bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring Augmentation of Thermal-Fluid Transport in Fractal Architectures
Authors: Shaw Surupa , Banerjee Debjyoti
Published: November 2016

Cost effective solutions involving thermal-fluid transport need to be developed for various energy applications. The miniaturization of the chip architecture in the electronic devices have caused the challenge of increased heat dissipation and higher power consumption. Hence there is an immediate need for developing efficient and cost-effective solutions for next generation cooling systems. This thermal management challenge can be addressed with maximizing the surface area of the heat exchanging surfaces that can allow dissipation of high heat fluxes. Fractal structures are known to maximize the surface area for compact volumes and are explored as a potential technique to addressing the issue of maximizing heat fluxes in compact volumes.

Fractal structures are effective in maximizing the surface area in compact volumes. Fractals possess the property of self-similarity (the pattern is similar to itself at different levels of magnifications) and infinite recursion (created by repeating a simple process infinitely). Enhanced heat transfer in microelectronic devices can be achieved by increasing the available surface area for heat exchanging fluids within a compact volume. Fractal structures can provide the appropriate technology for the enhancement in heat transfer for these devices.

The proposed model is used to predict the thermal-fluid flow characteristics in microchannel geometries with fractal hierarchies. The chosen fractal architectures in this study are observed to enhance the heat transfer due to the augmentation of surface area in the fractal branching networks of varying length-scales.
Monitoring What Matters: A Systematic Process for Selecting Training-Load Measures
Authors: Williams Sean , Trewartha Grant , Cross Matthew J. , Kemp Simon P.T. , Stokes Keith A.
Published: November 2016

Purpose:

Numerous derivative measures can be calculated from the simple session rating of perceived exertion (sRPE), a tool for monitoring training loads (eg, acute:chronic workload and cumulative loads). The challenge from a practitioner’s perspective is to decide which measures to calculate and monitor in athletes for injury-prevention purposes. The aim of the current study was to outline a systematic process of data reduction and variable selection for such training-load measures.

Methods:

Training loads were collected from 173 professional rugby union players during the 2013–14 English Premiership season, using the sRPE method, with injuries reported via an established surveillance system. Ten derivative measures of sRPE training load were identified from existing literature and subjected to principal-component analysis. A representative measure from each component was selected by identifying the variable that explained the largest amount of variance in injury risk from univariate generalized linear mixed-effects models.

Results:

Three principal components were extracted, explaining 57%, 24%, and 9% of the variance. The training-load measures that were highly loaded on component 1 represented measures of the cumulative load placed on players, component 2 was associated with measures of changes in load, and component 3 represented a measure of acute load. Four-week cumulative load, acute:chronic workload, and daily training load were selected as the representative measures for each component.

Conclusions:

The process outlined in the current study enables practitioners to monitor the most parsimonious set of variables while still retaining the variation and distinct aspects of “load” in the data.
Upper Extremity and Cue Kinematics, and Shoulder Muscle Electromyographic Activity of Novus Players of Different Skill Levels
Authors: Talts Viire , Ereline Jaan , Kums Tatjana , Pääsuke Mati , Gapeyeva Helena
Published: November 2016

Our aim with the current study was to compare upper extremity and cue kinematics, and electromyographic (EMG) activation of shoulder muscles during novus (a special form of billiards) shots of different difficulty levels. Ten proficient and 10 less-skilled novus players performed 3 types of novus shots (penalties, cuts, rebounds) 10 times each. During each shot, elbow flexion and cue–forearm angles (using a movement analysis system), and surface EMG activity of the trapezius, posterior, and lateral deltoid muscles of each subject’s dominant side, were measured. Data were compared between more- and less-skilled players, and successful compared with unsuccessful shots. Elbow flexion angle among the more-skilled players was 24.5% larger (P < .001) during unsuccessful cut shots than successful ones. The more-skilled players performed successful penalty and rebound shots with 26.8% and 49.8% lower (P < .01 and P < .001, respectively) EMG activity of the trapezius muscle than unsuccessful ones. Less-skilled players’ shots were characterized by higher EMG activity in the trapezius muscle. The obtained findings suggest that the more-skilled novus players had acquired a different muscle recruitment pattern than less-skilled players.
Minimum Detectable Change in Medial Tibiofemoral Contact Force Parameters: Derivation and Application to a Load-Altering Intervention
Authors: Barrios Joaquin , Willson John
Published: November 2016

Medial tibiofemoral joint contact forces can be estimated using musculoskeletal models. To assess change in these forces that accompany load-modifying interventions, minimum detectable change (MDC) thresholds must be established. The primary study purpose was to derive MDCs for medial tibiofemoral peak force and force impulse during walking. The secondary purpose was to identify the proportions of individuals exhibiting reductions greater than these MDCs when walking with lateral foot wedging. Eight healthy individuals provided 3-dimensional gait data over 3 test sessions to serve as inputs for an inverse dynamics-driven medial tibiofemoral contact force model, from which MDCs for peak force and impulse were derived. The MDC was 0.246 BW (8.7%) for peak force and 0.0385 BW∙s (3.7%) for impulse. Then, 25 healthy individuals provided gait data by walking with and without 6° laterally wedged foot orthoses, and the proportion of individuals exhibiting changes in medial tibiofemoral contact peak force and impulse values exceeding the MDC threshold was determined. For impulse and peak force, 52% and 4% of participants exhibited a decrease exceeding the MDC, respectively. In summary, medial tibiofemoral contact force MDCs were derived, with impulse showing greater sensitivity than peak force to the effects of a biomechanical intervention.
Relative Contribution of Lower Body Work as a Biomechanical Determinant of Spine Sparing Technique During Common Paramedic Lifting Tasks
Authors: Makhoul Paul J. , Sinden Kathryn E. , MacPhee Renée S. , Fischer Steven L.
Published: November 2016

Paramedics represent a unique occupational group where the nature of their work, providing prehospital emergency care, makes workplace modifications to manage and control injury risks difficult. Therefore, the provision of workplace education and training to support safe lifting remains a viable and important approach. There is, however, a lack of evidence describing movement strategies that may be optimal for paramedic work. The purpose of this study was to determine if a strategy leveraging a greater contribution of work from the lower body relative to the torso was associated with lower biomechanical exposures on the spine. Twenty-five active duty paramedics performed 3 simulated lifting activities common to paramedic work. Ground reaction forces and whole body kinematics were recorded to calculate: peak spine moment and angle about the L4/L5 flexion-extension axis as indicators of biomechanical exposure; and, joint work, integrated from net joint power as a measure of technique inclusive of movement dynamics. Paramedics generating more work from the lower body, relative to the trunk, were more likely to experience lower peak L4/L5 spine moments and angles. These data can inform the development of workplace training and education on safe lifting that focuses on paramedics generating more work from the lower body.
Linking Narcissism, Motivation, and Doping Attitudes in Sport: A Multilevel Investigation Involving Coaches and Athletes
Authors: Matosic Doris , Ntoumanis Nikos , Boardley Ian David , Stenling Andreas , Sedikides Constantine
Published: November 2016

Research on coaching (Bartholomew, Ntoumanis, & Thøgersen-Ntoumani, 2009) has shown that coaches can display controlling behaviors that have detrimental effects on athletes’ basic psychological needs and quality of sport experiences. The current study extends this literature by considering coach narcissism as a potential antecedent of coaches’ controlling behaviors. Further, the study tests a model linking coaches’ (n = 59) own reports of narcissistic tendencies with athletes’ (n = 493) perceptions of coach controlling behaviors, experiences of need frustration, and attitudes toward doping. Multilevel path analysis revealed that coach narcissism was directly and positively associated with athletes’ perceptions of controlling behaviors and was indirectly and positively associated with athletes’ reports of needs frustration. In addition, athletes’ perceptions of coach behaviors were positively associated—directly and indirectly—with attitudes toward doping. The findings advance understanding of controlling coach behaviors, their potential antecedents, and their associations with athletes’ attitudes toward doping.
Moderators of Implicit–Explicit Exercise Cognition Concordance
Authors: Berry Tanya R. , Rodgers Wendy M. , Markland David , Hall Craig R.
Published: November 2016

Investigating implicit–explicit concordance can aid in understanding underlying mechanisms and possible intervention effects. This research examined the concordance between implicit associations of exercise with health or appearance and related explicit motives. Variables considered as possible moderators were behavioral regulations, explicit attitudes, and social desirability. Participants (N = 454) completed measures of implicit associations of exercise with health and appearance and questionnaire measures of health and appearance motives, attitudes, social desirability, and behavioral regulations. Attitudes significantly moderated the relationship between implicit associations of exercise with health and health motives. Identified regulations significantly moderated implicit–explicit concordance with respect to associations with appearance. These results suggest that implicit and explicit exercise-related cognitions are not necessarily independent and their relationship to each other may be moderated by attitudes or some forms of behavioral regulation. Future research that takes a dual-processing approach to exercise behavior should consider potential theoretical moderators of concordance.
The Acute Effect of Cryotherapy on Muscle Strength and Shoulder Proprioception
Authors: Torres Rui , Silva Filipa , Pedrosa Vera , Ferreira João , Lopes Alexandre
Published: November 2016

Context:

Cryotherapy, a common intervention used by clinicians, poses several benefits in managing acute injuries. However, cooling muscle tissue can interfere with muscular properties and the sensory-motor system.

Objective:

The aim of this study was to analyze the influence of cryotherapy with a crushed-ice pack on shoulder proprioception concerning joint position sense, force sense, the threshold for detecting passive movement, and maximal force production.

Design:

A randomized, double-blind controlled trial.

Participants:

48 healthy women aged 22.6 ± 0.4 y with a mean body mass index of 22.8 ±0.37 kg/m2 and a percentage of body fat of 15.4 ± 1.5%.

Methods:

In the experimental group, a crushed-ice pack was applied to the shoulder for 15 min, whereas participants in the control group applied a sandbag at skin temperature, also for 15 min. An isokinetic dynamometer was used to assess maximal voluntary contraction, force sense, joint position sense, and the threshold for detecting passive movement.

Results:

Paired sample t tests revealed that maximal voluntary isometric contraction decreased significantly after cryotherapy (P ≤ .001), or approximately 10% of the reduction found in both muscular groups assessed. Shoulder position sense (P < .001) and the threshold for detecting passive movement (P = .01 and P = .01 for lateral and medial shoulder rotator muscles, respectively) also suffered significant impairment. Nevertheless, no significant differences emerged in force sense at 20% and 50% of maximal force reproduction (P = .41 and P = .10 for lateral rotator muscles at 20% and 50%, respectively; and P = .20 and P = .09 for medial rotator muscles at 20% and 50%, respectively).

Conclusion:

Applying a crushed-ice pack to the shoulder for 15 min negatively affected muscle strength and impaired shoulder proprioception by decreasing joint position sense and the threshold for detecting passive movement.
Patient-Reported Efficacy 6 Months After a 4-Week Rehabilitation Intervention in Individuals With Chronic Ankle Instability
Authors: Wright Cynthia J. , Linens Shelley W.
Published: November 2016

Objective:

To track the patient-reported efficacy of a 4-wk intervention (wobble board [WB] or resistance tubing [RT]) in decreasing symptoms of chronic ankle instability (CAI) at 6 mo postintervention (6PI) as compared with immediately postintervention (IPI).

Design:

Randomized controlled trial.

Participants:

Fourteen of 21 participants (66.7%) responded to an electronic 6-m follow-up questionnaire (age 19.6 ± 0.9 y, height 1.63 ± 0.18 m, weight 70.5 ± 16.3 kg; 2 male, 12 female; 5 WB, 9 RT). All participants met CAI criteria at enrollment, including a history of ankle sprain and recurrent episodes of giving way.

Interventions:

Participants completed either RT or WB protocols, both 12 sessions over 4 wk of progressive exercise. WB sessions consisted of five 40-s sets of clockwise and counterclockwise rotations. RT sessions consisted of 30 contractions against resistance tubing in each of 4 ankle directions.

Main Outcome Measurements:

Patient-reported symptoms of “giving way” preintervention and at 6PI, global rating of change (GRC) frequencies at IPI and 6PI, and resprains at 6PI were reported descriptively. Changes in global rating of function (GRF) and giving way were compared using Wilcoxon tests, while GRC was compared with Fisher exact test.

Results:

All participants reported giving way preintervention, only 57.1% reported giving way at 6PI. Resprains occurred in 21.4% of participants. Giving-way frequency (P = .017), but not GRF or GRC (P > .05), was significantly different at IPI vs 6PI.

Conclusions:

Simple 4-wk interventions maintained some but not all improvements at 6PI. At least 42.9% of participants would no longer meet the current study’s CAI inclusion criteria due to a reduction in giving way.
Maturation-Related Effect of Low-Dose Plyometric Training on Performance in Youth Hockey Players
Authors: Moran Jason , Sandercock Gavin R.H. , Ramírez-Campillo Rodrigo , Todd Oliver , Collison Jay , Parry Dave A.
Published: November 2016

Purpose:

The purpose of this intervention study was to investigate if a low-dose of plyometric training (PT) could improve sprint and jump performance in groups of different maturity status.

Method:

Male youth field hockey players were divided into Pre-PHV (from -1 to -1.9 from PHV; Experimental: n = 9; Control = 12) and Mid-PHV (0 to +0.9 from PHV; Experimental: n = 8; Control = 9) groups. Participants in the experimental groups completed 60 foot contacts, twice-weekly for 6 weeks.

Results:

PT exerted a positive effect (effect size: 0.4 [-0.4–1.2]) on 10 m sprint time in the experimental Mid-PHV group but this was less pronounced in the Pre-PHV group (0.1 [-0.6–0.9]). Sprint time over 30 m (Mid-PHV: 0.1 [-0.8–0.9]; Pre-PHV: 0.1 [-0.7–0.9]) and CMJ (Mid-PHV: 0.1 [-0.8–0.9]; Pre-PHV: 0.0 [-0.7–0.8]) was maintained across both experimental groups. Conversely, the control groups showed decreased performance in most tests at follow up. Between-group analysis showed positive effect sizes across all performance tests in the Mid-PHV group, contrasting with all negative effect sizes in the Pre-PHV group.

Conclusion:

These results indicate that more mature hockey players may benefit to a greater extent than less mature hockey players from a low-dose PT stimulus. Sixty foot contacts, twice per week, seems effective in improving short sprint performance in Mid-PHV hockey players.
An Exploration of Trainee Practitioners’ Experiences When Using Observation
Authors: Martin Emily A. , Winter Stacy , Holder Tim
Published: November 2016

Observation provides applied sport psychologists with a direct assessment of client behavior within the sporting environment. Despite the unique properties and the insightful information that observation allows, it has received limited literary attention within the applied sport psychology domain. The current study aimed to explore and further understand the observation practices of current trainee practitioners. All participants were enrolled on a training program toward becoming either a chartered psychologist (BPS) or an accredited sport and exercise scientist (BASES). In total, five focus groups were conducted and analyzed using an interpretative phenomenological approach (IPA; Smith, 1996). Four superordinate themes emerged: value of observation, type of observation, challenges of observation, and suggestions for observation training. Results demonstrate the increased value that observation brings to effective service delivery and intervention. Specifically, informal observation is commended for its propensity to build greater contextual intelligence and to develop stronger client relationships.
Mindfulness Intervention With a U.S. Women’s NCAA Division I Basketball Team: Impact on Stress, Athletic Coping Skills and Perceptions of Intervention
Authors: Vidic Zeljka , St. Martin Mark , Oxhandler Richard
Published: November 2016

This mixed methodology study investigated the effects of a ten session mindfulness-based intervention on a women’s collegiate basketball team’s (n = 13) perceived stress, athletic coping resources, and perceptions of the mindfulness intervention. Quantitative results showed a progressive decrease in stress and an increase in athletic coping skills over the course of the intervention. Qualitative results indicated the mindfulness intervention was beneficial in various aspects of the athletes’ lives in the form of improved awareness, control, focus, presence and relaxation. These results suggest that mindfulness training may be an effective approach in assisting college athletes attain benefits in both sport and life.
Study suggests hidden epidemic in CF patients
Authors: Kupferschmidt Kai
Published: November 2016

Dangerous
Mycobacterium
strains appear to be spreading.
The lost norse
Authors: Kintisch Eli
Published: November 2016

Archaeologists have a new answer to the mystery of Greenland's Norse, who thrived for centuries and then vanished.
The DNA-sensing AIM2 inflammasome controls radiation-induced cell death and tissue injury
Authors: Hu Bo , Jin Chengcheng , Li Hua-Bing , Tong Jiyu , Ouyang Xinshou , Cetinbas Naniye Malli , Zhu Shu , Strowig Till , Lam Fred C. , Zhao Chen , Henao-Mejia Jorge , Yilmaz Omer , Fitzgerald Katherine A. , Eisenbarth Stephanie C. , Elinav Eran , Flavell Richard A.
Published: November 2016

AIMing to block tissue damage

Ionizing radiation kills actively dividing cells such as those in the gut and in the bone marrow. Hu
et al.
found a pathological role for the protein AIM2 in irradiation-induced tissue damage. AIM2 is best known for its role in sensing double-stranded DNA in the cytoplasm and alerting the body to infections. It seems that AIM2 also senses DNA damage caused by radiation and then triggers intestinal epithelial cells and bone marrow cells to die. Deficiency in AIM2 protected mice from irradiation-induced gastrointestinal syndrome and hematopoietic failure.

Science
, this issue p.
765
Emergence and spread of a human-transmissible multidrug-resistant nontuberculous mycobacterium
Authors: Bryant Josephine M. , Grogono Dorothy M. , Rodriguez-Rincon Daniela , Everall Isobel , Brown Karen P. , Moreno Pablo , Verma Deepshikha , Hill Emily , Drijkoningen Judith , Gilligan Peter , Esther Charles R. , Noone Peadar G. , Giddings Olivia , Bell Scott C. , Thomson Rachel , Wainwright Claire E. , Coulter Chris , Pandey Sushil , Wood Michelle E. , Stockwell Rebecca E. , Ramsay Kay A. , Sherrard Laura J. , Kidd Timothy J. , Jabbour Nassib , Johnson Graham R. , Knibbs Luke D. , Morawska Lidia , Sly Peter D. , Jones Andrew , Bilton Diana , Laurenson Ian , Ruddy Michael , Bourke Stephen , Bowler Ian C. J. W. , Chapman Stephen J. , Clayton Andrew , Cullen Mairi , Dempsey Owen , Denton Miles , Desai Maya , Drew Richard J. , Edenborough Frank , Evans Jason , Folb Jonathan , Daniels Thomas , Humphrey Helen , Isalska Barbara , Jensen-Fangel Søren , Jönsson Bodil , Jones Andrew M. , Katzenstein Terese L. , Lillebaek Troels , MacGregor Gordon , Mayell Sarah , Millar Michael , Modha Deborah , Nash Edward F. , O’Brien Christopher , O’Brien Deirdre , Ohri Chandra , Pao Caroline S. , Peckham Daniel , Perrin Felicity , Perry Audrey , Pressler Tania , Prtak Laura , Qvist Tavs , Robb Ali , Rodgers Helen , Schaffer Kirsten , Shafi Nadia , van Ingen Jakko , Walshaw Martin , Watson Danie , West Noreen , Whitehouse Joanna , Haworth Charles S. , Harris Simon R. , Ordway Diane , Parkhill Julian , Floto R. Andres
Published: November 2016

Global spread of aggressive mycobacteria

Many mycobacteria, in addition to those causing leprosy and tuberculosis, are capable of infecting humans. Some can be particularly dangerous in patients suffering from immunosuppression or chronic disease, such as cystic fibrosis (CF). Bryant
et al.
observed clusters of near-identical isolates of drug-resistant
Mycobacterium abscessus
in patients reporting to CF clinics. The similarity of the isolates suggests transmission between patients, rather than environmental acquisition. Although this bacterium is renowned for its environmental resilience, the mechanism for its long-distance transmission among the global CF patient community remains a puzzle.

Science
, this issue p.
751
Potent protection against H5N1 and H7N9 influenza via childhood hemagglutinin imprinting
Authors: Gostic Katelyn M. , Ambrose Monique , Worobey Michael , Lloyd-Smith James O.
Published: November 2016

Lifelong protection against severe influenza

The first influenza attack that a child suffers can affect the way that their lifelong immunity to the virus builds up. A wide range of influenza A virus subtypes infect humans. Subtype H5 belongs to HA group 1 (which also includes H1 and H2 subtypes), and subtype H7 belongs to HA group 2 (which also includes the H3 subtype). Gostic
et al.
found that birth-year cohorts that experienced first infections with seasonal H3 subtype viruses were less susceptible to the potentially fatal avian influenza H7N9 virus (see the Perspective by Viboud and Epstein). Conversely, older individuals who were exposed to H1 or H2 subtype viruses as youngsters were less susceptible to avian H5N1-bearing viruses. A mathematical model of the protective effect of this imprinting could potentially prove useful to predict the age distribution and severity of future pandemics.

Science
, this issue p.
722
; see also p.
706
Precaution and governance of emerging technologies
Authors: Kaebnick Gregory E. , Heitman Elizabeth , Collins James P. , Delborne Jason A. , Landis Wayne G. , Sawyer Keegan , Taneyhill Lisa A. , Winickoff David E.
Published: November 2016

Precaution can be consistent with support of science
Gliogenic LTP spreads widely in nociceptive pathways
Authors: Kronschläger M. T. , Drdla-Schutting R. , Gassner M. , Honsek S. D. , Teuchmann H. L. , Sandkühler J.
Published: November 2016

Activation of spinal glial cells induces long-term potentiation at specific synapses that spreads widely in spinal pain-sensing pathways.
Tinkering with evolution
Redesigning Life How Genome Editing Will Transform the World
John Parrington
Oxford University Press, 2016. 364 pp.
Authors: Woolfson Adrian
Published: November 2016

A comprehensive tome explores the far-reaching implications of genome editing
Crops on demand
Evolution Made to Order Plant Breeding and Technological Innovation in Twentieth-Century America
Helen Anne Curry
University of Chicago Press, 2016. 295 pp.
Authors: Campos Luis
Published: November 2016

A probing portrait of early plant-breeding technologies unearths surprising roots of genetic engineering efforts
Ammonia activation at a metal
Authors: Hoover Jessica
Published: November 2016

A cationic molybdenum complex weakens the N–H bond of ammonia and generates H
2
Other Slow-Growing Nontuberculous Mycobacteria
Authors: Bittner Marvin J. , Preheim Laurel C.
Published: November 2016

The list of clinically important slow-growing nontuberculous mycobacteria (NTM) continues to expand as new species are identified and older ones are found to be pathogenic. Based on pigment production, the strains may be classified as photochromogenic, scotochromogenic, or unpigmented. Some of these organisms are not newly discovered but have heretofore been considered virtually nonpathogenic. Previously, many were regarded as contaminants when isolated from clinical specimens. Ubiquitous in nature, many NTM have been isolated from groundwater or tap water, soil, house dust, domestic and wild animals, and birds. Most infections result from inhalation or direct inoculation from environmental sources. They are not spread from person to person. The infections may be localized or disseminated. In most cases, the optimal regimen or duration of therapy has not been firmly established. The results of
in vitro
susceptibility testing may be used to select a therapeutic regimen. Many experts recommend clarithromycin with companion drugs such as rifampin and ethambutol for most, but not all, slowly growing species. Aminoglycosides, clofazimine, fluoroquinolones, linezolid, pyrazinamide, or trimethoprim-sulfamethoxazole also may be effective against some strains. Immunocompetent patients with clinically significant infections with NTM usually should receive 18 to 24 months of therapy. Infected immunocompromised patients, particularly those with disseminated infection, probably should receive therapy as long as their immune systems remain impaired. Some of the species discussed include
Mycobacterium alsiense
,
M. celatum
,
M. gordonae
,
M. haemophilum
,
M. kyorinense
,
M. malmoense
,
M. simiae
complex,
M. szulgai
,
M. terrae
complex,
M. ulcerans
, and
M. xenopi
.
What causes the nonclassical structure of 2-norbornyl ion?
Authors: Patel Ruchit A. , East Allan L.L.
Published: November 2016

A recent publication of a general carbocation rearrangement mechanism highlighted protonated cyclopropane (PCP+) intermediates, whose structures are meso between the nonclassical hypotheses of edge-PCP+ and corner-PCP+. Unlike the nonclassical structures, which possess 3-centre–2-electron bonds, the meso-PCP+ structures appear as closed classical structures. The 2-norbornyl ion, however, is known to have a nonclassical corner-PCP+ structure, and here we explore (using computational chemistry) the reasons why. The main reasons are due to the three 5-membered carbon rings, whose ring strain resist relaxation to a meso-PCP+ structure, but an additional reason is the trisubstitution on one side of the PCP+ face, which causes unfavourable C–C bond eclipsing.
A comparative analysis of empirical equations describing pressure dependence of equilibrium and reaction rate constants
Authors: Spooner Jacob , Weinberg Noham
Published: November 2016

General properties of the empirical analytical functions used to describe the effect of pressure on rate and equilibrium constants in solution are reviewed, and the effects of experimental errors on the accuracy of activation and reaction volumes predicted by these equations are compared. When the error levels are low (1%–2%) and pressure ranges are small (0–1 kbar), all functions perform well, but when fitting data with high error or extending to higher pressures, special care must be taken to obtain reliable results. Analysis of the results from fitting the equations to simulated data, as well as experimental data for Diels–Alder, Menshutkin, and methanolysis reactions, allows us to propose a set of general recommendations when using these equations as a tool for obtaining accurate activation and reaction volumes.
Enhanced ferromagnetic characteristics in Mn-doped ZnO: A promising diluted magnetic semiconductor
Authors: Yousaf Muhammad , Rafique Hafiz Muhammad , Amin Muhammad , Ramay Shahid Mahmood , Atiq Shahid
Published: November 2016

Zn[Formula: see text]Mn[Formula: see text]O ([Formula: see text] = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) nanocrystalline diluted magnetic semiconductors (DMSs) were synthesized using sol–gel-based auto-combustion technique. X-ray diffraction (XRD) analysis of all the synthesized samples indicated pure wurtzite hexagonal structure without any secondary phase with perfect solubility of Mn contents in ZnO matrix. The increase in Mn concentration reduced the average crystallite size as evaluated by the Scherrer’s formula. Morphological analysis performed using a field emission scanning electron microscope (FESEM) indicated nearly an ordered surface morphology with some porosity and few cracks. Energy dispersive X-ray (EDX) spectroscopy confirmed the stoichiometric contents of Zn, Mn and O in each sample. Micrographs of all the samples exhibited a decrease in grain size with increase of Mn contents. Magnetic measurements performed using vibrating sample magnetometer (VSM) confirmed room temperature ferromagnetism exhibiting an increase in saturation magnetization and coercivity with increasing Mn contents in all the prepared samples.
Spectrally tunable femtosecond erbium fiber laser based on large-normal-dispersion cavity
Authors: Lv Zhiqiang , Wu Jiarui , Gong Zibo , Lu Xing , Shi Kebin
Published: November 2016

We report on a wavelength-tunable large-normal-dispersion erbium-doped mode-locking fiber oscillator. By using a grating as spectral filter, the intra-cavity mode-locking spectrum can be tuned continuously. The laser produces 250[Formula: see text]fs pulses with average power of 130[Formula: see text]mW and a tunable center wavelength range from 1528[Formula: see text]nm to 1570[Formula: see text]nm.
1D graded thickness nonlinear structure as an optical diode
Authors: Entezar S. Roshan , Vatannejad R.
Published: November 2016

The linear and nonlinear optical properties of a defective one-dimensional (1D) graded thickness nonlinear structure are investigated using the well-known transfer matrix method. It is shown that the structure can support a perfect transmission resonance (defect mode) in its forbidden band gap. The frequency of such a defect mode is independent from the value of the thickness modulation parameter. However, its Q-factor decreases and the spatial asymmetry of the structure increases by increasing the thickness modulation parameter. Due to the large spatial asymmetry of the structure, the nonlinear properties of the structure are sensitive to the direction of the impinging light and the structure acts as an optical.
Exact localized solutions of (1 + 1)-dimensional nonlinear Schrödinger equation with complex 𝒫𝒯 symmetric potentials and power-law nonlinearity
Authors: Nath D. , Roy P.
Published: November 2016

Using the concept of deformed supersymmetry, we obtain exact localized solutions of nonlinear Schrödinger equation (NLSE) with a number of [Formula: see text] symmetric potentials and [Formula: see text]th power-law nonlinearity. Linear stability of these solutions for focusing as well as de-focusing nonlinearity has been examined for various values of the nonlinearity parameter [Formula: see text].
Kinetic energy distribution of photoelectrons in the tunnel ionization process in the case of ultrashort laser pulses
Authors: Petrović V. M. , Miladinović T. B.
Published: November 2016

In this paper, we use semiclassical model to discusse the kinetic electron energy distribution in the single tunnel ionization process of an atom with respect on the pulse duration and the spatial–temporal laser beam distribution. Our theoretical study show that the pulse duration is an important parameter in the ionization process, as well as beam shape.
Computational bounce flash for indoor portraits
Authors: Murmann Lukas , Davis Abe , Kautz Jan , Durand Frédo
Published: November 2016

Portraits taken with direct flash look harsh and unflattering because the light source comes from a small set of angles very close to the camera. Advanced photographers address this problem by using
bounce flash
, a technique where the flash is directed towards other surfaces in the room, creating a larger, virtual light source that can be cast from different directions to provide better shading variation for 3D modeling. However, finding the right direction to point a bounce flash requires skill and careful consideration of the available surfaces and subject configuration. Inspired by the impact of automation for exposure, focus and flash metering, we automate control of the flash direction for bounce illumination. We first identify criteria for evaluating flash directions, based on established photography literature, and relate these criteria to the color and geometry of a scene. We augment a camera with servomotors to rotate the flash head, and additional sensors (a fisheye and 3D sensors) to gather information about potential bounce surfaces. We present a simple numerical optimization criterion that finds directions for the flash that consistently yield compelling illumination and demonstrate the effectiveness of our various criteria in common photographic configurations.
Action-driven 3D indoor scene evolution
Authors: Ma Rui , Li Honghua , Zou Changqing , Liao Zicheng , Tong Xin , Zhang Hao
Published: November 2016

We introduce a framework for
action-driven evolution
of 3D indoor scenes, where the goal is to simulate how scenes are altered by human actions, and specifically, by object placements necessitated by the actions. To this end, we develop an
action model
with each type of action combining information about one or more human poses, one or more object categories, and spatial configurations of objects belonging to these categories which summarize the object-object and object-human relations for the action. Importantly, all these pieces of information are learned from annotated
photos.
Correlations between the learned actions are analyzed to guide the construction of an
action graph.
Starting with an initial 3D scene, we probabilistically sample a sequence of actions from the action graph to drive progressive scene evolution. Each action triggers appropriate object placements, based on object co-occurrences and spatial configurations learned for the action model. We show results of our scene evolution that lead to realistic and messy 3D scenes, as well as quantitative evaluations by user studies which compare our method to manual scene creation and state-of-the-art, data-driven methods, in terms of scene plausibility and naturalness.
Motion parallax in stereo 3D
Authors: Kellnhofer Petr , Didyk Piotr , Ritschel Tobias , Masia Belen , Myszkowski Karol , Seidel Hans-Peter
Published: November 2016

Binocular disparity is the main depth cue that makes stereoscopic images appear 3D. However, in many scenarios, the range of depth that can be reproduced by this cue is greatly limited and typically fixed due to constraints imposed by displays. For example, due to the low angular resolution of current automultiscopic screens, they can only reproduce a shallow depth range. In this work, we study the motion parallax cue, which is a relatively strong depth cue, and can be freely reproduced even on a 2D screen without any limits. We exploit the fact that in many practical scenarios, motion parallax provides sufficiently strong depth information that the presence of binocular depth cues can be reduced through aggressive disparity compression. To assess the strength of the effect we conduct psycho-visual experiments that measure the influence of motion parallax on depth perception and relate it to the depth resulting from binocular disparity. Based on the measurements, we propose a joint disparity-parallax computational model that predicts apparent depth resulting from both cues. We demonstrate how this model can be applied in the context of stereo and multiscopic image processing, and propose new disparity manipulation techniques, which first quantify depth obtained from motion parallax, and then adjust binocular disparity information accordingly. This allows us to manipulate the disparity signal according to the strength of motion parallax to improve the overall depth reproduction. This technique is validated in additional experiments.
Pyramid of arclength descriptor for generating collage of shapes
Authors: Kwan Kin Chung , Sinn Lok Tsun , Han Chu , Wong Tien-Tsin , Fu Chi-Wing
Published: November 2016

This paper tackles a challenging 2D collage generation problem, focusing on shapes: we aim to fill a given region by packing irregular and reasonably-sized shapes with minimized gaps and overlaps. To achieve this nontrivial problem, we first have to analyze the boundary of individual shapes and then couple the shapes with partially-matched boundary to reduce gaps and overlaps in the collages. Second, the search space in identifying a good coupling of shapes is highly enormous, since arranging a shape in a collage involves a position, an orientation, and a scale factor. Yet, this matching step needs to be performed for every single shape when we pack it into a collage. Existing shape descriptors are simply infeasible for computation in a reasonable amount of time. To overcome this, we present a brand new, scale- and rotation-invariant 2D shape descriptor, namely
pyramid of arclength descriptor
(PAD). Its formulation is locally supported, scalable, and yet simple to construct and compute. These properties make PAD efficient for performing the partial-shape matching. Hence, we can prune away most search space with simple calculation, and efficiently identify candidate shapes. We evaluate our method using a large variety of shapes with different types and contours. Convincing collage results in terms of visual quality and time performance are obtained.
An intuitive control space for material appearance
Authors: Serrano Ana , Gutierrez Diego , Myszkowski Karol , Seidel Hans-Peter , Masia Belen
Published: November 2016

Many different techniques for measuring material appearance have been proposed in the last few years. These have produced large public datasets, which have been used for accurate, data-driven appearance modeling. However, although these datasets have allowed us to reach an unprecedented level of realism in visual appearance, editing the captured data remains a challenge. In this paper, we present an intuitive control space for predictable editing of captured BRDF data, which allows for artistic creation of plausible novel material appearances, bypassing the difficulty of acquiring novel samples. We first synthesize novel materials, extending the existing MERL dataset up to 400 mathematically valid BRDFs. We then design a large-scale experiment, gathering 56,000 subjective ratings on the high-level perceptual attributes that best describe our extended dataset of materials. Using these ratings, we build and train networks of radial basis functions to act as functionals mapping the perceptual attributes to an underlying PCA-based representation of BRDFs. We show that our functionals are excellent predictors of the perceived attributes of appearance. Our control space enables many applications, including intuitive material editing of a wide range of visual properties, guidance for gamut mapping, analysis of the correlation between perceptual attributes, or novel appearance similarity metrics. Moreover, our methodology can be used to derive functionals applicable to classic analytic BRDF representations. We release our code and dataset publicly, in order to support and encourage further research in this direction.
Towards foveated rendering for gaze-tracked virtual reality
Authors: Patney Anjul , Salvi Marco , Kim Joohwan , Kaplanyan Anton , Wyman Chris , Benty Nir , Luebke David , Lefohn Aaron
Published: November 2016

Foveated rendering
synthesizes images with progressively less detail outside the eye fixation region, potentially unlocking significant speedups for wide field-of-view displays, such as head mounted displays, where target framerate and resolution is increasing faster than the performance of traditional real-time renderers.

To study and improve potential gains, we designed a foveated rendering user study to evaluate the perceptual abilities of human peripheral vision when viewing today's displays. We determined that filtering peripheral regions reduces contrast, inducing a sense of tunnel vision. When applying a postprocess contrast enhancement, subjects tolerated up to 2× larger blur radius before detecting differences from a non-foveated ground truth. After verifying these insights on both desktop and head mounted displays augmented with high-speed gaze-tracking, we designed a
perceptual target
image to strive for when engineering a production foveated renderer.

Given our perceptual target, we designed a practical foveated rendering system that reduces number of shades by up to 70% and allows coarsened shading up to 30° closer to the fovea than Guenter et al. [2012] without introducing perceivable aliasing or blur. We filter both pre- and post-shading to address aliasing from undersampling in the periphery, introduce a novel multiresolution- and saccade-aware temporal antialising algorithm, and use contrast enhancement to help recover peripheral details that are resolvable by our eye but degraded by filtering.

We validate our system by performing another user study. Frequency analysis shows our system closely matches our perceptual target. Measurements of temporal stability show we obtain quality similar to temporally filtered non-foveated renderings.
Recovering shape and spatially-varying surface reflectance under unknown illumination
Authors: Xia Rui , Dong Yue , Peers Pieter , Tong Xin
Published: November 2016

We present a novel integrated approach for estimating both spatially-varying surface reflectance and detailed geometry from a video of a rotating object under unknown static illumination. Key to our method is the decoupling of the recovery of normal and surface reflectance from the estimation of surface geometry. We define an apparent normal field with corresponding reflectance for each point (including those not on the object's surface) that best explain the observations. We observe that the object's surface goes through points where the apparent normal field and corresponding reflectance exhibit a high degree of consistency with the observations. However, estimating the apparent normal field requires knowledge of the unknown incident lighting. We therefore formulate the recovery of shape, surface reflectance, and incident lighting, as an iterative process that alternates between estimating shape and lighting, and simultaneously recovers surface reflectance at each step. To recover the shape, we first form an initial surface that passes through locations with consistent apparent temporal traces, followed by a refinement that maximizes the consistency of the surface normals with the underlying apparent normal field. To recover the lighting, we rely on appearance-from-motion using the recovered geometry from the previous step. We demonstrate our integrated framework on a variety of synthetic and real test cases exhibiting a wide variety of materials and shape.
High-fidelity facial and speech animation for VR HMDs
Authors: Olszewski Kyle , Lim Joseph J. , Saito Shunsuke , Li Hao
Published: November 2016

Significant challenges currently prohibit expressive interaction in virtual reality (VR). Occlusions introduced by head-mounted displays (HMDs) make existing facial tracking techniques intractable, and even state-of-the-art techniques used for real-time facial tracking in unconstrained environments fail to capture subtle details of the user's facial expressions that are essential for compelling speech animation. We introduce a novel system for HMD users to control a digital avatar in real-time while producing plausible speech animation and emotional expressions. Using a monocular camera attached to an HMD, we record multiple subjects performing various facial expressions and speaking several phonetically-balanced sentences. These images are used with artist-generated animation data corresponding to these sequences to train a convolutional neural network (CNN) to regress images of a user's mouth region to the parameters that control a digital avatar. To make training this system more tractable, we use audio-based alignment techniques to map images of multiple users making the same utterance to the corresponding animation parameters. We demonstrate that this approach is also feasible for tracking the expressions around the user's eye region with an internal infrared (IR) camera, thereby enabling full facial tracking. This system requires no user-specific calibration, uses easily obtainable consumer hardware, and produces high-quality animations of speech and emotional expressions. Finally, we demonstrate the quality of our system on a variety of subjects and evaluate its performance against state-of-the-art real-time facial tracking techniques.
Temporal gradient-domain path tracing
Authors: Manzi Marco , Kettunen Markus , Durand Frédo , Zwicker Matthias , Lehtinen Jaakko
Published: November 2016

We present a novel approach to improve temporal coherence in Monte Carlo renderings of animation sequences. Unlike other approaches that exploit temporal coherence in a post-process, our technique does so already during sampling. Building on previous gradient-domain rendering techniques that sample finite differences over the image plane, we introduce temporal finite differences and formulate a corresponding 3D spatio-temporal screened Poisson reconstruction problem that is solved over windowed batches of several frames simultaneously. We further extend our approach to include second order, mixed spatio-temporal differences, an improved technique to compute temporal differences exploiting motion vectors, and adaptive sampling. Our algorithm can be built on a gradient-domain path tracer without large modifications. In particular, we do not require the ability to evaluate animation paths over multiple frames. We demonstrate that our approach effectively reduces temporal flickering in animation sequences, significantly improving the visual quality compared to both path tracing and gradient-domain rendering of individual frames.
Jump
Authors: Anderson Robert , Gallup David , Barron Jonathan T. , Kontkanen Janne , Snavely Noah , Hernández Carlos , Agarwal Sameer , Seitz Steven M.
Published: November 2016

We present Jump, a practical system for capturing high resolution, omnidirectional stereo (ODS) video suitable for wide scale consumption in currently available virtual reality (VR) headsets. Our system consists of a video camera built using off-the-shelf components and a fully automatic stitching pipeline capable of capturing video content in the ODS format. We have discovered and analyzed the distortions inherent to ODS when used for VR display as well as those introduced by our capture method and show that they are small enough to make this approach suitable for capturing a wide variety of scenes. Our stitching algorithm produces robust results by reducing the problem to one of pairwise image interpolation followed by compositing. We introduce novel optical flow and compositing methods designed specifically for this task. Our algorithm is temporally coherent and efficient, is currently running at scale on a distributed computing platform, and is capable of processing hours of footage each day.