Local Dynamic Stability of the Locomotion of Lower Extremity Joints and Trunk During Backward Upslope Walking

Backward slope walking was considered as a practical rehabilitation and training skill. However, its gait stability has been hardly studied, resulting in its limited application as a rehabilitation tool. In this study, the effect of walking direction and slope grade were investigated on the local dynamic stability of the motion of lower extremity joints and trunk segment during backward and forward upslope walking (BUW/FUW). The local divergence exponents (λ_S) of 16 adults were calculated during their BUW and FUW at grades of 0%, 5%, 10%, and 15%. Mean standard deviation over strides (MeanSD) was analyzed as their gait variability. Backward walking showed larger λ_S for the abduction-adduction and rotational angles of knee and ankle on inclined surface than forward walking, while λ_S for hip flexion-extension angle at steeper grades was opposite. No grade effect for any joint existed during BUW, while λ_S increased with the increasing grade during FUW. As to the trunk, walking direction did little impact on λ_S. Still, significant larger λ_S for its medial-lateral and vertical motion were found at the steeper grades during both FUW and BUW. Results indicate that during BUW, the backward direction may influence the stability of joint motions, while the trunk stability was challenged by the increasing grades. Therefore, BUW may be a training tool for the stability of both upper and lower body motion during gait.     

Estimating Gait Stability: Asymmetrical Loading Effects Measured Using Margin of Stability and Local Dynamic Stability

Changes to intersegmental locomotor control patterns may affect body stability. Our study aimed to (a) characterize upper body dynamic stability in response to the unilateral addition of mass to the lower extremity and (b) evaluate the efficacy of 2 different stability measures commonly used in the literature to detect resulting symmetrical step pattern modifications across the weighted segments (spatial) and between epochs of the gait cycle (temporal). Young adults walked on a treadmill while unloaded or with weights applied unilaterally to their foot, shank, or thigh. Both margin of stability and local dynamic stability (LDS) estimates detected similar trends of distal segment weighting resulting in more unstable upper body movement compared to proximal weighting; however only LDS detected anteroposterior changes in upper body stability over time.     

On the glass transition temperature and the elastic properties in Zr-based bulk metallic glasses

The temperature dependence of the elastic moduli was estimated from ultrasound time of flight measurements performed on bulk metallic glasses of composition Zr_{63? x} Cu₂₄Al _x Ni₁₀Co₃. Using the corresponding values at the glass transition temperature, the local atomic strain was determined. The obtained values for the critical atomic strain calculated for 8 at%?<?x?<?15 at% are close to the predicted universal criterion derived from a topological model, but may also reflect the difference in the chemical interaction that are not accounted by a topological approach.     

The role of surface discontinuity and shape in 4-month-old infants' object segregation

This research examined whether 4-month-old infants use a discontinuity in an object's front surface to visually segregate a display into two separate objects, and whether object shape enables its use. In Experiment 1, infants saw a three-dimensional display composed of two parts with distinctly different shapes. Two groups of infants saw a display in which these two shapes were divided by a visible discontinuity in the front surface (i.e., a boundary between the two objects). One of these groups saw the display move apart at the discontinuity when a gloved hand pulled one object; the second group saw the two objects move together as a single unit. A third group saw a modified version of this display that had no discontinuity present. The results suggested that infants regarded the discontinuity as an indication that the display could be composed of more than one object. In Experiment 2, infants saw the same display, but with a shape that did not highlight the discontinuity. The infants in this study showed no evidence of using the discontinuity. Together, the findings suggest that 4-month-old infants use the surface discontinuity between two objects as an indication that multiple objects could be present in a display, but only when scanning the outer edges of the display leads them to attend to it.     

The effect of body and part-based motion on the recognition of unfamiliar objects

We investigated the role of global (body) and local (parts) motion on the recognition of unfamiliar objects. Participants were trained to categorise moving objects and were then tested on their recognition of static images of these targets using a priming paradigm. Each static target shape was primed by a moving object that comprised either the same body and parts motion; same body, different parts motion; different body, same part motion as the learned target or was non-moving. Only the same body but not the same part motion facilitated shape recognition (Experiment 1), even when either motion was diagnostic of object identity (Experiment 2). When parts motion was more related to the object's body motion then it facilitated the recognition of the static target (Experiment 3). Our results suggest that global and local motions are independently accessed during object recognition and have important implications for how objects are represented in memory.     

胃癌辅助化疗的选择和应用

局部进展期胃癌手术后是否给予全身辅助化疗以及关于标准方案的临床研究,一直是临床关注的热点问题,对ⅡB期以上的进展期胃癌术后给予辅助治疗已经成为共识,但对于采用何种方案作为标准方案尚缺乏循证学依据,而且东西方医学界的意见存在较大的争议,我们一方面期待具有更高级别证据的临床研究结果,另一方面在现有证据下对胃癌术后进行最大程...     

Contingent Stimuli Signal Subsequent Reinforcer Ratios

Conditioned reinforcer effects may be due to the stimulus' discriminative rather than its strengthening properties. While this was demonstrated in a frequently‐changing choice procedure, a single attempt to replicate in a relatively static choice environment failed. We contend that this was because the information provided by the stimuli was nonredundant in the frequently‐changing preparation, and redundant in the steady‐state arrangement. In the present experiments, 6 pigeons worked in a steady‐state concurrent schedule procedure with nonredundant informative stimuli (red keylight illuminations). When a response‐contingent red keylight signaled that the next food delivery was more likely on one of the two alternatives, postkeylight choice responding was reliably for that alternative. This effect was enhanced after a history of extended informative red keylight presentation (Experiment 2). These results lend support to recent characterizations of conditioned reinforcer effects as reflective of a discriminative, rather than a reinforcing, property of the stimulus.     

Rudolph Hermann Lotze's philosophically informed psychology

This essay deals with four main topics: the notion of philosophical psychology; the idea that physical events and mental events cannot be compared to one another; psychophysical mechanism; and the theory of local signs. These are all key elements in the Medicinische Psychologie of Rudolph Hermann Lotze (1817‒1881). By philosophical psychology, Lotze understands not only the collection of experimental data regarding physiological and mental states but also their philosophical processing outlining an interpretation of the real nature of the mind‒body connection. Within this framework, Lotze introduces the psychophysical mechanism as based on a key philosophical idea: mind and body are incomparable, but, nevertheless, they are in reciprocal relation (Wechselwirkung). In virtue of said special relation, movements that take place in the mental sphere of reality are transferred or translated in the bodily sphere and vice versa. This rearrangement (Umgestaltung) from one sphere of reality to the other is termed by Lotze “transformation to equivalent.” Through the concept of equivalence, Lotze supports the idea that the mind and the body form an organic whole. However, psychophysical mechanisms should not be seen as not a fixed series of physical changes followed by an equally fixed series of mental changes: physical changes are “read,” organized, and then transformed by the mind into something purely mental. This, in turn, produces new mechanical force and more physical changes. Lotze's legacy and long-term impact is finally read against the background of his contributions.     

Constrained Maneuvering: Rhetoric as a Rational Enterprise

This paper discusses some of the ways recent models have brought rhetoric into argumentation theory. In particular, it explores the rationale for and role of rhetoric in the strategic maneuvering project of pragma-dialectics and compares it with the author’s own implementation of rhetorical features. A case is made for considering the active ways audiences influence the strategies of arguers and for seeing the role of rhetoric in argumentation as both fundamental and reasonable on its own terms.     

A latent trait theory via a stochastic learning theory for a knowledge space

To capture the cognitive organization of a set of questions or problems pertaining to a body of information, Doignon and Falmagne have proposed, and analyzed in a number of papers, the concept of aknowledge space, that is, a distinguished collection of subsets of questions, representing the possibleknowledge states. This collection of sets is assumed to satisfy a number of conditions. Since this concept is a deterministic one, the problem of empirical testing arises. A stochastic version of a knowledge space is developed in this paper, in which the knowledge states are considered as possible epochs in a subject's learning history. The knowledge space is decomposed as a union of a number of possible learning paths, calledgradations. The model specifies how a subject is channelled through and progresses along a gradation. A probabilistic axiom of the local indepencence type relates the knowledge states to the observable responses. The predictions of this model are worked out in details in the case of parametric assumptions involving gamma distributions. An application of the model to artificial data is described, based on maximum likelihood methods. The statistical analysis is shown to be capable of revealing the combinatoric core of the model.This work was supported by NSF grant IST-8418860 and ARI grant DAAG29-84-G-0083 to New York University. I am grateful to Jean-Paul Doignon, Mathieu Koppen, Geoff Iverson and Michael Landy for their reactions to previous drafts of this paper, to Michael Villano for carrying out the computer simulation and the analysis of the simulated data, and especially to one referee for his very useful comments.