bluuebunny/crossref_metadata_2025 huggingface dataset:
Local foods can meet micronutrient needs for women in urban Burkina Faso, but only if rarely consumed micronutrient‐dense foods are included in daily diets: A linear programming exercise
Authors: Arimond Mary , Vitta Bineti S. , Martin‐Prével Yves , Moursi Mourad , Dewey Kathryn G.
Published: May 2017

Women of reproductive age are at nutritional risk due to their need for nutrient‐dense diets. Risk is further elevated in resource‐poor environments. In one such environment, we evaluated feasibility of meeting micronutrient needs of women of reproductive age using local foods alone or using local foods and supplements, while minimizing cost. Based on dietary recall data from Ouagadougou, we used linear programming to identify the lowest cost options for meeting 10 micronutrient intake recommendations, while also meeting energy needs and following an acceptable macronutrient intake pattern. We modeled scenarios with maximum intake per food item constrained at the 75th percentile of reported intake and also with more liberal maxima based on recommended portions per day, with and without the addition of supplements. Some scenarios allowed only commonly consumed foods (reported on at least 10% of recall days). We modeled separately for pregnant, lactating, and nonpregnant, nonlactating women. With maxima constrained to the 75th percentile, all micronutrient needs could be met with local foods but only when several nutrient‐dense but rarely consumed items were included in daily diets. When only commonly consumed foods were allowed, micronutrient needs could not be met without supplements. When larger amounts of common animal‐source foods were allowed, all needs could be met for nonpregnant, nonlactating women but not for pregnant or lactating women, without supplements. We conclude that locally available foods could meet micronutrient needs but that to achieve this, strategies would be needed to increase consistent availability in markets, consistent economic access, and demand.
Primary malignant pericardial sarcomatoid mesothelioma: An autopsy report
Authors: Muta Hiroko , Sugita Yasuo , Ohshima Koichi , Otsubo Hitoshi
Published: May 2017

Primary malignant pericardial sarcomatoid mesothelioma (PMPSM) is an extremely rare tumor with poor prognosis. We present an autopsy case in an 80‐year‐old man admitted for heart failure after one month of treatment at an outpatient clinic. He died three months after symptom onset. A complete autopsy revealed localization of the tumor to the pericardium without other lesions. Histologically, mainly spindle‐shaped atypical cells with hyperchromatic nuclei and nucleoli were observed. Immunohistochemical markers for mesothelioma were positive for calretinin, cytokeratin AE1/AE3, and cytokeratin CAM5.2. Thus, we diagnosed primary sarcomatoid malignant mesothelioma of the pericardium. To our knowledge, only four PMPSM cases have been reported in the English literature in the past 30 years. Although PMPSM is rare, clinicians and pathologists should recognize it as a possible diagnosis of pericardial tumors. It is necessary to accumulate clinical and pathological diagnostic findings to establish early detection methods for this extremely rare disease.
The Contemporary Presidency: Do Presidential Memo Orders Substitute for Executive Orders? New Data
Authors: Woolley John T. , Peters Gerhard
Published: May 2017

We describe and implement a text‐search strategy for reliably identifying, among published presidential documents, orders not titled “executive order” or “proclamation.” Given the inconsistent use of terms and titles in these documents, we refer to them with an umbrella term: “memo orders.” We identify over 1,600 memo orders in the archives of the American Presidency Project (APP) from 1977 to 2012. Drawing on the Federal Register for the same period, we find additional orders not in the APP archives. This produces a comprehensive estimate of the total number of published presidential orders from 1977 to 2012. We further apply our strategy to presidential signing statements from 1985 to 2008 and estimate that around 10% can be considered to include presidential orders.
Polls and Elections: Under the Radar: Public Support for Vice Presidents
Authors: Baumgartner Jody C
Published: May 2017

Analysis of vice presidential favorability and job approval polling data for the past four vice presidents suggests that there is a mismatch between how scholars and the public perceive the vice presidency. Specifically, data illustrate that vice presidential favorability and job approval ratings are overwhelmingly influenced by presidential favorability and job approval ratings. While vice presidents advise and help their presidents carry out any number of important tasks, most citizens do not seem to form independent opinions about them. The analysis adds to our understanding of the institution and has normative implications, inasmuch as it suggests that there may be a lack of democratic accountability associated with one of the only two nationally elected officials in the United States.
Vetoes in the Early Republic: A Defense of Norms
Authors: Latimer Trevor
Published: May 2017

The first six presidents (1789–1829) vetoed bills far less frequently than their successors. Previous literature affords two competing explanations for this phenomenon. The constitutional norms approach contends that the early presidents used the veto only to reject unconstitutional legislation. The veto bargaining approach argues that the early presidents vetoed fewer bills because the electoral conditions under which vetoes typically occur had yet to emerge. This article accepts some of the insights of the veto bargaining approach, but defends a corrected version of the norms account. This account says the early presidents vetoed fewer bills because they were constrained by a norm according to which “adversarial” vetoes were considered illegitimate. The emergence of the modern veto required discursive legitimation of vetoes for adversarial purposes.
Polls and Elections: The Chicago Record Poll and the Election of 1896
Authors: Thies Clifford F.
Published: May 2017

The Chicago Record poll of the presidential election of 1896 was an enormous, multistate mail survey. Unfortunately, its results were incredible. The newspaper attempted to correct the results, making perhaps the first ever attempt to deal with nonresponse bias, but did not have much success. Had responses been properly corrected for differences in response rate, the poll would have generated a satisfactory set of predictions.
Mitochondrial characteristics in oocytes of the domestic cat (Felis catus) after in vitro maturation and vitrification
Authors: Sowińska N , Müller K , Niżański W , Jewgenow K
Published: May 2017

Contents

The objective of this study was to evaluate mitochondria in immature and in vitro‐matured domestic cat oocytes and to assess for the first time the effect of vitrification on mitochondrial traits. Mitochondrial distribution and aggregation were assessed using confocal microscopy after staining with the fluorescent dye—MitoTracker® Red CMXRos. Only cells at the germinal vesicle and the metaphase II stages of nuclear development, representing immature and mature oocytes, respectively, were included in our study. Our study shows that 80% of immature and 100% of mature oocytes exhibit a peripheral pattern of mitochondria distribution, indicating that, in contrast to the situation in other species, the mitochondria of cat oocytes are not dispersed throughout the cell after in vitro maturation but instead maintain a strong affinity for the oocyte periphery near the membrane. However, a loss of aggregation was observed during in vitro maturation—78% of immature oocytes showed homogeneous granulation versus only 18% of mature oocytes (p < .001). The increased intensity of MitoTracker® Red CMXRos staining after in vitro maturation (p < .05) may be tentatively attributed to an increase in mitochondrial activity but could likewise reflect a concomitant appearance of sulphhydryl groups in cytoplasm (known to be targeted by the dye). Mitochondrial distribution did not change upon vitrification; however, dye intensity decreased (p < .05) and mitochondrial aggregation was intensified in both immature and mature vitrified cat oocytes.
Cripping sexualities: An analytic review of theoretical and empirical writing on the intersection of disabilities and sexualities
Authors: Santinele Martino Alan
Published: May 2017

This paper provides a review of some of the literature addressing the juncture of disabilities and sexualities and invites sociologists to build on this work and take part in this important intersectional field. First, I discuss the central relevance of an intersectional lens for making sense of the unique experiences of queer people with disabilities who are located at the crossroads of various stratified systems. Then, I discuss some of the many unique challenges that queer disabled people face when exploring their sexuality, establishing relationships, and remaining sexual. The invisibility, marginalization, and discrimination of queer people with disabilities in both queer and disability communities are the focus on the third section. The fourth section speaks to current theoretical dialogues between disability studies and queer theory that have illuminated new pathways for theorizing the intersection of disabilities and sexualities, “cripping” sociological theories, and reimagining disability within sociology. As I demonstrate, this literature is growing; however, myriad exciting opportunities for empirical and theoretical sociological exploration remain and I will conclude with a discussion of possible directions for future research.
Citizenship and inequality in a global age
Authors: Aneesh A. , Wolover D.J.
Published: May 2017

Although the notion of national citizenship has long held the promise of equal membership, it has proved less useful in a world of circulating cultures, people, and loyalties through money, media, and migration. The increasing mobility of capital and people across national borders compels us to conceptualize welfare and inequality at the global level. Although the enforcement of citizen rights remains within the purview of the nation‐state, the source of these rights can no longer be firmly placed within the national framework. From cosmopolitan imaginations to postnational research, contemporary configurations of citizenship trace their legitimacy to global discourses that increasingly challenge the national order of citizenship. Yet current transformations in citizenship also point to the possibility of new inequalities, particularly, when nation‐states are increasingly able to modulate the rights they make available to immigrants, and differentiate among refugees, professionals, and investors among many other categories of people.
Environmental attitudes and the politics of distrust
Authors: Fairbrother Malcolm
Published: May 2017

This article reviews recent studies showing that distrust lies at the heart of the serious crisis of sustainability that humanity is failing to address, insofar as distrust of environmental scientists, communicators, and policymakers are all undermining public demand for better public policies. Generalised distrust of scientists is rare, but political distrust is ubiquitous, such that even people who are concerned about environmental problems are often opposed to potential policy solutions. There are also people, however, who do not even believe in some of the problems—most notably climate change. This scepticism is sometimes interpreted as a consequence of their preferring free markets to regulation; in other ways, though, the sceptics are not at all sympathetic to free markets. What appears more distinctive about them is their distrust of virtually all elite social institutions, including communities of experts, and a corresponding divide between their beliefs and preferences and those of experts generally.
Translating transgender: Using Western discourses to understand Samoan fa'afāfine
Authors: Schmidt Johanna M.
Published: May 2017

The analysis of gender as a socially constructed category is one of the foundations of the sociological project. The concept of transgender is of particular interest, in that it reveals that sex is not necessarily constitutive of gender. Gender nonconformity in non‐Western contexts particularly demonstrates that the ways in which sex, gender, and sexuality are conceptualised in Western discourses are open to challenge. However, academic research about non‐Western transgender identities and populations often ultimately replicates specific heteronormative and/or Western ways of seeing the world. In this article, I discuss how Samoan fa'afāfine have been represented by various academic disciplines, using a sociological perspective to deconstruct discourses commonly used in this process, which include Orientalism, essentialism, and functionalism. I then outline research that allows for a more nuanced understanding of the lived experience of fa'afāfine, situating them within the broader Samoan cultural context and paying attention to how fa'afāfine themselves construct and maintain their identities. I conclude that this more holistic approach should be taken with all representations of non‐Western and Western nonheteronormative identities and populations.
The impact of credit constraints on exporting firms: Evidence from the provision and subsequent removal of subsidised credit
Authors: Kapoor Mudit , Ranjan Priya , Raychaudhuri Jibonayan
Published: May 2017

We study the causal impact of credit constraints on exporters using a natural experiment provided by two policy changes in India, first in 1998 which made small‐scale firms eligible for subsidised direct credit, and a subsequent reversal in policy in 2000 wherein some of these firms lost their eligibility. Using firms that were not affected by these policy changes as our control group in each case, we find that credit expansion increased the growth rate of bank borrowing and had a positive effect on exports. The subsequent policy reversal in 2000 had no impact on the growth rate of bank borrowing or on exports.
Single layer cystotomy closure of excised porcine bladders with barbed versus smooth suture material
Authors: Montel Joshua S. , Duffy Daniel J. , Weng Hsin‐Yi , Freeman Lynetta J.
Published: May 2017

Objective

To determine which of 2 suture materials would be superior in terms of closure time and leakage pressure in open single‐layer cystotomy closure.

Study design

Experimental study.

Animals

Twenty‐four freshly harvested porcine urinary bladders.

Methods

A cystotomy was performed and the incision closed with a single layer simple continuous suture pattern with barbed (n = 12) or smooth (n = 12) suture. Time required for closure was measured. Each bladder was connected to a system for monitoring intraluminal pressure while inflated with saline until leakage occurred. Intraluminal pressure at time of initial leakage and leakage site were recorded. Two‐sample t tests were used to compare maximum leakage pressure and closure time between the 2 groups. P < .05 was considered significant.

Results

All bladders were sutured successfully with no difference in mean closure time (barbed suture 296 ± 46 seconds; smooth suture 293 ± 26 seconds) (P = .821). There was no difference in mean leakage pressure of porcine urinary bladder incisions closed in a single layer with barbed suture (28.8 ± 10.4 mm Hg) compared with smooth suture (30.6 ± 8.8 mm Hg) (P = .642).

Conclusions

Barbed suture provides comparable cystotomy repair to smooth suture, and no benefit to its use was identified in an open procedure. Barbed suture closure should be evaluated for adequate tensile strength in the presence of urine, satisfactory in vivo healing of cystotomies, and lack of long‐term urolith formation in dogs and cats.
An easy to produce and economical three‐dimensional brain phantom for stereotactic computed tomographic‐guided brain biopsy training in the dog*
Authors: Sidhu Deepinder S. , Ruth Jeffrey D. , Lambert Gregory , Rossmeisl John H.
Published: May 2017

Objective

To develop and validate a three‐dimensional (3D) brain phantom that can be incorporated into existing stereotactic headframes to simulate stereotactic brain biopsy (SBB) and train veterinary surgeons.

Study design

Experimental study.

Sample population

Canine brain phantoms were fabricated from osteological skull specimens, agarose brain parenchyma, and cheddar and mozzarella cheese molds (simulating meningiomas and gliomas).

Methods

The neuroradiologic and viscoelastic properties of phantoms were quantified with computed tomography (CT) and oscillatory compression tests, respectively. Phantoms were validated by experienced and novice operators performing SBB on phantoms containing randomly placed, focal targets. Target yield and needle placement error (NPE) were compared between operators.

Results

Phantoms were produced in <4 hours, at an average cost of $92. The CT appearances of the phantom skull, agarose, and cheese components approximated the in vivo features of skull, brain parenchyma, and contrast‐enhancing tumors of meningeal and glial origin, respectively. The complex moduli of the agarose and cheeses were comparable to the viscoelastic properties of in vivo brain tissues and brain tumors. The overall diagnostic yield of SBB was 88%. Although NPE did not differ between novice (median 3.68 mm; range, 1.46‐14.54 mm) and experienced surgeons (median 1.17 mm, range, 0.78‐1.58 mm), our results support the relevance of the learning curve associated with the SBB procedure.

Conclusion

This 3D phantom replicates anatomical, CT, and tactile features of brain tissues and tumors and can be used to develop the technical skills required to perform SBB.
Influence ofSalmonellastatus on the long‐term outcome of horses after colic surgery*
Authors: Southwood Louise L. , Lindborg Susan , Myers Marc , Aceto Helen W.
Published: May 2017

Objective

To compare long‐term outcome ofSalmonella‐positive versusSalmonella‐negative horses discharged from hospital after colic surgery.

Study design

Retrospective case‐control.

Animals

Horses discharged from the hospital after colic surgery. For each horse with positive culture forSalmonella enterica(SAL‐POS, n = 59), at least 2 horses testing negative forS. enterica(SAL‐NEG, n = 119) were enrolled.

Methods

Owners were interviewed via phone at least 12 months after surgery regarding: (1) complications after discharge from the hospital; (2) duration of survival; and (3) return to prior or intended use. Association between immediate postoperative clinical variables such asSalmonellastatus and long‐term measures of outcome was tested via ratios (odds ratio [OR]) and 95% confidence intervals. Data were analyzed for survival using a Cox proportional hazards model and for return to use using multivariable logistic regression.

Results

SAL‐POS horses had a higher OR of surgical site infection (2.7 [1.1‐6.9]P = .027) and weight loss (6.8 [1.8‐26.1]P = .002). At the time of follow‐up, there were 53/56 (95%) SAL‐POS and 99/118 (84%) SAL‐NEG horses alive. The final multivariable model for nonsurvival included postoperative colic (hazard ratio 7.6 [2.8‐19.2]P = .002) and the interaction betweenSalmonellastatus and duration of rectal temperature > 103°F postoperatively (SAL‐POS 1.04 [1.01‐1.07] and SAL‐NEG 1.16 [1.06‐1.25],P = .005). The majority of horses returned to their intended use regardless of their SAL‐POS (38/50, 76%) or SAL‐NEG (77/96, 80%,P = .498) status.

Conclusion

Salmonella‐positive horses that survive to discharge from the hospital after colic surgery have similar risks of long‐term complications (colic/diarrhea), survival, and return to function thanSalmonella‐negative horses.
Soil erosion susceptibility of Johor River basin
Authors: Obaid H. A. , Shahid S.
Published: May 2017

Malaysia is undergoing tremendous environmental changes due to population growth, economic development and urbanization. This has stimulated a rapid land use changes which in turn has increased the rate of soil erosion and river sedimentation. In this study, Universal Soil Loss Equation (USLE) and the Modified Universal Soil Loss Equation (MUSLE) are applied within a geographical information system (GIS) to assess the spatial pattern of soil erosion susceptibility of Johor River basin, Malaysia. Geomorphological, landuse and soil information along with other hydrological data such as, annual peak flow and runoff volumes are used to estimate the parameters required for the calculation of soil erosion susceptibility. The results show that annual erosion rate varies between 0.2 and 248.2 t/ha/year according to USLE, and between 19.2 and 2179.9 thousand tons per event according to MUSLE. The land cover management is found as the major factor responsible for soil erosion in the basin.
Isolation of CD248‐expressing stromal vascular fraction for targeted improvement of wound healing
Authors: Brett Elizabeth , Zielins Elizabeth R. , Chin Monica , Januszyk Michael , Blackshear Charles P. , Findlay Michael , Momeni Arash , Gurtner Geoffrey C. , Longaker Michael T. , Wan Derrick C.
Published: May 2017

Wound healing remains a global issue of disability, cost, and health. Addition of cells from the stromal vascular fraction (SVF) of adipose tissue has been shown to increase the rate of full thickness wound closure. This study aimed to investigate the angiogenic mechanisms of CD248+ SVF cells in the context of full thickness excisional wounds. Single cell transcriptional analysis was used to identify and cluster angiogenic gene‐expressing cells, which was then correlated with surface marker expression. SVF cells isolated from human lipoaspirate were FACS sorted based on the presence of CD248. Cells were analyzed for angiogenic gene expression and ability to promote microvascular tubule formation in vitro. Following this, 6mm full thickness dermal wounds were created on the dorsa of immunocompromised mice and then treated with CD248+, CD248–, or unsorted SVF cells delivered in a pullalan‐collagen hydrogel or the hydrogel alone. Wounds were measured every other day photometrically until closure. Wounds were also evaluated histologically at 7 and 14 days post‐wounding and when fully healed to assess for reepithelialization and development of neovasculature. Wounds treated with CD248+ cells healed significantly faster than other treatment groups, and at 7 days, had quantitatively more reepithelialization. Concurrently, immunohistochemistry of CD31 revealed a much higher presence of vascularity in the CD248+ SVF cells treated group at the time of healing and at 14 days post‐op, consistent with a pro‐angiogenic effect of CD248+ cells in vivo. Therefore, using CD248+ pro‐angiogenic cells obtained from SVF presents a viable strategy in wound healing by promoting increased vessel growth in the wound.
LAWS IN ECOLOGY: DIVERSE MODES OF EXPLANATION FOR A HOLISTIC SCIENCE
Authors: Gunton Richard , Gilbert Francis
Published: May 2017

Ecology's reputation as a holistic science is partly due to widespread misconceptions of its nature as well as shortcomings in its methodology. This article argues that the pursuit of empirical laws of ecology can foster the emergence of a more unified and predictive science based on complementary modes of explanation. Numerical analyses of population dynamics have a distinguished pedigree, spatial analyses generate predictive laws of macroecology, and physical analyses are typically pursued by the ecosystem paradigm. The most characteristically ecological laws, however, are found in biotic analyses in the functional trait paradigm. Holistic credentials for ecology may thus be restored on two bases: its accommodating complementary modes of analysis and explanation, and its having some laws within the least reductionistic mode consistent with its subject matter. These claims, grounded in the aspectual theory of Herman Dooyeweerd, lead to some suggestions for enhancing the versatility and usefulness of ecology—and other sciences—by balancing different research paradigms under a holistic vision.
HOLISTIC BIOLOGY: WHAT IT IS AND WHY IT MATTERS
Authors: Watts Fraser , Reiss Michael J.
Published: May 2017

Recent developments toward a more holistic biology do not eliminate reductionism and determinism, but they do suggest more complex forms of them, in which there are multiple, interacting influences, as there are in complex or chaotic systems. Though there is a place in biology for both systemic and atomistic modes of explanation, for those with a theological perspective the shift to complex explanations in biology is often welcome. It suggests a more subtle view of divine action in which God's purposes are affected through engagement with the complex systems of creation rather than by discrete interventions. It also invites us to connect the biological interdependence with the interdependence in the nature and purposes of God, and it is consonant with a mystical vision of the unity of all things.
Computational Parametric Analysis of the Mechanical Response of Structurally Varying Pacinian Corpuscles
Authors: Quindlen Julia C. , Güçlü Burak , Schepis Eric A. , Barocas Victor H.
Published: May 2017

The Pacinian corpuscle (PC) is a cutaneous mechanoreceptor that senses low-amplitude, high-frequency vibrations. The PC contains a nerve fiber surrounded by alternating layers of solid lamellae and interlamellar fluid, and this structure is hypothesized to contribute to the PC's role as a band-pass filter for vibrations. In this study, we sought to evaluate the relationship between the PC's material and geometric parameters and its response to vibration. We used a spherical finite element mechanical model based on shell theory and lubrication theory to model the PC's outer core. Specifically, we analyzed the effect of the following structural properties on the PC's frequency sensitivity: lamellar modulus (E), lamellar thickness (h), fluid viscosity (μ), PC outer radius (Ro), and number of lamellae (N). The frequency of peak strain amplification (henceforth “peak frequency”) and frequency range over which strain amplification occurred (henceforth “bandwidth”) increased with lamellar modulus or lamellar thickness and decreased with an increase in fluid viscosity or radius. All five structural parameters were combined into expressions for the relationship between the parameters and peak frequency, ωpeak=1.605×10−6N3.475(Eh/μRo), or bandwidth, B=1.747×10−6N3.951(Eh/μRo). Although further work is needed to understand how mechanical variability contributes to functional variability in PCs and how factors such as PC eccentricity also affect PC behavior, this study provides two simple expressions that can be used to predict the impact of structural or material changes with aging or disease on the frequency response of the PC.
Nonuniform Moving Boundary Method for Computational Fluid Dynamics Simulation of Intrathecal Cerebrospinal Flow Distribution in a Cynomolgus Monkey
Authors: Khani Mohammadreza , Xing Tao , Gibbs Christina , Oshinski John N. , Stewart Gregory R. , Zeller Jillynne R. , Martin Bryn A.
Published: May 2017

A detailed quantification and understanding of cerebrospinal fluid (CSF) dynamics may improve detection and treatment of central nervous system (CNS) diseases and help optimize CSF system-based delivery of CNS therapeutics. This study presents a computational fluid dynamics (CFD) model that utilizes a nonuniform moving boundary approach to accurately reproduce the nonuniform distribution of CSF flow along the spinal subarachnoid space (SAS) of a single cynomolgus monkey. A magnetic resonance imaging (MRI) protocol was developed and applied to quantify subject-specific CSF space geometry and flow and define the CFD domain and boundary conditions. An algorithm was implemented to reproduce the axial distribution of unsteady CSF flow by nonuniform deformation of the dura surface. Results showed that maximum difference between the MRI measurements and CFD simulation of CSF flow rates was <3.6%. CSF flow along the entire spine was laminar with a peak Reynolds number of ∼150 and average Womersley number of ∼5.4. Maximum CSF flow rate was present at the C4-C5 vertebral level. Deformation of the dura ranged up to a maximum of 134 μm. Geometric analysis indicated that total spinal CSF space volume was ∼8.7 ml. Average hydraulic diameter, wetted perimeter, and SAS area were 2.9 mm, 37.3 mm and 27.24 mm2, respectively. CSF pulse wave velocity (PWV) along the spine was quantified to be 1.2 m/s.
Design and Performance Analysis of Double C-Type Flexure Hinges
Authors: Qiu Lifang , Huang Gang , Yin Siqi
Published: May 2017

This paper proposes a series of double C-type flexure hinges for lamina emergent mechanisms (LEMs), designs the structure, and deduces the formula of the equivalent stiffness of the double C-type flexure hinge. Theoretical calculation and finite element simulation analyses of the design examples are used to verify the correctness of the equivalent stiffness calculation formula. In order to improve the bending performance of the flexure hinges, we propose a method to remove some materials of the semicircle of the flexure hinges according to certain rules. Then, the structure of the double C-type flexure hinge is further improved. Finally, the performance of the improved and unimproved double C-type flexure hinges is compared through the finite element simulation analysis, and the results show that the bending performance of the improved double C-type flexure hinge is better than the unimproved double C-type flexure hinge, while the antitensile properties undergo no significant decline.
Design and Development of a Two Degree-of-Freedom Rotational Flexure Mechanism for Precise Unbalance Measurements
Authors: Hongzhe Zhao , Siyuan Ren , Ming Li , Shuqing Zhang
Published: May 2017

To measure unbalanced moments, the knife-edge is used as a support module in traditional platforms, but performances rapidly deteriorate as the edge is worn down. In this paper, considering the requirements of measurements, a two degree-of-freedom (DOF) flexure mechanism is, thus, presented to overcome this drawback. First, off-axis stiffness and manufacturability are improved qualitatively by means of configuration analysis. Then, four generalized cross-spring pivots are exploited in the 2DOF flexure mechanism, and the geometric parameters are analyzed to achieve approximately constant rotational stiffness and reduced center shift simultaneously, which benefits calibration procedure and measurement precision. Models are further developed to determine the shape parameters of leaf-springs and transducer performances. Therefore, a low rotational stiffness is obtained to ensure a high resolution for measurements, and a high load-carrying capacity is achieved via strength checking. Finally, finite element analysis (FEA) is carried out to validate the proposed design, and experimental results demonstrate that the developed platform is capable of unbalance measurements with a high precision and resolution.
Motion Generation of Passive Slider Multiloop Wearable Hand Devices
Authors: Tan Guan Rong , Robson Nina Patarinsky , Soh Gim Song
Published: May 2017

This paper describes a dimensional synthesis method used in the design of a passive finger exoskeleton that takes into account the user limb anthropometric dimensions and contact requirements for grasping objects. The paper is the first step in our current efforts on the design of wearable devices that use a common slider at the hand to passively drive each exofinger. The finger exoskeleton is comprised of a 3R serial limb and is constrained to multiloop eight-bar slider mechanism using two RR constraints. To design the exolimb, the pose of the limb was captured using an optical motion capture and its dimensions were determined using a constrained least square optimization, which takes into account human skin movement. To illustrate the generality of our approach, an example of the design of an index and middle finger exolimb is described.
Extended High-Order Theory for Curved Sandwich Panels and Comparison With Elasticity
Authors: Rodcheuy Nunthadech , Frostig Yeoshua , Kardomateas George A.
Published: May 2017

A new one-dimensional high-order sandwich panel theory for curved panels is presented and compared with the theory of elasticity. The theory accounts for the sandwich core compressibility in the radial direction as well as the core circumferential rigidity. Two distinct core displacement fields are proposed and investigated. One is a logarithmic (it includes terms that are linear, inverse, and logarithmic functions of the radial coordinate). The other is a polynomial (it consists of second and third-order polynomials of the radial coordinate), and it is an extension of the corresponding field for the flat panel. In both formulations, the two thin curved face sheets are assumed to be perfectly bonded to the core and follow the classical Euler–Bernoulli beam assumptions. The relative merits of these two approaches are assessed by comparing the results to an elasticity solution. The case examined is a simply supported curved sandwich panel subjected to a distributed transverse load, for which a closed-form elasticity solution can be formulated. It is shown that the logarithmic formulation is more accurate than the polynomial especially for the stiffer cores and for curved panels of smaller radius.
Experimental Investigation and Three-Dimensional Numerical Analysis of Ferroconvection Through Horizontal Tube Under Magnetic Field of Fixed Parallel Magnet Bars
Authors: Sheikhnejad Yahya , Mehrdad Hosseini Mir , Teixeira Antonio , Shahpari Ali , Hosseini Reza , Saffar Avval Majid
Published: May 2017

This study includes experimental and three-dimensional numerical analysis of conjugate steady-state laminar forced ferroconvection of Newtonian incompressible ferrofluid through a horizontal circular pipe under constant heat flux and in presence of transverse magnetic field. The magnetic field was applied by two fixed parallel magnet bars at the beginning of the tube. To validate the thermohydrodynamic characteristics obtained by numerical results, appropriate experimental setup with accurate instrumentations was conducted. Based on presence and absence of porous media and solid rod inside of pipe, six conditions were compared for quantifying the heat transfer enhancement and effectiveness. Governing equations were discretized by finite volume method (FVM) and solved using the semi-implicit method for pressure linked equations (SIMPLE) algorithm and computational fluid dynamic (CFD) techniques. It was found that magnetic field, porous media, and solid rod increase heat transfer and pressure loss in the pipe such that solid rod has the best effect on heat transfer and worst effect on effectiveness.
Structural and Chemical Modification to Improve Adhesive and Material Properties of Fibrin-Genipin for Repair of Annulus Fibrosus Defects in Intervertebral Disks
Authors: Cruz Michelle A. , McAnany Steven , Gupta Nikita , Long Rose G. , Nasser Philip , Eglin David , Hecht Andrew C. , Illien-Junger Svenja , Iatridis James C.
Published: May 2017

Annulus fibrosus (AF) defects from intervertebral disk (IVD) herniation and degeneration are commonly associated with back pain. Genipin-crosslinked fibrin hydrogel (FibGen) is an injectable, space-filling AF sealant that was optimized to match AF shear properties and partially restored IVD biomechanics. This study aimed to enhance mechanical behaviors of FibGen to more closely match AF compressive, tensile, and shear properties by adjusting genipin crosslink density and by creating a composite formulation by adding Poly(D,L-lactide-co-glycolide) (PDLGA). This study also evaluated effects of thrombin concentration and injection technique on gelation kinetics and adhesive strength. Increasing FibGen genipin concentration from 1 to 36 mg/mL significantly increased adhesive strength (∼5 to 35 kPa), shear moduli (∼10 to 110 kPa), and compressive moduli (∼25 to 150 kPa) with concentration-dependent effects, and spanning native AF properties. Adding PDLGA to FibGen altered the material microstructure on electron microscopy and nearly tripled adhesive strength, but did not increase tensile moduli, which remained nearly 5× below native AF, and had a small increase in shear moduli and significantly decreased compressive moduli. Increased thrombin concentration decreased gelation rate to < 5 min and injection methods providing a structural FibGen cap increased pushout strength by ∼40%. We conclude that FibGen is highly modifiable with tunable mechanical properties that can be formulated to be compatible with human AF compressive and shear properties and gelation kinetics and injection techniques compatible with clinical discectomy procedures. However, further innovations, perhaps with more efficient fiber reinforcement, will be required to enable FibGen to match AF tensile properties.
Imaging XPS and photoemission electron microscopy; surface chemical mapping and blood cell visualization
Authors: Skallberg Andreas , Brommesson Caroline , Uvdal Kajsa
Published: May 2017

Combined photoemission electron microscopy (PEEM) and imaging x-ray photoelectron spectroscopy (XPS), i.e., electron spectroscopy for chemical analysis in the nanoregion, has been used for surface characterization of bio-relevant and biological samples. In the first example, the authors prepared a gold patterned silicon substrate, stepwise surface modified by self-assembled monolayers followed by quantum dot (QDot) specific linking and investigated by means of work function mapping and elemental imaging in the submicrometer range. Spatially resolved core level images of C1s, V2p, and Y3d are obtained, which verify the selective thiol adsorption on the gold squares and specific binding of europium doped yttrium vanadate QDots on the self-assembled monolayer. The second example is platelet adhesion to Immunoglobulin G modified silicon surfaces, investigated by means of laterally resolved PEEM. Images of platelets clearly show activated cells with a morphology change including an enlarged surface area and elongated pseudopodia, with a lateral resolution of 140 nm. In the last example, neutrophils were allowed to attach to plain silicon surfaces and investigated by means of PEEM and imaging XPS. Here, the cells show a round shaped morphology, as expected. Threshold imaging with work function contrast is used to localize the area of interest, followed by elemental specific mapping on cells in the submicrometer region. Chemical shifts of C1s in photoemission are used to distinguish vital parts of the cell structure. The strong C1s (C-C) signal is achieved from the region of the cell membrane, i.e., high density of phospholipids, while C1s (C-N) and C1s (C-O) signals are obtained from the core of the cell, in good agreement with the presence of cytoplasm and deoxyribonucleic acid containing cell nucleus. The combination of PEEM and imaging XPS is shown here as a tool to deliver new insight into biological samples, i.e., a rapid sample overview is obtained based on low energy secondary electrons with work function contrast, followed by detailed studies in the narrow mode for elemental compositions based on photoemission. This study illustrates the strength of combined PEEM and XPS in the imaging mode on cell studies.
Inductively coupled plasma etching of bulk, single-crystal Ga2O3
Authors: Yang Jiancheng , Ahn Shihyun , Ren Fan , Pearton Stephen , Khanna Rohit , Bevlin Kristen , Geerpuram Dwarakanath , Kuramata Akito
Published: May 2017

High ion density dry etching of bulk single-crystal β-Ga2O3 was carried out as a function of source power (100–800 W), chuck power (15–400 W), and frequency (13.56 or 40 MHz) in inductively coupled plasma (ICP) systems using Cl2/Ar or BCl3/Ar discharges. The highest etch rate achieved was ∼1300 Å min−1 using 800 W ICP source power and 200 W chuck power (13.56 MHz) with either Cl2/Ar or BCl3/Ar. This is still a comfortably practical set of conditions, where resist reticulation does not occur because of the effective He backside cooling of the sample in the tool and the avoidance of overly high powers in systems capable of 2000 W of source power. The etching is ion-assisted and produces anisotropic pattern transfer. The etched surface may become oxygen-deficient under strong ion-bombardment conditions. Schottky diodes fabricated on these surfaces show increased ideality factors (increasing from 1.00 to 1.29 for high power conditions) and reduced barrier heights (1.1 on reference diodes to 0.86 eV for etched surfaces). This electrically active damage is dependent on ion energy and flux during the etching. An obvious strategy is to reduce plasma powers toward the end of an etch sequence to reduce the disruption to the Ga2O3 surface.
Localizing graphene at the interface of cocontinuous polymer blends: Morphology, rheology, and conductivity of cocontinuous conductive polymer composites
Authors: Bai Lian , He Siyao , Fruehwirth John W. , Stein Andreas , Macosko Christopher W. , Cheng Xiang
Published: May 2017

Interfacial localization of graphene in cocontinuous polymer blends is shown to be effective in stabilizing the cocontinuous morphology and increasing conductivity with a low electrical percolation threshold. We created polylactic acid (PLA) and polystyrene (PS) cocontinuous blends filled with thermally reduced graphene oxide (r-GO) localized at the interface. The resulting conductive composites show dramatically improved conductivity at low filler loadings and an ultralow percolation threshold of 0.028 vol. %. We systematically studied the changes of conductivity and rheology of the PLA-PS composites during annealing. We found that r-GO transfers from the PLA phase to the interface during melt compounding and annealing and forms a spanning 3D network, which effectively suppresses the coarsening of the cocontinuous structure. Our study demonstrated that the 3D r-GO network significantly increases the conductivity and the storage modulus of the melt blends. Finally, we constructed a simple model, which quantitatively explains the correlations between structural, electrical, and rheological properties of conductive polymer composites.
Transition from chain- to crystal-network in extension induced crystallization of isotactic polypropylene
Authors: Wang Zhen , Su Fengmei , Ji Youxin , Yang Haoran , Tian Nan , Chang Jiarui , Meng Lingpu , Li Liang bin
Published: May 2017

With a combination of extensional rheology and in-situ small-angle X-ray scattering measurements, the protocol of two-step extension is proposed to investigate the early stage of flow-induced crystallization (FIC) in supercooled isotactic polypropylene melt at 138 °C. After both step strains, the crystallization half-time presents a nonmonotonic dependence on the interval time between two extensional operations, based on which three different stages of structural evolution are defined. In stage I, both nucleation and chain relaxation occur, which enhances the crystallization rate but reduces the final lamellar crystal orientation. In this stage, each part of the melt is considered to have approximately the same dynamics to respond homogeneously to the second extension and thus the system is still dominated by a chain-network. When entering into stage II, the sparse large-scaled crystal is formed to construct a heterogeneous crystal-network superimposed on the chain-network, which decelerates the second extension induced crystallization by causing stress concentration on the crystal-network at low faction. In stage III, the crystal-network dominates the sample deformation due to the formation of abundant lamellar crystal, which recreates the approximately same dynamics for each part of sample and brings about an enhancement of crystallization rate again. The transition from chain- to crystal-network revealed in this work demonstrates a dynamical coupling of chain relaxation, crystal nucleation, and growth in FIC of polymers.
BMP8A sustains spermatogenesis by activating both SMAD1/5/8 and SMAD2/3 in spermatogonia
Authors: Wu Fang-Ju , Lin Ting-Yu , Sung Li-Ying , Chang Wei-Fang , Wu Po-Chih , Luo Ching-Wei
Published: May 2017

BMP8A activates distinct sets of SMADs to control the proliferation and differentiation of spermatogonia in mice.
Paper of note in
Nature
544
(7651)
Authors: VanHook Annalisa M.
Published: May 2017

This week’s article identifies a receptor that is important for phagocytosis of some tumor cells by macrophages.
Competitive Fitness of Fluconazole-Resistant Clinical Candida albicans Strains
Authors: Popp Christina , Hampe Irene A. I. , Hertlein Tobias , Ohlsen Knut , Rogers P. David , Morschhäuser Joachim
Published: May 2017

The pathogenic yeast
Candida albicans
can develop resistance to the widely used antifungal agent fluconazole, which inhibits ergosterol biosynthesis. Resistance is often caused by gain-of-function mutations in the transcription factors Mrr1 and Tac1, which result in constitutive overexpression of multidrug efflux pumps, and Upc2, which result in constitutive overexpression of ergosterol biosynthesis genes. However, the deregulated gene expression that is caused by hyperactive forms of these transcription factors also reduces the fitness of the cells in the absence of the drug. To investigate whether fluconazole-resistant clinical
C. albicans
isolates have overcome the fitness costs of drug resistance, we assessed the relative fitness of
C. albicans
isolates containing resistance mutations in these transcription factors in competition with matched drug-susceptible isolates from the same patients. Most of the fluconazole-resistant isolates were outcompeted by the corresponding drug-susceptible isolates when grown in rich medium without fluconazole. On the other hand, some resistant isolates with gain-of-function mutations in
MRR1
did not exhibit reduced fitness under these conditions. In a mouse model of disseminated candidiasis, three out of four tested fluconazole-resistant clinical isolates did not exhibit a significant fitness defect. However, all four fluconazole-resistant isolates were outcompeted by the matched susceptible isolates in a mouse model of gastrointestinal colonization, demonstrating that the effects of drug resistance on
in vivo
fitness depend on the host niche. Collectively, our results indicate that the fitness costs of drug resistance in
C. albicans
are not easily remediated, especially when proper control of gene expression is required for successful adaptation to life within a mammalian host.