bluuebunny/crossref_metadata_2025_split huggingface dataset:
Feature Vector Identification and Prognostics of SAC305 PCB’s for Varying Conditions of Temperature and Vibration Loads
Authors: Lall Pradeep , Thomas Tony , Blecker Ken 
Published: December 2020

Abstract
This study focuses on the feature vector identification of SAC305 solder alloy PCB’s of two different configurations during varying conditions of temperature and vibration. The feature vectors are identified from the strain signals, that are acquired from four symmetrical locations of the PCB at regular intervals during vibration. The changes in the vibration characteristics of the PCB are characterized by three different types of experiments. First type of analysis emphasizes the vibration characteristic for varying conditions of acceleration levels keeping the temperature constant during vibration. The second analysis studies the characteristics changes for varying temperature levels by keeping the acceleration levels constant. Finally, the third analysis focuses on the combined changes in temperature and acceleration levels for the board during vibration. The above analyses try to imitate the actual working conditions of an electronic board in an automobile which is subjected to varying environments of temperature and vibration. The strain signals acquired during each of these experiments are compared based on both time and frequency domain characteristics. Different statistical and frequency based techniques were used to identify the variations in the strain signal with changes in the environment and loading conditions. The feature vectors of failure at a constant working condition and load were identified and as an extension to the previous work, the effectiveness of the feature vectors during these varying conditions of temperature and acceleration levels are investigated using the above analyses. The feature vector of a PCB under varying conditions of temperature and load are identified and compared with different operating environments.
Evaluation of the Creep Response of Lead Free Solder Materials Subjected to Thermal Cycling
Authors: Hasan S. M. Kamrul , Fahim Abdullah , Suhling Jeffrey C. , Lall Pradeep 
Published: December 2020

Abstract
In the electronic assembly arena, lead is being targeted due to the concern regarding environmental pollutants. So, the lead-free solder and its reliability are getting highlighted. During qualification testing or actual use lead-free solders in electronic assemblies, they are often subjected to thermal cycling. In the lead-free solder material, microstructural evolution and material property degradation occurs due to the thermal aging phenomena during dwell periods at the high temperature extreme of thermal cycling. In addition, during ramping between low and high temperature extreme, lead-free solders can experience additional aging phenomena. In our prior work, we have compared material properties (stiffness and strength) degradation of lead-free solder materials in isothermal aging and five different thermal cycling exposures. Changes in material properties were higher for all the thermal cycling exposures compared to the aging. In addition, microstructural evolution and material property degradation were exacerbated as the ramp rate decreased in the thermal cycling.
In this study, the creep behavior evolutions occurring in SAC305 lead free solder subjected to isothermal aging and slow thermal cycling exposures have been investigated. Uniaxial test specimens were prepared by reflowing solder in rectangular cross-section glass tubes with a controlled temperature profile. Afterwards, the reflowed samples were exposed to either isothermal aging at 125 °C, or to thermal cycling from −40 to +125 °C, under a stress-free condition (no load) for various durations in an environmental chamber. A slow thermal cycling profile, e.g. 150 minutes cycle with 45 minutes ramps and 30 minutes dwells, was chosen for this study as it was found in our previous work that it caused the most detrimental effects on the mechanical behavior evolution. The thermally exposed samples were isothermally aged for 0, 1, 2, and 5 days; or were thermally cycled for 0, 48, 96, and 240 slow thermal cycles, which had the same aging times at the high temperature extreme of T = 125 °C.
After aging or cycling, creep testing was performed at room temperature on the thermally exposed samples at three different stress levels (10, 12, 15 MPa). The evolutions of the secondary creep strain rate were obtained as a function of the stress level, as well as the net aging time at the high temperature extreme, and then compared. Results showed that secondary creep strain rate increased dramatically with equivalent aging time, and that the degradation effects were larger for slow thermal cycling than for pure aging. For example, the creep rate increased by 3.0–3.4X for 5 days of pure aging at T = 125 °C; while they increased by 10.9–13.1X for 240 thermal cycles, when there had been 5 days of equivalent aging at the T = 125 °C high temperature extreme.
Deformation Behavior of SAC305 Solder Joints With Multiple Grains
Authors: Mondal Debabrata , Fahim Abdullah , Hassan KM Rafidh , Suhling Jeffrey C. , Lall Pradeep 
Published: December 2020

Abstract
Lead-free solder joints are the most widely used interconnects in electronic packaging industries. Usually solder joints in most of the electronic devices are exposed to an environment where variation of temperature exists, which indicates cyclic thermal loading to be a very common type of external loading. Moreover, due to difference in the coefficient of thermal expansion (CTE) among dissimilar contact materials, shear stress develops in junctions under thermal loading, which significantly deteriorates the overall reliability. Hence, characterization of lead-free solder materials under thermal loading is essential to predict the performance and deformation behavior of joints in practical applications. A significant portion of the studies in this field are concerned with thermal loading of lead-free solder interconnects, each of which has a very small diameter, in sub-millimeter range. Although the solder balls have very small dimensions, most of the analyses considered them as a bulk material with homogeneous and isotropic properties. However, with the decrease of specimen dimensions, size effects and material directionality play a significant role in deformation mechanisms. Since a very few grains exist in a small specimen, individual grain properties play a vital role on overall material response. Therefore, modeling from the grain structure and orientation point of view could be an effective and more accurate way to predict solder joint deformation behavior under thermal loading.
In this study, the effect of grain size and orientation of SAC305 is investigated for predicting anisotropic behavior of solder joints under thermal load. A simplified three-dimensional model of beach-ball configuration solder joint was generated and simulated using ABAQUS finite element (FE) software. Experimentally obtained directional properties such as elastic modulus and CTE were assigned to the computational geometry to create material anisotropy. The effects of material anisotropy were studied for varying grain size specimens, as well as for specimens with varying grain orientation.
‘Should have gone to …’: bilateral papilloedema with normal CSF pressure due to vestibular schwannoma
Authors: Ronan Geoffrey Peter , Gailani Gaafar , Costello Ciara , Sweeney Brian 
Published: December 2020

A 24-year-old woman presented with bilateral blurring of her distance vision and ‘dizzy spells’. She had no other neurological symptoms or medical history. She consulted an optometrist, and optical coherence tomography (OCT) was performed, which demonstrated papilloedema. She was referred to the local eye clinic for assessment and from there was referred for neurological assessment.Her initial investigations revealed no abnormalities, and brain imaging was reported to be normal. In the absence of an alternative diagnosis, idiopathic intracranial hypertension (IIH) was considered and a lumbar puncture was performed. This showed elevated protein but normal cerebrospinal fluid (CSF) pressure. MRI of the brain the next day revealed a large cerebellopontine lesion in keeping with vestibular schwannoma. She was referred to neurosurgery for operative management.This case highlights three interesting points: the aetiology of her papilloedema without raised intracranial pressure, the decision to perform a lumbar puncture in suspected IIH and community OCT as a clinical adjunct.
Histamine causes an imbalance between pro-angiogenic and anti-angiogenic factors in the retinal pigment epithelium of diabetic retina via H4 receptor/p38 MAPK axis
Authors: Lee Byung Joo , Byeon Hye Eun , Cho Chang Sik , Kim Young Ho , Kim Jin Hyoung , Che Jeong-Hwan , Seok Seung Hyeok , Kwon Jung-Won , Kim Jeong Hun , Lee Kihwang 
Published: December 2020

IntroductionSystemic histaminergic activity is elevated in patients with diabetes mellitus. There are a few studies suggesting that histamine is implicated in the pathogenesis of diabetes, but the exact role of histamine in the development of diabetic retinopathy is unclear. The aim of this study was to investigate the role of histamine receptor H4 (HRH4) in the regulation of retinal pigment epithelium (RPE)-derived pro-angiogenic and anti-angiogenic factors under diabetic conditions.Research design and methodsThe levels of vascular endothelial growth factor (VEGF), interleukin-6 (IL-6), histamine and histidine decarboxylase (HDC) in the serum and vitreous samples of patients with diabetes were compared with those of patients without diabetes. The effect of hyperglycemia on expression levels of HRH4, VEGF, IL-6 and pigment epithelium-derived factor (PEDF) in the RPE was determined. The role of HRH4 in high glucose-induced regulation of VEGF, IL-6 and PEDF in ARPE-19 cells and the underlying regulatory mechanism were verified using an RNA interference-mediated knockdown study.ResultsThe serum and vitreous levels of VEGF, IL-6, histamine and HDC were more increased in patients with diabetic retinopathy than in patients without diabetes. HRH4 was overexpressed in RPE both in vitro and in vivo. Histamine treatment upregulated VEGF and IL-6 and downregulated PEDF expression in ARPE-19 cells cultivated under hyperglycemic conditions. Hyperglycemia-induced phosphorylation of p38 and subsequent upregulation of VEGF and IL-6 and downregulation of PEDF were dampened by small interfering RNA-mediated knockdown of HRH4 in ARPE-19 cells.ConclusionsTaken together, HRH4 was a critical regulator of VEGF, IL-6 and PEDF in the RPE under hyperglycemic conditions and the p38 mitogen-activated protein kinase pathway mediated this regulatory mechanism.
Person-centered diabetes care and patient activation in people with type 2 diabetes
Authors: Rutten Guy E H M , Van Vugt Heidi , de Koning Eelco 
Published: December 2020

IntroductionThe American Diabetes Association and the European Association for the Study of Diabetes advocate a person-centered approach to enhance patient engagement in self-care activities. To that purpose, people with diabetes need adequate diabetes knowledge, motivation, skills and confidence. These prerequisites are captured by the concept ‘patient activation’. The Dutch Diabetes Federation implemented a person-centered consultation model for the annual diabetes review. To assess its relationship with patient activation, we measured thechangein patient activation, and in person and disease-related factors in people with type 2 diabetes after their second person-centered annual review.Research design and methodsObservational study in 47 primary care practices and six outpatient hospital clinics. Follow-up: 1 year. From 2.617 people with diabetes and capable of completing questionnaires (no additional exclusion criteria) 1.487 (56.8%) participated, 1366 with type 2 diabetes. Main outcome: patient activation (13-item Patient Activation Measure, score 0–100). Before the first and after the second review, participants completed questionnaires. Medical data were retrieved from electronic records. We performed a repeated measure analysis using a linear mixed model in 1299 participants, who completed the first set of questionnaires.ResultsIn 1299 participants (41.6% female, mean age 66 years, median diabetes duration 10 years, median glycated hemoglobin (HbA1c) 6.8%/51 mmol/mol), the mean baseline activation level was 58.9 (SD 11.7). Independent of actual diabetes care, activation levels increased 1.53 units (95% CI 0.67 to 2.39, p=0.001). Several diabetes perceptions improved significantly; diabetes distress level decreased significantly. Body mass index (−0.22, 95% CI −0.33 to −0.10, p<0.001) and low-density lipoprotein cholesterol (−2.71 mg/dL, 95% CI −4.64 to −0.77, p=0.004) decreased, HbA1c increased 0.08% (95% CI 0.03 to 0.12) (p=0.001).ConclusionsPerson-centered diabetes care was associated with a slightly higher patient activation level, improved diabetes perception and small improvements in clinical outcomes. Person-centered care may enhance patient engagement, but one should not expect substantial improvement in patient outcomes in the short term.
Size at birth and cognitive function among rural adolescents: a life course epidemiology study protocol of the Kisalaya cohort in Mysuru, South India
Authors: Chandrashekarappa Smitha Malenahalli , Krishna Murali , Krupp Karl , Jaykrishna Poornima , Urs Chaithra V , Goswami Satyapal Puri , Ravi Kavitha , Khan Anisa , Arun Anjali , Dawes Piers , Newall John , Madhivanan Purnima 
Published: December 2020

IntroductionIt is proven that adverse intrauterine environment results in ‘early life programming,’ alterations in metabolism and physiological development of the fetus, often termed as ‘Developmental Origins of Health and Disease’ (DOHaD) resulting in a smaller size at birth, greater non-communicable diseases (NCD) risk factors during childhood and adolescence, and cardiometabolic disorders in adulthood. Nevertheless, very few studies have examined the relationship between DOHaD programming and cognition. This study aims to examine if impaired prenatal growth indicated by birth weight is associated with cognition among adolescents in the Kisalaya cohort, a rural birth cohort in South India, thus providing newer insights into DOHaD programming for adolescent mental health in a low-income and middle-income country setting.Methods and analysisKisalaya cohort was established in 2008, to provide integrated antenatal care and HIV testing using mobile clinics to improve maternal and child health outcomes. This cohort included pregnant women residing in 144 villages of Mysuru Taluk (rural) who received antenatal care through mobile clinics and delivered their children between 2008 and 2011. Data related to mother–infant dyads for all pregnant women who received care in the Kisalaya programme are available for this study. Presently, children born to women who received care through Kisalaya are adolescents between 10 and 12 years. At this point, information would be collected on sociodemographic data and assessments of mental health, stressful life events, cognition, vision, speech, language, hearing and anthropometric measures would be done and relevant maternal data and child data, available from the cohort would be retracted for analysis. We plan to retrace as many adolescents as possible out of 1544 adolescents who are currently available for study excluding twins, abortions, stillbirths and postdelivery deaths. Analyses will be extended to construct a life course pathway for cognition using structural equation modelling.
Development of a virtual reality clinically oriented temporal bone anatomy module with randomised control study of three-dimensional display technology
Authors: Copson Bridget , Wijewickrema Sudanthi , Sorace Laurence , Jones Randall , O'Leary Stephen 
Published: December 2020

ObjectiveTo investigate the effectiveness of a virtual reality (VR), three-dimensional (3D) clinically orientated temporal bone anatomy module, including an assessment of different display technologies.MethodsA clinically orientated, procedural and interactive anatomy module was generated from a micro-CT of a cadaveric temporal bone. The module was given in three different display technologies; 2D, 3D with monoscopic vision, and 3D with stereoscopic vision. A randomised control trial assessed the knowledge acquisition and attitudes of 47 medical students though a pretutorial and post-tutorial questionnaire. The questionnaire included questions identifying anatomic structures as well as understanding structural relations and clinical relevance. Furthermore, a five-point Likert scale assessed the students’ attitudes to the module and alternative learning outcomes, such as interest in otology and preparedness for clinical rotations.ResultsAs a whole cohort, the total test score improved significantly, with a large effect size (p≤0.005, Cohen’s d=1.41). The 23 students who returned the retention questionnaire had a significant improvement in total test score compared with their pretutorial score, with a large effect size (p≤0.005, Cohen’s d=0.83). Display technology did not influence the majority of learning outcomes, with the exception of 3D technologies, showing a significantly improvement in understanding of clinical relevance and structural relations (p=0.034). Students preferred 3D technologies for ease of use, perceived effectiveness and willingness to use again.ConclusionsThe developed VR temporal bone anatomy tutor was an effective self-directed education tool. 3D technology remains valuable in facilitating spatial learning and superior user satisfaction.
Galectin-9 expression defines exhausted T cells and impaired cytotoxic NK cells in patients with virus-associated solid tumors
Authors: Okoye Isobel , Xu Lai , Motamedi Melika , Parashar Pallavi , Walker John W , Elahi Shokrollah 
Published: December 2020

BackgroundWe have previously reported that the upregulation of galectin-9 (Gal-9) on CD4+and CD8+T cells in HIV patients was associated with impaired T cell effector functions. Gal-9 is a ligand for T cell immunoglobulin and mucin domain-3, and its expression on T cells in cancer has not been investigated. Therefore, we aimed to investigate the expression level and effects of Gal-9 on T cell functions in patients with virus-associated solid tumors (VASTs).Methods40 patients with VASTs through a non-randomized and biomarker-driven phase II LATENT trial were investigated. Peripheral blood mononuclear cells and tumor biopsies were obtained and subjected to immunophenotyping. In this trial, the effects of oral valproate and avelumab (anti-PD-L1) was investigated in regards to the expression of Gal-9 on T cells.ResultsWe report the upregulation of Gal-9 expression by peripheral and tumor-infiltrating CD4+and CD8+T lymphocytes in patients with VASTs. Our results indicate that Gal-9 expression is associated with dysfunctional T cell effector functions in the periphery and tumor microenvironment (TME). Coexpression of Gal-9 with PD-1 or T cell immunoglobulin and ITIM domain (TIGIT) exhibited a synergistic inhibitory effect and enhanced an exhausted T cell phenotype. Besides, responding patients to treatment had lower Gal-9 mRNA expression in the TME. Translocation of Gal-9 from the cytosol to the cell membrane of T cells following stimulation suggests persistent T cell receptor (TCR) stimulation as a potential contributing factor in Gal-9 upregulation in patients with VASTs. Moreover, partial colocalization of Gal-9 with CD3 on T cells likely impacts the initiation of signal transduction via TCR as shown by the upregulation of ZAP70 in Gal-9+ T cells. Also, we found an expansion of Gal-9+ but not TIGIT+ NK cells in patients with VASTs; however, dichotomous to TIGIT+ NK cells, Gal-9+ NK cells exhibited impaired cytotoxic molecules but higher Interferon gamma (IFN-γ) expression.ConclusionOur data indicate that higher Gal-9-expressing CD8+T cells were associated with poor prognosis following immunotherapy with anti-Programmed death-ligand 1 (PD-L1) (avelumab) in our patients’ cohort. Therefore, for the very first time to our knowledge, we report Gal-9 as a novel marker of T cell exhaustion and the potential target of immunotherapy in patients with VASTs.
Palatini quadratic gravity: spontaneous breaking of gauged scale symmetry and inflation
Authors: Ghilencea D. M. 
Published: December 2020

AbstractWe study quadratic gravity$$R^2+R_{[\mu \nu ]}^2$$R2+R[μν]2in the Palatini formalism where the connection and the metric are independent. This action has agaugedscale symmetry (also known as Weyl gauge symmetry) of Weyl gauge field$$v_\mu = (\tilde{\Gamma }_\mu -\Gamma _\mu )/2$$vμ=(Γ~μ-Γμ)/2, with$$\tilde{\Gamma }_\mu $$Γ~μ($$\Gamma _\mu $$Γμ) the trace of the Palatini (Levi-Civita) connection, respectively. The underlying geometry is non-metric due to the$$R_{[\mu \nu ]}^2$$R[μν]2term acting as a gauge kinetic term for$$v_\mu $$vμ. We show that this theory has an elegant spontaneous breaking of gauged scale symmetry and mass generation in the absence of matter, where the necessary scalar field ($$\phi $$ϕ) is not added ad-hoc to this purpose but is “extracted” from the$$R^2$$R2term. The gauge field becomes massive by absorbing the derivative term$$\partial _\mu \ln \phi $$∂μlnϕof the Stueckelberg field (“dilaton”). In the broken phase one finds the Einstein–Proca action of$$v_\mu $$vμof mass proportional to the Planck scale$$M\sim \langle \phi \rangle $$M∼⟨ϕ⟩, and a positive cosmological constant. Below this scale$$v_\mu $$vμdecouples, the connection becomes Levi-Civita and metricity and Einstein gravity are recovered. These results remain valid in the presence of non-minimally coupled scalar field (Higgs-like) with Palatini connection and the potential is computed. In this case the theory gives successful inflation and a specific prediction for the tensor-to-scalar ratio$$0.007\le r\le 0.01$$0.007≤r≤0.01for current spectral index$$n_s$$ns(at$$95\%$$95%CL) and$$N=60$$N=60efolds. This value ofris mildly larger than in inflation in Weyl quadratic gravity of similar symmetry, due to different non-metricity. This establishes a connection between non-metricity and inflation predictions and enables us to test such theories by future CMB experiments.