bluuebunny/crossref_metadata_2025 huggingface dataset:
Four Faces of Baroreflex Failure
Authors: Ketch Terry , Biaggioni Italo , Robertson RoseMarie , Robertson David
Published: July 2002

Background

—

The baroreflex normally serves to buffer blood pressure against excessive rise or fall. Baroreflex failure occurs when afferent baroreceptive nerves or their central connections become impaired. In baroreflex failure, there is loss of buffering ability, and wide excursions of pressure and heart rate occur. Such excursions may derive from endogenous factors such as stress or drowsiness, which result in quite high and quite low pressures, respectively. They may also derive from exogenous factors such as drugs or environmental influences.

Methods and Results

—

Impairment of the baroreflex may produce an unusually broad spectrum of clinical presentations; with acute baroreflex failure, a hypertensive crisis is the most common presentation. Over succeeding days to weeks, or in the absence of an acute event, volatile hypertension with periods of hypotension occurs and may continue for many years, usually with some attenuation of pressor surges and greater prominence of depressor valleys during long-term follow-up. With incomplete loss of baroreflex afferents, a mild syndrome of orthostatic tachycardia or orthostatic intolerance may appear. Finally, if the baroreflex failure occurs without concomitant destruction of the parasympathetic efferent vagal fibers, a resting state may lead to malignant vagotonia with severe bradycardia and hypotension and episodes of sinus arrest.

Conclusions

—

Although baroreflex failure is not the most common cause of the above conditions, correct differentiation from other cardiovascular disorders is important, because therapy of baroreflex failure requires specific strategies, which may lead to successful control.
Socioeconomic Inequalities in Hypertension Prevalence and Care
Authors: de Gaudemaris Régis , Lang Thierry , Chatellier Gilles , Larabi Lynda , Lauwers-Cancès Valérie , Maître Anne , Diène Eloi
Published: July 2002

To analyze the health disparities relative to the prevalence of arterial hypertension and its therapeutic control in the active French population, in relation to occupational categories (OC), a population of 17 359 men and 12 267 women was assessed from January 1997 to April 1998. The initial phase was a cross-sectional analysis of a cohort study designed to assess the incidence of arterial hypertension in a French working population. Information was collected by the worksite physician during the annual examination. Blood pressure (BP) was measured using a validated automatic device. Among subjects with a BP ≥140/90 mm Hg, patients not treated with antihypertensive drugs were invited to have an additional BP measurement, 1 month later. Overall prevalence was 16.1% for men and 9.4% for women. Both prevalence and therapeutic control of high BP were related to OCs in this study. Prevalence of hypertension was higher and maintenance of therapeutic control lower among lower OCs. In contrast, awareness of high BP and the proportion of hypertensive subjects under current treatment were not related to OCs. Educational level and low OC were significantly related to prevalence of high BP after adjustment for obesity, excessive alcohol consumption, and sedentary lifestyle in women only. A poor BP control under treatment was related to high alcohol intake and low OC in men. In women only, however, low educational level was related to high prevalence of hypertension and poor BP control under antihypertensive treatment. Inequalities in hypertension prevalence persist, with prevalence being higher among lower OCs. Social disparities were not observed, however, in awareness of their condition among hypertensive subjects and among patients for receiving versus not receiving any treatment for hypertension. In contrast, BP control under antihypertensive treatment was lower among lower OCs.
ADD1
460W Allele Associated With Cardiovascular Disease in Hypertensive Individuals
Authors: Morrison Alanna C. , Bray Molly S. , Folsom Aaron R. , Boerwinkle Eric
Published: July 2002

High blood pressure is a predictor of cardiovascular disease. Hence, genes contributing to essential hypertension may play a role in the etiology of cardiovascular disease. For this reason, we examined the association between the α-adducin (
ADD1
) G460W and G-protein β3 subunit (
GNB3
) 825C>T polymorphisms and the prevalence of peripheral arterial disease (PAD) and incidence of coronary heart disease (CHD) in non-Hispanic whites from the Atherosclerosis Risk in Communities (ARIC) Study. PAD prevalence was defined by an ankle-brachial index, ie, the ratio of ankle systolic blood pressure to brachial artery systolic blood pressure, of ≤0.90 for men and ≤0.85 for women. CHD incidence was determined by following the ARIC cohort for a median of 5.3 years for potential coronary events. Stratified random samples of the ARIC cohort (n=703 and n=684) were used, respectively, as the comparison groups for the PAD (n=144) and incident CHD (n=408) cases. The
GNB3
825T allele and the
ADD1
460W allele were not significantly associated with prevalence of PAD or incidence of CHD. However, a test of the interaction between hypertension status and the
ADD1
G460W polymorphism indicated that further evaluation of the
ADD1
polymorphism in only hypertensive individuals was warranted. The
ADD1
460W allele was significantly associated with PAD (odds ratio [OR]: 2.61, 95% CI, 1.27–5.37,
P
=0.01) and CHD (hazard rate ratio [HRR]: 2.30, 95% CI, 1.20–4.42,
P
=0.01) in hypertensive individuals after adjustment for multiple cardiovascular disease risk factors. An interaction with hypertension in the association between the
ADD1
G460W polymorphism and cardiovascular disease merits further testing in additional populations.
Silent Cerebral Microbleeds on T2*-Weighted MRI
Authors: Kato Hiroyuki , Izumiyama Masahiro , Izumiyama Kimiaki , Takahashi Akira , Itoyama Yasuto
Published: July 2002

Background and Purpose

—

Gradient-echo T2*-weighted MRI is uniquely sensitive to detect silent, old hemosiderin deposits, but the clinical significance of such “microbleeds” remains to be determined. Therefore, we investigated the incidence and the number of microbleeds among different stroke subtypes and the correlation with stroke recurrence and the severity of leukoaraiosis.

Methods

—

This study consisted of 213 patients (73.5±9.1 years old, 104 men and 109 women), who were classified according to stroke subtypes into atherothrombotic infarction (24 patients), cardioembolic infarction (23 patients), lacunar infarction (66 patients), intracerebral hemorrhage (35 patients), and control (65 patients) groups. Gradient-echo T2*-weighted MRI was performed with a 1.5 T system, and asymptomatic microbleeds were located and counted.

Results

—

The incidence and the number of microbleeds were significantly greater in patients with intracerebral hemorrhage (71.4% and 9.1±13.8, respectively) and lacunar infarction (62.1% and 7.4±16.1) compared with patients with cardioembolic infarction (30.4% and 2.5±5.6), atherothrombotic infarction (20.8% and 0.63±1.53), and controls (7.7% and 0.09±0.34). There was a correlation between the number of microbleeds and the severity of periventricular hyperintensity (
r
=0.626,
P
<0.0001). There was also a correlation between the number of microbleeds and the number of intracerebral hemorrhages (
r
=0.689,
P
<0.0001) or lacunar infarctions (
r
=0.514,
P
<0.0001). The locations of microbleeds were subcortical white matter (31.8%), thalamus (24.8%), basal ganglia (19.8%), brain stem (12.0%), and cerebellum (11.7%).

Conclusions

—

The findings suggest that microbleeds on T2*-weighted MRI are an indicator of advanced small artery disease of the brain with an increased risk for bleeding. This result should be taken into consideration when treating patients with stroke, and further studies are required.
A Predatory Social Structure: Informers in Westminster, 1737-1741
Authors: Warner Jessica , Ivis Frank , Demers Andrée
Published: July 2002

Archival data about, and contemporary accounts of, the Gin Acts illustrate the careers of 198 informers known to have operated in Westminster between 1737 and 1741, providing an idea of their interrelationships. Visible links among the informers appear to have been generally weak. Most of the sample at hand operated as isolates on an opportunistic basis, informing only once. Their network, such as it was, seems to have functioned primarily as a clearinghouse, connecting informers with victims in neighborhoods where the informers were as yet unknown and thus less vulnerable to attack by the community.
An Interactive Test of Color and Contour Perception by Artists and Non-Artists
Authors: Washburn Dorothy K.
Published: July 2002

The author explores Richard Latto's proposition that art com-municates effectively because art-ists manipulate basic features of form that the human perceptual system has evolved to detect. She offers an empirical test of the correlated proposition-that view-ers of art use these same fea-tures to assess art. The author presents the results of an experi-ment in which both artists and non-artists were asked to discern and draw shapes in patterns de-fined by iterating dots. She finds that both groups used color in the case of positive shape and form edge in the case of negative space, thereby confirming that both makers and viewers of art fo-cus on the same kinds of features to recognize and assess form.
The Systematic Refusal of Modern Music and the Cult of Classicism
Authors: Pedler Emmanuel
Published: July 2002

The author argues that electronic music and classical music do not constitute two separate and isolated worlds, but instead are subject to the same well-established rules of categorization and access. Through an informal inquiry, the author shows that familiarity with contemporary composers' names (which are well assimilated by regular concertgoers) does not reflect familiarity with their actual musical works.
Pseudocleft Connectedness: Implications for the LF Interface Level
Authors: Heycock Caroline , Kroch Anthony
Published: July 2002

Pseudoclefts constitute a difficult challenge for linguistic theory, displaying effects of core syntactic conditions in a noncanonical configuration that cannot be normalized with standard syntactic operations. We argue that these “connectedness” effects follow from the nature of pseudoclefts as equatives. This treatment yields an integrated account of the syntactic and semanticopragmatic properties of the construction, but leads to the conclusion that certain syntactic constraints apply to a level of representation more abstract than LF under most current conceptions. This representation is built up in the process of discourse interpretation and may constitute the interface with the conceptual-intentional system of mind.
Models of the Posterior Parietal Cortex Which Perform Multimodal Integration and Represent Space in Several Coordinate Frames
Authors: Xing Jing , Andersen Richard A.
Published: July 2002

Many neurons in the posterior-parietal cortex (PPC) have saccadic responses to visual and auditory targets. The responses are modulated by eye position and head position. These findings suggest that PPC integrates multisensory inputs and may provide information about saccadic targets represented in different coordinate frames. In addition to an eye-centered output representation, PPC may also project to brain areas which contain head-centered and body-centered representations of the space. In this report, possible coordinate transformations in PPC were examined by comparing several sets of models of PPC, each having different representations in the output layer: (i) an eye-centered map only; (ii) a head-centered map only; (iii) an eye-centered map and a head-centered map; and (iv) an eye-centered map, a head-centered map, and a body-centered map. These output maps correctly encoded saccades to visual and auditory targets through training. The units in the hidden layers of the models exhibited the following properties: (1) The units had gain fields (GFs) for eye position, and also for head position if the model had a body-centered output representation; (2) As the result of the GF and the nonlinear activation function of the units, the hidden layers often employed “intermediate” coding, e.g., the hidden units coded targets partially in eye-centered coordinates and, partially, in head-centered coordinates; (3) Different types of coordinate transformations in these models were carried out by different relationships between the receptive fields (RFs) and the GFs of the hidden units; and (4) The properties of PPC neurons are in better accordance with the hidden units of the models that had multiple-output representations than the models that had only one single-output representation. In conclusion, the results show that the GF is an effective mechanism for performing coordinate transformations. The models also suggest that neurons with intermediate coding are to be expected in the process of coordinate transformations.
Motor Cortical Activity during Interception of Moving Targets.
Authors: Port Nicholas L. , Kruse Wolfgang , Lee Daeyeol , Georgopoulos Apostolos P.
Published: July 2002

The single-unit activity of 831 cells was recorded in the arm area of the motor cortex of tow monkeys while the monkeys intercepted a moving visual stimulus (interception task) or remained immobile during presentation of the same moving stimulus (no-go task). The moving target traveled on an oblique path from either lower corner of a screen toward the vertical meridian, and its movement time (0.5,1.0, or 1.5 sec) and velocity profile (accelerating, decelerating, or constant velocity) were pseudorandomly varied. The moving target had to be intercepted within 130 msec of target arrival at an interception point. By comparing motor cortical activity at the single-neuron tasks, we tested whether information about parameters of moving target is represented in the primary motor cortex to generate appropriate motor responses. A substantial number of neurons displayed modulation of their activity during the no-go task, and this activity was often affected by the stimulus parameters. These results suggest a role of motor cortex in specifying the timing of movement initiation based on information about target motion. In addition, there was a lack of systematic relation between the onset times of neural activity in the interception and no-go task, suggesting that processing of information concerning target motion and generation of hand movement occurs in parallel. Finally, the activity in the most motor cortical neurons was modulated according to an estimate of the time-to-target interception, raising the possibility that time-to-interception may be coded in the motor cortical activity.
On Connectedness: A Solution Based on Oscillatory Correlation
Authors: Wang DeLiang L.
Published: July 2002

A long-standing problem in neural computation has been the problem of connectedness, first identified by Minsky and Papert (1969). This problem served as the cornerstone for them to establish analytically that perceptrons are fundamentally limited in computing geometrical (topological) properties. A solution to this problem is offered by a different class of neural networks: oscillator networks. To solve the problem, the representation of oscillatory correlation is employed, whereby one pattern is represented as a synchronized block of oscillators and different patterns are represented by distinct blocks that desynchronize from each other. Oscillatory correlation emerges from LEGION (locally excitatory globally inhibitory oscillator network), whose architecture consists of local excitation and global inhibition among neural oscillators. It is further shown that these oscillator networks exhibit sensitivity to topological structure, which may lay a neurocomputational foundation for explaining the psychophysical phenomenon of topological perception.
Self-Organization of Topographic Mixture Networks Using Attentional Feedback
Authors: Williamson James R.
Published: July 2002

This article proposes a neural network model of supervised learning that employs biologically motivated constraints of using local, on-line, constructive learning. The model possesses two novel learning mechanisms. The first is a network for learning topographic mixtures. The network's internal category nodes are the mixture components, which learn to encode smooth distributions in the input space by taking advantage of topography in the input feature maps. The second mechanism is an attentional biasing feedback circuit. When the network makes an incorrect output prediction, this feedback circuit modulates the learning rates of the category nodes, by amounts based on the sharpness of their tuning, in order to improve the network's prediction accuracy. The network is evaluated on several standard classification benchmarks and shown to perform well in comparison to other classifiers.
Specification of Training Sets and the Number of Hidden Neurons for Multilayer Perceptrons
Authors: Camargo L. S. , Yoneyama T.
Published: July 2002

This work concerns the selection of input-output pairs for improved training of multilayer perceptrons, in the context of approximation of univariate real functions. A criterion for the choice of the number of neurons in the hidden layer is also provided. The main idea is based on the fact that Chebyshev polynomials can provide approximations to bounded functions up to a prescribed tolerance, and, in turn, a polynomial of a certain order can be fitted with a three-layer perceptron with a prescribed number of hidden neurons. The results are applied to a sensor identification example.
Unitary Events in Multiple Single-Neuron Spiking Activity: I. Detection and Significance
Authors: Grün Sonja , Diesmann Markus , Aertsen Ad
Published: July 2002

It has been proposed that cortical neurons organize dynamically into functional groups (cell assemblies) by the temporal structure of their joint spiking activity. Here, we describe a novel method to detect conspicuous patterns of coincident joint spike activity among simultaneously recorded single neurons. The statistical significance of these unitary events of coincident joint spike activity is evaluated by the joint-surprise. The method is tested and calibrated on the basis of simulated, stationary spike trains of independently firing neurons, into which coincident joint spike events were inserted under controlled conditions. The sensitivity and specificity of the method are investigated for their dependence on physiological parameters (firing rate, coincidence precision, coincidence pattern complexity) and temporal resolution of the analysis. In the companion article in this issue, we describe an extension of the method, designed to deal with nonstationary firing rates.
On the Role of Biophysical Properties of Cortical Neurons in Binding and Segmentation of Visual Scenes
Authors: Verschure Paul F. M. J. , König Peter
Published: July 2002

Neuroscience is progressing vigorously, and knowledge at different levels of description is rapidly accumulating. To establish relationships between results found at these different levels is one of the central challenges. In this simulation study, we demonstrate how microscopic cellular properties, taking the example of the action of modulatory substances onto the membrane leakage current, can provide the basis for the perceptual functions reflected in the macroscopic behavior of a cortical network. In the first part, the action of the modulatory system on cortical dynamics is investigated. First, it is demonstrated that the inclusion of these biophysical properties in a model of the primary visual cortex leads to the dynamic formation of synchronously active neuronal assemblies reflecting a context-dependent binding and segmentation of image components. Second, it is shown that the differential regulation of the leakage current can be used to bias the interactions of multiple cortical modules. This allows the flexible use of different feature domains for scene segmentation. Third, we demonstrate how, within the proposed architecture, the mapping of a moving stimulus onto the spatial dimension of the network results in an increased speed of synchronization. In the second part, we demonstrate how the differential regulation of neuromodulatory activity can be achieved in a self-consistent system. Three different mechanisms are described and investigated. This study thus demonstrates how a modulatory system, affecting the biophysical properties of single cells, can be used to achieve context-dependent processing at the system level.
A Neural Network Model of Temporal Code Generation and Position-Invariant Pattern Recognition
Authors: Buonomano Dean V. , Merzenich Michael
Published: July 2002

Numerous studies have suggested that the brain may encode information in the temporal firing pattern of neurons. However, little is known regarding how information may come to be temporally encoded and about the potential computational advantages of temporal coding. Here, it is shown that local inhibition may underlie the temporal encoding of spatial images. As a result of inhibition, the response of a given cell can be significantly modulated by stimulus features outside its own receptive field. Feedforward and lateral inhibition can modulate both the firing rate and temporal features, such as latency. In this article, it is shown that a simple neural network model can use local inhibition to generate temporal codes of handwritten numbers. The temporal encoding of a spatial patterns has the interesting and computationally beneficial feature of exhibiting position invariance. This work demonstrates a manner by which the nervous system may generate temporal codes and shows that temporal encoding can be used to create position-invariant codes.
Island Landscape: Following in Humboldt's Footsteps through the Acoustic Spaces of the Tropics
Authors: Velasco Daniel
Published: July 2002

The author describes his sound-image installation Island Landscape and its inspirations: the flora and fauna of Cuba and the writings of Alexander von Humboldt. Humboldt was a forerunner of the acoustic ecology movement, which endeavors to preserve and record the natural sounds of environments. Through his vividly written descriptions of the sound landscapes of the New World, Humboldt created a lasting work that continues to inspire artists today.
Talking Drum: A Local Area Network Music Installation
Authors: Brown Chris
Published: July 2002

Talking Drum is an interactive computer network music installation designed for the diffusion of cyclically repeating rhythms produced by four electronically synchronized instruments separated by distances up to 50 feet (16 m). The reverberant character of the performance space and the distance-related time-delays between stations combine with the speed and rhythms of the music to create a complex, multifocal mix that audiences explore by moving independently through the installation. The software uses Afro-Cuban musical concepts as a model for creating an interactive drum machine. It implements a simple genetic algorithm to mediate the interaction between pre-composed and improvised rhythms.
Interactions in Perceived Quality of Auditory-Visual Displays
Authors: Storms Russell L. , Zyda Michael J.
Published: July 2002

The quality of realism in virtual environments (VEs) is typically considered to be a function of visual and audio fidelity mutually exclusive of each other. However, the VE participant, being human, is multimodal by nature. Therefore, in order to validate more accurately the levels of auditory and visual fidelity that are required in a virtual environment, a better understanding is needed of the intersensory or crossmodal effects between the auditory and visual sense modalities. To identify whether any pertinent auditory-visual cross-modal perception phenomena exist, 108 subjects participated in three experiments which were completely automated using HTML, Java, and JavaScript programming languages. Visual and auditory display quality perceptions were measured intraand intermodally by manipulating the pixel resolution of the visual display and Gaussian white noise level, and by manipulating the sampling frequency of the auditory display and Gaussian white noise level. Statistically significant results indicate that high-quality auditory displays coupled with highquality visual displays increase the quality perception of the visual displays relative to the evaluation of the visual display alone, and that low-quality auditory displays coupled with high-quality visual displays decrease the quality perception of the auditory displays relative to the evaluation of the auditory display alone. These findings strongly suggest that the quality of realism in VEs must be a function of both auditory and visual display fidelities inclusive of each other.
Cyclopean Vision, Size Estimation, and Presence in Orthostereoscopic Images
Authors: Harper Bernard , Latto Richard
Published: July 2002

Stereo scene capture and generation is an important facet of presence research in that stereoscopic images have been linked to naturalness as a component of reported presence. Three-dimensional images can be captured and presented in many ways, but it is rare that the most simple and “natural” method is used: full orthostereoscopic image capture and projection. This technique mimics as closely as possible the geometry of the human visual system and uses convergent axis stereography with the cameras separated by the human interocular distance. It simulates human viewing angles, magnification, and convergences so that the point of zero disparity in the captured scene is reproduced without disparity in the display. In a series of experiments, we have used this technique to investigate body image distortion in photographic images. Three psychophysical experiments compared size, weight, or shape estimations (perceived waist-hip ratio) in 2-D and 3-D images for the human form and real or virtual abstract shapes. In all cases, there was a relative slimming effect of binocular disparity. A well-known photographic distortion is the perspective flattening effect of telephoto lenses. A fourth psychophysical experiment using photographic portraits taken at different distances found a fattening effect with telephoto lenses and a slimming effect with wide-angle lenses. We conclude that, where possible, photographic inputs to the visual system should allow it to generate the cyclopean point of view by which we normally see the world. This is best achieved by viewing images made with full orthostereoscopic capture and display geometry. The technique can result in more-accurate estimations of object shape or size and control of ocular suppression. These are assets that have particular utility in the generation of realistic virtual environments.
Making Networked Virtual Environments Work
Authors: Greenhalgh Chris , Bullock Adrian , Frécon Emmanuel , Lloyd David , Steed Anthony
Published: July 2002

Collaborative virtual environments (CVEs) are a promising technology enabling remote participants to share a common place through three-dimensional graphical scenes. Within the COVEN project (Normand, 1999), we have run prolonged series of Internet trials that have allowed us to gather valuable data to formulate usability guidelines and networking requirements. However, running such trials in a real setting and making sure that the application and networking infrastructures will be stable enough is still a challenge. In this paper, we describe some of our experiences, together with the technical choices that have permitted many hours of successful Internet trials. We also make a thorough analysis of different correlated logging data. This analysis allows us to propose and confirm a model of a CVE application's network behavior, together with a number of interesting results that disprove some common assumptions. Furthermore, we use the model and the logging data to highlight the benefits of IP multicasting and for predicting traffic behaviors and bandwidth use on top of different logical network topologies.
Effects of Field of View on Judgments of Self-Location: Distortions in Distance Estimations Even When the Image Geometry Exactly Fits the Field of View
Authors: Psotka Joseph , Lewis Sonya A. , King Donald
Published: July 2002

This research stems from the casual observation that the image of a television screen with 18° geometric ®eld of view (FOVg) as seen on a real television with 17° real FOV appears much “nearer” than the real televisionas much as 98% closer. Does the image appear “nearer” because the distance to the real television is misjudged or is a mental model of a virtual subjective self-location created? Either way, all the projective mapping in the world, whether only in the z plane or in all x, y, and z planes, is irrelevant to explain this powerful perceptual or cognitive effect that the neglected variable of FOV has on self-location in virtual space. Accurate perception of the scene and precise self-location in virtual environments is the goal of accurate perspective geometries, scene computation, and helmet-mounted display (HMD) optics. Yet, as research has already clearly shown, accurate geometric projection is no guarantee of accurate perception: for instance, images viewed exactly at their proper projection points have repeatedly been seen at distorted distances or inaccurate directions. In addition to precise engineering, it is important to understand the psychology of selflocation, also called egocenters, to obtain an understanding of virtual space. A new theory, Cognitive Frame Theory, is proposed to deal with cognitive modi®cations of perception in a way that emphasizes the importance of self-location. Cognitive Frame Theory builds on the phenomenal geometry underlying self-location perceptions: the localization of objects in space requires a combination of perceived distance, perceived direction, and the perception of the position or motion of the self. A fundamentally novel component of the theory suggests that observers use their natural ®elds of view of 120° vertical by 180° horizontal as the primary standard for interpreting visual displays and their self-location in the space of those displays.
Learning to Solve Planning Problems Efficiently by Means of Genetic Programming
Authors: Aler Ricardo , Borrajo Daniel , Isasi Pedro
Published: July 2002

Declarative problem solving, such as planning, poses interesting challenges for Genetic Programming (GP). There have been recent attempts to apply GP to planning that fit two approaches: (a) using GP to search in plan space or (b) to evolve a planner. In this article, we propose to evolve only the heuristics to make a particular planner more efficient. This approach is more feasible than (b) because it does not have to build a planner from scratch but can take advantage of already existing planning systems. It is also more efficient than (a) because once the heuristics have been evolved, they can be used to solve a whole class of different planning problems in a planning domain, instead of running GP for every new planning problem. Empirical results show that our approach (EVOCK) is able to evolve heuristics in two planning domains (the blocks world and the logistics domain) that improve PRODIGY4.0 performance. Additionally, we experiment with a new genetic operator—Instance-Based Crossover—that is able to use traces of the base planner as raw genetic material to be injected into the evolving population.
When You Find Yourself in a Hole, Stop Digging: Comments on Earth Systems Engineering
Authors: Friedman Robert M.
Published: July 2002

In an earlier “Forum” article in this journal, Brad Allenby outlined his views of a new approach to managing the unintended consequences of human activity, “earth systems engineering.” He argues that we must develop the tools, institutions, and moral and ethical systems to allow us to “assume an active management role for most global systems.” I believe this to be a significant departure from a core concept of industrial ecology: learning from ecosystems how the natural world operates to be able to more effectively design and manage coupled human‐natural systems. Such lessons are more likely to lead away from tightly managed, centralized approaches, and favor approaches with as little intervention as feasible. More important, I believe that we are far less likely to learn how to implement earth systems engineering than simpler approaches, hence less likely to minimize environmental damage.
Sense Organs and the Activity of Sensation in Aristotle
Authors: Magee Joseph
Published: July 2002

Amid the ongoing debate over the proper interpretation of Aristotle's theory of sense perception in the De Anima, Steven Everson has recently presented a well-documented and ambitious treatment of the issue, arguing in favor of Richard Sorabji's controversial position that sense organs literally take on the qualities of their proper objects. Against the interpretation of M. F. Burnyeat, Everson and others make a compelling case the Aristotelian account of sensation requires some physical process to occur in sense organs. A detailed examination of the interpretation by Everson and Sorabji of Aristotle's theory, however, shows that their reading cannot be the correct one, since it involves many textual and philosophical difficulties. Their interpretation, for instance, would require abandoning Aristotle's requirement that only a transparent substance is suitable matter for an eye. Likewise, their understanding of the Aristotle's doctrine of sensation as the reception of form without matter in DA 2.12 cannot be reconciled with other texts of his from On Generation and Corruption. An analysis of these texts, as well as DA 2.7 and De Sensu 6 on the roles of light and the transparent medium in vision, show that, for Aristotle, the physical processes which sense organs undergo are not standard qualitative changes (i.e. alterations), but activities or the actualizations of potencies in the material constituents of living animal bodies.
BEHAVIOR AND ECOLOGY OF SPELEONECTES EPILIMNIUS (REMIPEDIA, SPELEONECTIDAE) FROM SURFACE WATER OF AN ANCHIALINE CAVE ON SAN SALVADOR ISLAND, BAHAMAS
Authors: Carpenter Jerry
Published: July 2002

Speleonectes epilimnius (described earlier in this issue), was observed at the surface of cave pools and in the laboratory. This unique cave habitat for remipedes is described. Videotapes of six live specimens shot under a microscope provided the only detailed observations to date for feeding, grooming, and resting behaviors for remipedes. During feeding, maxillae 1 and 2 held food tightly while repeatedly piercing, scratching, and rotating it; they periodically moved food to the mandibles, which rapidly chewed off tissue in typical crustacean fashion. Peristalsis moved food throughout the midgut and to diverticula of trunk segments, but not to the anal segment. Several structures were used in grooming. Antenna 1 was groomed by power strokes of anterior swimming appendages. Antenna 2 and frontal filaments groomed each other. Maxillae 1-2 and maxillipeds groomed the mouth area, posterior third of the body, and each other.
Speleonectes epilimnius (decrit precedemment dans ce fascicule), a ete observe dans une grotte a la surface des bassins d'eau souterraines et au laboratoire. Cet habitat de grotte, unique pour les remipedes est decrit. Les enregistrements videos, realises au microscope sur six specimens vivants ont fourni les seules observations detailees a ce jour sur les comportements d'alimentation, de toilettage et de repos chez les remipedes. Au cours de la prise de nourriture, les maxilles 1 et 2 maintiennent la nourriture fermement pendant qu'elle est percee, grattee, retournee; elles portent periodiquement la nourriture aux mandibules qui rapidement mastiquent les tissus d'une facon typique chez les crustaces. Des mouvements peristaltiques font avancer la nourriture a travers l'intestin moyen et vers les diverticules des segments du tronc, mais pas jusqu'au segment anal. Plusieurs structures sont utilisees pour le toilettage. L'antennule est nettoyee grace a de puissants coups des appendices natatoires anterieurs. L'antenne et les filaments frontaux se nettoient les uns les autres. Les premieres et deuxiemes maxilles et les maxillipedes nettoient la region buccale, le tiers posterieur du corps et egalement se nettoient reciproquement.
Mineralogical and geochemical characteristics of late Cretaceous bentonite deposits of the Kelkit Valley Region, northern Turkey
Authors: Yalçin H. , Gümüşer G.
Published: July 2002

Late Cretaceous bentonitic clays in the Kelkit Valley region of Turkey are composed of an alternation of limestone lenses and silicified tuff nodule-bearing pyroclastic rocks and their alteration products. Quartz, feldspar, biotite, trace amounts of augite together with pumice and volcanic rock fragments comprise the volcanogenic components. Diagenetic minerals are represented by clay, calcite, opal-CT, zeoliteand dolomite. The clay fraction is dominated by smectite and lesser amounts of I-S, illite, chlorite and kaolinite. Thed001basal spacing of dioctahedral smectites ranges from 12.51 to 12.55Å in Na-smectites and 14.97 to 15.52 A˚in Ca-smectites. The CaO/Na2O ratio of smectites ranges from 0.15 to 19.50, and the interlayer Na and Ca contents are 0.22–0.30 in beidellitesand 0.02–0.09 while those in montmorillonites are 0.01–0.13 and 0.03–0.15, respectively. The data obtained indicate that bentonites formed in a marine environment by the alteration of volcanic ash of rhyodacitic/dacitic and intermediate/acidic composition.
Formation of gibbsite in the presence of 2:1 minerals: an example from Ultisols of northeast India
Authors: Bhattacharyya T. , Pal D. K. , Srivastava P.
Published: July 2002

There are two different views regarding the genesis of gibbsite in tropical acid soils: (1) direct weathering of primary Al-silicate minerals; and (2) transformation through clay mineral intermediates. We investigated the genesis of gibbsite in two representative Ultisols from northeastern India. Gibbsite in these Ultisols appears to be the remnant of earlier weathering products of aluminosilicate minerals formed in a neutral to alkaline pedochemical environment. The mere presence of gibbsite in these soils, therefore, does not indicate their advanced stage of weathering. The formation of typically rod-shaped and well-crystallized gibbsite in both the coarse and fine soil fractions in the presence of large amounts of 2:1 minerals indicates that the anti-gibbsite hypothesis may not be tenable in these tropical acid soils. A schematic model for the formation of gibbsite and kaolin in Ultisols is proposed.
Intercalation of an amphiphilic azobenzene derivative into the interlayer space of a layered silicate, magadiite
Authors: Ogawa M. , Yamamoto M. , Kuroda K.
Published: July 2002

Intercalation of an ammonium amphiphile having an azobenzene chromophore, 4-dodecyloxy-4 ‘-(trimethylammoniopentyloxy)azobenzene and 4-(ω-trimethylammoniodecyloxy) -p’- (octyloxy)azobenzene bromide, into the layered silicate magadiite (ideal formula Na2Si14O29·nH2O) was carried out by a conventional ion exchange reaction in an aqueous medium. An intercalation compound with the ideal formula {(C12AzoC5N+)1.4H0.6·Si14O29·nH2O} was obtained. Based on the change in the basal spacing (to 4.21 nm) after the reaction and the visible absorption spectrum of the product, the intercalated azo dyes appear to form a J-aggregate in the interlayer space of magadiite. Under UV and visible light irradiation, the intercalated azo chromophore exhibited reversible transcis isomerization in the interlayer space of magadiite. This is the first successful report of photochemical reactions of guest species in the interlayer space of magadiite.
Degradation of phosphatic waste forms incorporating long-lived radioactive isotopes
Authors: Read D. , Williams C. T.
Published: July 2002

This paper provides a brief perspective on synthetic, phosphate-based waste forms for high level radioactive waste (HLW). Evidence in support of their long-term stability is then discussed by reference to the degradation of natural monazites with emphasis on the fate of released uranium, thorium and the rare earths (REE). It is apparent that the REE can be mobilized and fractionated at temperatures anticipated in a HLW repository (∼200°C). This provides an indication of the likely fate of the trivalent actinides (Am(III), Cm(III)) if incorporated in similar matrices. Thorium, though released on alteration of monazite, tends to re-concentrate locally in secondary, microcrystalline phases. In relative terms, U is readily removed from monazites. Although it can be re-concentrated in alteration products, the potential exists for substantial loss of U to groundwater. The findings of this research have important implications for the performance of radioactive waste disposal systems where there is a clear need for improved chemical data to describe the precipitation-dissolution of phosphate phases. It is concluded that monazite-like ceramics designed for the containment of HLW will retain tetravalent actinides but may release uranium in response to natural degradative processes.
Longitudinal analysis of T-cell receptor gene use by CD8+ T cells in early human immunodeficiency virus infection in patients receiving highly active antiretroviral therapy
Authors: Schito Anna M. , Vittinghoff Eric , Hecht Frederick M. , Elkins Mary K. , Kahn James O. , Levy Jay A. , Oksenberg Jorge R.
Published: July 2002

The effects of early antiretroviral therapy on the peripheral CD8+ T-cell population were assessed by sequentially determining the T-cell receptor (TCR) repertoire complexity in a cohort of 15 individuals recently diagnosed with human immunodeficiency virus infection. Analysis was based on quantitative TCR variable B gene (TCRBV) usage and complementary-determining region 3 length assessment. Repertories were assessed at baseline and at weeks 2, 4, 12, 24, and 72 after initiation of therapy. Early administration of highly active antiretroviral therapy has a positive effect on the preservation and homeostasis of the CD8+ cell repertoire. Nevertheless, differences from average baseline and control TCR profiles and initial development of repertoire perturbations were observed. The findings suggest that additional therapeutic protocols will be required during primary infection to significantly prevent long-term erosion of the T-cell–mediated immune response.
Efficient retrovirus-mediated PIG-A gene transfer and stable restoration of GPI-anchored protein expression in cells with the PNH phenotype
Authors: Nishimura Jun-ichi , Phillips Ken L. , Ware Russell E. , Hall Sharon , Wilson Lee , Gentry Tracy L. , Howard Thad A. , Murakami Yoshiko , Shibano Masaru , Machii Takashi , Gilboa Eli , Kanakura Yuzuru , Takeda Junji , Kinoshita Taroh , Rosse Wendell F. , Smith Clay A.
Published: July 2002

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal hematopoietic stem cell disorder characterized by complement-mediated hemolysis due to deficiencies of glycosylphosphatidylinositol-anchored proteins (GPI-APs) in subpopulations of blood cells. Acquired mutations in the X-linked phosphatidylinositol glycan–class A (PIG-A) gene appear to be the characteristic and pathogenetic cause of PNH. To develop a gene therapy approach for PNH, a retroviral vector construct, termed MPIN, was made containing the PIG-A complementary DNA along with an internal ribosome entry site and the nerve growth factor receptor (NGFR) as a selectable marker. MPIN transduction led to efficient and stable PIG-A and NGFR gene expression in a PIG-A–deficient B-cell line (JY5), a PIG-A–deficient K562 cell line, an Epstein-Barr virus–transformed B-cell line (TK-14−) established from a patient with PNH, as well as peripheral blood (PB) mononuclear cells from a patient with PNH. PIG-A expression in these cell lines stably restored GPI-AP expression. MPIN was transduced into bone marrow mononuclear cells from a patient with PNH, and myeloid/erythroid colonies and erythroid cells were derived. These transduced erythroid cells restored surface expression of GPI-APs and resistance to hemolysis. These results indicate that MPIN is capable of efficient and stable functional restoration of GPI-APs in a variety of PIG-A–deficient hematopoietic cell types. Furthermore, MPIN also transduced into PB CD34+ cells from a normal donor, indicating that MPIN can transduce primitive human progenitors. These findings set the stage for determining whether MPIN can restore PIG-A function in multipotential stem cells, thereby providing a potential new therapeutic option in PNH.
Targeting of the CD33-calicheamicin immunoconjugate Mylotarg (CMA-676) in acute myeloid leukemia: in vivo and in vitro saturation and internalization by leukemic and normal myeloid cells
Authors: van der Velden Vincent H. J. , te Marvelde Jeroen G. , Hoogeveen Patricia G. , Bernstein Irwin D. , Houtsmuller Adriaan B. , Berger Mark S. , van Dongen Jacques J. M.
Published: July 2002

Antibody-targeted chemotherapy is a promising therapy in patients with acute myeloid leukemia (AML). In a phase II study of Mylotarg (CMA-676, gemtuzumab ozogamicin), which consists of a CD33 antibody linked to calicheamicin, saturation and internalization by leukemic and normal myeloid cells were analyzed in 122 patients with relapsed AML. Peripheral blood samples were obtained just before and 3 and 6 hours after the start of the first and second Mylotarg treatment cycles. Within 3 to 6 hours after infusion, near complete saturation of CD33 antigenic sites by Mylotarg was reached for AML blasts, monocytes, and granulocytes, whereas Mylotarg did not bind to lymphocytes. Saturation levels prior to the start of the second Mylotarg treatment cycle were significantly increased compared with background levels before the start of the first cycle. This apparently was caused by remaining circulating Mylotarg from the first treatment cycle (∼2 weeks earlier). On binding of Mylotarg to the CD33 antigen, Mylotarg was rapidly internalized, as determined by the decrease in maximal surface membrane Mylotarg binding. Internalization of Mylotarg was also demonstrated in myeloid cells in vitro and was confirmed by confocal laser microscopy. In vitro studies using pulse labeling with Mylotarg showed a continuous renewed membrane expression of CD33 antigens, which can significantly increase the internalization process and thereby the intracellular accumulation of the drug. Finally, Mylotarg induced dose-dependent apoptosis in myeloid cells in vitro. These data indicate that Mylotarg is rapidly and specifically targeted to CD33+ cells, followed by internalization and subsequent induction of cell death.