating the Effect of Artificial Ageing on the Creep and Recovery of SBS-Modified Bitumen
Authors: Cuciniello Giacomo , Leandri Pietro , Lo Presti Davide , Losa Massimo , Airey Gordon
Published: April 2019

Polymer additives are widely used to improve the performances of road bitumen and mixtures including their oxidative resistance. However, their effect on the oxidative mechanism remains unclear. This study includes the investigation of the changes in the rheological response of Polymer Modified Bitumen (PMBs) prepared with the Styrene Butadiene Styrene (SBS) copolymer and Sulphur as cross-linker. The bitumen samples were aged in the Rolling Thin Film Oven (RTFO) and in multiple cycles of Pressure Aging Vessel (PAV). The rheological properties were measured by means of the Multiple Stress Creep and Recovery (MSCR) test. Results show that in the case of cross-linked SBS modified bitumen the polymer phase mitigates the effect of hardening of the bitumen phase on the rheological response as a function of the polymer concentration. Adversely, in the SBS modified bitumen without cross-linker, the effect of the polymer vanishes after the RTFO.
Cost-Effective ECC with Low Fiber Content for Pavement Application
Authors: Arce Gabriel , Noorvand Hassan , Hassan Marwa , Rupnow Tyson , Hungria Ricardo
Published: April 2019

The objective of this study was to evaluate the feasibility of a cost-effective Engineered Cementitious Composite (ECC) with low fiber content (1.5% volume fraction) for pavement application. The ECC material studied was evaluated in compression, uniaxial tension and bending. In addition, flexural fatigue performance was evaluated. The cost-effective ECC material evaluated in this study exhibited a compressive strength of 37.6 MPa, a tensile ductility of 2.61%, and a flexural strength of 9.58 MPa. Moreover, the ECC material exhibited an equivalent flexural fatigue life to that of concrete at approximately two times the applied stress. Based on the experimental findings, it was shown that the cost-effective ECC materials with low fiber content can be promising for pavement application.
Shrinkage in Ultra-High Performance Concrete Overlays on Concrete Bridge Decks
Authors: Toledo William , Davila Leticia , Al-Basha Ahmed , Newtson Craig , Weldon Brad
Published: April 2019

This paper investigates the shrinkage and thermal effects of an ultra-high performance concrete (UHPC) mixture proposed for use as an overlay material for concrete bridge decks. In this study, early-age and longer-term shrinkage tests were performed on the locally produced UHPC. Thermal and shrinkage effects in normal strength concrete slabs overlaid with UHPC were also observed. Early-age shrinkage testing showed that approximately 55% of the strain occurred in the plastic state and may not contribute to bond stresses since the elastic modulus of the UHPC should be small at such early ages. Thickness of the substrate and amount of reinforcing steel were important factors for shrinkage in the slabs. The thickest slab experienced greater shrinkage than thinner slabs. Comparing this slab to a thinner slab with the same reinforcement indicated that reinforcement ratio is more important than the area of steel.
Potential Use of Rice Husk Ash (RHA) in Flowable Fill Concrete
Authors: Islam Kazi , Hossain Zahid
Published: April 2019

Flowable fill is a self-compacting material, which has been developed in recent years. It is a relatively new construction technology where rapid construction is needed for different applications such as backfilling walls, sewer trenches, bridge abutments, conduit trenches, pile excavations, and retaining walls. The objective of this study is to evaluate the usage of RHA in producing low strength and self-consolidating flowable fill concrete (FFC). Two different RHA samples (600 µm and 150 µm) in three different percentages (40%, 60%, and 80% by the weight) of Ordinary Portland Cement (OPC) have been used to prepare flowable fill mixture. The evaluation processes of these fresh FFC mixtures includes determination of strength, setting time, flowability, unit weight, and air content in the laboratory. Further, two field demonstration projects have been planned to evaluate their workability, placement, and in-service performance. Findings of this study will help the transportation and the construction agencies in finding a cost-effective construction material.
Development of Deflection Parameters to Evaluate the Structural Capacity of Flexible Pavements at the Network Level: Case Study for the State of Texas
Authors: Loganathan Karthikeyan , Isied Mayzan , Coca Ana Maria , Souliman Mena , Romanoschi Stefan , Dessouky Samer
Published: April 2019

Pavement deflection has been used widely as a nondestructive technique to evaluate the structural capacity of pavements at both network and project levels. Various transportation agencies use several evaluation methods to evaluate the integrity of the pavement layers. Most of these up-to-date developed indices are exclusively based on either central deflections or one deflection point along FWD deflection bowl. However, no standardized method that utilizes the full FWD deflection bowl is available. This study aims to introduce new comprehensive pavement layer deflection and deflection bowl area parameters that are based on the entire FWD deflection bowl rather than one single deflection point and to relate the developed parameters to the field measured distress data. Thirty-five different pavement sections in the State of Texas were utilized in the study. Two comprehensive deflection parameters and a ranking scale were developed that may be utilized for the overall pavement structural condition evaluation.
Guidelines for Identification of Top-down Cracks (TDC) in In-Service Flexible Pavements
Authors: Dhakal Nirmal , Bashar Mohammad , Elseifi Mostafa
Published: April 2019

The objective of this study was to establish guidelines to identify top-down cracking (TDC) in flexible pavements using digital image analysis and the characteristics of these cracks. Past studies indicated that the time after construction of the pavement and location of the cracks are key parameters to identify top-down cracking. The cracks were reported to appear on the wheel path or at the outer edge of the wheel path typically within 3 to 8 years of construction. In-service pavement sections were selected for analysis based on the parameters identified from the literature and computer-vision techniques were employed to investigate the geometric characteristics of these cracks. Based on the results of the analysis, the average crack width was observed to be 3 to 7 mm. With respect to the orientation of the crack, the cracks segments were mostly longitudinal with typical deviation of 20 degrees. The orientation and intensity characteristics of top-down cracks were found as useful features in crack identification.
Use of LTPP Data to Quantify Moisture Damage under Crack Sealing and Surface Treatments in Asphalt Pavements
Authors: Mousa Momen R. , Elseifa Mostafa A. , Bashar Mohammed Z.
Published: April 2019

Crack sealing and seal coats are used to prevent the ingress of water into the pavement, thus delaying its deterioration. Yet, earlier studies indicated that sealing pavements in areas with high ground water table (GWT) prevented moisture from escaping upwards through the cracks of asphalt pavements, therefore, accelerating stripping. The objectives of this study were to determine whether these treatments contribute to stripping in Asphalt Concrete (AC) and/or moisture accumulation in the base and to evaluate the effect of GWT, rain, and traffic on subsurface failures under these treatments. In this study, nine test sections included in the Long-Term Pavement Performance (LTPP) program and several field chip seal projects in Louisiana were analyzed. Results indicated that these treatments do not contribute to stripping. However, the cause of common stripping under these treatments in the Southern United States is moisture entrapment under the AC layer under shallow GWT conditions, which is also the key contributor to stripping under unsealed sections.
New proposals for modelling and solving the problem of covering solids using spheres of different radii
Authors: González Silva Pedro Henrique , Macambira Ana Flávia U. S. , Pinto Renan Vicente , Simonetti Luidi , Maculan Nelson , Michelon Philippe
Published: April 2019

Given a solid T, represented by a compact set in ℝ3, the aim of this work is to find a covering of T by a finite set of spheres of different radii. Some level of intersection between the spheres is necessary to cover the solid. Moreover, the volume occupied by the spheres on the outside of T is limited. This problem has an application in the planning of a radio-surgery treatment known by Gamma Knife and can be formulated as a non-convex optimization problem with quadratic constraints and linear objective function. In this work, two new linear mathematical formulations with binary variables and a hybrid method are proposed. The hybrid method combines heuristic, data mining and an exact method. Computational results show that the proposed methods outperform the ones presented in the literature.
Selten, oft übersehen und tödlich: stumpfes Thoraxtrauma mit Bronchusabriss bei täglichen Unfällen
Authors: Rielage Thomas
Published: April 2019

Es wird von einer 32-jährigen Frau, die mit ihrem Kleinwagen mit überhöhter Geschwindigkeit innerstädtisch verunfallte und dabei ein isoliertes Hals-Thorax-Trauma erlitt, berichtet. Als lebensbedrohliches Verletzungsmuster kam es zu einem tracheobronchialen Trauma mit Einriss der Trachealhinterwand, einem Bronchusabriss und Pneumothorax. In der Folge verstarb die Patientin an einer Hypoxämie, bevor eine operative Versorgung erfolgen konnte. In der Diskussion wird auf die Prävalenz des Verletzungsmusters und auf die notfallmedizinische Versorgung eingegangen.
Evaluation des Fragebogens zur Erfassung des stimmlichen
Selbstkonzepts durch HNO-Tumorpatienten
Authors: Lehnert Bernhard , Janotte Ben
Published: April 2019

Hintergrund Der Fragebogen zur Erfassung des stimmlichen Selbstkonzepts
(FESS) fragt persönlichkeitsbezogene Aspekte der Stimme ab. Untersucht werden
soll, wie geeignet der Fragebogen für Patienten mit Kopf-Hals-Tumoren ist. Zuvor
wurde er anonym in einer Tumornachsorgesprechstunde erhoben. Dort gaben die
Patienten ganz überwiegend an, dass Ihnen das Ausfüllen leichtfalle. Um zu
erheben, wo noch Schwierigkeiten liegen, wurden Einzelgespräche mit einer
Patientengruppe über den Fragebogen geführt. Als Nebenfragestellungen wurden die
für das Ausfüllen des Fragebogens benötigte Zeit und etwaige Zusammenhänge mit
der objektiven Stimmqualität erhoben.

Material und Methoden 113 Patienten einer HNO-Tumornachsorgesprechstunde
füllten den Fragebogen aus und wurden dazu individuell befragt. Die für das
Ausfüllen benötigte Zeit wurde gemessen und der Acoustic Voice Quality Index
(AVQI) bestimmt.

Ergebnisse Eine Mehrheit von Patienten fand den Fragebogen leicht
auszufüllen. Für einen kleineren Anteil an Patienten enthält der Bogen schwer zu
beantwortende Items, unverständliche Items und ein für sie zu kompliziertes
Antwortschema. Im Durchschnitt benötigten die Patienten 3 Minuten pro Bogen, 90
% füllten ihn in 4,5 oder weniger Minuten aus. Erwartungsgemäß korrelierte dies
schwach mit Bildungsniveau und Alter.

Schlussfolgerungen Die Einzelbefragungsergebnisse widersprechen nicht der
erhofften Anwendbarkeit des Fragebogens in einem großen Teil der Patienten und
mit durchschnittlich 3 Minuten ist die Belastung nicht zu groß. Ein nicht
vernachlässigbarer Anteil dieser Gruppe ist mit den Items und dem Antwortformat
überfordert, etwa jeder 7. hält den Fragebogen nicht für klinisch anwendbar.
Unsere Interviews zeigen eine Reihe von kritischen Items und den damit
verbundenen Schwierigkeiten auf, so dass der Anwender Limitationen eher
abschätzen und verstehen kann.
Chronische Rhinosinusitis mit Nasenpolypen: Schleimhaut
„rebooten“
Authors: Reichel Oliver
Published: April 2019

Alsharif S et al. Endoscopic Sinus Surgery for Type-2 CRS wNP: An Endotype-Based
Retrospective Study. Laryngoscope 2019; doi: 10.1002/lary.27815

HNO-Ärzte aus Gent haben eine neue Operationstechnik zur Behandlung einer
chronischen Rhinosinusitis mit Nasenpolypen (CRSwNP) entwickelt. Bei diesem
„Reboot“-Verfahren wird die gesamte Sinusschleimhaut maximal entfernt, um
eine gesunde Reepithelialisierung aus der konservierten Nasenschleimhaut zu
ermöglichen. Verglichen wurde die klassische, schleimhautschonende,
endoskopische Nasennebenhöhlenoperation (ESS) mit dem
„Reboot“-Verfahren.
Psychologische Aspekte von Hochintensivem Intervalltraining (HIIT) in der Therapie: Eine Übersicht der Literatur
Authors: Kleinert Jens , Bassek Manuel
Published: April 2019

Der Beitrag gibt eine Literaturübersicht zu psychologischen Aspekten von Hochintensivem Intervalltraining (HIIT) in der Therapie anhand von 13 Studien mit insgesamt 1204 Patienten. Die bisherige Forschung analysiert überwiegend Lebensqualität, Depression, Angst und Erschöpfung. Hinsichtlich positiver Effekte sind die Ergebnisse inkonsistent. Negative psychische Effekte von HIIT konnten nicht nachgewiesen werden.
Hoch-intensives Intervalltraining in der onkologischen Rehabilitation – Erfahrungen aus der Therapiepraxis
Authors: Schmitt Joachim
Published: April 2019

Aerobes Ausdauertraining stellt in der Rehabilitation verschiedenster Indikationen eine wesentliche Trainingsform dar, um die individuellen Leistungs- und Gesundheitsressourcen zu verbessern. Allerdings fühlt sich nicht jeder Patient von aerobem Training ausgelastet und lässt sich dazu motivieren. Eine aktuelle, zunehmend erforschte Trainingsform stellt Hochintensives Intervalltraining (HIIT) dar, da Studien gezeigt haben, dass im Vergleich zu niedrig-intensivem Training in kürzerer Zeit ähnliche oder höhere Effekte auf die körperliche Leistungsfähigkeit zu erwarten sind. In der Rehaklinik Am Kurpark in Bad Kissingen wurde HIIT 2015 erstmals als zusätzliche Trainingsvariante implementiert und in der Therapie onkologischer Patienten erprobt. Unter anderem konnte so das Fatigue-Syndrom deutlich gemildert werden. HIIT, als umsetzbare und sichere Trainingsform nach Krebs, könnte somit künftig eine Alternative zum herkömmlichen Ausdauertraining werden.
Auswirkungen sportlicher Aktivitäten bei Kindern mit Aufmerksamkeits-Defizit-Hyperaktivitäts-Störung (ADHS) unter besonderer Betrachtung von Hochintensivem Intervalltraining als innovativen, therapeutischen Ansatz
Authors: Meßler Carolin Friederike
Published: April 2019

Literaturanalysen haben ergeben, dass Hochintensives Intervalltraining positive Ergebnisse in Bezug auf die Leitsymptomatik, die motorischen Fähigkeiten und sozialen Kompetenzen von Kindern mit Aufmerksamkeits-Defizit-Hyperaktivitäts-Störung (ADHS) erzielt. Ebenso lassen sich der Selbstwert und die Lebensqualität von ADHS-betroffenen Kindern durch eine 3-wöchige Interventionsphase positiv beeinflussen. Ein 1:1-Training ermöglicht individuelle Betreuung und erhöht die Compliance der Kinder. Das Hochintensive Intervalltraining greift das natürliche intervallartige Bewegungsverhalten der Kinder auf und bietet eine Möglichkeit, durch kurze Trainingszeiten dies in den Alltag der Kinder zu integrieren. Es stellt so eine attraktive und speziell auf Kinder ausgerichtete Intervention dar, welche nebenwirkungsfrei, effektiv und kostengünstig ist.
Related Risk Factors between Subclinical Carotid Atherosclerosis and Diabetic Retinopathy in Newly Diagnosed Type 2 Diabetes Mellitus in China
Authors: Guo Fengqi , Zhou Ting , Tang Juan , Dong Mingxia , Wei Qianping
Published: April 2019

Purpose To analyze the clinical features and related risk factors in diabetic retinopathy (DR) and subclinical atherosclerosis, the micro- and macro-vascular diseases in newly diagnosed type 2 diabetes mellitus (T2DM).

Methods A retrospective study of 435 cases of inpatients with newly diagnosed T2DM from 2013–2017, and compare the 2 types of T2DM related vascular complications.

Results The macro- and microvascular complications are not rare at this stage. Subclinical atherosclerosis was found in 251 subjects (57.7%), which was higher than that of DR (13.1%). In addition, some cases of subclinical atherosclerosis co-existed with DR, suggesting that DR was related with subclinical atherosclerosis (r=0.098, P=0.041). Older age showed a significant association with both subclinical atherosclerosis and DR. Single factor analysis indicated that dyslipidemia was the common risk factor in DR and subclinical atherosclerosis.

Conclusions It should be paid attention to the screening of both DR and subclinical atherosclerosis in each age group of newly diagnosed T2DM. Except for the control of blood glucose, the control of the dyslipidemia is important in the prevention and treatment of the micro- and macro-vascular diseases.
Sprachverstehen und kognitive Leistungen bei Senioren ohne
subjektive Hörminderung
Authors: Weißgerber Tobias , Müller Carmen , Stöver Timo , Baumann Uwe
Published: April 2019

Ziel der Arbeit war es, die Hörleistung von Senioren ohne selbst empfundene
Hörminderung hinsichtlich des Sprachverstehens in Ruhe sowie im Störgeräusch zu
untersuchen und auf Zusammenhänge mit dem Lebensalter und der kognitiven
Leistungsfähigkeit zu prüfen. Es wurden 40 Probanden im Alter von über 60 Jahren
(Durchschnittsalter: 69,3 ± 7,1 Jahre) in die Studie eingeschlossen.
Anhaltspunkte für bedeutende Defizite der kognitiven Leistungsfähigkeit der
Probanden wurden mit einem Demenzscreening-Test (DemTect) untersucht. Weiterhin
wurden der mittlere Hörverlust (PTA_4) sowie mittlerer Hochtonhörverlust
(PTA_HT) bestimmt. Das Sprachverstehen in Ruhe wurde mit dem Freiburger
Sprachverständlichkeitstest und im Störgeräusch mit dem Oldenburger Satztest mit
verschiedenen Störgeräuschen (zeitlich kontinuierliches und amplitudenmoduliert)
gemessen.

Die Ergebnisse des DemTect-Testes waren bei 65 % der Probanden altersgemäß, bei
den restlichen 35 % ergab sich der Verdacht auf eine milde Einschränkung der
kognitiven Fähigkeiten. Die Hörverluste PTA_4 und PTA_HT der Probanden
korrelierten signifikant sowohl mit dem Alter als auch mit den Ergebnissen des
DemTect-Tests. Das Sprachverstehen der Probanden in Ruhe und im Störgeräusch
nahm signifikant sowohl mit dem Alter als auch in den Parametern zur
Einschätzung der kognitiven Leistungsfähigkeit ab. Um eine fehlende oder späte
Versorgung mit Hörgeräten aufgrund einer nicht oder nicht frühzeitig erkannten
Hörminderung bei Senioren zu vermeiden, wären routinemäßig Hörtests
wünschenswert, sodass zum einen eine rechtzeitige Gewöhnung an die Hörhilfe und
ein besserer Hörerfolg erzielt und zum anderen die Lebensqualität erhalten
werden kann.
Computer-Assisted Surgery Using 3D Printed Saw Guides for Acute Correction of Antebrachial Angular Limb Deformities in Dogs
Authors: Worth Andrew , Crosse Katherine , Kersley Andrew
Published: April 2019

Objective The aim of this study was to report the use of custom saw guides produced using computed tomographic imaging (CT), computer simulation and three-dimensional (3D) printing to aid surgical correction of antebrachial deformities in six dogs.

Materials and Methods Antebrachial limb deformities in four small, and two large, breed dogs (seven limbs) were surgically corrected by a radial closing wedge ostectomy and ulnar osteotomy. The location and orientation of the wedge ostectomy were determined using CT data, computer-assisted planning and production of a saw guide in plastic using a 3D printer. At surgery, the guide was clamped to the surface of the radius and used to direct the oscillating saw blade. The resultant ostectomy was closed and stabilized with a bone plate.

Results Five limbs healed without complications. One limb was re-operated due to a poorly resolved rotational component of the deformity. One limb required additional stabilisation with external fixation due to screw loosening. The owners of five dogs completed a Canine Orthopedic Index survey at a follow-up period of 37 to 81 months. The median preoperative score was 3.5 and the median postoperative score was 1, representing an overall positive effect of surgery. Radiographically, 5/7 limbs were corrected in the frontal plane (2/7 were under-corrected). Similarly, 5/7 limbs were corrected in the sagittal plane, and 2/7 were over-corrected in the sagittal place.

Conclusions Computer-aided design and rapid prototyping technologies can be used to create saw guides to simplify one-stage corrective osteotomies of the antebrachium using internal fixation in dogs. Despite the encouraging results, accurate correction of rotational deformity was problematic and this aspect requires further development.
Enhanced photoneutron production by intense picoseconds laser interacting with gas-solid hybrid targets
Authors: Qi Wei , Zhang Xiaohui , Zhang Bo , He Shukai , Zhang Feng , Cui Bo , Yu Minghai , Dai Zenghai , Peng Xinyu , Gu Yuqiu
Published: April 2019

Experiments to enhance photoneutron production from the Ta (γ,xn) reaction with 100 TW picosecond laser pulses irradiating on gas-solid hybrid targets have been performed on the XingGuangIII laser facility at the Laser Fusion Research Center (LFRC) in Mianyang. The so-called gas-solid hybrid target was composed of a 1 mm thick N2 gas jet and a 2 cm thick Ta block. Picosecond laser pulses with intensities up to 1019 W/cm2 first interact with the tenuous gas to enhance the yields of high energy electrons through the direct laser acceleration (DLA) mechanism, and then through bremsstrahlung and subsequent (γ, n) reactions in a Ta converter, photoneutrons were enhanced effectively and the total number of neutrons was optimized by changing the gas density. A maximum neutron yield of 4 × 107/shot over 4π was achieved which is 200 times higher than that in the direct laser-solid interaction shot in our experiment. The spectrum of photoneutrons was measured which is in agreement with Monte Carlo (MC) simulation. From the size of the reaction area and the neutron pulse duration inferred from simulation, the corresponding flux was calculated to be 1.2 × 1016 n/cm2/s.
Weak-shock wave propagation in polymer-based particulate composites
Authors: Ravindran S. , Tessema A. , Kidane A. , Jordan J.
Published: April 2019

Shock waves are common in polymer-based particulate composites that are subjected to intermediate to high-velocity impact loading. However, quantitative information on the spatial variation of stress, particle velocities, and energy dissipation during the formation and propagation of weak-shock waves is limited. In this paper, a systematic experimental study is conducted to understand the characteristics of weak-shocks in polymer-bonded particulate composites. Specimens made of polymer-bonded sugar are subjected to a projectile impact loading, at varying velocities, using a modified Hopkinson pressure bar apparatus. Full-field displacement and strains of the deformed samples are obtained with the help of an ultrahigh-speed imaging and digital image correlation technique. Using the full-field displacement data, the shock wave velocity, shock front thickness, and the full-field stress fields are calculated. From the spatial stress field and the strain rate data, the spatial energy dissipation profile is also estimated. The effect of impact velocity on the spatial stress profile, shock wave velocity, and energy dissipation are discussed.
Non-adiabatic quantum molecular dynamics by the basis expansion leaping multi-configuration Gaussian (BEL MCG) method: Multi-set and single-set formalisms
Authors: Murakami Tatsuhiro , Frankcombe Terry J.
Published: April 2019

Non-adiabatic transitions are quite often of critical importance in chemical reactions. We have recently developed the basis expansion leaping multi-configuration Gaussian (BEL MCG) method to obtain time-propagated wave packets describing multidimensional reactive molecular systems such as quantum tunneling [T. Murakami and T. J. Frankcombe, J. Chem. Phys. 149, 134113 (2018)]. In this work, we develop BEL MCG for multiple electronic state problems. We present two formalisms for the BEL MCG description of multi-state wave packets, namely, “multi-set” and “single-set.” We pay particular attention to investigate what is required to yield accurate dynamics. When there is low population on an electronic state, it is important in the “multi-set” case that the reexpression on that electronic state is applied rigorously. The sharing of basis functions in the single-set approach leads to needing a lower number of basis functions than in the multi-set approach, making it preferable for direct dynamics.
On the spectrum-generating superalgebras of the deformed one-dimensional quantum oscillators
Authors: Aizawa N. , Cunha I. E. , Kuznetsova Z. , Toppan F.
Published: April 2019

We investigate the dynamical symmetry superalgebras of the one-dimensional matrix superconformal quantum mechanics with inverse-square potential. They act as spectrum-generating superalgebras for the systems with the addition of the de Alfaro-Fubini-Furlan oscillator term. The undeformed quantum oscillators are expressed by 2n × 2n supermatrices; their corresponding spectrum-generating superalgebras are given by the osp(2n|2) series. For n = 1, the addition of an inverse-square potential does not break the osp(2|2) spectrum-generating superalgebra. For n = 2, two cases of inverse-square potential deformations arise. The first one produces Klein deformed quantum oscillators; the corresponding spectrum-generating superalgebras are given by the D(2, 1; α) class, with α determining the inverse-square potential coupling constants. The second n = 2 case corresponds to deformed quantum oscillators of non-Klein type. In this case, the osp(4|2) spectrum-generating superalgebra of the undeformed theory is broken to osp(2|2). The choice of the Hilbert spaces corresponding to the admissible range of the inverse-square potential coupling constants and the possible direct sum of lowest weight representations of the spectrum-generating superalgebras is presented.
Symplectic integration and physical interpretation of time-dependent coupled-cluster theory
Authors: Pedersen Thomas Bondo , Kvaal Simen
Published: April 2019

The formulation of the time-dependent Schrödinger equation in terms of coupled-cluster theory is outlined, with emphasis on the bivariational framework and its classical Hamiltonian structure. An indefinite inner product is introduced, inducing physical interpretation of coupled-cluster states in the form of transition probabilities, autocorrelation functions, and explicitly real values for observables, solving interpretation issues which are present in time-dependent coupled-cluster theory and in ground-state calculations of molecular systems under the influence of external magnetic fields. The problem of the numerical integration of the equations of motion is considered, and a critical evaluation of the standard fourth-order Runge–Kutta scheme and the symplectic Gauss integrator of variable order are given, including several illustrative numerical experiments. While the Gauss integrator is stable even for laser pulses well above the perturbation limit, our experiments indicate that a system-dependent upper limit exists for the external field strengths. Above this limit, time-dependent coupled-cluster calculations become very challenging numerically, even in the full configuration interaction limit. The source of these numerical instabilities is shown to be rapid increases of the amplitudes as ultrashort high-intensity laser pulses pump the system out of the ground state into states that are virtually orthogonal to the static Hartree-Fock reference determinant.
An explicit electron-vibron model for olfactory inelastic electron transfer spectroscopy
Authors: Liza Nishattasnim , Blair Enrique P.
Published: April 2019

The vibrational theory of olfaction was posited to explain subtle effects in the sense of smell inexplicable by models in which a molecular structure alone determines an odorant’s smell. Amazingly, behavioral and neurophysiological evidence suggests that humans and some insects can be trained to distinguish isotopologue molecules that are related by the substitution of isotopes for certain atoms, such as a hydrogen-to-deuterium substitution. How is it possible to smell a neutron? The physics of olfaction may explain this isotopomer effect. Inelastic electron transfer spectroscopy (IETS) has been proposed as a candidate mechanism for such subtle olfactory effects: the vibrational spectrum of an appropriately quantized odorant molecule may enhance a transfer rate in the discriminating electron transfer (ET) process. In contrast to other semiclassical or quantum-master-equation-based models of olfactory IETS, the model presented here explicitly treats the dynamics of a dominant odorant vibrational mode, which provides an indirect dissipative path from the electron to the thermal environment. A direct dissipative path to the environment is also included. Within this model, a calculation of the ET rate is developed, along with a calculation of power dissipation to the thermal environment. Under very weak direct dissipative coupling, spectroscopic behaviors of the indirect path are revealed, and the resulting ET rate exhibits resonant peaks at certain odorant frequencies. Resonant peaks in the ET rate also correlate to peaks in power dissipation. Spectroscopic behaviors are masked by strong direct dissipative coupling. Results support a rate-based discrimination between a preferred ligand and an isotopomer if indirect dissipative coupling dominates.
Predissociation dynamics of D2 + hv → D(1s1/2) + D(2p1/2,3/2, 2s1/2) revealed by the spin-orbit state resolved fragment branching ratios and angular distributions
Authors: Wang Jie , Mo Yuxiang
Published: April 2019

For molecular photodissociations, the spin-orbit state resolved fragment branching ratios and angular distributions provide deep insight into the dynamics. For the first excited state of the H(2p1/2,3/2) atom, a branching ratio measurement is a challenge because of small energy spacing between them. For the D(2p1/2,3/2) fragments from the predissociation of D2 + 14.76 eV → D(1s) + D(2s, 2p1/2,3/2) in the 2pπC1Πu (υ = 19) state, we made such measurements by pumping the D(2s, 2p1/2,3/2) fragments to high-lying Rydberg states that are subsequently ionized by a delayed-pulse electric field. In the 2pπC1Πu (υ = 19) state, the D2 molecule dissociates via both shape and Feshbach resonances correlating to the channels D(1s) + D(2p3/2) and D(1s) + D(2p1/2), respectively. The measured spin-orbit branching ratios, 2p3/2/(2p1/2 + 2p3/2), correspond to the diabatic limit, 2/3, which indicates strong spin-orbit state mixings near the dissociation limits. The spin-orbit state resolved fragment angular distributions also support the diabatic dissociation mechanism and illustrate simultaneous shape and Feshbach resonances for the R(0) transition.
Characterization of gas-phase thorium nitride
Authors: Le Anh T. , Nakhate Sanjay G. , Nguyen Duc-Trung , Steimle Timothy C. , Heaven Michael C.
Published: April 2019

Properties of gas-phase thorium nitride, ThN, have been experimentally determined from a combined optical and microwave spectroscopic study. An intense band near 555 nm has been assigned as the [18.0]1.5–X2Σ+ (0,0) transition and recorded at high resolution in the presence of static electric and magnetic fields. The observed optical Stark shifts were analyzed to determine permanent electric dipole moments, μ→el for the [18.0]1.5 and X2Σ+ states of 4.38 ± 0.02D and 5.11 ± 0.09D, respectively. Zeeman shifts were used to determine the magnetic g-factors. The pure rotational spectrum was recorded using a separated field optical pump/probe microwave repopulation scheme and analyzed to determine the bond length and 14N magnetic hyperfine and nuclear electric quadrupole parameters. A molecular orbital correlation diagram and ligand field electronic structure models are used to provide a qualitative interpretation of the electronic state ordering, magneto- and electro-static properties, and hyperfine interactions. Electronic structure calculations for the X2Σ+ state were performed, and results were compared with observations. Observed trends in μ→el for the ThX (X = N, S, O, F, and Cl) series are discussed.
Tamm phonon-polaritons: Localized states from phonon-light interactions
Authors: Juneau-Fecteau Alexandre , Savin Rémy , Boucherif Abderraouf , Fréchette Luc G.
Published: April 2019

We present experimental evidence of optical Tamm states at the interface of a one-dimensional photonic crystal made of porous Si and hexagonal SiC. This phenomenon occurs in the mid-infrared within the Reststrahlen band where SiC optically behaves as a metal due to phonons. We name the observed interface states Tamm phonon-polaritons by analogy to Tamm plasmon-polaritons at the interface of a photonic crystal and a metal. The high quality factor of the observed resonance makes polar dielectrics attractive materials to achieve Tamm states in the mid-infrared, which could benefit applications such as selective thermal emission and mid-infrared sensing.
Infrared bands of CS2 dimer and trimer at 4.5 μm
Authors: Barclay A. J. , Esteki K. , Michaelian K. H. , McKellar A. R. W. , Moazzen-Ahmadi N.
Published: April 2019

We report observation of new infrared bands of (CS2)2 and (CS2)3 in the region of the CS2 ν1 + ν3 combination band (at 4.5 µm) using a quantum cascade laser. The complexes are formed in a pulsed supersonic slit-jet expansion of a gas mixture of carbon disulfide in helium. We have previously shown that the most stable isomer of (CS2)2 is a cross-shaped structure with D2d symmetry and that for (CS2)3 is a barrel-shaped structure with D3 symmetry. The dimer has one doubly degenerate infrared-active band in the ν1 + ν3 region of the CS2 monomer. This band is observed to have a rather small vibrational shift of −0.844 cm−1. We expect one parallel and one perpendicular infrared-active band for the trimer but observe two parallel bands and one perpendicular band. Much larger vibrational shifts of −8.953 cm−1 for the perpendicular band and −8.845 cm−1 and +16.681 cm−1 for the parallel bands are observed. Vibrational shifts and possible vibrational assignments, in the case of the parallel bands of the trimer, are discussed using group theoretical arguments.
Cephalopod biodiversity of the Kermadec Islands: implications for conservation and some future taxonomic priorities
Authors: Braid Heather E. , Bolstad Kathrin S. R.
Published: April 2019

In order to establish the Kermadec–Rangitāhua Ocean Sanctuary, which will protect a large, unique, near-pristine section of New Zealand’s marine environment, an improved understanding of the marine biodiversity of this area is required. Over 150 cephalopod specimens were collected from the Kermadecs during a recent biodiversity survey, providing the first opportunity in over a century to directly assess locally occurring taxa. Specimens were morphologically identified and DNA barcoded. DNA sequences were analysed using the Barcode Index Number (BIN) system in the Barcode of Life Data System. This study nearly doubles the previously known cephalopod biodiversity of the Kermadecs, adding 28 species (bringing the total to 70), and reporting three cephalopod orders from this area for the first time. The BIN analysis highlighted several taxa that are badly in need of revision, including some supposedly monotypic genera that now appear to contain multiple species, and at least five species that may be new to science. The Kermadec region also hosts 34 cephalopod species not known to occur elsewhere in New Zealand waters. Most taxa reported herein are deep-sea species whose habitat is not protected by the existing marine reserve; we therefore strongly support the establishment of the proposed Sanctuary.
Biased competition in the absence of input bias revealed through corticostriatal computation
Authors: Ardid Salva , Sherfey Jason S. , McCarthy Michelle M. , Hass Joachim , Pittman-Polletta Benjamin R. , Kopell Nancy
Published: April 2019

Significance

The canonical model of the basal ganglia is based on competing direct (GO) vs. indirect (NO-GO) pathways. However, how is either of the two pathways activated if they receive the same corticostriatal inputs as experimental evidence suggests? Also, in the context of rule-based decisions, how is a specific action selected among competing GO pathways? We introduce a neural circuit model that identifies three alternative mechanisms flexibly supporting preferential processing between GO and NO-GO alternatives under balanced input. Only one of these mechanisms, however, is capable of enabling action selection by reinforcing, in the striatum, the rule-based rhythmic biases reported in prefrontal cortex.
Propagation of pop ups in kirigami shells
Authors: Rafsanjani Ahmad , Jin Lishuai , Deng Bolei , Bertoldi Katia
Published: April 2019

Significance

Kirigami—the Japanese art of cutting paper—has become an emergent tool to realize highly stretchable devices and morphable structures. While kirigami structures are fabricated by simply perforating an array of cuts into a thin sheet, the applied deformation and associated instabilities can be exploited to transform them into complex 3D morphologies. However, to date, such reconfiguration always happen simultaneously through the system. By borrowing ideas from phase-transforming materials, we combine cuts and curvature to realize kirigami structures in which deformation-induced shape reconfiguration initially nucleates near an imperfection and then, under specific conditions, spreads through the system. We envision that such control of the shape transformation could be used to design the next generation of responsive surfaces and smart skins.
Preclinical candidate for the treatment of visceral leishmaniasis that acts through proteasome inhibition
Authors: Wyllie Susan , Brand Stephen , Thomas Michael , De Rycker Manu , Chung Chun-wa , Pena Imanol , Bingham Ryan P. , Bueren-Calabuig Juan A. , Cantizani Juan , Cebrian David , Craggs Peter D. , Ferguson Liam , Goswami Panchali , Hobrath Judith , Howe Jonathan , Jeacock Laura , Ko Eun-Jung , Korczynska Justyna , MacLean Lorna , Manthri Sujatha , Martinez Maria S. , Mata-Cantero Lydia , Moniz Sonia , Nühs Andrea , Osuna-Cabello Maria , Pinto Erika , Riley Jennifer , Robinson Sharon , Rowland Paul , Simeons Frederick R. C. , Shishikura Yoko , Spinks Daniel , Stojanovski Laste , Thomas John , Thompson Stephen , Viayna Gaza Elisabet , Wall Richard J. , Zuccotto Fabio , Horn David , Ferguson Michael A. J. , Fairlamb Alan H. , Fiandor Jose M. , Martin Julio , Gray David W. , Miles Timothy J. , Gilbert Ian H. , Read Kevin D. , Marco Maria , Wyatt Paul G.
Published: April 2019

Visceral leishmaniasis (VL), caused by the protozoan parasites
Leishmania donovani
and
Leishmania infantum
, is one of the major parasitic diseases worldwide. There is an urgent need for new drugs to treat VL, because current therapies are unfit for purpose in a resource-poor setting. Here, we describe the development of a preclinical drug candidate, GSK3494245/DDD01305143/compound 8, with potential to treat this neglected tropical disease. The compound series was discovered by repurposing hits from a screen against the related parasite
Trypanosoma cruzi
. Subsequent optimization of the chemical series resulted in the development of a potent cidal compound with activity against a range of clinically relevant
L. donovani
and
L. infantum
isolates. Compound 8 demonstrates promising pharmacokinetic properties and impressive in vivo efficacy in our mouse model of infection comparable with those of the current oral antileishmanial miltefosine. Detailed mode of action studies confirm that this compound acts principally by inhibition of the chymotrypsin-like activity catalyzed by the β5 subunit of the
L. donovani
proteasome. High-resolution cryo-EM structures of apo and compound 8-bound
Leishmania tarentolae
20S proteasome reveal a previously undiscovered inhibitor site that lies between the β4 and β5 proteasome subunits. This induced pocket exploits β4 residues that are divergent between humans and kinetoplastid parasites and is consistent with all of our experimental and mutagenesis data. As a result of these comprehensive studies and due to a favorable developability and safety profile, compound 8 is being advanced toward human clinical trials.
Modulation of fear generalization by the zona incerta
Authors: Venkataraman Archana , Brody Natalia , Reddi Preethi , Guo Jidong , Gordon Rainnie Donald , Dias Brian George
Published: April 2019

Significance

The generalization of fear responses toward neutral stimuli is a highly prevalent and debilitating dimension of trauma- and anxiety-related disorders. Understanding the neural circuits that underlie the ability to suppress fear generalization is of significant translational interest. Recent studies have largely focused on examining fear generalization in the context of traditionally discussed fear-related circuitry like the amygdala, prefrontal cortex, and hippocampus, which monitor and detect threatening stimuli. However, very little is understood about the role of thalamic and subthalamic regions in modulating fear generalization. Combining discriminative auditory fear conditioning in mice with C-FOS mapping and chemogenetic manipulation of neuronal activity, we demonstrate a role for the subthalamic zona incerta in suppressing fear generalization.
Ultrafast folding kinetics of WW domains reveal how the amino acid sequence determines the speed limit to protein folding
Authors: Szczepaniak Malwina , Iglesias-Bexiga Manuel , Cerminara Michele , Sadqi Mourad , Sanchez de Medina Celia , Martinez Jose C. , Luque Irene , Muñoz Victor
Published: April 2019

Significance

Natural proteins fold and unfold with rates that define their biological properties and vary vastly from protein to protein. A major fundamental question refers to how fast a protein can possibly fold, how does this limit compare with chemical reaction rates, and whether it is universal or depends on the protein’s chemical properties. We apply ultrafast kinetic methods to investigate five proteins that share the simplest all-β fold but have different amino acid sequence. In these studies, we measure the folding speed limit for each one of them and discover rather substantial differences. Our results shed light onto the fundamentals of biomolecular rate theory and onto our general understanding of how proteins fold, function, and evolve.