Large-Scale Modeling of Wordform Learning and Representation

The forms of words as they appear in text and speech are central to theories and models of lexical processing. Nonetheless, current methods for simulating their learning and representation fail to approach the scale and heterogeneity of real wordform lexicons. A connectionist architecture termed the sequence encoder is used to learn nearly 75,000 wordform representations through exposure to strings of stress-marked phonemes or letters. First, the mechanisms and efficacy of the sequence encoder are demonstrated and shown to overcome problems with traditional slot-based codes. Then, two large-scale simulations are reported that learned to represent lexicons of either phonological or orthographic wordforms. In doing so, the models learned the statistics of their lexicons as shown by better processing of well-formed pseudowords as opposed to ill-formed (scrambled) pseudowords, and by accounting for variance in well-formedness ratings. It is discussed how the sequence encoder may be integrated into broader models of lexical processing.     

骨髓造血干细胞移植治疗自身免疫性疾病的进展

自身免疫疾病发病机制复杂,目前尚缺少有效的治疗方法。近年来发现造血干细胞移植可以通过免疫重建显著缓解甚至治愈自身免疫病。笔者对近年来造血干细胞移植治疗自身免疫病进行了介绍和综述,就其在1型糖尿病这一领域的研究进展进行了述评,探讨造血干细胞移植用于治疗自身免疫病的前景和待解决的问题。     

辩证看待干细胞移植的热化问题

现代科学技术的发展已经并正在给人类展现一个相互矛盾的事实：一方面是科学技术推动人类社会的巨大进步,促进社会生活的极大提高。如核能的利用、转基因作物、转基因治疗、动物克隆、干细胞的开发与应用等等,无不让人类充分地享受到现代科技带来的种种利益和好处。另外一方面人类的生存危机前所未有的加深,环境的恶化、水资源的污染、新的疾病和变异的菌种诞生等等。怎样运用哲学的理性的思维和方法来评判现代科技对人类的影响,摆脱其发展对社会所造成的两难困境,是一个必须解决的难题。以干细胞移植研究为例,如何辩证看待干细胞移植热化问题,如何运用哲学思维来看待干细胞移植的有利性和危害性,探究科学技术的可持续发展道路。     

Human Allocentric Heading Orientation and Ability

ABSTRACT— Since the discovery of head-direction cells in nonhuman mammals, we have learned a great deal about how an internal compass-like system functions in the mammalian brain. In contrast, we know very little about how this system operates in humans—or, for that matter, whether humans even have an internal compass for computing body heading. This article reviews a recent line of inquiry that uses animal models of head-direction-system functioning to motivate behavioral research on human sense of direction.     

Bioterrorism, Embryonic Stem Cells, and Frankenstein

The stem cell controversy raises a fundamental question for humankind. Does science have a right to pursue knowledge whatever the cost? Our Enlightenment culture says yes. However, human history and literature are sending warning signals. Ethical issues impact the “knowledge for its own sake” imperative, and must be addressed.     

Scientific Self-Regulation—So Good, How Can it Fail?

To be a functional alternative to government regulation, self-regulation of science must be credible to both scientists and the public, accountable, ethical, and effective. According to some, serious problems continue in research ethics in the United States despite a rich history of proposed self-regulatory standards and oversight devices. Successful efforts at self-regulation in stem cell research contrast with unsuccessful efforts in research ethics, particularly conflicts of interest. Part of the cause for a lack of success in self-regulation is fragmented, disconnected oversight, and failure to embody genuine scientific and public consensus. To be accountable, credible and effective, self-regulation must be inclusive and multidisciplinary, publicly engaged, sufficiently disinterested, operationally integrated with institutional goals, and must implement a genuine consensus among scientists and the public. The mechanisms of self-regulation must be sufficiently broad in their oversight, and interconnected with other institutional forces and actors, that they do not create fragmented solutions.

Approaching Religious Guidelines for Chimera Policymaking

Recent developments in the use of cow egg cells to clone human somatic cells, and the grafting by researchers at several universities of human neurons into mice, bring the notion of the chimera, a mixture of several living organisms, from myth into reality. In his article “Cross‐Species Chimeras: Exploring a Possible Christian Perspective,” Neville Cobbe considers the religious arguments overlying the creation of human‐nonhuman chimeras. In my commentary I focus on the distinction between germline‐ and tissue transplant‐related chimeric techniques implicit in Cobbe's essay and argue that the former poses more serious moral difficulties than the latter if the chimeric product is brought to term. The substantive view of the imago Dei, or image of God, serves as a scaffold by which to judge the permissibility of chimera creation using stem cell and other tissue implants. While useful for judging the rights of such artificially generated beings, I argue that specific criteria such as proportion of tissue uptake, mental capacity, and adherence with the organism's telos are more appropriately considered within a composite image of the living being reflecting its unique integrality. Human co‐creativity with the Divine will inevitably prompt attempts to generate medically useful chimeras. Religious dialogue, combined with the categories of religious moral argument appearing in Cobbe's essay, will help to establish the outline of feasible policy guidelines addressing the complexities inherent in the creation of chimeras.     

Emergent simple discrimination established by indirect relation to differential consequences

Three experiments examined a discrimination training sequence that led to emergent simple discrimination in human subjects. The experiments differed primarily in their subject populations. Normally capable adults served in the first experiment, preschool children in the second, and mentally retarded adults in the third. In all experiments, subjects learned a simple simultaneous discrimination: When visual stimuli A1 and A2 were displayed together, reinforcers followed selections of A1, the S+, but not A2, the S-. The subjects also learned a conditional discrimination taught with an arbitrary visual-visual matching-to-sample procedure. Comparisons were two additional visual stimuli, B1 and B2, and samples were A1 and A2. Reinforcers followed selections of B1 in the presence of A1 and of B2 in the presence of A2. After the simple-discrimination and conditional-discrimination baselines had been acquired, B1 and B2 were displayed alone (without a sample) on probe trials. Subjects had never been taught explicitly how to respond to such displays. Nonetheless, they almost always selected B1, which was involved in a conditional relation with A1, the stimulus that served as S+ on the simple-discrimination trials. This outcome suggested the formation of stimulus classes during conditional-discrimination training. Through class formation, B1 and B2 had apparently acquired stimulus functions similar to those shown by A1 and A2 on simple-discrimination trials, thereby leading to emergent selections of B1 on the probes.     

生物自组织临界性与肿瘤

分析了局部组织由再生、化生和癌变呈现的各种宏观行为和性质,从生物自组织临界性的角度讨论了这类行为和性质的演化模式及机制,指出肿瘤实质是局部组织经历一系列临界状态下相变造成的。