Is there a ‚Depth versus Participation‘ Dilemma in International Cooperation?

Much of the International Relations literature assumes that there is a “depth versus participation” dilemma in international politics: shallower international agreements attract more countries and greater depth is associated with less participation. We argue that this conjecture is too simple and probably misleading because the depth of any given cooperative effort is in fact multidimensional. This multidimensionality manifests itself in the design characteristics of international agreements: in particular, the specificity of obligations, monitoring and enforcement mechanisms, dispute settlement mechanisms, positive incentives (assistance), and organizational structures (secretariats). We theorize that the first three of these design characteristics have negative and the latter three have positive effects on participation in international cooperative efforts. Our empirical testing of these claims relies on a dataset that covers more than 200 global environmental treaties. We find a participation-limiting effect for the specificity of obligations, but not for monitoring and enforcement. In contrast, we observe that assistance provisions in treaties have a significant and substantial positive effect on participation. Similarly, dispute settlement mechanisms tend to promote treaty participation. The main implication of our study is that countries do not appear to stay away from agreements with monitoring and enforcement provisions, but that the inclusion of positive incentives and dispute settlement mechanisms can promote international cooperation. In other words, our findings suggest that policymakers do not necessarily need to water down global treaties in order to obtain more participation.

Recent skin self-examination and doctor visits in relation to melanoma risk and tumour depth

BACKGROUND Little is known about the potential benefit of skin self-examination for melanoma prevention and early detection. Objectives: To determine whether skin self-examination is associated with reduced melanoma risk, self-detection of tumours, and reduced risk of deeper melanomas. METHODS We used data from a population-based case-control study (423 cases, 678 controls) to assess recent skin self-examination in relation to self-detection, melanoma risk and tumour depth ( ≤1 mm; > 1 mm). Logistic regression was used to estimate odds ratios (ORs) and confidence intervals (CIs) for associations of interest. RESULTS Skin self-examination conducted 1-11 times during a recent year was associated with a possible decrease in melanoma risk (OR 0·74; 95% CI 0·54-1·02). Melanoma risk was decreased for those who conducted skin self-examination and saw a doctor (OR 0·52; 95% CI 0·30-0·90). Among cases, those who examined their skin were twice as likely to self-detect the melanoma (OR 2·23; 95% CI 1·47-3·38), but self-detection was not associated with shallower tumours. Tumour depth was reduced for those who conducted skin self-examination 1-11 times during a recent year (OR 0·39; 95% CI 0·18-0·81), but was not influenced by seeing a doctor, or by conducting skin self-examination and seeing a doctor. CONCLUSIONS Risk of a deeper tumour and possibly risk of melanoma were reduced by skin self-examination 1-11 times annually. Melanoma risk was markedly reduced by skin self-examination coupled with a doctor visit. We cannot, however, exclude the possibility that our findings reflect bias or confounding. Additional studies are needed to elucidate the potential benefits of skin self-examination for melanoma prevention and early detection.

The optimal lead insertion depth for esophageal ECG recordings with respect to atrial signal quality

BACKGROUND Diagnosing supraventricular arrhythmias by conventional long-term ECG can be cumbersome because of poor p-waves. Esophageal long-term electrocardiography (eECG) has an excellent sensitivity for atrial signals and may overcome this limitation. However, the optimal lead insertion depth (OLID) is not known. METHODS We registered eECGs at different lead insertion depths in 27 patients and analyzed 199,716 atrial complexes with respect to signal amplitude and slope. Correlation and regression analyses were used to find a criterion for OLID. RESULTS Atrial signal amplitudes and slopes significantly depend on lead insertion depth. OLID correlates with body height (rSpearman=0.71) and can be estimated by OLID [cm]=0.25*body height[cm]-7cm. At this insertion depth, we recorded the largest esophageal atrial signal amplitudes (1.27±0.86mV), which were much larger compared to conventional surface lead II (0.19±0.10mV, p<0.0001). CONCLUSION The OLID depends on body height and can be calculated by a simple regression formula.

The influence of yield surface shape and damage in the depth-dependent response of bone tissue to nanoindentation using spherical and Berkovich indenters

Prevention and treatment of osteoporosis rely on understanding of the micromechanical behaviour of bone and its influence on fracture toughness and cell-mediated adaptation processes. Postyield properties may be assessed by nonlinear finite element simulations of nanoindentation using elastoplastic and damage models. This computational study aims at determining the influence of yield surface shape and damage on the depth-dependent response of bone to nanoindentation using spherical and conical tips. Yield surface shape and damage were shown to have a major impact on the indentation curves. Their influence on indentation modulus, hardness, their ratio as well as the elastic-to-total work ratio is well described by multilinear regressions for both tip shapes. For conical tips, indentation depth was not statistically significant (p<0.0001). For spherical tips, damage was not a significant parameter (p<0.0001). The gained knowledge can be used for developing an inverse method for identification of postelastic properties of bone from nanoindentation.

Vibrations, Posture, and the Stabilization of Gaze: An Experimental Study on Impedance Control

Vibrations, Posture, and the Stabilization of Gaze: An Experimental Study on Impedance Control R. KREDEL, A. GRIMM & E.-J. HOSSNER University of Bern, Switzerland Introduction Franklin and Wolpert (2011) identify impedance control, i.e., the competence to resist changes in position, velocity or acceleration caused by environmental disturbances, as one of five computational mechanisms which allow for skilled and fluent sen-sorimotor behavior. Accordingly, impedance control is of particular interest in situa-tions in which the motor task exhibits unpredictable components as it is the case in downhill biking or downhill skiing. In an experimental study, the question is asked whether impedance control, beyond its benefits for motor control, also helps to stabi-lize gaze what, in turn, may be essential for maintaining other control mechanisms (e.g., the internal modeling of future states) in an optimal range. Method In a 3x2x4 within-subject ANOVA design, 72 participants conducted three tests on visual acuity and contrast (Landolt / Grating and Vernier) in two different postures (standing vs. squat) on a platform vibrating at four different frequencies (ZEPTOR; 0 Hz, 4 Hz, 8 Hz, 12 Hz; no random noise; constant amplitude) in a counterbalanced or-der with 1-minute breaks in-between. In addition, perceived exertion (Borg) was rated by participants after each condition. Results For Landolt and Grating, significant main effects for posture and frequency are re-vealed, representing lower acuity/contrast thresholds for standing and for higher fre-quencies in general, as well as a significant interaction (p < .05), standing for in-creasing posture differences with increasing frequencies. Overall, performance could be maintained at the 0 Hz/standing level up to a frequency of 8 Hz, if bending of the knees was allowed. The fact that this result is not only due to exertion is proved by the Borg ratings showing significant main effects only, i.e., higher exertion scores for standing and for higher frequencies, but no significant interaction (p > .40). The same pattern, although not significant, is revealed for the Vernier test. Discussion Apparently, postures improving impedance control not only turn out to help to resist disturbances but also assist in stabilizing gaze in spite of these perturbations. Con-sequently, studying the interaction of these control mechanisms in complex unpre-dictable environments seems to be a fruitful field of research for the future. References Franklin, D. W., & Wolpert, D. M. (2011). Computational mechanisms of sensorimotor control. Neuron, 72, 425-442.

Gaze perception in social anxiety and social anxiety disorder

Clinical observations suggest abnormal gaze perception to be an important indicator of social anxiety disorder (SAD). Experimental research has yet paid relatively little attention to the study of gaze perception in SAD. In this article we first discuss gaze perception in healthy human beings before reviewing self-referential and threat-related biases of gaze perception in clinical and non-clinical socially anxious samples. Relative to controls, socially anxious individuals exhibit an enhanced self-directed perception of gaze directions and demonstrate a pronounced fear of direct eye contact, though findings are less consistent regarding the avoidance of mutual gaze in SAD. Prospects for future research and clinical implications are discussed.

Relationship between threshold and suprathreshold perception of position and stereoscopic depth.

We seek to determine the relationship between threshold and suprathreshold perception for position offset and stereoscopic depth perception under conditions that elevate their respective thresholds. Two threshold-elevating conditions were used: (1) increasing the interline gap and (2) dioptric blur. Although increasing the interline gap increases position (Vernier) offset and stereoscopic disparity thresholds substantially, the perception of suprathreshold position offset and stereoscopic depth remains unchanged. Perception of suprathreshold position offset also remains unchanged when the Vernier threshold is elevated by dioptric blur. We show that such normalization of suprathreshold position offset can be attributed to the topographical-map-based encoding of position. On the other hand, dioptric blur increases the stereoscopic disparity thresholds and reduces the perceived suprathreshold stereoscopic depth, which can be accounted for by a disparity-computation model in which the activities of absolute disparity encoders are multiplied by a Gaussian weighting function that is centered on the horopter. Overall, the statement "equal suprathreshold perception occurs in threshold-elevated and unelevated conditions when the stimuli are equally above their corresponding thresholds" describes the results better than the statement "suprathreshold stimuli are perceived as equal when they are equal multiples of their respective threshold values."

Mechanisms of perceptual learning of depth discrimination in random dot stereograms.

Perceptual learning is a training induced improvement in performance. Mechanisms underlying the perceptual learning of depth discrimination in dynamic random dot stereograms were examined by assessing stereothresholds as a function of decorrelation. The inflection point of the decorrelation function was defined as the level of decorrelation corresponding to 1.4 times the threshold when decorrelation is 0%. In general, stereothresholds increased with increasing decorrelation. Following training, stereothresholds and standard errors of measurement decreased systematically for all tested decorrelation values. Post training decorrelation functions were reduced by a multiplicative constant (approximately 5), exhibiting changes in stereothresholds without changes in the inflection points. Disparity energy model simulations indicate that a post-training reduction in neuronal noise can sufficiently account for the perceptual learning effects. In two subjects, learning effects were retained over a period of six months, which may have application for training stereo deficient subjects.

All eyes on me?! Social anxiety and self-directed perception of eye gaze

To date, only little is known about the self-directed perception and processing of subtle gaze cues in social anxiety that might however contribute to excessive feelings of being looked at by others. Using a web-based approach, participants (n=174) were asked whether or not briefly (300 ms) presented facial expressions modulated in gaze direction (0°, 2°, 4°, 6°, 8°) and valence (angry, fearful, happy, neutral) were directed at them. The results demonstrate a positive, linear relationship between self-reported social anxiety and stronger self-directed perception of others' gaze directions, particularly for negative (angry, fearful) and neutral expressions. Furthermore, faster responding was found for gaze more clearly directed at socially anxious individuals (0°, 2°, and 4°) suggesting a tendency to avoid direct gaze. In sum, the results illustrate an altered self-directed perception of subtle gaze cues. The possibly amplifying effects of social stress on biased self-directed perception of eye gaze are discussed.

Cell and matrix morphology in articular cartilage from adult human knee and ankle joints suggests depth-associated adaptations to biomechanical and anatomical roles

OBJECTIVE Marked differences exist between human knee and ankle joints regarding risks and progression of osteoarthritis (OA). Pathomechanisms of degenerative joint disease may therefore differ in these joints, due to differences in tissue structure and function. Focussing on structural issues which are design goals for tissue engineering, we compared cell and matrix morphologies in different anatomical sites of adult human knee and ankle joints. METHODS Osteochondral explants were acquired from knee and ankle joints of deceased persons aged 20 to 40 years and analyzed for cell, matrix and tissue morphology using confocal and electron microscopy and unbiased stereological methods. Variations associated with joint (knee versus ankle) and biomechanical role (convex versus concave articular surfaces) were identified by 2-way analysis of variance and post-hoc analysis. RESULTS Knee cartilage exhibited higher cell densities in the superficial zone than ankle cartilage. In the transitional zone, higher cell densities were observed in association with convex versus concave articular surfaces, without significant differences between knee and ankle cartilage. Highly uniform cell and matrix morphologies were evident throughout the radial zone in the knee and ankle, regardless of tissue biomechanical role. Throughout the knee and ankle cartilage sampled, chondron density was remarkably constant at approximately 4.2×10(6) chondrons/cm(3). CONCLUSION Variation of cartilage cell and matrix morphologies with changing joint and biomechanical environments suggests that tissue structural adaptations are performed primarily by the superficial and transitional zones. Data may aid the development of site-specific cartilage tissue engineering, and help identify conditions where OA is likely to occur.