bluuebunny/crossref_metadata_2025 huggingface dataset:
Mean-Field Approaches to Independent Component Analysis
Authors: Højen-Sørensen Pedro A.d.F.R. , Winther Ole , Hansen Lars Kai
Published: July 2002

We develop mean-field approaches for probabilistic independent component analysis (ICA). The sources are estimated from the mean of their posterior distribution and the mixing matrix (and noise level) is estimated by maximum a posteriori (MAP). The latter requires the computation of (a good approximation to) the correlations between sources. For this purpose, we investigate three increasingly advanced mean-field methods: the variational (also known as naive mean field) approach, linear response corrections, and an adaptive version of the Thouless, Anderson and Palmer (1977) (TAP) mean-field approach, which is due to Opper and Winther (2001). The resulting algorithms are tested on a number of problems. On synthetic data, the advanced mean-field approaches are able to recover the correct mixing matrix in cases where the variational mean-field theory fails. For handwritten digits, sparse encoding is achieved using nonnegative source and mixing priors. For speech, the mean-field method is able to separate in the underdetermined (overcomplete) case of two sensors and three sources. One major advantage of the proposed method is its generality and algorithmic simplicity. Finally, we point out several possible extensions of the approaches developed here.
On Material II Fautrier
Authors: Tatsumi Hijikata
Published: July 2002

For the first time in English, we present many of Hijikata's aesthetic and poetic texts. These texts are put into context by Kurihara Nanako's introductory essay. The section includes an interview with Hijikata and a conversation between Hijikata and Japanese experimental theatre innovator Suzuki Tadashi.
The Simple Virtual Environment Library: An Extensible Framework for Building VE Applications
Authors: Kessler G. Drew , Bowman Doug A. , Hodges Larry F.
Published: July 2002

As virtual environment (VE) technology becomes accessible to (and affordable for) an ever-widening audience of users, the demand for VE applications will increase. Tools that assist and facilitate the development of these applications, therefore, will also be in demand. To support our efforts in quickly designing and implementing VE applications, we have developed the Simple Virtual Environment (SVE) library. In this article, we describe the characteristics of the library that support the development of both simple and complex VE applications. Simple applications are created by novice programmers or for rapid prototyping. More-complex applications incorporate new user input and output devices, as well as new techniques for user interaction, rendering, or animation. The SVE library provides more-comprehensive support for developing new VE applications and better supports the various device configurations of VE applications than current systems for 3-D graphical applications. The development of simple VE applications is supported through provided default interaction, rendering, and user input and output device handling. The library's framework includes an execution framework that provides structure for incrementally adding complexity to selected tasks of an application, and an environment model that provides a layer of abstraction between the application and the device configuration actually used at runtime. This design supports rapid development of VE applications through incremental development, code reuse, and independence from hardware resources during the development.
Virtual Gain for Audio Windows
Authors: Cohen Michael , Koizumi Nobuo
Published: July 2002

Audio windowing is a front-end, or user interface, to an audio system with a real-time spatial sound back end. Complementing directionalization by a digital signal processor (DSP), gain adjustment is used to control the volume of the various mixels ([sound] mixing elements). Virtual gain can be synthesized from components derived from collective iconic size, mutual distance, orientation and directivity, and selectively enabled according to room-wise partitioning of sources across sinks. This paper describes a derivation of virtual gain, and outlines the deployment of these expressions in an audio windowing system.
Adaptive Linkage Crossover
Authors: Salman Ayed A. , Mehrotra Kishan , Mohan Chilukuri K.
Published: July 2002

Problem-specific knowledge is often implemented in search algorithms using heuristics to determine which search paths are to be explored at any given instant. As in other search methods, utilizing this knowledge will more quickly lead a genetic algorithm (GA) towards better results. In many problems, crucial knowledge is not found in individual components, but in the interrelations between those components. For such problems, we develop an interrelation (linkage) based crossover operator that has the advantage of liberating GAs from the constraints imposed by the fixed representations generally chosen for problems. The strength of linkages between components of a chromosomal structure can be explicitly represented in a linkage matrix and used in the reproduction step to generate new individuals. For some problems, such a linkage matrix is known a priorifrom the nature of the problem. In other cases, the linkage matrix may be learned by successive minor adaptations during the execution of the evolutionary algorithm. This paper demonstrates the success of such an approach for several problems.
Looking Beyond Selection Probabilities: Adaptation of the χ2 Measure for the Performance Analysis of Selection Methods in GAs
Authors: Schell Thomas , Wegenkittl Stefan
Published: July 2002

Viewing the selection process in a genetic algorithm as a two-step procedure consisting of the assignment of selection probabilities and the sampling according to this distribution, we employ the χ2 measure as a tool for the analysis of the stochastic properties of the sampling. We are thereby able to compare different selection schemes even in the case that their probability distributions coincide. Introducing a new sampling algorithm with adjustable accuracy and employing two-level test designs enables us to further reveal the intrinsic correlation structures of well-known sampling algorithms. Our methods apply well to integral methods like tournament selection and can be automated.
An Analysis of Two-Parent Recombinations for Real-Valued Chromosomes in an Infinite Population
Authors: Nomura Tatsuya , Shimohara Katsunori
Published: July 2002

This paper concerns recombinations which produce offspring from two parents. We assume an infinite population and regard recombinations as transformations of stochastic variables represented as chromosomes. We then formalize recombinations with the probability density functions of stochastic variables represented as the parameters and describe the change of the probability density functions of chromosomes before and after recombination. Our formalization includes various proposed recombinations, such as multi-point, uniform, and linear crossover, as well as BLX-α. We also derive certain properties of the operators, such as diversification and decorrelation.
The Evolution and Understanding of Hierarchical Complexity in Biology from an Algebraic Perspective
Authors: Nehaniv Chrystopher L. , Rhodes John L.
Published: July 2002

We develop the rigorous notion of a model for understanding state transition systems by hierarchical coordinate systems. Using this we motivate an algebraic definition of the complexity of biological systems, comparing it to other candidates such as genome size and number of cell types. We show that our complexity measure is the unique maximal complexity measure satisfying a natural set of axioms. This reveals a strong relationship between hierarchical complexity in biological systems and the area of algebra known as global semigroup theory. We then study the rate at which hierarchical complexity can evolve in biological systems assuming evolution is “as slow as possible” from the perspective of computational power of organisms. Explicit bounds on the evolution of complexity are derived showing that, although the evolutionary changes in hierarchical complexity are bounded, in some circumstances complexity may more than double in certain “genius jumps” of evolution. In fact, examples show that our bounds are sharp. We sketch the structure where such complexity jumps are known to occur and note some similarities to previously identified mechanisms in biological evolutionary transitions. We also address the question of, How fast can complexity evolve over longer periods of time? Although complexity may more than double in a single generation, we prove that in a smooth sequence of t “inclusion” steps, complexity may grow at most from N to .N C 1/t C N, a linear function of number of generations t, while for sequences of “mapping” steps it increases by at most t. Thus, despite the fact that there are major transitions in which complexity jumps are possible, over longer periods of time, the growth of complexity may be broken into maximal intervals on which it is bounded above in the manner described.
Constructing Environmental Conflicts from Resource Scarcity
Authors: Haas Peter M.
Published: July 2002

This essay reviews Malthusian themes in current discourses about resource scarcity and environmental security. It argues that these themes are unjustifiably dominant in current discussions, and suggests that increased attention should be to paid to discourses revolving around Sustainable Development, as well as on institutional designs that can influence patterns of resource consumption and collective responses to perceptions of resource scarcity
UNIVERSALS REVISITED: HUMAN BEHAVIORS AND CULTURAL VARIATIONS
Authors: Paden William
Published: July 2002

This paper explores one way of addressing current skepticism about cross-cultural comparisons. The typical challenge to comparativism is that it either imposes or suppresses cultural meanings; religion, as a form of culture, is contextual and hence intrinsically incomparable. In contrast, I advance a model that identifies panhuman forms of behavior shared by any culture. Differences in historical religious life, in turn, can be described as cultural versions and transformations of those default behaviors. Comparativism then finds a broader, species-level basis for both commonality and significant variation. The paper explores various theoretic underpinnings and implications of this approach.
Description of the tadpole of Leptodactylus syphax, with a comparison of morphological and ecological characters of tadpoles and adults of the species in the L. pentadactylus group (Leptodactylidae, Anura)
Authors: Sazima Ivan , Eterovick Paula
Published: July 2002

Leptodactylus syphax belongs to the L. pentadactylus group, one of five species groups defined for the genus. The tadpole of L. syphax develops in lotic habitats, as do the tadpoles of L. lithonaetes and L. rugosus. The tadpole of L. syphax is here described and differs from the tadpole of L. rugosus by having a less flattened and larger body, from the tadpole of L. lithonaetes by having a larger body in relation to total length and a larger oral disc in relation to body length. Further, it differs from the tadpole of L. rhodomystax by its color, body shape in dorsal profile and mouth shape, and from the tadpole of L. rhodonotus by its body shape in dorsal profile and spiracle position. A cluster analysis of several morphological and ecological features of adults and tadpoles from the species of the L. pentadactylus group grouped L. syphax with L. rhodomystax and L. rhodonotus, species with chest spines, moderate body size, relatively small head, unbarred lips, tadpoles with five tooth rows and aquatic development. The remaining species of the L. pentadactylus group were distributed among four additional clusters.
Phylogenetic relationships within the Hyperolius viridiflavus complex (Anura: Hyperoliidae), and comments on taxonomic status
Authors: Wieczorek Ania , Drewes Robert , Channing Alan
Published: July 2002

The taxonomy of the Hyperolius viridiflavus complex, a group of African frogs, has been problematic. Mitochondrial DNA sequence data were used to reconstruct the phylogenetic history of these frogs. The phylogeny showed that subspecies were grouped into clades, within which certain taxa were not supported by fixed characters. We used the phylogenetic species concept to identify the smallest monophyletic clades supported by at least one fixed character, and suggest taxonomic revisions based on our results. We identify ten species within the H. viridiflavus complex.
TYMPANUM FLUCTUATING ASYMMETRY, BODY SIZE AND MATE CHOICE IN FEMALE MIDWIFE TOADS (ALYTES OBSTETRICANS)
Authors: Bosch Jaime , Márquez Rafael
Published: July 2002

We address whether fluctuating asymmetry (FA) in an external ear element is correlated with the accuracy of location of a sound source (synthetic male advertisement calls) by female midwife toads (Alytes obstetricans). Fluctuating asymmetry in the tympanum was measured in gravid females. We studied the relationship between FA, snout - vent - length (SVL), and precision in approaching an acoustic stimulus through playback tests. Female mass was negatively correlated with jump length. Tympanum FA was negatively correlated with the accuracy of location of a sound source. Thus, FA can play an important role in sexual selection by conferring an advantage in access to available males by females with low values of asymmetry.
MUDBALLING REVISITED: FURTHER INVESTIGATIONS INTO THE CONSTRUCTION BEHAVIOUR OF MALE UCA TANGERI
Authors: Burford Fiona R.L. , McGregor Peter , Oliveira Rui
Published: July 2002

Male and female Uca tangeri (the only fiddler crab species to inhabit Europe) construct mudballs from mud excavated from within their burrows. Individual males placed similar patterns of mudballs each low tide, suggesting that there is some degree of stereotypy. When mudballs were experimentally moved further from the burrow or closer to it, males only repositioned those that were moved closer, placing them further away again. However, males did not replace mudballs that had been experimentally destroyed at the end of the mudballing phase when they had started to court females. In binary presentation tests, females showed no significant differences in response to mudballs made from different types of mud, or different numbers of mudballs. These results are consistent with earlier findings that male mudballs function as territory boundaries. However, we provide evidence that male mudballs have no function in female attraction, contrasting with previous studies.
THE MATING PATTERNS OF FEMALES WHEN TERRITORIAL DIFFERENCES AMONG MALES ARE REDUCED: A TEST IN THE POLYGYNOUS BEAUGREGORY DAMSELFISH
Authors: Itzkowitz  , Draud  , Triefenbach  , Haley
Published: July 2002

Using the Caribbean beaugregory damselfish (Stegastes leucostictus) we tested whether patterns of male reproduction could be modified by reducing differences among males, in this case by giving males identical artificial breeding sites. Previous studies have shown that very few males using the natural small rubble habitat reproduced and variations in male reproductive success were based mainly on the differences in the quality of their natural breeding sites. By providing males with identical artificial breeding sites, we tested whether females would be less likely to confine their reproduction to only a few of the available males. We examined male reproductive patterns by first simulating females choosing males (1) 'randomly,' (i.e. the number of males that receive eggs is based on each female randomly choosing a mate from a group of males), or (2) 'exclusively' (i.e. only one female mates with one male on a given day), or (3) 'highly selectively' (i.e. this is the typical polygynous pattern in which many females select the same few males). We tested these simulations against the actual daily amounts of eggs deposited and the number of different males that received eggs in each of 4 summers. Although the regression trend line from the daily patterns did resemble the Random Mating Pattern, egg clutches were more widely dispersed than random but less dispersed than the Exclusive Mating Pattern. That is, with more females mating on a particular day, more males received eggs. We speculated that this might have resulted from females aggressively excluding other females from mating with the same male on a given day. In contrast, males using the variable quality natural sites rarely mated and those that did receive eggs, received them in larger amounts than males using the artificial sites. Thus, for natural sites, more females seemed to be mating with the same few males. Perhaps for these natural sites any intra-female aggression may have been ineffective when so few superior spawning sites were available. For males using the artificial sites, the total amount of eggs received over a two-month period was nonrandom and resembled the 'highly selected pattern.' This resulted from some males receiving egg clutches on more days. Other traits, besides breeding site structure, may have been important in causing different females to select the same males on subsequent days.
Scanning electron microscopical observations on the coastal marine nematode Epsilonema pustulatum (Gerlach, 1952) Lorenzen, 1973 (Nematoda: Epsilonematidae)
Authors: De Deyn Gerlinde , Van Aelst Adriaan , Karssen Gerrit
Published: July 2002

Additional detailed morphological information on features of the marine nematode Epsilonema pustulatum is presented for the first time. Lip structure, amphideal fovea, cuticular appendages (setae, spines, anal and copulatory thorns), annules and vacuoles, body inversion, setae ambulatoriae region, vulva, cloaca/anus and tail end are SEM studied and illustrated. Additionally, E. pustulatum (from Spain, Italy and Lebanon) is compared with other former Bathyepsilonema species. E. anulosum (Verschelde & Vincx, 1992) is proposed as a junior synonym of E. pustulatum. Observations au microscope électronique à balayage sur le nématode marin côtier Epsilonema pustulatum (Gerlach, 1952) Lorenzen, 1973 (Nematoda: Epsilonematidae) - Des données morphologiques nouvelles concernant le nématode marin Epsilonema pustulatum sont présentées pour la première fois. Sont étudiés en microscopie électronique à balayage et illustrés des caractères tels que la structure labiale, les fovea amphidiales, les appendices cuticulaires (sétes, épines du corps, épines anales et copulatoires), anneaux et vacuoles, courbure du corps, région des sétes ambulatoires, vulve, cloaque/anus et extrémité de la queue. De plus, E. pustulatum (provenant d'Espagne, Italie et Liban) est comparé avec d'autres espèces auparavant placées dans le genre Bathyepsilonema. E. anulosum (Verschelde & Vincx, 1992) est proposé comme synonyme mineur d'E. pustulatum.
The influence of in-egg mortality and spontaneous hatching on the decline of Globodera rostochiensis during crop rotation in the absence of the host potato crop in the field
Authors: Devine Ken , Dunne Colum , O'Gara Fergal , Jones Peter
Published: July 2002

The decline of Globodera rostochiensis (Woll.) populations in two fields was
57% during the first and 40.3% during the second year of crop rotation in
the absence of a potato crop in Co. Cork, Ireland. The decline was found to
be due to both spontaneous hatch and in-egg mortality. Spontaneous hatch
accounted for between 75.8 and 80.2% of the decline experienced during
rotation. In-egg mortality was found to be responsible for a reduction of
approximately 10% in the total number of viable eggs in both fields, and was
positively correlated with soil temperature in the field. The number of
culturable bacteria and the composition of the bacterial microflora in the
cysts was found to change with increasing soil temperatures. The increase in
cellulase-positive isolates reflected the effect of temperature on egg
degradation. Der Einfluss von Absterben im Ei und spontanem Schlupfen auf
die Abnahme von Globodera rostochiensis im Feld im Laufe des Fruchtwechsels
bei Abwesenheit des Wirtes Kartoffel - In Co. Cork, Irland, betrug die
Abnahme der Populationen von Globodera rostochiensis (Woll.) in zwei Feldern
in einer Fruchtfolge ohne Kartoffeln im ersten Jahr 57% und im zweiten Jahr
40,3%. Es wurde festgestellt, dass die Abnahme durch spontanes Schlupfen und
durch Absterben im Ei verursacht wurde. Spontanes Schlupfen war fur 75,8 und
80,2% des wahrend des Fruchtwechsels beobachteten Ruckganges verantwortlich.
Etwa 10% der Gesamtzahl infektionsfahiger Eier in den beiden Feldern gingen
durch Absterben im Ei zugrunde. Dieser Ruckgang war positiv korreliert mit
der Bodentemperatur im Feld. Der Anteil der kulturfahigen Bakterien und die
Zusammensetzung der Bakterienflora in den Zysten nahmen mit steigenden
Bodentemperaturen zu. Der Anstieg der zellulase-positiven Isolate spiegelte
die Wirkung der Temperatur auf die Zersetzung der Eier wider.
Vermiculitization of smectite interfaces and illite layer growth as a possible dual model for illite-smectite illitization in diagenetic environments: a synthesis
Authors: Meunier A. , Lanson B. , Beaufort D.
Published: July 2002

A structural model is proposed for illite-smectite (I-S) from diagenetic environments which accounts for the presence of three different layer types which are defined as follows: montmorillonite (low-charge, octahedrally substituted, fully expandable), vermiculite (high-cha rge, octa- and tetrahed rally substitut ed, only partly expandabl e) and illite (K0.9Si3.3Al0.7R1.83+R0.22+O10(OH)2). All three layers may be found within the MacEwan crystallites, whereas external edges of the crystallites are only vermiculitic during the illitization process. In the proposed model, a layer is defined symmetrically on each side of the interlayer space, leading to the existence of polar 2:1 units. It is proposed that the I-S growth is a three step mechanism: (1) formation, from sediments of variable composition, of montmorillon ite crystallites; (2) vermiculitization of the montmorillonite crystallite interfaces and of inner montmorillonite layers; and (3) precipitation of illite of fixed chemical composition. The I-S crystal grows by addition of illite layers linked by K+ or NH4+ ions saturating the vermiculitic interfaces.
Diagenesis of silica minerals from clay minerals in volcanic soils of Mexico
Authors: Elsass F . , Dubroeucq D. , Thiry M.
Published: July 2002

Indurated volcanic soils (tepetates) of the Mexican Altiplano display thick columnar horizons, hard laminar horizons, and grey mottles at depth. X-ray diffraction (XRD) studies show a relative enrichment in cristobalite vs. halloysite in the indurated plates of the laminar horizons and in the clay fraction of the mottles. Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) studies of these two soil components have shown that they are composed of small tubes of halloysite in which numerous globular grains ∼1 μm in diameter are embedded. Based on the relative abundance of cristobalite in pedological features and on the spatial relations between successive mineral phases, we interpret the cristobalite as a transformation of halloysite with a transitional amorphous phase. In the globular grains, large platy 1:1 clay minerals undergo a progressive transformation into platy particles of opal-A and opal-C. These are in turn transformed into cristobalite without further major change in their shape and appearance, except for a higher electron density than opal and clay.
Fe, Mg and Al distribution in the octahedral sheet of montmorillonites. An infrared study in the OH- bending region
Authors: Vantelon D. , Pelletier M. , Michot L. J. , Barres O. , Thomas F.
Published: July 2002

Ten montmorillonites of different origins with variable Fe contents were analysed using transmission IR spectroscopy. Special attention was devoted to the OH-bending region to obtain information about the distribution of octahedral cations. For low to medium Fe contents (≤0.56 per Si8 formula unit), a linear relationship between the position of the δAlFeOH band and Fe content was observed. Such correlation might be explained by changes in the cis-trans occupancy of Fe in the octahedral sheet. Deconvolution of the OH-bending domain allows us to discriminate three components (δAlAlOH, δAlMgOH and δAlFeOH) which are correlated with cation abundances derived from chemical analysis. The relative area of each band can then be compared with theoretical areas calculated assuming a fully random distribution of cations in the octahedral sheet. Using such treatment, eight of the 10 montmorillonites studied presented a nearly randomized octahedral distribution. The two samples from Wyoming were clearly different as they exhibited a strong ordering tendency.
Menshikovite, Pd-Ni arsenide and synthetic equivalent
Authors: Barkov A. Y. , Laajoki K. , Gervilla F. , Makovicky E.
Published: July 2002

The average compositions of menshikovite (Pd3Ni2As3) from the type locality (Lukkulaisvaara layered intrusion, Russian Karelia) and a Pd-Ni arsenide synthesized at 450°C, are very close. The observed ΣMetal:As ratio is close to 5:3, as in the case of previously described arsenides from the Stillwater and Two-Duck Lake intrusions. The compositions suggest that these unnamed Pd-Ni arsenides and the synthetic phase are in fact menshikovite.
Crystal chemistry of basic lead carbonates. III. Crystal structures of Pb3O2(CO3) and NaPb2(OH)(CO3)2
Authors: Krivovichev S. V. , Burns P. C.
Published: July 2002

The crystal structures of synthetic Pb3O2(CO3) and NaPb2(OH)(CO3)2, have been solved by direct methods and refined to R = 0.062 and 0.024, respectively. Pb3O2(CO3) is orthorhombic, Pnma, a = 22.194(3), b = 9.108(1), c = 5.7405(8) Å, V = 1160.4(3) Å3, Z = 8. There are four symmetrically distinct Pb2+ cations in irregular coordination polyhedra due to the effect of stereoactive s2 lone electron pairs. The structure is based upon double [O2Pb3] chains of [O(1)Pb4] and [O(2)Pb4] oxocentred tetrahedra and CO3 groups. The [O2Pb3] chains are parallel to the c axis, whereas the CO3 groups are parallel to the (010) plane. NaPb2(OH)(CO3)2 is hexagonal, P63mc, a = 5.276(1), c = 13.474(4)Å, V = 324.8(1) Å3, Z = 2 and has been solved by direct methods. There are two symmetrically distinct Pb2+ cations in asymmetric coordination polyhedra due to the effect of stereoactive s2 lone-electron pairs. The single symmetrically unique Na+ cation is in trigonal prismatic coordination. The structure is based on hexagonal sheets of Pb atoms. Within these sheets, Pb atoms are located at vertices of a 36 net, such that each Pb atom has six adjacent Pb atoms that are ~5.3 Å away. Two sheets are stacked in a close-packing arrangement, forming layers that contain the (CO3) groups. The layers are linked by OH groups that are linearly coordinated by two Pb2+ cations. Na+ cations are located between the layers. The structure is closely related to the structures of other lead hydroxide carbonates (leadhillite, macphersonite, susannite, hydrocerussite, ‘plumbonacrite’).
A new mineral, chrisstanleyite, Ag2Pd3Se4, from Hope's Nose, Torquay, Devon, England
Authors: Paar W. H. , Roberts A. C. , Criddle A. J. , Topa D.
Published: July 2002

Chrisstanleyite, Ag2Pd3Se4, is a new mineral from gold-bearing carbonate veins in Middle Devonian limestones at Hope's Nose, Torquay, Devon, England. It is associated with palladian and argentian gold, fischesserite, clausthalite, eucairite, tiemannite, umangite, a Pd arsenide-antimonide (possibly mertieite II), cerussite, calcite and bromian chlorargyrite. Also present in the assemblage is a phase similar to oosterboschite, and two unknown minerals with the compositions, PdSe2 and HgPd2Se3. Chrisstanleyite occurs as composite grains of anhedral crystals ranging from a few µm to several hundred µm in size. It is opaque, has a metallic lustre and a black streak, VHN100 ranges from 371–421, mean 395 kp/mm2 (15 indentations), roughly approximating to a Mohs hardness of 5. Dcalc = 8.308 g/cm3 for the ideal formula with Z = 2. In plane-polarised reflected light, the mineral is very slightly pleochroic from very light buff to slightly grey-green buff; is weakly bireflectant and has no internal reflections. Bireflectance is weak to moderate (higher in oil). Anisotropy is moderate and rotation tints vary from rose-brown to grey-green to pale bluish grey to dark steel-blue. Polysynthetic twinning is characteristic of the mineral. Reflectance spectra and colour values are tabulated. Very little variation was noted in eleven electron-microprobe analyses on five grains, the mean is: Ag 25.3, Cu 0.17, Pd 37.5, Se 36.4, total 99.37 wt.%. The empirical formula (on the basis of ∑M + Se = 9) is (Ag2.01Cu0.02)∑2.03 Pd3.02Se3.95, ideally Ag2Pd3Se4. Chrisstanleyite is monoclinic, a 6.350(6), b 10.387(4), c 5.683(3) Å β 114.90(5)°, space group P21/m (11) or P21(4). The five strongest X-ray powder-diffraction lines [d in Å (I)(hkl)] are: 2.742 (100) (–121), 2.688 (80) (–221), 2.367 (50) (140), 1.956 (100) (–321,150) and 1.829 (30) (–321, 042). The name is in honour of Dr Chris J. Stanley of The Natural History Museum in London. The mineral and its name have been approved by the Commission on New Minerals and Mineral Names of the International Mineralogical Association.
Primitive quiescent leukemic cells from patients with chronic myeloid leukemia spontaneously initiate factor-independent growth in vitro in association with up-regulation of expression of interleukin-3
Authors: Holyoake Tessa L. , Jiang Xiaoyan , Jorgensen Heather G. , Graham Susan , Alcorn Michael J. , Laird Chris , Eaves Allen C. , Eaves Connie J.
Published: July 2002

It was previously shown that patients with chronic myeloid leukemia (CML) have a rare but consistently detectable population of quiescent (G0) leukemic (Philadelphia chromosome–positive and BCR-ABL–positive [BCR-ABL+]) CD34+ cells. In the study described here, most such cells expressed a primitive phenotype (CD38−, CD45RA−, CD71−, and HLA-DRlo) and cultures of these cells containing growth factors produced ultimately larger, but initially more slowly growing clones than do cultures of initially cycling CD34+ leukemic cells. Initially quiescent leukemic cells expressing BCR-ABLproliferated in single-cell cultures in the absence of added growth factors, thereby demonstrating their ability to spontaneously exit G0 and enter a continuously cycling state. Interestingly, on isolation, few of these quiescentBCR-ABL+ cells contained either interleukin-3 (IL-3) or granulocyte colony-stimulating factor (G-CSF) transcripts, whereas both were present in most cyclingBCR-ABL+ CD34+ cells. However, after 4 days of culture in the absence of added growth factors and in association with their entry into the cell cycle (as indicated by up-regulation of Ki-67 and cdc25 transcripts), IL-3 transcripts became detectable. These findings show that entry of leukemic (BCR-ABL–expressing) progenitors into a quiescent (G0) state in vivo is highest among the most primitive leukemic cell populations, associated with a down-regulation of IL-3 and G-CSF gene expression, and spontaneously reversible in association with up-regulation of IL-3 expression. These results highlight the potential physiologic relevance of quiescent CML progenitors, even in treated patients, in whom these cells would be predicted to have a proliferative advantage over their quiescent normal counterparts when cytokine concentrations are low.
Suicide gene therapy of graft-versus-host disease: immune reconstitution with transplanted mature T cells
Authors: Cohen José L. , Boyer Olivier , Klatzmann David
Published: July 2002

After allogeneic hematopoietic stem cell transplantation (HSCT), mature transplanted T cells play a major role in restoration of the immune system. However, they can also induce a life-threatening complication: graft-versus-host disease (GVHD). Suicide gene therapy of GVHD aims to selectively eliminate alloreactive T cells mediating GVHD while sparing nonalloreactive T cells that should contribute to immune reconstitution. It was demonstrated previously that treatment with ganciclovir (GCV) can control GVHD in mice by killing donor T cells engineered to express the thymidine kinase (TK) suicide gene. TK allows phosphorylation of nontoxic GCV into triphosphate GCV, which is selectively toxic for dividing cells. Thus, in the TK-GCV system, the specificity of cell killing depends on the cycling status of TK T cells rather than allogeneic recognition. This is a potential drawback because in recipients of lymphopenic allogeneic HSCT, alloreactive and homeostatic signals drive the proliferation of donor T cells. It is shown here that the onset of alloreactive T-cell division occurs earlier than that of nonalloreactive T cells, thus establishing a time frame for GCV administration. A 7-day GCV treatment initiated at the time of HSCT allowed efficient prevention of GVHD, while sparing a pool of nondividing donor TK T cells. These cells later expanded and contributed to the replenishment of the recipient immune system with a diversified T-cell receptor repertoire. These results provide a rationale for designing the therapeutic scheme when using TK-GCV suicide gene therapy in allogeneic HSCT.
Transformation of interleukin-3–dependent cells without participation of Stat5/bcl-xL: cooperation of akt with raf/erk leads to p65 nuclear factor κB–mediated antiapoptosis involving c-IAP2
Authors: Gelfanov Vasily M. , Burgess Gem S. , Litz-Jackson Sara , King Alastair J. , Marshall Mark S. , Nakshatri Harikrishna , Boswell H. Scott
Published: July 2002

Tyrosine kinase oncogenes such as p210BCR-ABL activate multiple signal pathways. As a result, it is difficult to infer the functional relevance of a pathway acting alone or in cooperation with another. One or 2 second-tier kinases represented in the p21ras and phosphatidylinositol-3-kinase (PI-3-kinase) pathways (activated RafCAAX and gag-akt, respectively) were expressed in parental H7 interleukin-3 (IL-3)–dependent myeloid cells. IL-3–dependent cells served, independently, as recipients of p210BCR-ABL, which activated p21ras and PI-3-kinase pathways, including raf/erk and akt, respectively, en route to transformation. By contrast, neither RafCAAX nor gag-akt when expressed in parental cells in isolation produced factor-independent cells. On the other hand, H7 cells expressing both RafCAAX and gag-akt (H7gag-akt/RafCAAX) were transformed. Such transformation in H7gag-akt/RafCAAX was accomplished in the absence of active versions of Shc or cbl, and there was no evidence of Stat activity and only modest amounts of bcl-xL, a Stat5 transcriptional target protein, all of which characterized the cells transformed by BCR-ABL. However, H7gag-akt/RafCAAX cells and H7BCR-ABL cells cultured in the absence of IL-3 shared strikingly increased p65 nuclear factor κB (NFκB) activity. Treatment of cells with a specific NFκB inhibitor, parthenolide, led to loss of NFκB activity and down-regulation of antiapoptotic c-IAP2. In cells with only gag-akt/RafCAAX, this was sufficient to allow polyADP ribosyltransferase (PARP)–degradative apoptosis, but in cells with p210BCR-ABL, apoptosis was blocked, possibly by a Stat5/bcl-xL–dependent mechanism. Therefore, one hematopoietic antiapoptotic program, among others, available to certain tyrosine kinase oncogenes involves a cooperative response between raf/erk and akt, unambiguous components of p21ras and PI-3-kinase pathways, to induce p65 NFκB and c-IAP2.
Stromal-derived factor 1 inhibits the cycling of very primitive human hematopoietic cells in vitro and in NOD/SCID mice
Authors: Cashman Johanne , Clark-Lewis Ian , Eaves Allen , Eaves Connie
Published: July 2002

Stromal-derived factor 1 (SDF-1) is a -CXC- chemokine that plays a critical role in embryonic and adult hematopoiesis, and its specific receptor, CXCR4, has been implicated in stem cell homing. In this study, it is shown that the addition of SDF-1 to long-term cultures (LTCs) of normal human marrow can selectively, reversibly, and specifically block the S-phase entry of primitive quiescent erythroid and granulopoietic colony-forming cells (CFCs) present in the adherent layer. Conversely, addition of anti–SDF-1 antibody or SDF-1(G2), a specific CXCR4 antagonist, to preactivated human LTCs prevented both types of primitive CFCs from re-entering a quiescent state, demonstrating that endogenous SDF-1 contributes to the control of primitive CFC proliferation in the LTC system. Interestingly, SDF-1 failed to arrest the proliferation of primitive chronic myeloid leukemia CFCs in the adherent layer of LTCs containing normal marrow stromal cells. In vivo, injection of SDF-1 arrested the cycling of normal human LTC-initiating cells as well as primitive CFCs in the marrow of nonobese diabetic/severe combined immunodeficient mice engrafted with human cord blood cells. Conversely, injection of the antagonist, SDF-1(G2), reactivated the cycling of quiescent primitive human CFCs present in the marrow of mice engrafted with human marrow cells. These studies are the first to demonstrate a potential physiological role of SDF-1 in regulating the cell-cycle status of primitive hematopoietic cells and suggest that the deregulated cycling activity of primitive chronic myeloid leukemia (CML) cells is due to the BCR-ABL–mediated disruption of a pathway shared by multiple chemokine receptors.
Up-regulation of the chemokine receptor CCR7 in classical but not in lymphocyte-predominant Hodgkin disease correlates with distinct dissemination of neoplastic cells in lymphoid organs
Authors: Höpken Uta E. , Foss Hans-Dieter , Meyer Dagmar , Hinz Michael , Leder Korinna , Stein Harald , Lipp Martin
Published: July 2002

Chemokines and chemokine receptors are key mediators for regulating cell traffic and positioning in both homeostatic and inflammatory conditions. It is also presumed that chemokines and their receptors are likely to play a critical role in the localization of malignant hematopoietic cells in their target organs. This study analyzed chemokine and chemokine receptor expression in several Hodgkin disease (HD)–derived cell lines and in HD tumors. All HD-derived cell lines expressed functional CCR7 and CXCR4 receptors. CCR7 up-regulation was mediated by constitutive NF-κB activity. Lymphoid tissues in HD revealed differential expression levels of CCR7, CXCR4, and CXCR5, depending on the distinct subtypes of HD. HD of the classical subtypes, predominantly located in the interfollicular zone, showed strong CCR7 and CXCR4 expression and moderate CXCR5 expression. In contrast, the nodular lymphocyte-predominant HD (NLP) subtype, regularly associated with follicular structures, exhibited no CCR7 reactivity but abundant CXCR4 staining. Their respective chemokine ligands showed marked expression by reactive cells within the tumors of classical HD and outside of the tumor nodules in NLPHD. Functionally, such differential chemokine receptor expression might contribute to specific localization and confinement of neoplastic cells within the target organs in the distinct HD entities.
Equipping Dermatologists to Address Structural and Social Drivers of Inequities—Structural Competency
Authors: Riley Cruz , Vasquez Rebecca , Pritchett Ellen N.
Published: July 2024

This Viewpoint defines structural competency and applies its 5 core elements to a hypothetical case of atopic dermatitis in a pediatric patient.
Immune-Mediated and Psychiatric Comorbidities Among Patients Newly Diagnosed With Alopecia Areata
Authors: Mostaghimi Arash , Soliman Ahmed M. , Li Chao , Barqawi Yazan K. , Grada Ayman
Published: July 2024

Importance

Alopecia areata (AA) has been associated with multiple comorbidities, yet information regarding the timing of comorbidity development after AA diagnosis is limited.

Objective

To evaluate the prevalence and new-onset incidence of psychiatric and autoimmune comorbidities in patients with AA in the US.

Design, Setting, and Participants

This retrospective cohort analysis used data collected from January 1, 2007, to April 30, 2023, from the Merative MarketScan Research Databases, which contains medical and drug claims data from more than 46 million patients in the US. Data from adolescent and adult patients (aged 12-64 years) diagnosed with AA and patients without AA (ie, controls) were evaluated. For some analyses, patients with AA were matched (1:4) to controls based on sex, age, and geographic region.

Main Outcomes and Measures

Prevalence (at the time of AA diagnosis) and incidence (new onset after AA diagnosis) of psychiatric and autoimmune diseases were reported as percentage of patients. Risk of developing a new-onset psychiatric or autoimmune disease after AA diagnosis was calculated as adjusted hazard ratios (AHRs) with 95% CIs.

Results

At baseline, 63 384 patients with AA and 3 309 107 without AA were identified. After matching, there were 16 512 and 66 048 patients in the AA and control groups, respectively, with a mean (SD) age of 36.9 (13.4) years and 50.6% of whom were female. Compared with the unmatched controls, patients with AA had higher prevalence of psychiatric (30.9% vs 26.8%; P < .001) and autoimmune (16.1% vs 8.9%; P < .0001) comorbidities at AA diagnosis; incidence was also higher in patients with AA (without history of these comorbidities) vs the matched control group. Patients with AA vs controls had a significantly higher risk of developing a psychiatric (AHR, 1.3; 95% CI, 1.3-1.4) or autoimmune (AHR, 2.7; 95% CI, 2.5-2.8) comorbidity.

Conclusions and Relevance

In this cohort study, patients with AA had a higher prevalence of autoimmune and psychiatric comorbidities at AA diagnosis and demonstrated an elevated risk of new-onset autoimmune and psychiatric comorbidities after their diagnosis. These data highlight the most common comorbidities among patients with AA and may help physicians counsel and monitor patients newly diagnosed with AA.
Bioinspired AlFeO3 Memristor with Sensing, Storage, and Synaptic Functionalities
Authors: Ganaie Mubashir Mushtaq , Kumar Amit , Shringi Amit K. , Sahu Satyajit , Saliba Michael , Kumar Mahesh
Published: July 2024

In conventional designs, sensory systems are segregated from memory and computing units. The conversion and transmission of data from analog sensing domains to digital storage result in inefficient power utilization and increased latency. Here, a multifunctional memristor capable of detecting gamma radiation while also serving as a data storage device and an artificial synapse is reported. Large‐scale integration of oxide‐based memristors for artificial neural networks faces major challenges due to the sneak‐path current issue in crossbar arrays. Consequently, material combinations and fabrication variables significantly shape nanoscale processes, which are essential in determining resistive switching properties and functionalities. Resistive switching in AlFeO3 is studied using different electrode materials (silver (Ag), gold (Au), chromium (Cr), fluorine‐doped tin oxide, and silicon), embedding metal (Ag, Au) nanocrystals to engineer a class of tunable memories capable of functioning as selector, memory, artificial synapse, and dosimeter. Techniques like electrode engineering, nanocrystal seeding, and temperature‐dependent thin film deposition are employed to tune resistive and threshold switching functionalities. Accessing different functionalities requires changing the electrode materials or changing the synthesis conditions of the AlFeO3 resistive switching layer and are not interconvertible in the same device simultaneously. The devices emulate critical neural functions and demonstrate interconversion dynamics between short‐term and long‐term plasticity.
Pure Zwitterionic Hydrogel with Mechanical Robustness and Dynamic Tunability Enabled by Synergistic Non‐Covalent Interactions
Authors: Li Xiaohui , Wu Yu , Wu Mengdi , Gao Jiawei , Zhang Yan , Zhang Yongjun , Wu Tengling , Gao Hui
Published: July 2024

Zwitterionic hydrogels with exceptional antifouling properties and biocompatibility have gained widespread attention in biomedical applications. However, achieving robust mechanical performance while maintaining high water content within a single‐network zwitterionic hydrogel remains challenging. Traditional covalent crosslinking strategies often lead to brittleness and irreversible damage. Herein, a novel acylsemicarbazide‐containing carboxybetaine methacrylate (ACBMA) monomer is designed and synthesized that enables the construction of a pure zwitterionic poly(ACBMA) (pACBMA) hydrogel without chemical crosslinkers. The pACBMA hydrogel exhibits high water content exceeding 95% and superior mechanical properties, including compressive fracture stress of 3.92 MPa, compressive strain up to 99% without breaking, and toughness of 212 ± 2.4 kJ m−3, outperforming chemically crosslinked poly(carboxybetaine methacrylate) (pCBMA) hydrogel. Additionally, the pACBMA hydrogel exhibits excellent injectability, moldability, and even recyclability through the preparation of microgels. Through the unique molecular design, the pACBMA hydrogel integrates multiple non‐covalent interactions, including hydrogen bonding, electrostatic interactions, polymer chain entanglement, and steric hindrance of the α‐methyl group. These interactions synergistically contribute to the combination of high hydration, mechanical robustness, and dynamic tunability. These results provide a new design strategy for constructing high‐performance zwitterionic hydrogels with promising potential for diverse biomedical applications.
Emulsion‐Based Multi‐Phase Integrated Microbeads with Inner Multi‐Interface Structure Enable Dual‐Modal Imaging for Precision Endovascular Embolization
Authors: Li Zhihua , Huang Man , Li Yingnan , Wang Yongchao , Ma Yutao , Ma Le , Jiang Hongliang , Ngai To , Tang Jianbo , Guo Qiongyu
Published: July 2024

Microsphere‐based embolic agents have gained prominence in transarterial embolization (TAE) treatment, a critical minimally invasive therapy widely applied for a variety of diseases such as hypervascular tumors and acute bleeding. However, the development of microspheres with long‐term, real‐time, and repeated X‐ray imaging as well as ultrasound imaging remains challenging. In this study, emulsion‐based dual‐modal imaging microbeads with a unique internal multi‐interface structure is developed for TAE treatment. The embolic microbeads are fabricated from a solidified oil‐in‐water (O/W) emulsion composed of crosslinked CaAlg‐based aqueous matrix and dispersed radiopaque iodinated oil (IO) droplets through a droplet‐based microfluidic fabrication method. The CaAlg‐IO microbeads exhibit superior X‐ray imaging visibility due to the incorporation of exceptionally high iodine level up to 221 mgI mL−1, excellent ultrasound imaging capability attributed to the multi‐interface structure of the O/W emulsion, great microcatheter deliverability thanks to their appropriate biomechanical properties and optimal microbead density, and extended drug release behavior owing to the biodegradation nature of the embolics. Such an embolic agent presents a promising emulsion‐based platform to utilize multi‐phased structures for improving endovascular embolization performance and assessment capabilities.