bluuebunny/crossref_metadata_2025 huggingface dataset:
A review of Ga2O3 materials, processing, and devices
Authors: Pearton S. J. , Yang Jiancheng , Cary Patrick H. , Ren F. , Kim Jihyun , Tadjer Marko J. , Mastro Michael A.
Published: January 2018

Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics, solar blind UV photodetectors, solar cells, and sensors with capabilities beyond existing technologies due to its large bandgap. It is usually reported that there are five different polymorphs of Ga2O3, namely, the monoclinic (β-Ga2O3), rhombohedral (α), defective spinel (γ), cubic (δ), or orthorhombic (ε) structures. Of these, the β-polymorph is the stable form under normal conditions and has been the most widely studied and utilized. Since melt growth techniques can be used to grow bulk crystals of β-GaO3, the cost of producing larger area, uniform substrates is potentially lower compared to the vapor growth techniques used to manufacture bulk crystals of GaN and SiC. The performance of technologically important high voltage rectifiers and enhancement-mode Metal-Oxide Field Effect Transistors benefit from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. However, the absence of clear demonstrations of p-type doping in Ga2O3, which may be a fundamental issue resulting from the band structure, makes it very difficult to simultaneously achieve low turn-on voltages and ultra-high breakdown. The purpose of this review is to summarize recent advances in the growth, processing, and device performance of the most widely studied polymorph, β-Ga2O3. The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed. Areas where continued development is needed to fully exploit the properties of Ga2O3 are identified.
Two-component Gaussian core model: Strong-coupling limit, Bjerrum pairs, and gas-liquid phase transition
Authors: Frydel Derek , Levin Yan
Published: January 2018

In the present work, we investigate a gas-liquid transition in a two-component Gaussian core model, where particles of the same species repel and those of different species attract. Unlike a similar transition in a one-component system with particles having attractive interactions at long separations and repulsive interactions at short separations, a transition in the two-component system is not driven solely by interactions but by a specific feature of the interactions, the correlations. This leads to extremely low critical temperature, as correlations are dominant in the strong-coupling limit. By carrying out various approximations based on standard liquid-state methods, we show that a gas-liquid transition of the two-component system poses a challenging theoretical problem.
Numerical study on dusty shock reflection over a double wedge
Authors: Yin Jingyue , Ding Juchun , Luo Xisheng
Published: January 2018

The dusty shock reflection over a double wedge with different length scales is systematically studied using an adaptive multi-phase solver. The non-equilibrium effect caused by the particle relaxation is found to significantly influence the shock reflection process. Specifically, it behaves differently for double wedges with different length scales of the first wedge L1. For a double wedge with L1 relatively longer than the particle relaxation length λ, the equilibrium shock dominates the shock reflection and seven typical reflection processes are obtained, which is similar to the pure gas counterpart. For a double wedge with L1 shorter than λ, the non-equilibrium effect manifests more evidently, i.e., three parts of the dusty shock system including the frozen shock, the relaxation zone, and the equilibrium shock together dominate the reflection process. As a result, the shock reflection is far more complicated than the pure gas counterpart and eleven transition processes are found under various wedge angles. These findings give a complete description of all possible processes of dusty shock reflection over a double wedge and may be useful for better understanding the non-equilibrium shock reflection over complex structures.
High-speed atomic force microscopy reveals structural dynamics of α-synuclein monomers and dimers
Authors: Zhang Yuliang , Hashemi Mohtadin , Lv Zhengjian , Williams Benfeard , Popov Konstantin I. , Dokholyan Nikolay V. , Lyubchenko Yuri L.
Published: January 2018

α-Synuclein (α-syn) is the major component of the intraneuronal inclusions called Lewy bodies, which are the pathological hallmark of Parkinson’s disease. α-Syn is capable of self-assembly into many different species, such as soluble oligomers and fibrils. Even though attempts to resolve the structures of the protein have been made, detailed understanding about the structures and their relationship with the different aggregation steps is lacking, which is of interest to provide insights into the pathogenic mechanism of Parkinson’s disease. Here we report the structural flexibility of α-syn monomers and dimers in an aqueous solution environment as probed by single-molecule time-lapse high-speed AFM. In addition, we present the molecular basis for the structural transitions using discrete molecular dynamics (DMD) simulations. α-Syn monomers assume a globular conformation, which is capable of forming tail-like protrusions over dozens of seconds. Importantly, a globular monomer can adopt fully extended conformations. Dimers, on the other hand, are less dynamic and show a dumbbell conformation that experiences morphological changes over time. DMD simulations revealed that the α-syn monomer consists of several tightly packed small helices. The tail-like protrusions are also helical with a small β-sheet, acting as a “hinge”. Monomers within dimers have a large interfacial interaction area and are stabilized by interactions in the non-amyloid central (NAC) regions. Furthermore, the dimer NAC-region of each α-syn monomer forms a β-rich segment. Moreover, NAC-regions are located in the hydrophobic core of the dimer.
Quantum theory of multiscale coarse-graining
Authors: Han Yining , Jin Jaehyeok , Wagner Jacob W. , Voth Gregory A.
Published: January 2018

Coarse-grained (CG) models serve as a powerful tool to simulate molecular systems at much longer temporal and spatial scales. Previously, CG models and methods have been built upon classical statistical mechanics. The present paper develops a theory and numerical methodology for coarse-graining in quantum statistical mechanics, by generalizing the multiscale coarse-graining (MS-CG) method to quantum Boltzmann statistics. A rigorous derivation of the sufficient thermodynamic consistency condition is first presented via imaginary time Feynman path integrals. It identifies the optimal choice of CG action functional and effective quantum CG (qCG) force field to generate a quantum MS-CG (qMS-CG) description of the equilibrium system that is consistent with the quantum fine-grained model projected onto the CG variables. A variational principle then provides a class of algorithms for optimally approximating the qMS-CG force fields. Specifically, a variational method based on force matching, which was also adopted in the classical MS-CG theory, is generalized to quantum Boltzmann statistics. The qMS-CG numerical algorithms and practical issues in implementing this variational minimization procedure are also discussed. Then, two numerical examples are presented to demonstrate the method. Finally, as an alternative strategy, a quasi-classical approximation for the thermal density matrix expressed in the CG variables is derived. This approach provides an interesting physical picture for coarse-graining in quantum Boltzmann statistical mechanics in which the consistency with the quantum particle delocalization is obviously manifest, and it opens up an avenue for using path integral centroid-based effective classical force fields in a coarse-graining methodology.
Excitation-dependent carrier lifetime and diffusion length in bulk CdTe determined by time-resolved optical pump-probe techniques
Authors: Ščajev Patrik , Miasojedovas Saulius , Mekys Algirdas , Kuciauskas Darius , Lynn Kelvin G. , Swain Santosh K. , Jarašiūnas Kęstutis
Published: January 2018

We applied time-resolved pump-probe spectroscopy based on free carrier absorption and light diffraction on a transient grating for direct measurements of the carrier lifetime and diffusion coefficient D in high-resistivity single crystal CdTe (codoped with In and Er). The bulk carrier lifetime τ decreased from 670 ± 50 ns to 60 ± 10 ns with increase of excess carrier density N from 1016 to 5 × 1018 cm−3 due to the excitation-dependent radiative recombination rate. In this N range, the carrier diffusion length dropped from 14 μm to 6 μm due to lifetime decrease. Modeling of in-depth (axial) and in-plane (lateral) carrier diffusion provided the value of surface recombination velocity S = 6 × 105 cm/s for the untreated surface. At even higher excitations, in the 1019–3 × 1020 cm−3 density range, D increase from 5 to 20 cm2/s due to carrier degeneracy was observed.
In situ Zn/ZnO mapping elucidating for “shape change” of zinc electrode
Authors: Nakata Akiyoshi , Arai Hajime , Murayama Haruno , Fukuda Katsutoshi , Yamane Tomokazu , Hirai Toshiro , Uchimoto Yoshiharu , Yamaki Jun-ichi , Ogumi Zempachi
Published: January 2018

For the use of the zinc anode in secondary batteries, it is necessary to solve the “shape change” deterioration issue in that zinc species agglomerate in the center of the electrode to fade the available capacity. The local chemical compositions of the zinc electrodes during “shape change” were precisely analyzed using the synchrotron X-ray diffraction mapping analysis of practical zinc-nickel cells in a non-destructive manner. The in situ Zn/ZnO mapping shows that metallic Zn deposition chiefly occurs in the periphery of ZnO while ZnO are left in the center of electrode like a hill on charging. On discharging, the ZnO hill grows to the perpendicular direction on the electrode while metallic zinc is oxidized and dissolved. These findings allow us to propose a mechanism for the shape change; thus dissolved zincate species are decomposed on the ZnO hill during discharging to be accumulated in the center of the electrode. It is suggested that suppressing zincate dissolution and non-uniform zinc deposition slow the growth rate of the ZnO hill to enhance the cyclability of zinc-based secondary batteries.
A study of the rheology and micro-structure of dumbbells in shear geometries
Authors: Mandal Sandip , Khakhar D. V.
Published: January 2018

We study the flow of frictional, inelastic dumbbells made of two fused spheres of different aspect ratios down a rough inclined plane and in a simple shear cell, using discrete element simulations. At a fixed inclination angle, the mean velocity decreases, and the volume fraction increases significantly with increasing aspect ratio in the chute flow. At a fixed solid fraction, the shear stress and pressure decrease significantly with increasing aspect ratio in the shear cell flow. The micro-structure of the flow is characterized. The translational diffusion coefficient in the normal direction to the flow is found to scale as Dyy=bγ̇d2, independent of aspect ratio, where b is a constant, γ̇ is the shear rate, and d is the diameter of the constituent spheres of the dumbbells. The effective friction coefficient (μ, the ratio of shear stress to pressure) increases by 30%-35% on increasing the aspect ratio λ, from 1.0 to 1.7, for a fixed inertial number I. The volume fraction (ϕ) also increases significantly with increasing aspect ratio, especially at high inertial numbers. The effective friction coefficient and volume fraction are found to follow simple scalings of the form μ = μ(I, λ) and ϕ = ϕ(I, λ) for all the data from both systems, and the results are in reasonable agreement with kinetic theory predictions at low I. The computational results are in reasonable agreement with the experimental data for flow in a rotating cylinder.
Observation of the negative pressure derivative of the bulk modulus in monoclinic ZrO2
Authors: Fujimoto Manato , Akahama Yuichi , Fukui Hiroshi , Hirao Naohisa , Ohishi Yasuo
Published: January 2018

Using synchrotron radiation x-ray diffraction techniques, the equation of state of monoclinic ZrO2 has been investigated under a hydrostatic pressure condition at 298 K. Monoclinic ZrO2 transformed to the orthorhombic I phase at between 5.7 and 7.0 GPa. Lattice constants of monoclinic ZrO2 refined from the Reitveld analysis showed extreme anisotropic pressure dependence. From the pressure–volume data, using least-squares fit of the Birch–Murnaghan formula, the bulk modulus, K0 and its pressure derivative: K0′, were estimated to be 159(3) GPa and −3.6(6), respectively. A negative K0′ suggests the abnormal softening of the elastic modulus in monoclinic ZrO2 with compression. First-principles calculations supported present experimental results.
Developing a quantum theory of multiscale coarse-graining
Authors: Kim Meeri
Published: January 2018

Theoretical chemists have come up with a theory of coarse-graining for the quantum mechanical regime to simplify complex molecular simulations.
Towards a supportive policy and commissioning environment for chemsex in England
Authors: Moncrieff Monty
Published: January 2018

The use of drugs in sexual settings among gay men (colloquially referred to as ‘chemsex’) was first observed in services supporting gay men in London in the late 2000s. A decade on and it now features as a policy issue in the UK Government’s latest Drug Strategy, with several actions to support a health system response. However, reaching this point has been a slow and challenging process and much remains to be done to facilitate an environment in which evidence-based chemsex interventions can be delivered. With a view to informing the development of policies and services in other contexts, this case report examines the initiatives that have driven a response to chemsex and contributed to policy development in England and highlights remaining challenges to effective service provision.
Linked networks for learning and expressing location-specific threat
Authors: Suarez-Jimenez Benjamin , Bisby James A. , Horner Aidan J. , King John A. , Pine Daniel S. , Burgess Neil
Published: January 2018

Learning locations of danger within our environment is a vital adaptive ability whose neural bases are only partially understood. We examined fMRI brain activity while participants navigated a virtual environment in which flowers appeared and were “picked.” Picking flowers in the danger zone (one-half of the environment) predicted an electric shock to the wrist (or “bee sting”); flowers in the safe zone never predicted shock; and household objects served as controls for neutral spatial memory. Participants demonstrated learning with shock expectancy ratings and skin conductance increases for flowers in the danger zone. Patterns of brain activity shifted between overlapping networks during different task stages. Learning about environmental threats, during flower approach in either zone, engaged the anterior hippocampus, amygdala, and ventromedial prefrontal cortex (vmPFC), with vmPFC–hippocampal functional connectivity increasing with experience. Threat appraisal, during approach in the danger zone, engaged the insula and dorsal anterior cingulate (dACC), with insula–hippocampal functional connectivity. During imminent threat, after picking a flower, this pattern was supplemented by activity in periaqueductal gray (PAG), insula–dACC coupling, and posterior hippocampal activity that increased with experience. We interpret these patterns in terms of multiple representations of spatial context (anterior hippocampus); specific locations (posterior hippocampus); stimuli (amygdala); value (vmPFC); threat, both visceral (insula) and cognitive (dACC); and defensive behaviors (PAG), interacting in different combinations to perform the functions required at each task stage. Our findings illuminate how we learn about location-specific threats and suggest how they might break down into overgeneralization or hypervigilance in anxiety disorders.
Older Adults’ Utilization of Community Resources Targeting Fall Prevention and Physical Activity
Authors: McMahon Siobhan K , Park Young Shin , Lewis Beth , Guan Weihua , Oakes J Michael , Wyman Jean F , Rothman Alexander J
Published: January 2018

Background and Objectives

Despite the availability of community resources, fall and inactivity rates remain high among older adults. Thus, in this article, we describe older adults’ self-reported awareness and use of community resources targeting fall prevention and physical activity.

Research Design and Methods

In-depth, semistructured interviews were conducted in Phase 1 with community center leaders (n = 5) and adults (n = 16) ≥70 years old whose experience with community programs varied. In Phase 2, surveys were administered to intervention study participants (n = 102) who were ≥70 years old, did not have a diagnosis of dementia, and reported low levels of physical activity.

Results

Four themes emerged from Phase 1 data: (a) identifying a broad range of local community resources; (b) learning from trusted sources; (c) the dynamic gap between awareness and use of community resources; and (d) using internal resources to avoid falls. Phase 2 data confirmed these themes; enabled the categorization of similar participant-identified resources (10); and showed that participants who received encouragement to increase community resource use, compared to those who did not, had significantly greater odds of using ≥1 resource immediately postintervention, but not 6 months’ postintervention.

Discussion and Implications

Although participants in this study were aware of a broad range of local community resources for physical activity, they used resources that support walking most frequently. Additionally, receiving encouragement to use community resources had short-term effects only. Findings improve our understanding of resources that need bolstering or better dissemination and suggest researchers identify best promotion, dissemination, implementation strategies.
Psychotherapy and Social Work
Authors: Drisko James
Published: January 2018

Psychotherapy is an interactive process for the treatment of a client’s mental health or behavioral problems. It seeks to explore thoughts, feelings, and behaviors in order to solve intrapsychic problems or to enhance one’s level of interpersonal functioning. Psychotherapy may be provided in individual, couple, dyadic, family, group or multiple family group modalities—though this bibliography will focus only on psychotherapy with adults using an individual modality. Psychotherapy is provided by a qualified mental health professional, typically a clinical social worker, psychologist, psychiatrist or other licensed professional. Depending on the issue being addressed, psychotherapy may be provided alone or in combination with medications or other related support and service programs. Psychotherapy is a term that encompasses a wide variety of theories, methods, and techniques. Its great variety makes it difficult to define and describe succinctly. Psychotherapy has deep and longstanding roots in medicine, traditional healing, psychology, social work, nursing, and education. Various psychotherapies may draw upon single or combined theoretical foundations, may use unique or widely shared methods and techniques. The evidence base for different psychotherapies varies widely, and may take on different forms to address appropriately the theoretical premises, specific objectives, and methods employed. There are many types of psychotherapy: Wikipedia lists 150 named types; GoodTherapy.org lists 148 of the “most common” types of psychotherapy. The American Psychological Association identifies five broad approaches to psychotherapy: psychodynamic, behavioral, cognitive, humanistic, and integrative. This bibliography will focus mainly on these five widely practiced forms of psychotherapy as well as trauma theory and therapy. This bibliography will also address the research evidence supporting the effectiveness of psychotherapy in this era of evidence-based practice.
Clinical Social Work Practice with Males
Authors: Blundo Robert , Hall J. Christopher
Published: January 2018

Social work practice focuses specifically on males or females is a more limited area of scholarship when compared to those focused on general models of practice within social work. The majority of practice texts and journals do not differentiate gender when presenting a theory or method of practice. Males are similarly less of a focus than women and other specified groups other than gender. Overall, males are less likely to be a focus of social work practice literature than in other disciplines such as psychology and counseling. Many of the approaches to working with males, in particular early writings, address issues of masculinity as a necessary step in working with males. Social work practice with males can be examined from a policy, population, community or individual perspective, and while all of these areas of practice are important, this article is limited to references addressing clinical practice with individuals and small groups. To that end, while the primary focus is clinical social work practice, references are included from psychology, psychotherapy, and counseling. These references are important, as significant crossover scholarship and research from parallel fields adds to the literature base of social work practice with males. While this article focuses primarily on practice with adult males, a section and selected references addressing practice with male youth and children is included.
Buddhism and Nationalism
Authors: Grabowsky Volker
Published: January 2018

Theoretical works pertaining to the birth and development of modern nationalism have a strong focus on Europe and the Americas. This is due to the axiomatic contention that nationalism originated in the West and only later spread to Asia and Africa in the course of European colonialism and imperialism. Such a conventional approach, positioning nationalism as the outcome of homogenizing historical processes in the fields of economy, education, print-capitalist culture, and industrial social organization, tend to overlook the significance of primordial ethno-religious loyalties for the emergence of nationalism. Buddhism, the dominant religion in large parts of East, South, and Southeast Asia, has played a crucial role in Asian nationalist movements. Given the close connection between Buddhism and traditional precolonial polities, particularly Burma (Myanmar) and Sri Lanka, it is not surprising that Buddhism was used to arouse nationalist sentiments against foreign powers, and that it contributed to new forms of national integration in the postcolonial period. It may be even argued that purely secular nationalism, without a major admixture of religious movements, has been rare in Asia. The identification of Western domination with Christianity, for example, gave rise to nationalist movements in mainland Southeast Asia to defend traditional cultural values in the midst of a process of social and economic modernization. Buddhists often embraced nationalism in the name of modernity. Regarding Buddhism as part of their indigenous heritage, Buddhists developed national pride. In Sri Lanka and Burma, Buddhism was identified with the history of the nation, and thus this religion was promoted as a tool to defend the nation against Western colonialism. In Thailand, the only noncolonialized country in Southeast Asia, Buddhism has constituted a pivotal pillar of “official state nationalism” since the late 19th century. In China, Buddhists also used their religion to counterbalance the challenges of Western cultural encroachments. In neighboring Japan, which actively embraced Western civilization, Buddhists tried to prove, in a defensive manner, that Buddhism represented a religious practice essential to Japanese cultural identity. In Korea, under Japanese colonial rule since 1910, and in Tibet, considered as part of China since the Qing dynasty, a Buddhist nationalism had to develop its own identities as distinct from Japanese and Chinese Buddhism, respectively. In the increasingly transnational, globalized world of the 21st century, Buddhism still provides a source of legitimacy for the nation-state, and a source of national identity for the majority populations in several Asian countries, sometimes directed against non-Buddhist (Muslim, Hindu, etc.) minorities perceived as cultural threats.
Colonial Governance in the Atlantic World
Authors: Krause Thiago , Cardim Pedro
Published: January 2018

From the beginning of the European overseas expansion into the Atlantic in the 15th century onward, Europeans had to figure how to govern the newly conquered lands and peoples across Africa and the Americas. Western European polities transplanted to their Atlantic territories forms of governance already tested within the European context, but institutions of colonial governance were built in fits and starts and constantly adapted to local demands and characteristics. American elites sought and sometimes achieved a relationship with the imperial center that could be similar to the one experienced by European local elites. However, Old World models of government were deeply transformed by distance, by environmental conditions, and, above all, by the variety of peoples that were under European rule. Atlantic governance involved the (often violent) seizure of substantial portions of the American and (in a much lesser scale) African and Asian lands, along with the transfer of people of European descent to settle the conquered lands. Local populations were often forced to labor for their new overlords and were gradually dispossessed of their lands and institutions, while sub-Saharan Africans were compulsorily transported across the Atlantic to work as slaves. As a result of racial prejudice and power relations, they were assigned a subaltern status that deprived them from many civic and political rights, becoming a subaltern majority. This posed new problems that transformed templates brought by European colonizers, such as the patterns of government developed in the Iberian Reconquista and in the English domination of Ireland. All empires dealt with similar problems in the Atlantic: the need to establish its own authority, to defend the settlements, and to produce enough revenue to pay for it all. A high level of flexibility was needed at first because European authorities had little knowledge of Atlantic realities. Afterward, the slowness of communication and the need to obtain local cooperation to achieve any goal, from the conquest itself to defense and taxing local production, required collaboration, not only from colonists of European descent but also from Native Americans, sub-Saharan Africans, and the multiethnic populations that grew throughout the Early Modern era. Colonial governance should not be understood, therefore, as a top-down imposition from Europe to Africa and the Americas, but as a contested struggle between many opposing groups and factions. Recent historiography has been increasingly cognizant of temporal and spatial differences, but there is still need for a deeper engagement between different linguistic traditions. Atlantic expansion was a multinational endeavor, and so should be its study.
Anthony Burgess
Authors: Clarke Jim
Published: January 2018

John Anthony Burgess Wilson (b. 1917–d. 1993) was a prominent British-born novelist, composer, critic, essayist, journalist, playwright, poet, and librettist of the post–World War II period. His best-known work remains A Clockwork Orange (first published in 1962; see Burgess 2010 and Burgess 2012, cited under Critical Editions), a violent morality-tale novella that he later repeatedly disavowed. However, in the 21st century critics have also turned attention to other parts of his extensive output, identifying, in particular, his Malayan Trilogy (1956–1959) as an early example of postcolonial fiction written from the colonial perspective. His reputation also rests upon his longest novel, Earthly Powers, a satire of the airport blockbuster of the 1970s, and his novels about the Elizabethan playwrights William Shakespeare and Christopher Marlowe, entitled Nothing like the Sun and A Dead Man in Deptford, respectively. He was the author of thirty-two novels, two verse novels, two children’s books, two volumes of autobiography, at least ten major translations, nine book-length literary studies, two studies of popular linguistics, a volume of short stories, multiple libretti, thousands of pieces of journalism, numerous film and TV scripts, and hundreds of pieces of original musical composition. Despite an upturn in critical attention toward his work, much of his nonfiction remains uncollected and many of his novels are currently out of print, though a critical edition of his collected fiction is under way. His major theme, according to both himself and his early critics, was the limitations of human free will. He derived this concept from his upbringing as a Lancastrian Catholic, an influence that shaped much of his thinking for the rest of his life and writing career. Many of his major works feature artists and writers as protagonists, indicating a fixation on aesthetics and the artistic process. Additionally, he often fictionalized the lives of historical personages, from Shakespeare to Napoleon to Jesus Christ. Critics have identified his fiction as particularly significant in relation to the boundary of colonial and postcolonial literature, and that between modernism and postmodernism.
Potentially Preventable Stillbirth in a Diverse U.S. Cohort
Authors: Page Jessica M. , Thorsten Vanessa , Reddy Uma M. , Dudley Donald J. , Hogue Carol J. Rowland , Saade George R. , Pinar Halit , Parker Corette B. , Conway Deborah , Stoll Barbara J. , Coustan Donald , Bukowski Radek , Varner Michael W. , Goldenberg Robert L. , Gibbins Karen , Silver Robert M.
Published: January 2018

OBJECTIVE:

To estimate the proportion of potentially preventable stillbirths in the United States.

METHODS:

We conducted a secondary analysis of 512 stillbirths with complete evaluation enrolled in the Stillbirth Collaborative Research Network from 2006 to 2008. The Stillbirth Collaborative Research Network was a multisite, geographically, racially, and ethnically diverse, population-based case–control study of stillbirth in the United States. Cases of stillbirth underwent standard evaluation that included maternal interview, medical record abstraction, biospecimen collection, postmortem examination, placental pathology, and clinically recommended evaluation. Each stillbirth was assigned probable and possible causes of death using the Initial Causes of Fetal Death algorithm system. For this analysis, we defined potentially preventable stillbirths as those occurring in nonanomalous fetuses, 24 weeks of gestation or greater, and weighing 500 g or greater that were 1) intrapartum, 2) the result of medical complications, 3) the result of placental insufficiency, 4) multiple gestation (excluding twin–twin transfusion), 5) the result of spontaneous preterm birth, or 6) the result of hypertensive disorders of pregnancy.

RESULTS:

Of the 512 stillbirths included in our cohort, causes of potentially preventable stillbirth included placental insufficiency (65 [12.7%]), medical complications of pregnancy (31 [6.1%]), hypertensive disorders of pregnancy (20 [3.9%]), preterm labor (16 [3.1%]), intrapartum (nine [1.8%]), and multiple gestations (four [0.8%]). Twenty-seven stillbirths fit two or more categories, leaving 114 (22.3%) potentially preventable stillbirths.

CONCLUSION:

Based on our definition, almost one fourth of stillbirths are potentially preventable. Given the predominance of placental insufficiency among stillbirths, identification and management of placental insufficiency may have the most immediate effect on stillbirth reduction.
Risk Factors, Incidence, and Morbidity Associated With Obstetric Clostridium difficile Infection
Authors: Ruiter-Ligeti Jacob , Vincent Sophie , Czuzoj-Shulman Nicholas , Abenhaim Haim Arie
Published: January 2018

OBJECTIVE:

To evaluate the risk factors, incidence, and morbidity associated with the diagnosis of obstetric Clostridium difficile infection.

METHODS:

We performed a retrospective cohort study on women admitted for delivery using the Healthcare Cost and Utilization Project Nationwide Inpatient Sample from the United States. The delivery admission records of pregnant women were reviewed between 1999 and 2013. After adjusting for demographic and clinical characteristics, we assessed risk factors for the diagnosis of C difficile infection using unconditional logistic regression.

RESULTS:

Of the total 13,881,592 births in our cohort, we identified 2,757 (0.02%) admissions for delivery complicated by a diagnosis of C difficile infection. During the study period, the rate of C difficile infection diagnoses among women hospitalized for delivery doubled from 15 (95% CI 11.87–16.96) to 30 (24.42–31.78) per 100,000 deliveries per year (P<.001). Risk factors associated with the diagnosis of C difficile infection included age older than 35 years, multiple gestations, smoking, Crohn's disease, ulcerative colitis, long-term antibiotic use, pneumonia, pyelonephritis as well as cesarean or perineal wound infection. The diagnosis of C difficile infection in pregnancy was associated with a significant increase in maternal death (8.0/1,000 vs 0.1/1,000, adjusted odds ratio [OR] 56.8, 95% CI 35.8–90.1). Furthermore, there was an increase in sepsis (46.4/1,000 vs 0.6/1,000, adjusted OR 59.1, 95% CI 48.8–71.6), paralytic ileus (58.0/1,000 vs 1.5/1,000, adjusted OR 33.1, 95% CI 27.5–39.8), venous thromboembolism (38.4/1,000 vs 3.1/1,000, adjusted OR 8.1, 95% CI 6.5–10.2), and hospital stays greater than 2 weeks (173.0/1,000 vs 6.5,1,000, adjusted OR 24.3, 95% CI 21.6–27.4) among pregnant women with C difficile infection.

CONCLUSION:

The diagnosis of C difficile infections in pregnancy has increased over the past 15 years and this diagnosis is associated with significant maternal morbidity and mortality.
Antecedents of Abnormally Invasive Placenta in Primiparous Women
Authors: Baldwin Heather J. , Patterson Jillian A. , Nippita Tanya A. , Torvaldsen Siranda , Ibiebele Ibinabo , Simpson Judy M. , Ford Jane B.
Published: January 2018

OBJECTIVE:

To evaluate the association between prior invasive gynecologic procedures and the risk of subsequent abnormally invasive placenta (ie, placenta accreta, increta, and percreta).

METHODS:

We conducted a population-based data linkage study including all primiparous women who delivered in New South Wales, Australia, between 2003 and 2012. Data were obtained from linked birth and hospital admissions with a minimum lookback period of 2 years. Prior procedures invasive of the uterus were considered including gynecologic laparoscopy with instrumentation of the uterus; hysteroscopy, including operative hysteroscopy; curettage, including suction curettage and surgical termination; and endometrial ablation. Modified Poisson regression was used to determine the association between the number of prior gynecologic procedures and risk of abnormally invasive placenta.

RESULTS:

Eight hundred fifty-four cases of abnormally invasive placenta were identified among 380,775 deliveries included in the study (22.4/10,000). In total, 33,296 primiparous women had at least one prior procedure (8.7%). Among women with abnormally invasive placenta, 152 (17.8%) had undergone at least one procedure compared with 33,144 (8.7%) among women without abnormally invasive placenta (P<.01). After adjustment, the relative risk was 1.5 for one procedure (99% CI 1.1–1.9), 2.7 for two procedures (99% CI 1.7–4.4), and 5.1 for three or more procedures (99% CI 2.7–9.6). Abnormally invasive placenta was also positively associated with maternal age, socioeconomic advantage, mother being Australia-born, placenta previa, hypertension, multiple births, use of assisted reproductive technology, and female fetal sex.

CONCLUSION:

Women with a history of prior invasive gynecologic procedures were more likely to develop abnormally invasive placenta. These insights may be used to inform management of pregnancies in women with a history of gynecologic procedures.
Subsequent Pregnancy Outcomes in Patients With Peripartum Cardiomyopathy
Authors: Codsi Elisabeth , Rose Carl H. , Blauwet Lori A.
Published: January 2018

OBJECTIVE:

To describe cardiac and obstetric outcomes in subsequent pregnancies of patients with peripartum cardiomyopathy and to report demographic and clinical characteristics of index pregnancies.

METHODS:

We conducted a retrospective cohort study of all pregnant patients with prior peripartum cardiomyopathy seen at the Mayo Clinic from January 2000 through March 2017. Maternal and neonatal outcome data of index and all subsequent pregnancies were abstracted, and all echocardiography examinations were individually reviewed.

RESULTS:

Twenty-five patients with prior peripartum cardiomyopathy were included; all except one had recovered left ventricular (LV) function (LV ejection fraction 50% or greater) before the subsequent pregnancy. Forty-three subsequent pregnancies were identified: six (14.0%) miscarriages, four (9.3%) terminations, and 33 (76.7%) live births. The rate of peripartum cardiomyopathy relapse was 20.9%; median LV ejection fraction nadir in patients with relapse was 43% (range 35–45%). None had LV ejection fraction decline to the level of their index pregnancy. No cardiac arrests or deaths were observed, and all patients with relapse recovered LV function. Median gestational age at delivery for all live births in subsequent pregnancies was 39.0 weeks (range 36 6/7–41 3/7 weeks).

CONCLUSION:

Patients with a history of peripartum cardiomyopathy who recover LV function are at risk for a transient minor decrease in LV ejection fraction during future pregnancies, but obstetric and neonatal outcomes are often favorable.
Effect of Cesarean Delivery on Long-term Risk of Small Bowel Obstruction
Authors: Abenhaim Haim A. , Tulandi Togas , Wilchesky Machelle , Platt Robert , Spence Andrea R. , Czuzoj-Shulman Nicholas , Suissa Samy
Published: January 2018

OBJECTIVE:

To evaluate the association of cesarean deliveries on the incidence of small bowel obstruction.

METHODS:

We formed a population-based cohort of all women with a first live birth between 1998 and 2007 using the U.K. Clinical Practice Research Datalink. Women were followed until 2015, the occurrence of a small bowel obstruction, or loss to follow-up. Cesarean delivery was identified from the Hospital Episode Statistics and small bowel obstruction events were identified using the Classification of Interventions and Procedures and International Classification of Diseases, 10th Revision codes. Cox proportional hazard models, with cesarean delivery defined as a time-dependent exposure, estimated the adjusted hazard ratios and 95% CIs of small bowel obstruction associated with cesarean delivery.

RESULTS:

The cohort included 81,480 women with a median follow-up of 8.0 years (range 6 months to 16.6 years), during which 575 new small bowel obstructions occurred (incidence 9.1/10,000 person-years). Risk of small bowel obstruction was higher among women with a cesarean delivery compared with women without (16.3 vs 6.4 patients/10,000 person-years, odds ratio [OR] 2.54, 95% CI 2.15–3.00). Increasing number of cesarean deliveries was associated with an increasing risk of small bowel obstruction (OR 1.61, 95% CI 1.46–1.78, per additional cesarean delivery). Repeated small bowel obstructions were more common among women with a cesarean delivery and the association remained when restricting to small bowel obstruction requiring surgical management.

CONCLUSION:

Although rare, small bowel obstructions are increased among women who have undergone a cesarean delivery. With increasing rates of cesarean deliveries worldwide, small bowel obstructions and related morbidities may become a more prevalent women's health concern.
Outcomes of Planned Compared With Urgent Deliveries Using a Multidisciplinary Team Approach for Morbidly Adherent Placenta
Authors: Shamshirsaz Alireza A. , Fox Karin A. , Erfani Hadi , Clark Steven L. , Shamshirsaz Amir A. , Nassr Ahmed A. , Sundgren Nathan C. , Jones Jeffery A. , Anderson Matthew L. , Kassir Elias , Salmanian Bahram , Buffie Alexandra W. , Hui Shiu-Ki , Espinoza Jimmy , Tyer-Viola Lynda A. , Rac Martha , Karbasian Niloofar , Ballas Jerasimos , Dildy Gary A. , Belfort Michael A.
Published: January 2018

OBJECTIVE:

To compare outcomes between planned and urgent cesarean hysterectomy for morbidly adherent placenta managed by a multidisciplinary team.

METHODS:

This is a retrospective case–control study of women with singleton pregnancies with antenatally suspected and pathologically confirmed morbidly adherent placenta who underwent cesarean hysterectomy between January 1, 2011, and February 30, 2017. Timing of delivery was classified as either planned (delivery at 34–35 weeks of gestation) or urgent (need for urgent delivery as a result of uterine contractions, bleeding, or both). The primary outcome variable was composite maternal morbidity. Logistic regression analysis was used to evaluate risk factors for urgent delivery.

RESULTS:

One hundred thirty patients underwent hysterectomy. Sixty (46.2%) required urgent delivery. Composite maternal morbidity was identified in 34 (56.7%) of the urgent and 26 (37.1%) of the planned deliveries (P=.03). Fewer units of red blood cells and fresh frozen plasma were transfused in the planned delivery group (red blood cells, median interquartile range 3 [0–8] versus 1 [0–4], P=.02; fresh frozen plasma, median interquartile range 1 [0–2] versus 0 [0–0], P=.001). Rates of low Apgar score and respiratory distress syndrome were higher in the urgent compared with the planned delivery group (5-minute Apgar score less than 7, 34 [59.6%] versus 14 [23.3%], P<.01; respiratory distress syndrome, 34 [61.8%] versus 16 [27.1%], P<.01). A history of two or more prior cesarean deliveries was an independent predictor of urgent delivery (adjusted odds ratio 11.4, 95% CI 1.8–71.1).

CONCLUSION:

Women with morbidly adherent placenta requiring urgent delivery have a worse outcome than women with planned delivery. Women with morbidly adherent placenta and two or more prior cesarean deliveries are at increased risk for urgent delivery. In such women, scheduling delivery before the standard 34- to 35-week timeframe may be reasonable.
Associations Between Childbirth and Urinary Incontinence After Midurethral Sling Surgery
Authors: Bergman Ida , Westergren Söderberg Marie , Lundqvist Andrea , Ek Marion
Published: January 2018

OBJECTIVE:

To assess whether subsequent childbirths affect the outcomes of midurethral sling surgery with regard to stress urinary incontinence (SUI).

METHODS:

In this population-based cohort study, we used the validated Swedish nationwide health care registers (the Patient Register and the Medical Birth Register) to identify women with a delivery after midurethral sling surgery (n=207, study group). From the same registers we then randomly identified a control group who had no deliveries after their midurethral sling procedure (n=521, control group). The women in the control group were matched to the women in the study group by age and year of surgery. The Urogenital Distress Inventory and the Incontinence Impact Questionnaire were sent out to the study population. Symptomatic SUI was defined as the primary outcome. Secondary outcomes included the total Urogenital Distress Inventory score, Urogenital Distress Inventory subscale scores, and Incontinence Impact Questionnaire scores.

RESULTS:

A total of 728 women were eligible for the study. The response rate was 74%; 163 in the study group (64 with vaginal delivery and 95 with cesarean delivery) and 374 women in the control group were included in the analysis. The rate of SUI (primary outcome) was 36 of 163 (22%) in the study group and 63 of 374 (17%) in the control group. In a multivariate regression analysis of the primary outcome, we found no significant difference between the groups (odds ratio [OR] 1.2, 95% CI 0.7–2.0). Vaginal childbirth after midurethral sling surgery did not increase the risk of SUI compared with cesarean delivery (22% vs 22%, OR 0.6, 95% CI 0.2–1.4). There were no significant differences in Urogenital Distress Inventory and Incontinence Impact Questionnaire scores between any of the groups.

CONCLUSION:

Childbirth after a midurethral sling procedure is not associated with an increased risk of patient-reported SUI, and continence status is not affected by the mode of a subsequent delivery.
Diagnosis and Treatment of Vulvar Dermatoses
Authors: Stockdale Colleen K. , Boardman Lori
Published: January 2018

Vulvar symptoms of pain, dyspareunia, and pruritus are common and may significantly affect a woman's sense of well-being and sexual function. Despite this, vulvar symptoms are often underreported by women. When identified, however, vulvovaginal symptoms should be addressed by health care providers to optimize care. The evaluation of patients with vulvovaginal complaints begins with a thorough history and physical examination. Biopsy is indicated when concern exists for malignancy or the diagnosis is uncertain. Treatment, if possible, should be evidence-based, although for many vulvar disorders including vulvar dermatoses, treatment is based on limited evidence and anecdotal experience. Although many vulvar dermatoses represent chronic conditions and thus cannot be simply cured, control is possible for the majority of women. Patient education regarding vulvar hygiene and skin care is the foundation for optimal management of inflammatory vulvar dermatoses. These conditions may be triggered or worsened by aggressive hygiene. Additionally, patients should be counseled regarding the need for individually tailored long-term maintenance to achieve optimal outcomes.