Vibration control of beams and plates with hybrid active-passive constrained layer damping treatments

The concept of hybrid active-passive constrained layer damping treatments, which consists of viscoelastic materials, piezoelectric materials and elastic constraining materials, was proposed in the 1990s in order to ameliorate problems of instability in traditional active control systems in the higher frequency range. In this paper, the performances of four types of hybrid active-passive constrained layer damping treatments are investigated for beam and plate applications. These types are Active Constrained Layer Damping (ACLD), Active-Passive Constrained Layer Damping (APCLD), Active Control/Passive Constrained Layer Damping (AC/PCLD) and Active Control/Passive Stand-Off Layer Damping (AC/PSOLD). The performances of each treatment are compared through simulation with numerical models using the Finite Element Method. Finally, control performances of all configurations for curved plates are discussed with measured Frequency Response Functions of each case

On the Correlation of Torque and Luminosity in GX 1+4

Over five years of daily hard X-ray (>20 keV) monitoring of the 2-min accretion-powered pulsar GX 1+4 with the Compton Gamma Ray Observatory/BATSE large-area detectors has found nearly continuous rapid spin-down, interrupted by a bright 200-d spin-up episode. During spin-down, the torque becomes more negative as the luminosity increases (assuming that the 20-60 keV pulsed flux traces bolometric luminosity), the opposite of what is predicted by standard accretion torque theory. No changes in the shape of the 20-100 keV pulsed energy spectrum were detected, so that a very drastic change in the spectrum below 20 keV or the pulsed fraction would be required to make the 20-60 keV pulsed flux a poor luminosity tracer. These are the first observations which flatly contradict standard magnetic disk accretion theory, and they may have important implications for understanding the spin evolution of X-ray binaries, cataclysmic variables, and protostars. We briefly discuss the possibility that GX 1+4 may be accreting from a retrograde disk during spin-down, as previously suggested.Comment: 10 pages including 3 PS figures. To appear in ApJ Letter

Role of detrusor PDGFRα+ cells in mouse model of cyclophosphamide-induced detrusor overactivity

Cyclophosphamide (CYP)-induced cystitis is a rodent model that shares many features common to the cystitis occurring in patients, including detrusor overactivity (DO). Platelet-derived growth factor receptor alpha positive (PDGFRα(+)) cells have been proposed to regulate muscle excitability in murine bladders during filling. PDGFRα(+) cells express small conductance Ca(2+)-activated K(+) channels (predominantly SK3) that provide stabilization of membrane potential during filling. We hypothesized that down-regulation of the regulatory functions of PDGFRα(+) cells and/or loss of PDGFRα(+) cells generates the DO in CYP-treated mice. After CYP treatment, transcripts of Pdgfrα and Kcnn3 and PDGFRα and SK3 protein were reduced in detrusor muscle extracts. The distribution of PDGFRα(+) cells was also reduced. Inflammatory markers were increased in CYP-treated detrusor muscles. An SK channel agonist, CyPPA, increased outward current and hyperpolarization in PDGFRα(+) cells. This response was significantly depressed in PDGFRα(+) cells from CYP-treated bladders. Contractile experiments and ex vivo cystometry showed increased spontaneous contractions and transient contractions, respectively in CYP-treated bladders with a reduction of apamin sensitivity, that could be attributable to the reduction in the SK conductance expressed by PDGFRα(+) cells. In summary, PDGFRα(+) cells were reduced and the SK3 conductance was downregulated in CYP-treated bladders. These changes are consistent with the development of DO after CYP treatment

Body Composition Estimation and Satisfaction in College Students

College students are at an elevated risk for engaging in unhealthy lifestyle behaviors, including disordered eating and low levels of exercise. Evidence also suggests that college students inaccurately estimate their weight status (e.g., reporting they are overweight when they are at a normal weight) and report high levels of body dissatisfaction. Efforts to promote healthy behavior change and body satisfaction first require an accurate perception of the problem. The purpose of this study was to 1) determine the accuracy with which college students estimate their weight and body composition, and 2) better understand the relationship between body composition and body satisfaction. Methods: Forty-five college students (males = 21 and females = 24), between 18 and 30 years of age, completed a survey with items assessing demographic characteristics, weight status estimation, body composition estimation, and the Body Part Satisfaction Scale (BPSS). Body composition was assessed using Dual x-ray absorptiometry (DXA). Paired samples t-tests were used to compare means between participant’s objective measurements and their estimated measurements. Bivariate analyses were used to determine relationships between body part dissatisfaction and body composition. Results: Males and females accurately estimated their weight (d =-.16, SD = 2.56, t(44) = -.414, p = 0.68), but significantly underestimated their body fat percentage (d =-4.37, SD = 7.62, t(44) = -3.85), p = 0.001). Greater body dissatisfaction was associated with a higher body fat percentage (r =. 353), but not body fat percentage estimation (r = .164). In the trunk region, a higher body fat percentage in that region was significantly associated with greater dissatisfaction for abdomen size (r = .323); higher body fat percentage in the arms and legs were mildly associated with greater dissatisfaction in the respective areas (r = .268; r = .260), though not statistically significant. Conclusions: Although college students accurately estimated their weight, they significantly underestimated their fat mass, indicating a misunderstanding regarding the proportion of their body weight composed of fat tissue. As expected, greater fat mass in specific body parts (e.g., arms, legs, and truck) was related with greater dissatisfaction in those specific areas. Future research should continue to investigate these relationships and body composition estimation accuracy in more diverse samples. Health promotion initiatives should aim to educate students on body composition and continue to promote healthy behavior change along with body satisfaction

Tumor cell invasion of collagen matrices requires coordinate lipid agonist-induced G-protein and membrane-type matrix metalloproteinase-1-dependent signaling

BACKGROUND: Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are bioactive lipid signaling molecules implicated in tumor dissemination. Membrane-type matrix metalloproteinase 1 (MT1-MMP) is a membrane-tethered collagenase thought to be involved in tumor invasion via extracellular matrix degradation. In this study, we investigated the molecular requirements for LPA- and S1P-regulated tumor cell migration in two dimensions (2D) and invasion of three-dimensional (3D) collagen matrices and, in particular, evaluated the role of MT1-MMP in this process. RESULTS: LPA stimulated while S1P inhibited migration of most tumor lines in Boyden chamber assays. Conversely, HT1080 fibrosarcoma cells migrated in response to both lipids. HT1080 cells also markedly invaded 3D collagen matrices (~700 μm over 48 hours) in response to either lipid. siRNA targeting of LPA(1 )and Rac1, or S1P(1), Rac1, and Cdc42 specifically inhibited LPA- or S1P-induced HT1080 invasion, respectively. Analysis of LPA-induced HT1080 motility on 2D substrates vs. 3D matrices revealed that synthetic MMP inhibitors markedly reduced the distance (~125 μm vs. ~45 μm) and velocity of invasion (~0.09 μm/min vs. ~0.03 μm/min) only when cells navigated 3D matrices signifying a role for MMPs exclusively in invasion. Additionally, tissue inhibitors of metalloproteinases (TIMPs)-2, -3, and -4, but not TIMP-1, blocked lipid agonist-induced invasion indicating a role for membrane-type (MT)-MMPs. Furthermore, MT1-MMP expression in several tumor lines directly correlated with LPA-induced invasion. HEK293s, which neither express MT1-MMP nor invade in the presence of LPA, were transfected with MT1-MMP cDNA, and subsequently invaded in response to LPA. When HT1080 cells were seeded on top of or within collagen matrices, siRNA targeting of MT1-MMP, but not other MMPs, inhibited lipid agonist-induced invasion establishing a requisite role for MT1-MMP in this process. CONCLUSION: LPA is a fundamental regulator of MT1-MMP-dependent tumor cell invasion of 3D collagen matrices. In contrast, S1P appears to act as an inhibitory stimulus in most cases, while stimulating only select tumor lines. MT1-MMP is required only when tumor cells navigate 3D barriers and not when cells migrate on 2D substrata. We demonstrate that tumor cells require coordinate regulation of LPA/S1P receptors and Rho GTPases to migrate, and additionally, require MT1-MMP in order to invade collagen matrices during neoplastic progression

Explainable artificial intelligence prediction-based model in laparoscopic liver surgery for segments 7 and 8: an international multicenter study

Artificial intelligence; Liver resection; Minimally invasive surgeryInteligencia artificial; Resección hepática; Cirugía mínimamente invasivaIntel·ligència artificial; Resecció hepàtica; Cirurgia mínimament invasivaBackground Artificial intelligence (AI) is becoming more useful as a decision-making and outcomes predictor tool. We have developed AI models to predict surgical complexity and the postoperative course in laparoscopic liver surgery for segments 7 and 8. Methods We included patients with lesions located in segments 7 and 8 operated by minimally invasive liver surgery from an international multi-institutional database. We have employed AI models to predict surgical complexity and postoperative outcomes. Furthermore, we have applied SHapley Additive exPlanations (SHAP) to make the AI models interpretable. Finally, we analyzed the surgeries not converted to open versus those converted to open. Results Overall, 585 patients and 22 variables were included. Multi-layer Perceptron (MLP) showed the highest performance for predicting surgery complexity and Random Forest (RF) for predicting postoperative outcomes. SHAP detected that MLP and RF gave the highest relevance to the variables “resection type” and “largest tumor size” for predicting surgery complexity and postoperative outcomes. In addition, we explored between surgeries converted to open and non-converted, finding statistically significant differences in the variables “tumor location,” “blood loss,” “complications,” and “operation time.” Conclusion We have observed how the application of SHAP allows us to understand the predictions of AI models in surgical complexity and the postoperative outcomes of laparoscopic liver surgery in segments 7 and 8

Discovery and Orbital Determination of the Transient X-ray Pulsar GRO J1750-27

We report on the discovery and hard X-ray (20-70 keV) observations of the 4.45 s period transient X-ray pulsar GRO J1750-27 with the BATSE all-sky monitor on board CGRO. A relatively faint outburst (<30 mcrab peak) lasting at least 60 days was observed during which the spin-up rate peaked at 38 pHz s^(-1) and was correlated with the pulsed intensity. An orbit with a period of 29.8 days was found. The large spin-up rate, spin period, and orbital period together suggest that accretion is occurring from a disk and that the outburst is a "giant" outburst typical of a Be/X-ray transient system. No optical counterpart has yet been reported

Patients with more comorbidities have better detection of chronic conditions, but poorer management and control:findings from six middle-income countries

Background The burden of non-communicable diseases (NCDs) is rising rapidly in middle-income countries (MICs), where NCDs are often undiagnosed, untreated and uncontrolled. How comorbidity impacts diagnosis, treatment, and control of NCDs is an emerging area of research inquiry and have important clinical implications as highlighted in the recent National Institute for Health and Care Excellence guidelines for treating patients suffering from multiple NCDs. This is the first study to examine the association between increasing numbers of comorbidities with being undiagnosed, untreated, and uncontrolled for NCDs, in 6 large MICs. Methods Cross-sectional analysis of the World Health Organisation Study of Global Ageing and Adult Health (WHO SAGE) Wave 1 (2007–10), which consisted of adults aged ≥18 years from 6 populous MICs, including China, Ghana, India, Mexico, Russia and South Africa (overall n = 41, 557). Results A higher number of comorbidities was associated with better odds of diagnosis for hypertension, angina, and arthritis, and higher odds of having treatment for hypertension and angina. However, more comorbidities were associated with increased odds of uncontrolled hypertension, angina, arthritis, and asthma. Comorbidity with concordant conditions was associated with improved diagnosis and treatment of hypertension and angina. Conclusion Patients with more comorbidities have better diagnosis of chronic conditions, but this does not translate into better management and control of these conditions. Patients with multiple NCDs are high users of health services and are at an increased risk of adverse health outcomes. Hence, improving their access to care is a priority for healthcare systems