bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adaptive dynamic surface asymptotic tracking for a class of uncertain nonlinear systems
Authors: Liu Yong‐Hua 
Published: September 2017

SummaryThis paper contributes to dynamic surface asymptotic tracking for a class of uncertain nonlinear systems in strict‐feedback form. By utilizing the nonlinear filters with a positive time‐varying integral function, an adaptive state feedback controller is explicitly designed via a dynamic surface approach, where the compensating term with the estimate of an unknown bound is introduced to eliminate the effect raised by the boundary layer error at each step. Compared with the existing results in the literature, the proposed control scheme not only avoids the issue of “explosion of complexity” inherent in the backstepping procedure but also holds the asymptotic output tracking. Finally, simulation results are presented to verify the effectiveness of the proposed methodology.
Hydrostatic versus nonhydrostatic hydrodynamic modelling of secondary flow in a tortuously meandering river: Application of Delft3D
Authors: Parsapour‐Moghaddam P. , Rennie C.D. 
Published: September 2017

AbstractGiven the importance of pressure gradients in driving secondary flow, it is worth studying how the modelled flow structures in a natural river bend can be impacted by the assumption of hydrodynamic pressure. In this paper, the performance of hydrostatic versus nonhydrostatic pressure assumption in the three‐dimensional (3D) hydrodynamic modelling of a tortuously meandering river is studied. Both hydrostatic and nonhydrostatic numerical models were developed using Delft3D‐Flow to predict the 3D flow field in a reach of Stillwater Creek in Ottawa, Canada. An acoustic Doppler velocimeter was employed to measure the 3D flow field at a section in a sharp bend of the simulated river at two flow stages. The results of the Delft3D hydrostatic model agreed well with the acoustic Doppler velocimeter measurements: The hydrostatic model predicted reasonably accurately both the streamwise velocity distribution across the section and the magnitude and location of the primary secondary flow cell. The results of the Delft3D nonhydrostatic approximation showed that the model was not conservative and could not accurately generate either the secondary flow or the streamwise velocity distribution. This study illustrated the superior performance of the hydrostatic over nonhydrostatic 3D modelling of the secondary flow using Delft3D. Several possible reasons for unfavourable performance of the nonhydrostatic version of Delft3D are discussed, including the pressure correction technique employed in Delft3D. Considering the uncertainties that may arise in both modelling and field measurements, the 3D hydrostatic Delft3D model was capable of reasonably predicting the river bend flow structures in the studied meandering creek.
The decline of science in corporate R&D
Authors: Arora Ashish , Belenzon Sharon , Patacconi Andrea 
Published: September 2017

Research summary: In this article, we document a shift away from science by large corporations between 1980 and 2006. We find that publications by company scientists have declined over time in a range of industries. We also find that the value attributable to scientific research has dropped, whereas the value attributable to technical knowledge (as measured by patents) has remained stable. These trends are unlikely to be driven principally by changes in publication practices. Furthermore, science continues to be useful as an input into innovation. Our evidence points to a reduction of the private benefits of internal research. Large firms still value the golden eggs of science (as reflected in patents), but seem to be increasingly unwilling to invest in the golden goose itself (the internal scientific capabilities).Managerial summary: There is a widespread belief among commentators that large American corporations are withdrawing from research. Large corporations may still collaborate with universities and acquire promising science‐based start‐ups, but their labs increasingly focus on developing existing knowledge and commercializing it, rather than creating new knowledge. In this article, we combine firm‐level financial information with a large and comprehensive data set on firm publications, patents and acquisitions to quantify the withdrawal from science by large American corporations between 1980 and 2006. This withdrawal is associated with a decline in the private value of research activities, even though scientific knowledge itself remains important for corporate invention. We discuss the managerial and policy implications of our findings.
Do ongoing networks block out new friends?Reconciling the embeddedness constraint dilemma on new alliance partner addition
Authors: Jiang Han , Xia Jun , Cannella Albert A. , Xiao Ting 
Published: September 2017

Research Summary:This study addresses a theoretical dilemma regarding how alliance network constraint (reflected by network cohesion) affects a firm’s alliance formation with new partners. Using a network pluralism approach, we separate a firm’s ego alliance network into two activity‐based networks—an exploratory network and an exploitative network—based on the primary value chain activity involved in each alliance. We argue that the cohesion of exploratory or exploitative networks has an inverted U‐shaped effect on the addition of new partners in the same activity‐based network, and a positive effect on the addition of new partners in the other network. Results based on data from the biotechnology industry largely support our predictions with one exception. Our study contributes to both scholarly understanding of network embeddedness and alliance practice.Managerial Summary:The structure of firms’ ongoing alliance networks may have paradoxical implications for their efforts to search for and form alliance with new partners. That is, when a firm’s alliance partners are tightly connected with each other, the cohesive network tends to both encourage and impede the focal firm to add new partners. We resolve this dilemma by showing that when a firm is deeply entrenched in a cohesive alliance network conducting a certain type of activities (e.g., R&D activities), it may not easily add new R&D alliance partners. However, it may still be able to escape from the cohesive R&D alliance network by seeking new partners conducting other activities (e.g., manufacturing activities).
BS in the boardroom: Benevolent sexism and board chair orientations
Authors: Oliver Abbie G. , Krause Ryan , Busenbark John R. , Kalm Matias 
Published: September 2017

Research Summary: Though research has focused on the ascent and acceptance of female CEOs, the post‐promotion circumstances female CEOs face remain unclear. In this study, we focus on a critical post‐promotion circumstance: the board chair–CEO relationship. Drawing on the gender stereotype literature, agency theory, and stewardship theory, we posit that firms appointing a female CEO are more likely to adopt a collaboration board chair orientation and less likely to adopt a control orientation. We further predict this effect is attenuated by female board representation. Using a sample of new S&P 1500 CEOs, we find support for our predictions regarding the collaboration orientation but not the control orientation. This research provides some evidence of benevolent sexism in the boardroom, with female directors acting as a countervailing influence.
Managerial Summary: Whereas the notion that females encounter a glass ceiling on their path toward CEO is well documented, the conditions female CEOs encounter after promotion are less understood. The relationship between the board chair and the CEO is one important post‐promotion condition. Board chairs can focus on monitoring and/or working together with the CEO. We suggest board chairs are more likely to work in close collaboration with female CEOs than with male CEOs. We attribute this to benevolent sexism, which explains that board chairs are more likely to collaborate with female CEOs because they view females as more conducive to, and in need of, this type of relationship. We also suggest this benevolent sexism is less prevalent when there are more females on the board.
Virtuous or vicious cycles? The role of divestitures as a complementary Penrose effect within resource‐based theory
Authors: Vidal Elena , Mitchell Will 
Published: September 2017

Research summary: Studies of how divestitures affect firm performance offer mixed results. This paper unpacks relationships between divestitures and subsequent performance, focusing first on the moderating role of prior performance and then on mechanisms through which divestitures by higher‐ and lower‐performing firms affect performance. The study suggests that divestitures can exacerbate weakness and reinforce strength: divestitures by lower performers improve profits but inhibit sales growth and tend to speed the firms’ exits as independent actors; by contrast, higher‐performing divesters invest in support of existing assets and gain new growth, while avoiding becoming acquisition targets. Most generally, divestitures help reduce constraints to changing a firm's resource base, which we refer to as a complementary Penrose effect.
Managerial summary: Divestitures help both struggling firms and high performers free financial and managerial resources that they can reinvest in more productive uses. In doing so, divestitures reinforce the strength of high performers but may exacerbate weaknesses of struggling firms. Divestitures by lower performers improve their profits but inhibit their sales growth and increase the chances that the firms will be acquired. By contrast, higher‐performing divesters gain new growth by investing in support of existing and recently acquired assets and, by doing so, are less likely to become targets of acquirers who seek their productive assets. Thus, divestiture is part of a downward cycle for struggling firms but supports a virtuous cycle for superior firms.
Clinicopathological Risk Factors for Distant Metastasis in Differentiated Thyroid Carcinoma: A Meta‐analysis
Authors: Vuong Huy Gia , Duong Uyen N. P. , Pham Thong Quang , Tran Hung Minh , Oishi Naoki , Mochizuki Kunio , Nakazawa Tadao , Hassell Lewis , Katoh Ryohei , Kondo Tetsuo 
Published: September 2017

AbstractIntroductionDistant metastasis (DM) is not a frequent event in differentiated thyroid carcinoma (DTC) but has an adverse impact on mortality of patients with DTC. In the current study, we aimed to conduct a comprehensive systematic review and meta‐analysis to investigate the risk factors for DM in DTCs and for each histological subtype.MethodsFive electronic databases were searched from inception to December 2016 for relevant articles. Pooled odd ratios and 95% confidence interval were calculated using random‐effect model.ResultsThirty‐four articles with 73,219 patients were included for meta‐analyses. In DTCs, male gender, age ≥45 years, tumor size ≥4 cm, multifocality, vascular invasion (VI), extrathyroidal extension (ETE), lymph node metastasis (LNM), and lateral LNM were demonstrated to be associated with significant risks for DM. In addition, several clinicopathological factors such as age ≥45 years, VI, ETE, and LNM were shown to be significant risk factors for DM in both PTC and FTC subgroups.ConclusionOur study demonstrated the promising value of several clinicopathological factors such as male gender, older age, VI, ETE, and LNM in predicting DM in PTCs and FTCs. Our study affirms the value of the selected clinicopathological factors for tumor risk stratification and assessment of patients’ prognosis.
Atherosclerotic Disease and its Relationship to Lumbar Degenerative Disk Disease, Facet Arthritis, and Stenosis With Computed Tomography Angiography
Authors: Beckworth William J. , Holbrook John F. , Foster Lisa G. , Ward Laura A. , Welle James R. 
Published: September 2017

AbstractBackgroundThe intervertebral disk is the largest avascular structure in the body. It relies on passive diffusion from arteries at the periphery of the disk for nutrition. Previous studies have suggested a correlation between vascular disease and lumbar degenerative disk disease (DDD), but the association with facet arthritis and stenosis has not been evaluated.ObjectiveTo evaluate the degree of lumbar artery stenosis, aortic atherosclerosis on computed tomography angiography, and its relationship to lumbar DDD, facet arthritis, and spinal canal stenosis.DesignRetrospective case review.SettingAcademic tertiary care hospital.ParticipantsNot applicable.MethodsA total of 300 lumbar arteries (150 lumbar artery pairs of the first to fifth lumbar arteries) were evaluated on consecutive computed tomography angiography scans. Severity of vascular disease of lumbar arteries was documented as normal, mild, moderate, severe, or occluded. Aortic vascular disease was documented along the posterior wall where the lumbar arteries originate.Main Outcome MeasurementsThe relationship between vascular disease with DDD, facet arthritis, and spinal canal stenosis was examined and further evaluated controlling for age.ResultsLumbar artery and aortic atherosclerosis had a positive relationship with DDD, facet arthritis, and spinal stenosis that was statistically significant (P < .05) even after controlling for age. The correlation coefficient was greatest in the younger age group when looking at lumbar artery vascular disease with DDD (0.73, confidence interval 0.50‐0.96, P < .0001) and aortic vascular disease with DDD (0.72, confidence interval 0.49‐0.94, P < .0001). The correlation of vascular disease with facet arthritis and stenosis was not strong in the older age group.ConclusionAtherosclerotic disease of the lumbar arteries and aorta correlated with lumbar DDD, facet arthritis, and spinal canal stenosis after we adjusted for age, although the correlation with facet arthritis and spinal canal stenosis was not as strong in the older age group.Level of EvidenceIV
Rapid Triage of Mental Health Risk in Emergency Medical Workers: Findings From Typhoon Haiyan
Authors: Sylwanowicz Lauren , Schreiber Merritt , Anderson Craig , Gundran Carlos Primero D. , Santamaria Emelie , Lopez Jaifred Christian F. 
Published: September 2017

AbstractObjectiveTo determine the ability of a novel responder mental health self-triage system to predict post-traumatic stress disorder (PTSD) in emergency medical responders after a disaster.MethodsParticipants in this study responded to Typhoon Haiyan, which struck the Philippines in November 2013. They completed the Psychological Simple Triage and Rapid Treatment (PsySTART) responder triage tool, the PTSD Checklist (PCL-5) and the Patient Health Questionnaire-8 (PHQ-8) shortly after responding to this disaster. The relationships between these 3 tools were compared to determine the association between different risk exposures while providing disaster medical care and subsequent levels of PTSD or depression.ResultsThe total number of PsySTART responder risk factors was closely related to PCL-5 scores ≥38, the threshold for clinical PTSD. Several of the PsySTART risk factors were predictive of clinical levels of PTSD as measured by the PCL-5 in this sample of deployed emergency medical responders.ConclusionsThe presence of a critical number and type of PsySTART responder self-triage risk factors predicted clinical levels of PTSD and subclinical depression in this sample of emergency medical workers. The ability to identify these disorders early can help categorize an at-risk subset for further timely “stepped care” interventions with the goals of both mitigating the long-term consequences and maximizing the return to resilience. (Disaster Med Public Health Preparedness. 2018;12:19–22)
Can National Healthcare-Associated Infections (HAIs) Data Differentiate Hospitals in the United States?
Authors: Masnick Max , Morgan Daniel J. , Sorkin John D. , Macek Mark D. , Brown Jessica P. , Rheingans Penny , Harris Anthony D. 
Published: September 2017

OBJECTIVETo determine whether patients using the Centers for Medicare and Medicaid Services (CMS) Hospital Compare website (http://medicare.gov/hospitalcompare) can use nationally reported healthcare-associated infection (HAI) data to differentiate hospitals.DESIGNSecondary analysis of publicly available HAI data for calendar year 2013.METHODSWe assessed the availability of HAI data for geographically proximate hospitals (ie, hospitals within the same referral region) and then analyzed these data to determine whether they are useful to differentiate hospitals. We assessed data for the 6 HAIs reported by hospitals to the Centers for Disease Control and Prevention (CDC).RESULTSData were analyzed for 4,561 hospitals representing 88% of registered community and federal government hospitals in the United States. Healthcare-associated infection data are only useful for comparing hospitals if they are available for multiple hospitals within a geographic region. We found that data availability differed by HAI.Clostridium difficileinfections (CDI) data were most available, with 82% of geographic regions (ie, hospital referral regions) having >50% of hospitals reporting them. In contrast, 4% of geographic regions had >50% of member hospitals reporting surgical site infections (SSI) for hysterectomies, which had the lowest availability. The ability of HAI data to differentiate hospitals differed by HAI: 72% of hospital referral regions had at least 1 pair of hospitals with statistically different risk-adjusted CDI rates (SIRs), compared to 9% for SSI (hysterectomy).CONCLUSIONSHAI data generally are reported by enough hospitals to meet minimal criteria for useful comparisons in many geographic locations, though this varies by type of HAI. CDI and catheter-associated urinary tract infection (CAUTI) are more likely to differentiate hospitals than the other publicly reported HAIs.Infect Control Hosp Epidemiol2017;38:1167–1171
Generation Mechanism and Reduction Method of Induced Drag Produced by Interacting Wingtip Vortex System
Authors: Zhang M. , Wang Y. K. , Fu S. 
Published: September 2017

AbstractThe formation and evolution of wingtip vortex system generated from three wing configurations are simulated with the improved delayed detached eddy simulation (IDDES) method. Numerical results show that each layout produces an interacting wingtip vortex system. These three corresponding vortical interactions are, respectively, the interaction between wingtip vortex and its counter-rotating vortex, winglet-tip vortex, and winglet four-vortex system. The fluid entrainment of ambient fluid and vortical impulse transport resulted from inductive effect have been founded generally existing in its formation and evolution. These two dominated mechanisms account for induced drag generation. On one hand, the winglet with toed-out angle is considered capable of changing the flow field around the winglet, and decomposing the winglet-tip vortex into four small vortices. Due to quite few fluid entrainment effects, this typical four-vortex system that cannot merge and only dissipate in the near wake scarcely contributes to the induced drag. On the other hand, a potential drag reduction method is also indicated that a lower induced drag can be obtained when the merger of wingtip and winglet-tip vortex is controlled and eliminated. This investigation will offer a novel perspective to guide the design of wingtip device and method of crusing resistance reduction for aircrafts.
Was the Milky Way Bulge Formed from the Buckling Disk Instability, Hierarchical Collapse, Accretion of Clumps, or All of the Above?
Authors: Nataf David M. 
Published: September 2017

AbstractThe assembly of the Milky Way bulge is an old topic in astronomy, one now in a period of renewed and rapid development. That is due to tremendous advances in observations of bulge stars, motivating observations of both local and high-redshift galaxies, and increasingly sophisticated simulations. The dominant scenario for bulge formation is that of the Milky Way as a nearly pure disk galaxy, with the inner disk having formed a bar and buckled. This can potentially explain virtually all bulge stars with [Fe/H] ≳ −1.0, which comprise 95% of the stellar population. The evidence is the incredible success in N-body models of this type in making non-trivial, non-generic predictions, such as the rotation curve and velocity dispersion measured from radial velocities, and the spatial morphologies of the peanut/X-shape and the long bar. The classical bulge scenario, whereby the bulge formed from early dissipative collapse and mergers, remains viable for stars with [Fe/H] ≲ −1.0 and potentially a minority of the other stars. A classical bulge is expected from Λ-CDM cosmological simulations, can accentuate the properties of an existing bar in a hybrid system, and is most consistent with the bulge abundance trends such as [Mg/Fe], which are elevated relative to both the thin and thick disks. Finally, the clumpy-galaxy scenario is considered, as it is the correct description of most Milky Way precursors given observations of high-redshift galaxies. Simulations predict that these star-forming clumps will sometimes migrate to the centres of galaxies where they may form a bulge, and galaxies often include a bulge clump as well. They will possibly form a bar with properties consistent with those of the Milky Way, such as the exponential profile and metallicity gradient. Given the relative successes of these scenarios, the Milky Way bulge is plausibly of composite origin, with a classical bulge and/or inner halo numerically dominant for stars with [Fe/H] ≲ −1.0, a buckling thick disk for stars with − 1.0 ≲ [Fe/H]] ≲ -0.50 perhaps descended from the clumpy-galaxy phase, and a buckling thin disk for stars with [Fe/H] ≳ −0.50. Overlaps from these scenarios are uncertain throughout.
Cold–temperate transition surface and permafrost base (CTS-PB) as an environmental axis in glacier–permafrost relationship, based on research carried out on the Storglaciären and its forefield, northern Sweden
Authors: Dobiński Wojciech , Grabiec Mariusz , Glazer Michał 
Published: September 2017

AbstractHere, we present empirical ground penetrating radar (GPR) and electroresistivity tomography data (ERT) to verify the cold-temperate transition surface-permafrost base (CTS-PB) axis theoretical model. The data were collected from Storglaciären, in Tarfala, Northern Sweden, and its forefield. The GPR results show a material relation between the glacial ice and the sediments incorporated in the glacier, and a geophysical relation between the “cold ice” and the “temperate ice” layers. Clearly identifying lateral glacier margins is difficult, as periglacial and glacial environments frequently overlap. In this case, we identified areas showing permafrost aggradation already under the glacier, particularly where the CTS is replaced by the PB surface. This structure appears as a result of the influence of a cold climate over both the glacial and periglacial environments. The results show how these surfaces form a specific continuous environmental axis; thus, both glacial and periglacial areas can be treated uniformly as a specific continuum in the geophysical sense. Similarly, other examples previously described also allow identifying a continuation of permafrost from the periglacial environment onto the glacial base. In addition, the ERT results show the presence of double-layered periglacial permafrost, possibly suggesting a past climatic fluctuation in the study area.