bluuebunny/crossref_metadata_2025 huggingface dataset:
Why cooperate? Social projection as a cognitive mechanism that helps us do good
Authors: Krueger Joachim I. , Acevedo Melissa
Published: April 2003

The mother sacrificing herself while rescuing someone else's child is a red herring. Neither behaviorism nor cognitivism can explain it. Unlike behaviorism, however, the cognitive process of projection can explain cooperation in one-shot social dilemmas.
Teleological behaviorism and altruism
Authors: Lacey Hugh
Published: April 2003

Rachlin shows that experiments about social cooperation may fruitfully be grouped with experiments on self-control, and that this suggests interesting possibilities for practical behavioral controls. The concepts of selfishness and altruism, however, that inform his theorizing about these experiments, do not serve to provide understanding of the behavior that commonly is referred to, derogatorily, as selfish.
Mental imagery is simultaneously symbolic and analog
Authors: Pani John R.
Published: April 2003

With admirable clarity, Pylyshyn shows that there is little evidence that mental imagery is strongly constrained to be analog. He urges that imagery must be considered part of a more general symbolic system. The ultimate solution to the challenges of image theory, however, rest on understanding the manner in which mental imagery is both a symbolic and an analog system.
The false dichotomy of imagery
Authors: Thomas Nigel J. T.
Published: April 2003

Pylyshyn's critique is powerful. Pictorial theories of imagery fail. On the other hand, the symbolic description theory he manifestly still favors also fails, lacking the semantic foundation necessary to ground imagery's intentionality and consciousness. However, contrary to popular belief, these two theory types do not exhaust available options. Recent work on embodied, active perception supports the alternative perceptual activity theory of imagery.
Dissolving the elusiveness of altruism
Authors: van der Steen Wim J.
Published: April 2003

Rachlin provides an impressive integrative view of altruism and selfishness that helps us correct older views. He presents a highly general theory, even though he is aware of context-dependence of key notions, including altruism. The context-dependence should extend much farther than Rachlin allows it to go. We had better replace theoretical notions of altruism and selfishness by common sense.
Valuable reputation gained by altruistic behavioral patterns
Authors: Wedekind Claus
Published: April 2003

On a proximate level, altruism may well be a temporally extended pattern of behavior that often seems to be maintained without extrinsic rewards (we may find it just valuable to be an altruistic person). However, recent theory and experiments have uncovered significant and often nonobvious extrinsic rewards for “altruistic” behavioral patterns. Ultimately, these patterns may mostly lead to a net benefit.
Generic assumptions shared by visual perception and imagery
Authors: Zaidi Qasim , Griffiths A. Fuzz
Published: April 2003

What is difficult to imagine is also surprising to perceive. This indicates that active visual imagery is an integral part of active visual perception. Erroneous mental transformations provide clues to prior assumptions in visual imagery, just as visual illusions provide clues to perceptual assumptions. Visual imagery and perception share generic assumptions about invariants in images of rigid objects.
Altruism, evolutionary psychology, and learning
Authors: Wilson David Sloan , Miller Ralph R.
Published: April 2003

Rachlin's substantive points about the relationship between altruism and self-control are obscured by simplistic and outdated portrayals of evolutionary psychology in relation to learning theory.
SOME FEASIBLE ALTERNATIVES TO CONVENTIONAL CAPITALISM
Authors: Barry Norman
Published: April 2003

The collapse of Communism and the retreat from, in theory as
well as practice, even moderate forms of collectivism have left
even the non-Marxist forms of socialism in disarray. While it
is true that forms of collectivism have remarketed themselves
under meretricious, insubstantial doctrinal headings such as
the “Third Way,” an unstable amalgam of capitalism,
communitarianism, and welfarism, there has been little original
work on how an economy and society might organize itself so as to
have neither the superficially objectionable features of modern
capitalism nor the economically untenable and morally odious properties
of full-blooded socialism. The former might include vast inequality
in resource ownership, the unequal political power such inequality
might generate, the increasing alienation produced by the soulless
possessive individualism that is allegedly engulfing the world,
and a myriad of other complaints that are regularly leveled
at capitalism.
Multimodal embodied agents
Authors: PELACHAUD CATHERINE , POGGI ISABELLA
Published: April 2003

1 Believable interactive embodied agents

Among the goals of research on autonomous agents one important aim is to build believable interactive embodied agents that are apt to application to friendly interfaces in e-commerce, tourist and service query systems, entertainment (e.g. synthetic actors) and education (pedagogical agents, agents for help and instruction to the hearing impaired).
NECESSARY AND SUFFICIENT CONDITIONS FOR THE STOCHASTIC
COMPARISON OF JACKSON NETWORKS
Authors: Economou Antonis
Published: April 2003

External and internal monotonicity properties for Jackson networks
have been established in the literature with the use of coupling
constructions. Recently, Lopez et al. derived necessary and
sufficient conditions for the (strong) stochastic comparison
of two-station Jackson networks with increasing service rates,
by constructing a certain Markovian coupling. In this article,
we state necessary and sufficient conditions for the stochastic
comparison of L-station Jackson networks in the general
case. The proof is based on a certain characterization of the
stochastic order for continuous-time Markov chains, written
in terms of their associated intensity matrices.
CONVERGENCE OF SIMULATION-BASED POLICY ITERATION
Authors: Cooper William L. , Henderson Shane G. , Lewis Mark E.
Published: April 2003

Simulation-based policy iteration (SBPI) is a modification
of the policy iteration algorithm for computing optimal policies
for Markov decision processes. At each iteration, rather than
solving the average evaluation equations, SBPI employs simulation
to estimate a solution to these equations. For recurrent
average-reward Markov decision processes with finite state and
action spaces, we provide easily verifiable conditions that
ensure that simulation-based policy iteration almost-surely
eventually never leaves the set of optimal decision rules. We
analyze three simulation estimators for solutions to the average
evaluation equations. Using our general results, we derive simple
conditions on the simulation run lengths that guarantee the
almost-sure convergence of the algorithm.
Interactive constraint-aided conceptual design
Authors: O'SULLIVAN BARRY
Published: April 2003

Engineering conceptual design can be defined as that phase
of the product development process during which the designer
takes a specification for a product to be designed and generates
many broad solutions to it. This paper presents a constraint-based
approach to supporting interactive conceptual design. The approach
is based on an expressive and general technique for modeling:
the design knowledge that a designer can exploit during a design
project; the life-cycle environment that the final product faces;
the design specification that defines the set of requirements
the product must satisfy; and the structure of the various schemes
that are developed by the designer. A computational reasoning
environment based on constraint filtering is proposed as the
basis of an interactive design support tool. Using such a tool,
human designers can be assisted in interactively developing
and evaluating a set of schemes that satisfy the various
constraints imposed on the design.
Center-surround organization in bipolar cells: Symmetry for
opposing contrasts
Authors: FAHEY PATRICK K. , BURKHARDT DWIGHT A.
Published: April 2003

Intracellular recordings were obtained from 73 cone-driven bipolar
cells in the light-adapted retina of the tiger salamander
(Ambystoma tigrinum). Responses to flashes of negative and
positive contrast for centered spots and concentric annuli of optimum
spatial dimensions were analyzed as a function of contrast magnitude.
For both depolarizing and hyperpolarizing bipolar cells, it was found
that remarkably similar responses were observed for the center and
surround when comparisons were made between responses of the same
response polarity and thus, responses to opposite contrast polarity.
Thus, spatial information and contrast polarity appear to be rather
strongly confounded in many bipolar cells. As a rule, the form of the
contrast/response curves for center and surround approximated
mirror images of each other. Contrast gain and C50
(the contrast required for half-maximal response) were quantitatively
similar for center and surround when comparisons were made for
responses of the same response polarity. The average contrast gain of
the bipolar cell surround was 3–5 times higher than that measured
for horizontal cells. Contrast/latency measurements and
interactions between flashed spots and annuli showed that the surround
response is delayed by 20–80 ms with respect to that of the
receptive-field center. Cones showed no evidence for center-surround
antagonism while for bipolar cells, the average strength of the
surround ranged from about 50% to 155% of the center, depending on the
test and response polarity. The results of experiments on the effects
of APB (100 μM) on depolarizing bipolar cells suggest that the
relative contribution of the feedback pathway (horizontal cell to
cones) and the feedforward pathway (horizontal cell to bipolar cell) to
the bipolar surround varies in a distributed manner across the bipolar
cell population.
Nonlocal origin of response suppression from stimulation outside
the classic receptive field in area 17 of the cat
Authors: BROWN H.A. , ALLISON J.D. , SAMONDS J.M. , BONDS A.B.
Published: April 2003

A stimulus located outside the classic receptive field (CRF) of a
striate cortical neuron can markedly influence its behavior. To study
this phenomenon, we recorded from two cortical sites, recorded and
peripheral, with separate electrodes in cats anesthetized with Propofol
and nitrous oxide. The receptive fields of each site were discrete
(2–7.3 deg between centers). A control orientation tuning (OT)
curve was measured for a single recorded cell with a drifting grating.
The OT curve was then remeasured while stimulating simultaneously the
cell's CRF as well as the peripheral site with a stimulus
optimized for that location. For 22/60 cells, the peripheral
stimulus suppressed the peak response and/or shifted the center of
mass of the OT curve. For 19 of these 22 cells, we then reversibly
blocked stimulus-driven activity at the peripheral site by
iontophoretic application of GABA (0.5 M). For 6/19 cells, the
response returned to control levels, implying that for these cells the
inhibitory influence arose from the blocked site. The responses of nine
cells remained reduced during inactivation of the peripheral site,
suggesting that influence was generated outside the region of local
block in area 17. This is consistent with earlier findings suggesting
that modulatory influences can originate from higher cortical areas.
Three cells had mixed results, suggesting multiple origins of
influence. The response of each cell returned to suppressed levels
after dissipation of the GABA and returned to baseline values when the
peripheral stimulus was removed. These findings support a cortical
model in which a cell's response is modulated by an inhibitory
network originating from beyond the receptive field that supplants
convergence of excitatory lateral geniculate neurons.
CERAMIC PRODUCTION IN SAN MARCOS ACTEOPAN, PUEBLA, MEXICO
Authors: Druc Isabelle C.
Published: April 2003

This article presents a study of ceramic production
in San Marcos Acteopan, a small village in the southern
part of the state of Puebla, Mexico. Field observation
and interviews with the families of two potters document
the different steps of the ceramic production process.
The approach is ethnographic and aims at better understanding
ancient ceramic production. Special emphasis is given to
raw material acquisition and paste preparation to provide
comparative data for analysis of archaeological material
and clay preparation strategies. This study adopts the
perspective of ceramic ecology, which situates the information
on ceramic production in environmental and socioeconomic
contexts.
CACAO AND CHOCOLATE
Authors: Dakin Karen , Wichmann Søren
Published: April 2003

The origin of the words $lsquo;cacao$rsquo; and
$lsquo;chocolate$rsquo; and their use in the reconstruction
of the early history of Mesoamerica, remain very controversial
issues. Cambell and Kaufman (1976, American Antiquity
41:80–89), for example, proposed that the word $lsquo;cacao$rsquo;
originated from Mixe–Zoque languages, thus possibly
representing Olmec traditions. According to this argument,
other Mesoamerican languages, including Nahuatl, borrowed
the word as a symbol of prestige and Olmec influence. Other
researchers claim the word $lsquo;chocolate$rsquo; represents
a more recent neologism, a possible Maya–Nahuatl
hybrid, due to the late appearance of the word in central
Mexico's Colonial sources. We refute the putative
Mixe–Zoque origin of $lsquo;cacao$rsquo; and provide
linguistic evidence to propose that $lsquo;cacao,$rsquo;
like $lsquo;chocolate,$rsquo; is a Uto-Aztecan term. Analysis
of these words highlights general and particular evolutionary
trends that originate from the Uto-Aztecan language family.
In addition, we show that these two words were initially
used as descriptive terms to refer to the shape of the
plant's bean and the techniques of drink preparation.
Etymological evidence verifies the use of a Mayan term
for cacao as early as the Classic period (fourth century
a.d.). This early appearance of the term in Mayan
and the later diffusion of the Nahua word throughout all
of Mesoamerica correlate with additional data to support
the conclusion that Teotihuacanos spoke Nahuatl.
INTRODUCTION
Authors: Fowler William R.
Published: April 2003

In this issue we present the second part of the special
section on recent research on Late Aztec Otumba, Tepeapulco,
and Teotihuacan by Thomas H. Charlton, Deborah L. Nichols, Cynthia
L. Otis Charlton, and their colleagues. The background to this
research was discussed by those authors in our previous issue
(Charlton, Nichols, and Otis Charlton 2000), and, as I pointed
out in the introduction to the first part (Fowler 2000), a distinct
advantage provided by the Otumba research is that the data
generated allow us to assess general models proposed for the
origin and development of city-states in the Basin of Mexico
during the last few centuries before the Spanish Conquest. To
summarize briefly, two general models have been proposed—one
emphasizing economic symbiosis and craft specialization and
the other focusing on regional political competition among elites.
The Otumba data and analyses allow us to perceive and explore
further valid aspects of both models.
LOS CAMINOS DE CALAKMUL, CAMPECHE
Authors: Folan William J. , Hau Jacinto May , Marcus Joyce , Miller W. Frank , Heredia y Raymundo González
Published: April 2003

Las ruinas de Calakmul se encuentran en la cuenca del mismo
nombre localizado dentro del 723,000 ha Reserva de la Biosfera
Calakmul en el sureste del Estado de Campeche. Investigaciones
del Centro de Investigaciones Históricas y Sociales de
la Universidad Autónoma de Campeche han demostrado que
Calakmul formaba una de las más grandes centros regionales
en el área maya desde 600 a.C. hasta los fines del siglo
IX dentro de su estado regional de 13,000 km2.
Investigaciones de prospección remoto alrededor de Calakmul
combinado con trabajos topográficos dentro de la ciudad
misma han revelado 15 sac beob identificados por nosotros
entre los tipos de vías terrestres descritos en los diccionarios
de la idioma Maya formados durante el período colonial. Entre
estos sac beob se encuentran tipos regionales, estatales
y los sac beob registrados dentro de la ciudad de
Calakmul. Aunque existe un traslapo entre varios tipos de sac
beob, pensamos que excavaciones futuras van a ayudarnos
a clasificar cada sac be en una forma más precisa.
FLOOD REPTILES, SERPENT TEMPLES, AND THE QUADRIPARTITE
UNIVERSE
Authors: Pugh Timothy W.
Published: April 2003

Mayapan, Yucatan, Mexico, was the most prominent Maya ceremonial
center from the mid-thirteenth to the mid-fifteenth century.
The city was a religious center for surrounding Maya populations.
Its construction was linked through cyclical reasoning to a
chain of antecedent centers, the ultimate link of which lay
in creation. In the heart of Mayapan lay its exemplary center,
an architectural model of cosmogony composed of five temple
assemblages. The central building of each assemblage was a temple
decorated with serpent imagery. These five serpent temples were
depicted on a mural in Structure Q-80 at Mayapan, with additional
symbolism suggesting that each building was tied to a specific
elite official, likely the Ajaw B'atab'ob,
Jalach Winik, and AjK'in as described
in ethnohistoric documents. The serpent temples also depict
the primordial flood crocodilian, who was both the world and
the world destroyer—hence, a symbol of both order and
chaos.
CLIMATIC AND ENVIRONMENTAL VARIABILITY IN THE RISE OF MAYA
CIVILIZATION: A preliminary perspective from northern Peten
Authors: Hansen Richard D. , Bozarth Steven , Jacob John , Wahl David , Schreiner Thomas
Published: April 2003

Archaeological and ecological investigations in the Mirador
Basin of northern Guatemala have recovered archaeological,
phytolith, palynological, and pedological data relevant to the
early occupation and development of Maya civilization in a specific
environmental matrix. Fluctuation in vegetation types as evident
in cores and archaeological profiles suggest that the seasonally
wet, forested bajo environment currently found in the
northern Peten was anciently more of a perennially wet marsh
system that may have been heavily used and influenced by large
Preclassic occupations. Data suggest that climatic and
environmental factors correspond with the cultural process in
the Mirador Basin, and research in progress is oriented to further
elucidating these issues.
BAJO SEDIMENTS AND THE HYDRAULIC SYSTEM OF CALAKMUL, CAMPECHE,
MEXICO
Authors: Gunn Joel D. , Foss John E. , Folan William J. , Carrasco Maria del Rosario Domínguez , Faust Betty B.
Published: April 2003

Maya Lowlands climate researchers have set aside earlier beliefs
that Maya civilization flourished in an unchanging environment.
Analyses of river discharge, weather patterns, lake-bottom
sediments, and settlement patterns reveal a highly variable
climate, considerable diversity in local geology and soils,
and a wide range of cultural adaptations tailored to distinctive
subregional settings. Significant knowledge gaps remain. Among
the unanswered questions is how cities in the elevated interior
were maintained without natural, permanent bodies of water even
during equitable climatic conditions, much less through the
episodes of severe drought that have become apparent in studies
of past climates. The research reported in this article lays
the groundwork for climate studies in the southwestern Yucatan
Peninsula.
HORSE POWER
Authors: Batten David C.
Published: April 2003

Lack of draft animals is often considered to have been
an impediment to urban growth in Mesoamerica. Transport,
however, was only one of several factors that influenced
the growth of cities. This paper contrasts the effects
of energetic efficiency differences between horses and
human porters with productivity differences between European
and Mesoamerican agricultural systems. Depending on strength
and nutritional requirements, horses may be from one to
five times as efficient as human porters. Furthermore,
horses compete with humans for food. Where the horse played
a major transport role, one-third of available, arable
land was devoted to oat production. With this in mind,
I compare maize versus wheat productivity to show that
a unit of land in Mesoamerica could support up to twice
as many people as the same unit of land in Europe. Thus,
the transport advantage enjoyed by European cities is essentially
offset by a more intensive agricultural system in Mesoamerica.
POSTCLASSIC MAYA RITUAL AT LAGUNA DE ON ISLAND, BELIZE
Authors: Masson Marilyn Andrews
Published: April 2003

Ritual contexts at Laguna de On Island are identified
in two structures that form part of a single household
cluster in the central area of the site. The features and
artifact assemblages of these structures indicate that
a continuum of domestic-to-ritual debris is found at each
location. Variation in the content of these assemblages
is used to identify the degree of ritual activity and the
function of each structure. Structure I is identified as
a dwelling where ritual activity was conducted. Structure
II is identified as a specialized household shrine or oratory.
This examination of the contexts for ritual practice at
Laguna de On addresses the issue of “secularization”
of Postclassic Maya religion and the connection between
status and ritual at a small, rural, Postclassic community.
THE “COATLICUES” AT THE TEMPLO MAYOR
Authors: Boone Elizabeth H.
Published: April 2003

The colossal “Coatlicue” sculpture
has usually been interpreted as a representation of the
female supernatural Coatlicue (Serpents Her Skirt) who
gave birth to the Mexica patron deity Huitzilopochtli,
or it has been identified as the cult figure of Cihuacoatl
(Woman Serpent) or Tlaltecuhtli (Earth Lord). This paper
offers an alternative reading of the monumental statue,
one that recognizes the existence of at least three nearly
identical “Coatlicues” and thus recontextualizes
the monument as one of a larger set. The iconography of
these great stone females points to their identity as Tzitzimime,
celestial demons who were understood to descend to devour
humankind if the sun were to fail. According to the Mexican
chroniclers, a cadre of these fearsome monoliths dominated
the sculpture progam of the Templo Mayor.
Theoretically derived CVLT subtypes in HIV-1 infection: Internal
and external validation
Authors: MURJI SHEMIRA , ROURKE SEAN B. , DONDERS JACOBUS , CARTER SHERRI L. , SHORE DOUGLAS , ROURKE BYRON P.
Published: April 2003

The present study sought to delineate empirically derived memory
subtypes using the California Verbal Learning Test (CVLT; Delis
et al., 1987) in a sample of adults with HIV-1 infection
(N = 154). Confirmatory factor analysis was used to
evaluate eight models of the CVLT structure suggested by Wiegner
and Donders (1999). A four-factor model, consisting of Attention
Span, Learning Efficiency, Delayed Recall, and Inaccurate Recall
appeared to be the best fitting model. Variables with the highest
factor loadings from the model were entered in a two-stage cluster
analysis. Four reliable CVLT clusters or subtypes were identified:
Normal, Atypical, Subsyndromal, and Frontal-striatal. Internal
and external validation of subtypes demonstrated that clusters
were stable and clinically interpretable. Subtypes were
meaningfully related to neuropsychological functioning, and
to some extent, depressive symptomatology. Subtypes did not
differ significantly with respect to subjective neurocognitive
complaints and markers of HIV-1 disease. The present findings
highlight the heterogeneity of memory profiles in HIV-1 infection
and support a frontal-striatal conceptualization of verbal memory
performance. The identification of robust HIV-1 memory subtypes
may have important implications for the clinical management
of adults infected with HIV-1 infection. (JINS, 2003,
9, 1–16.)
Ecological validity of a simplified version of the multiple
errands shopping test
Authors: ALDERMAN NICK , BURGESS PAUL W. , KNIGHT CAROLINE , HENMAN COLLETTE
Published: April 2003

Shallice and Burgess (1991) reported the utility of the Multiple
Errands Test (MET) in discriminating executive deficits in three
frontal lobe patients with preserved high IQ, who were otherwise
unimpaired on tests of executive function. The aim of this study
was to ascertain the value of a simplified version of the MET
(MET–SV) for use with the range of people more routinely
encountered in clinical practice. Main findings were as follows:
1) The test discriminated well between neurological patients
and controls, and the group effects remained when the difference
in current general cognitive functions (WAIS–R FSIQ) was
taken into account. 2) The best predictors of performance in
the healthy control group (n = 46) were age and the
number of times participants asked for help (with more requests
associated with poorer performance). 3) In the neurological
group, two clear patterns of failure emerged, with performance
either characterized by rule breaking or failure to achieve
tasks. These two patterns were associated with different
dysexecutive symptoms in everyday life. 4) The patients not
only made more errors than controls, but also different ones.
A scoring method that took this into account markedly increased
test sensitivity. 5) Many patients passed traditional tests
of executive frontal lobe function but still failed the
MET–SV. This pattern was strongly associated with observed
dysexecutive symptoms in everyday life. The results demonstrate
the clinical utility of the test, and suggest that there are
two common and independent sources of failure on multitasking
tests in a general neurological population: memory dysfunction,
and initiation problems. (JINS, 2003, 9,
31–44.)
Clinical validity of the Chinese version of Mattis Dementia
Rating Scale in differentiating dementia of Alzheimer's
type in Hong Kong
Authors: CHAN AGNES S. , CHOI ANGEL , CHIU HELEN , LAM LINDA
Published: April 2003

The present study aimed to examine the clinical validity and
applicability of the Chinese version of Mattis Dementia Rating
Scale (CDRS) for elderly Chinese individuals. The scale was
found to have good reliability with internal consistency ranging
from 0.7 to 0.9. Its significant correlation with the Chinese
version of Mini-Mental State Examination (CMMSE) suggested
satisfactory construct validity of the scale. The discriminant
validity of the CDRS in differentiating Alzheimer's disease
(AD) patients and Normal Control (NC) elderly was also supported
by the Receiver Operating Characteristics (ROC) analysis. Several
cut-off points were presented for different clinical or research
applications, and formulas to adjust for the age and educational
level of the CDRS total score were provided. The
Initiation/Perseveration and Memory subscales were suggested
to be an abbreviated version of the CDRS for a quick screening.
The present results also showed the association between the
impairment of the CDRS performance and the progress of the AD.
(JINS, 2003, 9, 45–55.)
Computerized reaction time battery versus a traditional
neuropsychological battery: Detecting HIV-related impairments
Authors: GONZALEZ RAUL , HEATON ROBERT K. , MOORE DAVID J. , LETENDRE SCOTT , ELLIS RONALD J. , WOLFSON TANYA , MARCOTTE THOMAS , CHERNER MARIANA , RIPPETH JULIE , GRANT IGOR , THE HNRC GROUP
Published: April 2003

In recent years, interest in the use of computerized
neuropsychological (NP) assessment measures has increased. However,
there are limited data regarding how performance on these measures
relates to performance on more traditional, clinical instruments.
In the present study, 82 HIV+ men, who were all believed on
clinical grounds to have neurobehavioral impairment, completed
a traditional NP battery (TNB) and the California Computerized
Assessment Package (CalCAP, a collection of computerized reaction
time tests). Summary scores based on a TNB, as well as those
based on the CalCAP, demonstrated significant associations with
both degree of immunosuppression (CD4 count) and detectable
viral load in cerebrospinal fluid, but not with detectable viral
load in plasma. Established norms on the TNB and CalCAP batteries
resulted in classifying 57% and 49% of the HIV+ sample as impaired,
respectively. When using the TNB as the “gold
standard,” impairment classifications based on CalCAP
summary scores exhibited a sensitivity of 68% and a specificity
of 77%. Overall agreement on impairment classifications between
batteries was low (kappa = .44). Data from this study suggest
that traditional NP batteries and computerized reaction time
tests do not measure the same thing, and are not interchangeable
in examining HIV-related NP impairments. (JINS, 2003,
9, 64–71.)
STATISTICAL LEARNING WITH TIME-VARYING PARAMETERS
Authors: McGough Bruce
Published: April 2003

In their landmark paper, Bray and Savin note that the constant-parameters model used by their agents to form expectations is misspecified and that, using standard econometric techniques, agents may be able to determine the time-varying nature of the model's parameters. Here, we consider the same type of model as employed by Bray and Savin except that our agents form expectations using a perceived model with parameters that vary with time. We assume agents use the Kalman filter to form estimates of these time-varying parameters. We find that, under certain restrictions on the structure of the stochastic process and on the value of the stability parameter, the model will converge to its rational expectations equilibrium. Further, the restrictions on the stability parameter required for convergence are identical to those found by Bray and Savin.
SUNSPOTS, ANIMAL SPIRITS, AND ECONOMIC FLUCTUATIONS
Authors: Chauvet Marcelle , Guo Jang-Ting
Published: April 2003

Multiple-equilibria macroeconomic models suggest that consumers' and investors' perceptions about the state of the economy may be important independent factors for business cycles. In this paper, we verify empirically the interrelations between waves of optimism and pessimism and subsequent economic fluctuations. We focus on the behavior of nonfundamental movements in the consumer sentiment index, as a proxy for consumers' sunspots, and in the business formation index, representing investors' animal spirits, around economic turning points. We find that bearish consumers and entrepreneurs were present before the onset of some U.S. economic downturns, sometimes even when the fundamentals were all very strong. In particular, our analysis shows that self-fulfilling pessimism may have played a nontrivial role in the 1969–1970, the 1973–1975, and the 1981–1982 recessions. The results are robust to a range of alternative linear and nonlinear specifications. Our evidence provides some empirical support for the role of nonfundamental rational expectations in economic fluctuations.
Social Capital and Civic Commitment: On Putnam's Way of Understanding
Authors: Evers Adalbert
Published: April 2003

The paper addresses two dimensions of the debate on social capital – the analytical concept of Robert Putnam and the way it may become interrelated with political concerns debated in public. It is argued that in Putnams' concept two dimensions of social capital – social bonds and civic commitment – are interrelated in a way that suggests that social capital is something like the basis for good policy making. Against this, the open interrelationship between the two is stressed: one does not only need ‘social capital to make democracy work’ (Putnam) but often more democratic politics in order to make social capital work.
On being a Welfare Consumer in a Consumer Society
Authors: Baldock John
Published: April 2003

This article focuses on two aspects of the real or imagined conflict between welfarism and consumerism; whether the experience of being a welfare user is somehow changed by living in a society in which people may see themselves less as workers and more as consumers; and whether the providers of welfare services and benefits can or should treat their users more like consumers than beneficiaries or even citizens with welfare rights.
Life annuities of compulsory savings and income adequacy of the elderly in Singapore
Authors: CHIA NGEE CHOON , TSUI ALBERT K. C.
Published: April 2003

Singapore has a publicly managed central provident fund (CPF) system, which is compulsory and based on individual accounts with an explicit link between contribution and benefits. This paper assesses the adequacy of the CPF saving to meet the retirement needs of the elderly in Singapore. Instead of emphasizing the mechanism of accumulation, we focus on the expenditure side of the lifetime budget of the elderly and estimate the present value of retirement consumption (PVRC). The estimated PVRC is obtained by simulations through three major components: calibration of subsistence and medical expenses of the elderly; forecast of cohort survival probability by age and by sex; and generation of yield curves to discount the future cash flows. Our results indicate that the existing CPF-decreed minimum sum is inadequate to meet the future consumption needs of the female elderly. The inadequacy becomes more severe when medical expense is set at higher growth rates. Moreover, the monthly payouts of a single premium deferred annuity are computed as illustrative examples.
Rapid Method for Measuring ScFv Thermal Stability by Yeast Surface Display
Authors: Orr Brent A. , Carr Lori M. , Wittrup K. Dane , Roy Edward J. , Kranz David M.
Published: April 2003

We have characterized a simplified method to determine the relative thermal stability of single‐chain antibodies by following the irreversible denaturation of scFv fusions on the surface of yeast by flow cytometry. The method was highly reproducible and correlated well with other methods used to monitor thermal denaturation of the soluble proteins. We found a range of thermal stabilities for wild‐type single‐chain antibodies with half‐maximum denaturation temperatures between 43 and 61 °C. The ability to quantitate thermal stability of antibodies or other proteins that are immobilized on the surface of yeast allows rapid comparisons of primary structural information with stability. Thermal denaturation could be a useful parameter to consider in the choice of scFv fragments for various applications.
Protein Separations Using Colloidal Magnetic Nanoparticles
Authors: Bucak Seyda , Jones Deverraux A. , Laibinis Paul E. , Hatton T. Alan
Published: April 2003

Phospholipid‐coated colloidal magnetic nanoparticles with mean magnetite core size of 8 nm are shown to be effective ion exchange media for the recovery and separation of proteins from protein mixtures. These particles have high adsorptive capacities (up to 1200 mg protein/mL adsorbent, an order of magnitude larger than the best commercially available adsorbents) and exhibit none of the diffusional resistances offered by conventional porous ion exchange media. Protein‐laden particles are readily recovered from the feed solution using high‐gradient magnetic filtration.
Recovery of Acinetobacter radioresistens Lipase by Hydrophobic Adsorption to n‐Hexadecane Coated on Nonwoven Fabric
Authors: Wang Hui‐Min , Wu Jau‐Yann , Chen Chuh‐Yung , Chen Teh‐Liang
Published: April 2003

A simple and clean adsorption/desorption process was proposed for recovering Acinetobacter radio resisten s lipase from fermentation broth. The adsorbent used was n‐hexadecane coated on a hydrophobic nonwoven fabric (NWF). n‐Hexadecane has a melting point of 16–18 °C, and its affinity for lipase decreases markedly from liquid to solid state. Accordingly, performing the adsorption and desorption above and below, respectively, the melting point would need no extraneous materials for separation. The adsorption isotherms at various temperatures were found to follow the Langmuir model. Simulation of the batch adsorption/desorption process showed that there exists an optimal amount of adsorbent for both concentration factor and enzyme recovery; the process is restrained by equilibrium. The performance of column adsorption/desorption could also be simulated using the adsorption isotherm, and it was shown that the concentration factor was proportional to the amount of adsorbent used. The benefits of this process include easy preparation of adsorbent, low operational cost, no extraneous materials needed, negligible enzyme denaturation, high efficiency, and simple process simulation.
Improved Catalytic Performance of Bacillusmegaterium Epoxide Hydrolase in a Medium Containing Tween‐80
Authors: Gong Peng‐Fei , Xu Jian‐He , Tang Yan‐Fa , Wu Hui‐Yuan
Published: April 2003

A new epoxide hydrolase with high enantioselectivity toward ( R)‐glycidyl phenyl ether ( R‐GPE) was partially purified from Bacillus megaterium strain ECU1001. The maximum activity of the isolated enzyme was observed at 30 °C and pH 6.5 in a buffer system with 5% (v/v) of DMSO as a cosolvent. The enzyme was quite stable at pH 7.5 and retained full activity after incubation at 40 °C for 6 h. Interestingly, when the cosolvent DMSO was replaced by an emulsifier (Tween‐80, 0.5% w/v) as an alternative additive to help disperse the water‐insoluble substrate, the apparent activity of the epoxide hydrolase significantly increased by about 1.8‐fold, while the temperature optimum shifted from 30 to 40 °C and the half‐life of the enzyme at 50 °C increased by 2.5 times. The enzymatic hydrolysis of rac‐GPE was highly enantioselective, with an E‐value (enantiomeric ratio) of 69.3 in the Tween‐80 emulsion system, which is obviously higher than that (41.2) observed in the DMSO‐containing system.
CO2 and Fluorinated Solvent‐Based Technologies for Protein Microparticle Precipitation from Aqueous Solutions
Authors: Sarkari Marazban , Darrat Inaas , Knutson Barbara L.
Published: April 2003

Precipitation with a compressed or supercritical fluid antisolvent (PCA) has been used to produce microparticles of biologically active proteins, pharmaceuticals, and polymers. However, the application of PCA to a wider range of proteins is limited by the low mutual solubility of water (necessary to dissolve most proteins) and CO2 (traditionally used as the compressed antisolvent). This investigation extends PCA to proteins in aqueous solutions by utilizing ethanol as a cosolvent to enhance the antisolvent properties of CO2 toward aqueous systems. α‐Chymotrypsin, a model protein, was precipitated from both compressed CO2 and a liquid fluorinated antisolvent, a hydrofluoroether (HFE). The equilibrium phase behavior of the antisolvent/ethanol/water systems was examined to identify a one‐phase region suitable for protein precipitation. Spherical protein microparticles with a primary particle size of approximately 0.2–0.6 μm were recovered using both the compressed CO2 and fluorinated antisolvents. Although the proteins retained significant activity using both antisolvent systems, the HFE‐precipitated chymotrypsin retained higher activity than the CO2‐precipitated protein.
Gene Array‐Based Identification of Changes That Contribute to Ethanol Tolerance in Ethanologenic Escherichia coli: Comparison of KO11 (Parent) to LY01 (Resistant Mutant)
Authors: Gonzalez Ramon , Tao Han , Purvis J. E. , York S. W. , Shanmugam K. T. , Ingram L. O.
Published: April 2003

Escherichia coli KO11 (parent) and LY01 (mutant) have been engineered for the production of ethanol. Gene arrays were used to identify expression changes that occurred in the mutant, LY01, during directed evolution to improve ethanol tolerance (defined as extent of growth in the presence of added ethanol). Expression levels for 205 (5%) of the ORFs were found to differ significantly ( p < 0.10) between KO11 and LY01 under each of six different growth conditions ( p < 0.000001). Statistical evaluation of differentially expressed genes according to various classification schemes identified physiological areas of importance. A large fraction of differentially expressed ORFs were globally regulated, leading to the discovery of a nonfunctional fnrgene in strain LY01. In agreement with a putative role for FNR in alcohol tolerance, increasing the copy number of fnr+ in KO11(pGS196) decreased ethanol tolerance but had no effect on growth in the absence of ethanol. Other differences in gene expression provided additional clues that permitted experimentation. Tolerance appears to involve increased metabolism of glycine (higher expression of gcv genes) and increased production of betaine (higher expression of betIBAand betT encoding betaine synthesis from choline and choline uptake, respectively). Addition of glycine (10 mM) increased ethanol tolerance in KO11 but had no effect in the absence of ethanol. Addition of betaine (10 mM) increased ethanol tolerance by over 2‐fold in both LY01 and KO11 but had no effect on growth in the absence of ethanol. Both glycine and betaine can serve as protective osmolytes, and this may be the basis of their beneficial action. In addition, the marAB genes encoding multiple antibiotic resistance proteins were expressed at higher levels in LY01 as compared to KO11. Interestingly, overexpression of marAB in KO11 made this strain more ethanol‐sensitive. Overexpression of marAB in LY01 had no effect on ethanol tolerance. Increased expression of genes encoding serine uptake ( sdaC) and serine deamination ( sdaB) also appear beneficial for LY01. Addition of serine increased the growth of LY01 in the presence and absence of ethanol but had no effect on KO11. Changes in the expression of several genes concerned with the synthesis of the cell envelope components were also noted, which may contribute to increased ethanol tolerance.
Broth Recycling To Reduce Process Noise Resulting from Concentrated Substrate Addition in Fed‐Batch Cultivation of Escherichiacoli
Authors: Johnston Wayne A. , Cooney Michael J.
Published: April 2003

In this work feed hardware for fed‐batch cultivation is presented (broth recycle feed injection system or BRFIS). BRFIS proved superior to conventional submerged or dripped feed systems in reducing dissolved oxygen (DO) oscillations during Escherichia coli fed‐batch cultivation (5 min coefficient of variation of 0.7% for BRFIS as compared to 26% or greater for conventional feeding hardware in a 2 L test reactor). Hence, BRFIS is useful for fed‐batch cultivation systems where the DO signal is used in measurement or control.
Purification and Properties of a NADPH‐Dependent Erythrose Reductase from the Newly Isolated Torulacorallina
Authors: Lee Jung‐Kul , Hong Kwang‐Won , Kim Sang‐Yong
Published: April 2003

Torula corallina (KCCM‐10171) is a yeast strain that is currently used for the industrial production of erythritol and has the highest erythritol yield ever reported for an erythritol‐producing microorganism. Production of erythritol in T. corallina is catalyzed by erythrose reductase, an enzyme that converts erythrose to erythritol using NADPH as a cofactor. In this study, NADPH‐dependent erythrose reductase was purified to homogeneity from the newly isolated T. corallina. The relative molecular weight of the erythrose reductase as determined by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and size exclusion chromatography was 35.4 and 71.0 kDa, respectively, indicating that the enzyme is dimeric. This enzyme catalyzed both erythrose reduction and erythritol oxidation; both enzyme activities required NADP(H). The pH and temperature optima for erythrose reduction and erythritol oxidation were 6.0, 40 °C and 8.0, 45 °C, respectively. The sequence of the first 10 amino acids of this enzyme was N‐V‐K‐N‐F‐Y‐Q‐P‐N‐D. The affinity ( Km = 7.12 mM) of the enzyme for erythrose was comparable to that of other known erythrose reductases, and the specificity for erythrose was very high, resulting in no production of other polyols, which may explain the high erythritol yield observed in this strain.
Loofa Sponge as a Scaffold for the Culture of Human Hepatocyte Cell Line
Authors: Chen Jyh‐Ping , Yu Sheng‐Chun , Hsu Brend Ray‐Sea , Fu Shin‐Huei , Liu Hwai‐Shen
Published: April 2003

Loofa sponge was investigated as a three‐dimensional scaffold for stationary and perfusion culture of human hepatoblastoma cell line C3A/HepG2. In stationary culture, C3A/HepG2 cells in loofa cubes showed higher α‐fetoprotein and albumin secretion rates than those in polyurethane foam (PU). To use loofa cylinders in a packed‐bed reactor, immobilization of C3A/HepG2 cells by recirculating medium at 26 mL/min (superficial velocity = 51.7 cm/min) resulted in a cell loading density of 5.15 × 107 cells/cm3‐loofa. This cell loading density is higher than values reported in the literature for packed‐bed reactor intended for bioartificial liver. During 9 days of perfusion culture in the reactor, immobilized C3A/HepG2 showed steady synthesis of albumin with an average synthesis rate at 42.2 μg/106 cells/day. These experimental results and observations by SEM suggested that loofa sponge is a suitable scaffold for high‐density culture of human hepatocyte cell line and the immobilized cells could express high levels of liver‐specific functions.
Application of Waste Activated Bleaching Earth Containing Rapeseed Oil on Riboflavin Production in the Culture of Ashbyagossypii
Authors: Ming H. , Pizarro Ana V. Lara , Park Enoch Y.
Published: April 2003

Waste activated bleaching earth (ABE) that contained 40% rapeseed oil and was discharged by an oil refinery plant, was used for riboflavin production in a culture of Ashbya gossypii. When 125 g/L waste ABE that contained 50 g/L rapeseed oil was added into the culture, the riboflavin concentration was 1.12 g/L, which was almost 1.6‐fold as high as that of pure rapeseed oil. However, in waste ABE concentration higher than 125 g/L, the produced riboflavin concentration decreased, which was due to the difficulty in mixing due to the presence of a high amount of solid material in the culture. The surface of the waste ABE was smooth without a hitch, because of being covered with rapeseed oil. However, after the culture, the surface of the waste ABE seemed like that of new one, and the oil content was nearly zero grams per liter. The waste ABE, oily clay, and its black color gradually fade and yellow little by little, and finally the waste ABE changed to yellow powder. Of the riboflavin produced during the culture, 70% was adsorbed in the oil free waste ABE. With diluted alkali solution, extraction only two times yielded 90% recovery of riboflavin adsorbed in the waste ABE. The waste ABE containing waste vegetable oil was suitable for raw material for production of the value‐added useful bioproducts, which might be a good model for reuse of the waste resource.
Histidine Tagged Protein Recovery from Tobacco Extract by Foam Fractionation
Authors: Crofcheck Czarena , Loiselle Melanie , Weekley James , Maiti Indu , Pattanaik Sitakanta , Bummer Paul M. , Jay Michael
Published: April 2003

Tobacco plants have the potential to be used for the production of proteins for pharmaceutical applications. This work describes a novel protein recovery strategy where the protein of interest is “tagged” with a histidine sequence, which forms a complex with cobalt ions and surfactant possessing a chelating functionality, such that the protein is recovered in the foamate of a foam fractionation step. His‐gus, a histidine‐tagged enzyme, was chosen as a model protein to study the feasibility of this strategy. The His‐gus is recovered from spiked prefoamed tobacco extract by foam fractionation in the presence of surfactant and cobalt ions with an enrichment of 1.29 and a recovery of 21.5% in terms of an adjusted activity.