bluuebunny/crossref_metadata_2025 huggingface dataset:
Modes of inheritance of X-Y dissociation in inter-subspecies hybrids between BALB/c mice and Mus musculus molossinus
Authors: Matsuda Y. , Imai H.T. , Moriwaki K. , Kondo K.
Published: May 2008

Genetic analysis of the high frequency of X-Y chromosome dissociation found in primary spermatocytes of F1hybrids between Japanese wild mice (Mus musculus molossinus) and inbred laboratory mice (BALB/c) was attempted. The frequency of X-Y dissociation (X//Y) in both BALB/c and M. m. molossinus was lower than 30% (Low X//Y), while the value was more than 70% (High X//Y) in their F1 hybrids. Two types of progeny (High X//Y and Low X//Y) appeared in the backcross between BALB/c and High X//Y males, although the frequency of Low X//Y progeny decreased with increasing numbers of backcross generations (26.5% at N2, 13.2% at N3, 5.3% at N4, and 0% at N5). Low X//Y sires produced only Low X//Y mice. We hypothesize that at least one heritable factor which is responsible for the end-to-end association of the sex chromosomes (temporally symbolized as Sxa) is located on the common part of the X and Y crhomosomes. The Sxa allele of BALB/c is Sxaaand that of M. m. molossinus is Sxab. The genotype expected in High X//Y males is SxaajSxaband in Low X//Y males and their parental stocks either Sxaa/Sxaaor Sxab/Sxab. The repeated segregation of Low X//Y progeny from High X//Y sires is interpreted simply by assuming that crossing-over has occurred between the X and Y chromosomes. The gradual decrease in the recombinant type mice (Low X//Y) during sequential backcrosses suggests the presence of some autosomal factors that suppress the crossing-over of the sex chromosomes and that do not seem to function in the inter-subspecies hybrids.
Evolution of chromosomal variation in cottontails, genus Sylvilagus (Mammalia: Lagomorpha): S. aquaticus, S. floridanus, and S. transitionalis
Authors: Robinson T.J. , Elder F.F.B. , Chapman J.A.
Published: May 2008

The banding patterns of mitotic chromosome from three cottontail species, Sylvilagus aquaticus (2n = 38), S. floridanus (2n = 42), and S. transitionalis (2n = 46), are presented and compared with those of the proposed leporid ancestral karyotype, the latter being reflected in a species of hare, Lepus saxatilis (2n = 48). The differences in the diploid numbers of the cottontail species are primarily due to the fixation of Robertsonian fusions which have occurred during the evolution of their respective genomes. Of the eight fusion products identified, seven were species specific, while one, which is thought to reflect their more recent common ancestory, is shared by both S. aquaticus and S. floridanus. Other karyotypic differences include interspecific variation in the amount and distribution of constitutive heterochromatin, as well as the presence of two autosomal pairs in S. transitionalis which do not have apparent banding homologies either with the chromosomes of other cottontails or with those of the Lepus genome. The tendency for certain chromosomes in the ancestral karyotype to show a predisposition to undergo fusion events within the Leporidae is discussed.
Fragile X expression studied by clonal analysis and somatic cell hybridization
Authors: Bryant E.M. , Martin G.M. , Hoehn H.
Published: May 2008

The expression of the fragile site on the X chromosome was examined in euploid somatic cell hybrids to determine if a normal genome could complement the abnormal genome and suppress fragile X expression. Fibroblasts from the patient showed the fragile X in 8% to 12% of cells, and fibroblasts from the normal individual showed no fragile X expression. Six fibroblast clones from the patient showed a variable frequency of fragile X expression (from 6.6% to 12%), suggesting that the fragile X is not expressed in a clonal fashion. Three clones from the normal individual did not show the fragile X. Four hybrid clones showed the fragile X in 5.6%, 4.0%, 7.0%, and 4.0% of cells, respectively, indicating that fragile X expression is not completely suppressed by the normal genome.
Identification of cell surface polypeptides encoded by human chromosomes 2 and 5 in human-mouse somatic cell hybrids
Authors: Carlin C.R.
Published: May 2008

Iodinated cell surface polypeptides of human-mouse somatic cell hybrids were analyzed by one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis and high resolution two-dimensional gel electrophoresis in an effort to identify human gene products. Expression of two cell surface polypeptides was positively correlated with retention of specific human chromosomes: a polypeptide of molecular weight 250,000 and isoelectric point 8.3 with the human 5, and a polypeptide of molecular weight 250,000 and isoelectric point 7.0 with the human 2.
Mechanisms involved in the spontaneous occurrence of diploid-triploid chimerism in the mink (Mustela vison) and chicken (Gallus domesticus)
Authors: Fechheimer N.S. , Isakova G.K. , Belyaev D.K.
Published: May 2008

Diploid-triploid chimeras have been observed both in man and in a number of laboratory and livestock animals. The mechanism(s) of their origin remains enigmatic. One approach is to calculate for each proposed mechanism the expected frequencies of zygotes bearing different gonosomic complements in the two cell lines. Observed samples are then compared with the expectations. The mechanisms that have been considered include: (1) fertilization of a blastomere, (2) absorption of the second polar body into a blastomere, (3) fertilization of the first polar body, (4) independent fertilization of both nuclei in binucleated oocytes, (5) fertilization of the second polar body as well as the egg, and (6) fusion of two eggs. The sample of minks comprised three preimplantation embryos, nine postimplantation embryos, and three neonatal pups, with gonosomic complements of 7 XX/XXX, 3 XX/XXY, 4XY/XXY, and 1 XY/XYY; the chicks comprised 13 embryos at 1 day of incubation, 1 embryo at 4 days, and one adult bird, with gonosomic complements of 5 ZZ/ZZZ, 1 ZZ/ZZW, 1 ZW/ZZZ, 3 ZW/ZZW, and 5 ZW/ZWW. If it is assumed that within each species all, or most, of the 2n/3n chimeras arise from the same mechanism, then the occurrence of a type that has an expected frequency of zero for a given proposed mechanism effectively eliminates that mechanism as a source. All of the chicks could have resulted from only one mechanism, viz., independent fertilization of both nuclei in binucleated oocytes. The sample of minks could have resulted from the same mechanism or from fertilization of a blastomere of a two-cell, 2n embryo.
Differential NOR activities in somatic and germ cells of Monodelphis domestica (Marsupialia, Mammalia)
Authors: Merry D.E. , Pathak S. , VandeBerg J.L.
Published: May 2008

Somatic and germ cells of the gray short-tailed opossum (Monodelphis domestica) were analyzed cytogenetically by C-banding, G-banding, and silver staining. The diploid chromosome number was found to be 18. C-banding revealed constitutive heterochromatin at the centromeres of all chromosomes, with additional heterochromatin on one arm of the Y. Silver staining for the localization of nucleolus organizer regions (NORs) showed NORs on the X and on a pair of autosomes, tentatively designated as chromosome 5. In females, the NORs on both X chromosomes were active in 98.3% of all somatic cells analyzed, indicating that this locus escapes sex-chromosome dosage compensation. Chromosome 5 showed an active NOR in only 16.2% of cells scored from the six females. In males, 100% of the somatic cells analyzed showed an active NOR on the X chromosome. Greater variability of autosomal NOR activity was observed between male individuals and between different tissues of the same male. Silver staining of pachytene spermatocytes revealed that (1) only an autosomal NOR was active, whereas the NOR of the X chromosome was inactive, and (2) the X and Y chromosomes showed asynaptic behavior, even though all autosomal synaptonemal complexes were fully formed during this stage.
Complexity of control of tumorigenic expression in intraspecies hybrids of human SV40-transformed fibroblasts and normal human fibroblast cell lines
Authors: Weissman B.E. , Stanbridge E.J.
Published: May 2008

Somatic cell hybrids between SV40-transformed human fibroblast cells and normal human fibroblasts were isolated and tested for growth in vitro and in athymic nujnu (nude) mice. All hybrid cells formed by a cross of WI-18/VA-2, a tumorigenic SV40-transformed human fibroblast, with IMR-90 expressed T antigen and grew in the appropriate selective medium. However, tumorigenic potential ranged from completely suppressed to fully expressed in these hybrid cells. In addition, all hybrid cells formed between LNSV, a nontumorigenic SV40-transformed human fibroblast, and IMR-90 were nontumorigenic. Previous studies have shown that the tumorigenic potential of hybrids cells formed between a variety of human tumor cell lines and normal human fibroblasts is completely suppressed. These results imply that the genetic control of tumorigenic expression in virally transformed human cells differs from that seen in spontaneously arising human tumor cells.
The meiotic chromosomes of Cebus apella (Cebidae, Platyrrhini)
Authors: Seuánez H.N. , Armada J.L. , Barroso C. , Rezende C. , da Silva V.F.
Published: May 2008

An analysis of the meiotic chromosomes of Cebus apella (Cebidae, Platyrrhini) has allowed for the visualization of constitutive heterochromatic regions throughout the meiotic cycle and has permitted the identification of four chromosomes in the first and the second divisions. In pachytene nuclei, and in pachytene spreads where synaptonemal complexes were visible, one heterochromatic region was frequently unpaired. No chiasmata were found in heterochromatic regions, and there was no evidence of chiasma terminalization. The role of heterochromatin in homologous pairing and its relationship to chiasma position and number in meiotic configurations were discussed. A comparison was made between bivalent 9 in C. apella and bivalent 21 in man, based on the interspecific homologies between these chromosomes. A similar comparison was made between the Algerian and Asian hedgehogs, where marked differences in the content of constitutive heterochromatin occur in two chromosome pairs.
The effect of cell kinetics and harvest time on SCE and NOR associations in Macaca fuscata lymphocytes
Authors: Ardito G. , Lamberti L. , Bigatti P. , Stanyon R.
Published: May 2008

The relationship between cell kinetics and cell harvest time on sister chromatid exchange (SCE) and NOR (marker chromosome) association was investigated in cultured Macaca fuscata lymphocytes. The average number of SCE’s in individuals ranged from 3.77 to 9.07 per cell. The highest SCE rate was founc in cultures harvested at 60 h. The data suggest a decrease in SCE frequency between 60 h and subsequent cell harvest at 72, 84, and 96 h. NOR association frequency was also affected by cell kinetics, as well as by eel harvest time. The highest association frequencies were at 48 h, when the number of first mitoses was greatest
Displacement of chromosomes in mitosis: a technique for assessing differential chromosome error
Authors: Ford J.H. , Roberts C.
Published: May 2008

To assess whether displacement—the appearance of individual chromosomes inside of the ring of chromosomes attached to spindle fibers—is a valid method of analyzing chromosome misdivision, displacement data from six healthy female subjects were compared with data for mitotic and meiotic nondisjunction. Statistical analysis indicated that nondisjunction and displacement are equivalent methods of assessing differential chromosome error. Tests for homogeneity of the data sets showed no significant heterogeneity for the mitotic data, but chromosomes 1, 2, 11, 16, 17, 19, and 20 were responsible for significant heterogeneity in the meiotic data.
Chiasma frequency and nondisjunction in heteromorphic bivalents: meiotic behavior in T(1;13)70H/T(1;13)lWa mice as compared to T(1;13)70H/T(1;13)70H mice
Authors: Wauben-Penris P.J.J. , van der Hoeven F.A. , de Boer P.
Published: May 2008

Two different reciprocal translocations between chromosomes 1 and 13 in the mouse, T(1;13)70H and T(l;13)lWa, were intercrossed, resulting in T(l;13)70H/T(l;13)lWa animals, possessing two heteromorphic marker bivalents. The meiotic behavior of these animals was compared to that of T(1;13)70H/T(1;13)70H animals. In females the chiasma frequency in the translocation bivalents was decreased by the presence of the loops following meiotic pairing, but in males chiasma frequencies were not changed. The nondisjunction level of both translocation bivalents was increased in females and males. The nondisjunction level of bivalents not involved in the translocations was increased in the females, but not in the males. Possible causes and relevance of these phenomena are discussed.
A direct demonstration of somatically paired heterochromatin of human chromosomes
Authors: Schmid M. , Grunert D. , Haaf T. , Engel W.
Published: May 2008

Human lymphocyte cultures were treated with different concentrations of 5-azacytidine for various lengths of time. This cytosine analog induces very distinct undercondensation in the heterochromatin of chromosomes 1,9, 15, 16, and Y if applied in low doses during the last hours of culture. These regions are further distinguished by their intense distamycin A/DAPI-staining and highly methylated DNA. In interphase nuclei, these heterochromatic regions are frequently somatically paired. These somatic pairings are preserved up to the metaphase stage in the 5-azacytidine-treated cultures and are thus susceptible to direct analysis. The specific effect of 5-azacytidine on the heterochromatin of these chromosomes, its conserving effect on somatic pairing, and some of the consequences of the somatic pairing on the development of human chromosome aberrations are discussed.
Assignment of the native Chinese hamster dihydrofolate reductase gene to chromosome 2
Authors: Roberts M. , Melera P.W. , Davide J.P. , Hart J.T. , Ruddle F.H.
Published: May 2008

The native Chinese hamster DHFR gene was localized to 2pter^-ql4 using a combination of somatic cell hybrid technology and molecular techniques. In addition, PGD, ENOJ, and DTS, previously mapped to Chinese hamster chromosome 2, were localized to 2ql4— > qter. Localization of PGM1 to this region was confirmed. The relationship of the site of the native DHFR gene to the location of the homogeneously staining region in methotrexate-resistant cells is discussed.
A male-sterile insertion in the mouse
Authors: Searle A.G. , Beechey C.V. , de Boer P. , de Rooij D.G. , Evans E.P. , Kirk M.
Published: May 2008

Is(7;l)40H was found in the daughter of a male mouse given spermatozoal X-irradiation. It is a non-inverted insertion of about half of chromosome 7 into chromosome 1, generating a long somatic marker chromosome. Breakpoints are in bands IB, 7B1, and 7F1; linkage tests show that these breakpoints are about midway between fz and In on the 1, and 0.2 units distal to ru-2 and 12 units proximal to fr on the 7. Female carriers had litters of about one-third normal size and showed some decline in length of reproductive life. Males were sterile, with testis weights only 30% of normal and with abrupt cessation of spermatogenesis in pachytene at stage IV of the seminiferous epithelial cycle. Positive sex-vesicle contact with the insertional configuration was found in only 40% of pachytene spermatocytes, which suggested that other factors may be involved in the spermatogonial breakdown. In oocytes at metaphase I 76% of insertion configurations were multivalent, because of one or more chiasmata in the inserted segment, as were 79% of synaptonemal complex configurations in male pachytenes. Karyotyping at 12.5 to 14.5 days of gestation showed that all embryos with duplications of the inserted segment were exencephalic, and the only example of a corresponding deficiency was retarded. Analysis of the consequences of heterozygosity for the insertion shows that the insertion length should be correlated with the frequency of unbalanced offspring and thus with the amount of F1lethality. The genetic length of 36 cM estimated in this way from data on liveborn offspring is in reasonable agreement with estimates from cytological measurements and meiotic configurations but rather higher than that from linkage tests.
Tumor formation by SV40-transformed human cells in nude mice: the role of SV40 T antigens
Authors: Choi K.-H. , Tevethia S.S. , Shin S.
Published: May 2008

Human cells transformed in vitro by SV40 rarely form tumors in nude mice. We examined whether these cells as a group are inherently nontumorigenic or whether they are potentially tumorigenic but rejected by the athymic host, possibly by nonspecific immune mechanisms. SV80 and NG8 are SV40-transformed human cell lines that express all of the transformed properties, including anchorage-independent growth, but do not form tumors in adult nude mice after injection of as many as 108 cells. Both the SV80 and NG8 cell lines have SV40-specific transplantation antigens which crossreact with those present on SV40-transformed (but tumorigenic) rodent cells. We found that SV80 cells, though not NG8 cells, induce progressively growing lethal tumors if the cells are injected repeatedly into neonatal nude mice. Somatic cell hybrids between SV80 or NG8 cells and a highly tumorigenic cell line derived from a human tumor continue to express the virus-induced antigens and fail to form tumors in adult nude mice. These results strongly suggest that at least for some SV40-transformed human cells, the failure to form tumors in nude mice may be due to their expression of virusinduced transplantation antigens rather than the absence of tumorigenic potential.
Extensive chromosomal repatterning in two congeneric species: Pytilia melba, L. and Pytilia phoenicoptera Swainson (Estrildidae; Aves)
Authors: Christidis L.
Published: May 2008

Chromosomal analysis of two species of African finches of the genus Pytilia has been carried out using both G- and C-banding. The karyotypes of these two species were found to differ radically, not only from each other, but also from those of other species in the family Estrildidae. The differences are due to paracentric and pericentric inversions and to tandem fusions. However, not all of the karyotypic differences can be explained by conventional mechanisms. These results are discussed in relation to the role of karyotypic rearrangement in avian evolution and the conversion of microchromosomes to macrochromosomes.
Aspects of a Northern Hemisphere Atmospheric Blocking Climatology
Authors: Tyrlis E. , Hoskins B. J.
Published: May 2008

A comprehensive climatology of Northern Hemisphere blocking is described based on a PV–θ wave-breaking index at the latitude of the climatological storm track and using the 40-yr ECMWF Re-Analysis (ERA-40) dataset. The general characterization of blocking regions is in agreement with most other studies, though more detail is provided here. In the annual average, blocking is most prevalent in the large region from the eastern Atlantic Ocean through Europe to central Asia with a secondary region in the central and eastern Pacific Ocean. Using a blocking criterion with the requirement for both longitudinal extent and temporal persistence, the peak in the frequency is in the Scandinavian region, where 24% of the days are characterized by blocking. In the east Pacific maximum, the corresponding number is 7%. However, there is considerable and very important interannual variability. The decay rate in the number of blocking events lasting at least a specified number of days is significantly less over Europe than elsewhere. However, the average intensity of blocking episodes is slightly higher in the east Pacific. The mean annual cycle of blocking is quite complex. Over most of Europe it continues through the year, with maximum intensities in the autumn and winter. To both the east and west, over the western Atlantic and Asia, there are two periods in the year of highest blocking frequency. Similar two-cycle behavior is found in the eastern Pacific region. The relationship of blocking with the storm track and the mean planetary-scale geopotential ridges is considered, and the evidence that blocking is a particular phenomenon with its own nonlinear dynamics is discussed.
Large-Eddy Simulation of Evaporatively Driven Entrainment in Cloud-Topped Mixed Layers
Authors: Yamaguchi Takanobu , Randall David A.
Published: May 2008

Cloud-top entrainment instability (CTEI) is a hypothesized positive feedback between cloud-top entrainment and enhanced turbulence associated with buoyancy reversal. A sufficiently strong positive feedback is hypothesized to lead to the destruction of the cloud. Numerous studies have investigated the possible role of CTEI in cloud breakup, with ambiguous results.

In this study, CTEI has been extensively investigated using many large-eddy simulations. An idealized experimental design has been used so as not to have any source of turbulence kinetic energy production except for entrainment due to evaporative cooling. A new method has been used to estimate the entrainment rate and to identify the inversion base and top.

The results of the experiments do show the hypothesized positive feedback when the Randall–Deardorff CTEI criterion is met. When CTEI takes place in the numerical experiments, entrainment develops spontaneously through buoyancy reversal and, as a result, leads to cloud dissipation. Cloud dissipation within several hours is simulated in the cases with strong instability. A hypothesized dependence of the strength of the evaporatively driven turbulence on the cloud-top liquid water mixing ratio is confirmed. As expected, with a typical stratocumulus liquid water mixing ratio, the evaporatively driven turbulence is weak.

Additional simulations with longwave radiation, surface latent heat flux, or both suggest that sufficiently strong radiative cooling can prevent cloud destruction by CTEI. For this reason, CTEI usually does not result in cloud dissipation in realistic cases.
The Structure and Mesoscale Organization of Precipitating Stratocumulus
Authors: Savic-Jovcic Verica , Stevens Bjorn
Published: May 2008

Large-eddy simulations are used to explore the structure and mesoscale organization of precipitating stratocumulus. The simulations incorporate a simple, two-moment, bulk representation of microphysical processes, which by varying specified droplet concentrations allows for comparisons of simulations that do and do not develop precipitation. The boundary layer is represented over a large (25.6 km × 25.6 km) horizontal domain using a relatively fine mesh, thereby allowing for the development of mesoscale circulations while retaining an explicit representation of cloud radiative, dynamical and microphysical interactions on scales much smaller than the dominant eddy scale. Initial conditions are based on measurements made as part of the Second Dynamics and Chemistry of the Marine Stratocumulus field study (DYCOMS-II). The simulations show that precipitation is accompanied by sharp reductions in cloudiness and changes in flow topology. Mesoscale features emerge in all of the simulations but are amplified in the presence of drizzle. A cloud albedo of near 75% in the nonprecipitating simulation is reduced to less than 35% in the precipitating case. The circulation transitions from a well-mixed, stationary stratocumulus layer with closed-cellular cloud planforms to a stationary cumulus-coupled layer, with incipient open-cellular cloud planforms and sustained domain-averaged surface precipitation rates near 1 mm day−1. The drizzling simulations embody many other features of observed precipitating stratocumulus, including elevated cloud tops in regions of precipitation and locally higher values of subcloud equivalent potential temperature. The latter is shown to result from the tendency for precipitating simulations to develop greater thermodynamic gradients in the subcloud layer as well as mesoscale circulations that locate regions of upward motion in the vicinity of precipitating cells.
Objective Identification of Nonlinear Convectively Coupled Phases of Monsoon Intraseasonal Oscillation: Implications for Prediction
Authors: Chattopadhyay R. , Sahai A. K. , Goswami B. N.
Published: May 2008

The nonlinear convectively coupled character of the summer monsoon intraseasonal oscillation (ISO) that manifests in its event-to-event variations is a major hurdle for skillful extended-range prediction of the active/break episodes. The convectively coupled character of the monsoon ISO implies that a particular nonlinear phase of the precipitation ISO is linked to a unique pattern of the large-scale variables. A methodology has been presented to capture different nonlinear phases of the precipitation ISO using a combination of a sufficiently large number of dynamical variables. This is achieved through a nonlinear pattern recognition technique known as self-organizing map (SOM) involving six daily large-scale circulation indices. It is demonstrated that the nonlinearly classified states of the large-scale circulation isolated at the SOM nodes without involving any information on rainfall are strongly linked to different phases of evolution of the rainfall ISO, including the active and break phases. While a lower SOM classification involving 9 different states identify the composite phases of the rainfall ISO, a higher SOM classification involving 81 states can identify different shades of composite phase of the rainfall ISO. The concept of isolating the nonlinear states, as well as the technique of doing so, is robust as almost identical phases of precipitation ISO are identified by the large-scale circulation indices derived from two different reanalysis datasets, namely, the 40-yr ECMWF Re-Analysis (ERA-40) and the NCEP–NCAR reanalysis.

The ability of the SOM technique to isolate spatial structure and evolutionary history of nonlinear convectively coupled states of the summer monsoon ISO opens up a new possibility of extended-range prediction of summer monsoon ISO. This knowledge is used to develop an analog technique for predicting different phases of monsoon ISO. Skillful four-pentad lead prediction of rainfall over central India is demonstrated with the model using only large-scale circulation fields. A major strength of the model is that it can easily be used for real-time extended-range prediction of monsoons.
A Novel Approach for Representing Ice Microphysics in Models: Description and Tests Using a Kinematic Framework
Authors: Morrison Hugh , Grabowski Wojciech W.
Published: May 2008

This paper documents the development of a novel approach for representing ice microphysics in numerical models. In this approach, the ice particle mass–dimension and projected-area–dimension relationships vary as a function of particle size and rimed mass fraction. All ice microphysical processes and parameters are calculated in a self-consistent manner in terms of these mass–dimension and area–dimension relationships. The rimed mass fraction is predicted locally by separately predicting the ice mixing ratios acquired through water vapor deposition and through riming. The third predicted variable is the number concentration of ice particles. This approach allows representing in a natural way the gradual transition from small to large ice particles due to growth by water vapor deposition and aggregation and from unrimed crystals to graupel due to riming. In traditional approaches, these processes are treated by separating ice particles into predefined categories (such as cloud ice, snow, and graupel) using fairly arbitrary thresholds and conversion rates. With some modifications, the new approach can be employed in either bin or bulk microphysical models.

In this paper, the new approach is implemented in a bulk two-moment microphysical scheme representing both warm-rain and ice processes and it is applied to an idealized 2D kinematic framework mimicking a shallow mixed-phase cumulus. The size distributions of cloud droplets, drizzle/rain drops, and ice particles are represented using gamma distributions. The new scheme is compared to a version of the scheme that uses the traditional approach for ice microphysics; that is, unrimed ice/snow and graupel are separate species, with threshold-based conversion rates between the former and the latter. The new and traditional schemes produce similar results, although the traditional scheme, unlike the new scheme, produces a distinct double maximum in the surface precipitation rate, corresponding to precipitation shafts consisting of either ice/snow or graupel. The relative magnitude of these peaks, as well as the ice water path and optical depth of the simulated cloud, is highly sensitive to the threshold for converting unrimed ice to graupel. In contrast, the new scheme does not require any conversion threshold and predicts formation of ice particles with wide range of rimed fractions.
Exponential Smallness of Inertia–Gravity Wave Generation at Small Rossby Number
Authors: Vanneste J.
Published: May 2008

This paper discusses some of the mechanisms whereby fast inertia–gravity waves can be generated spontaneously by slow, balanced atmospheric and oceanic flows. In the small Rossby number regime relevant to midlatitude dynamics, high-accuracy balanced models, which filter out inertia–gravity waves completely, can in principle describe the evolution of suitably initialized flows up to terms that are exponentially small in the Rossby number ɛ, that is, of the form exp(−α/ɛ) for some α > 0. This suggests that the mechanisms of inertia–gravity wave generation, which are not captured by these balanced models, are also exponentially weak. This has been confirmed by explicit analytical results obtained for a few highly simplified models. These results are reviewed, and some of the exponential-asymptotic techniques that have been used in their derivation are presented. Two types of mechanisms are examined: spontaneous-generation mechanisms, which generate exponentially small waves from perfectly balanced initial conditions, and unbalanced instability mechanisms, which amplify unbalanced initial perturbations of steady flows. The relevance of the results to realistic flows is discussed.
Factors Affecting ENSO’s Period
Authors: MacMynowski Douglas G. , Tziperman Eli
Published: May 2008

Accurately capturing the observed mean period of ENSO in general circulation models (GCMs) is often challenging, and it is therefore useful to understand which parameters and processes affect this period. A computationally efficient simulation-based approach is used to extract both the dominant eigenvalues and corresponding eigenvectors of the linearized model from the Zebiak–Cane intermediate-complexity model of ENSO without having to directly construct the linearization. The sensitivity of the period to a variety of parameters is examined, including atmosphere–ocean coupling, atmospheric heating parameterization, thermocline depth zonal profile, western boundary reflection coefficient, atmospheric and ocean wave speeds or Rossby radii of deformation, ocean decay time, and the strength of the annual cycle. In addition to the sensitivity information, the spatial structures of the main fields (SST, thermocline thickness, and more) that are involved in period changes are obtained to aid in the physical interpretation of the sensitivities.

There are three main time lags that together compose one-half of a model ENSO period: the Rossby-plus-Kelvin wave propagation time for a wind-caused central Pacific disturbance to propagate to the western ocean and back, SST dynamics that determine the lag between eastern ocean thermocline anomalies and eastern ocean SST anomalies, and the “accumulation” lag of integrating a sufficient delayed wave signal arriving from the western ocean to cancel the eastern ocean anomalies. For any of the parameter changes considered, the eigenvector changes show that the largest contributor to the period change is from changes to the last of these three mechanisms. Physical mechanisms that affect this accumulation delay are discussed, and the case is made that any significant change to ENSO’s period is in turn likely to involve changes to this delay.
Rossby Wave Ray Tracing in a Barotropic Divergent Atmosphere
Authors: Lu Chungu , Boyd John P.
Published: May 2008

The effects of divergence on low-frequency Rossby wave propagation are examined by using the two-dimensional Wentzel–Kramers–Brillouin (WKB) method and ray tracing in the framework of a linear barotropic dynamic system. The WKB analysis shows that the divergent wind decreases Rossby wave frequency (for wave propagation northward in the Northern Hemisphere). Ray tracing shows that the divergent wind increases the zonal group velocity and thus accelerates the zonal propagation of Rossby waves. It also appears that divergence tends to feed energy into relatively high wavenumber waves, so that these waves can propagate farther downstream. The present theory also provides an estimate of a phase angle between the vorticity and divergence centers. In a fully developed Rossby wave, vorticity and divergence display a π/2 phase difference, which is consistent with the observed upper-level structure of a mature extratropical cyclone. It is shown that these theoretical results compare well with observations.
Finescale Structure and Dynamics of an Atmospheric Temperature Interface
Authors: Hohreiter Vincent
Published: May 2008

Near-ground observations of an atmospheric temperature interface in the stable nocturnal boundary layer are reported. The thermal effect of the interface passage was a 5-K decrease in temperature during a 5-min period in which changes in wind speed and wind direction were also observed. The interface is of unknown origin and horizontal and vertical scale. A 32-Hz time series of temperature measured with a sonic anemometer–thermometer at 1.5 m above ground level revealed a sharp, nonintermittent decrease in temperature (∼1 K s−1) nested within a more gradual, intermittent decrease (∼1 K min−1). A first attempt to extricate this subtle feature with regard to the relevant physics of generalized density currents is presented. It is shown that a very similar feature has been observed in the literature, but not interpreted for its physical significance. The contribution of this paper is its unique interpretation of the high-resolution temperature time series as it corresponds to the finescale physical character of an interface of density or temperature, and the motion of such an interface along the ground. Parameters of interest, including a spatial temperature gradient normal to the interface (∼1 K m−1), an interfacial thickness (2.8 m), and a thermal boundary layer for the interface (288 m), are calculated. Additionally, theoretical and empirical arguments are presented for a viscous suppression of turbulent mixing in the immediate vicinity of an interface of density or temperature.
Evaluating the Consistency between Statistically Downscaled and Global Dynamical Model Climate Change Projections
Authors: Timbal B. , Hope P. , Charles S.
Published: May 2008

The consistency between rainfall projections obtained from direct climate model output and statistical downscaling is evaluated. Results are averaged across an area large enough to overcome the difference in spatial scale between these two types of projections and thus make the comparison meaningful. Undertaking the comparison using a suite of state-of-the-art coupled climate models for two forcing scenarios presents a unique opportunity to test whether statistical linkages established between large-scale predictors and local rainfall under current climate remain valid in future climatic conditions. The study focuses on the southwest corner of Western Australia, a region that has experienced recent winter rainfall declines and for which climate models project, with great consistency, further winter rainfall reductions due to global warming. Results show that as a first approximation the magnitude of the modeled rainfall decline in this region is linearly related to the model global warming (a reduction of about 9% per degree), thus linking future rainfall declines to future emission paths. Two statistical downscaling techniques are used to investigate the influence of the choice of technique on projection consistency. In addition, one of the techniques was assessed using different large-scale forcings, to investigate the impact of large-scale predictor selection. Downscaled and direct model projections are consistent across the large number of models and two scenarios considered; that is, there is no tendency for either to be biased; and only a small hint that large rainfall declines are reduced in downscaled projections. Among the two techniques, a nonhomogeneous hidden Markov model provides greater consistency with climate models than an analog approach. Differences were due to the choice of the optimal combination of predictors. Thus statistically downscaled projections require careful choice of large-scale predictors in order to be consistent with physically based rainfall projections. In particular it was noted that a relative humidity moisture predictor, rather than specific humidity, was needed for downscaled projections to be consistent with direct model output projections.
The Impact of the Time Step on the Intensity of ITCZ in an Aquaplanet GCM
Authors: Mishra Saroj K. , Srinivasan J. , Nanjundiah Ravi S.
Published: May 2008

Several numerical experiments have been conducted using the NCAR Community Atmosphere Model, version 3 (CAM3) to examine the impact of the time step on rainfall in the intertropical convergence zone (ITCZ) in an aquaplanet. When the model time step was increased from 5 to 60 min the rainfall in the ITCZ decreased substantially. The impact of the time step on the ITCZ rainfall was assessed for a fixed spatial resolution (T63 with L26) for the semi-Lagrangian dynamical core (SLD). The increase in ITCZ rainfall at higher temporal resolution was primarily a result of the increase in large-scale precipitation. This increase in rainfall was caused by the positive feedback between surface evaporation, latent heating, and surface wind speed. Similar results were obtained when the semi-Lagrangian dynamical core was replaced by the Eulerian dynamical core. When the surface evaporation was specified, changes in rainfall were largely insensitive to temporal resolution. The impact of temporal resolution on rainfall was more sensitive to the latitudinal gradient of SST than to the magnitude of SST.
Locke, Natural Law, and New World Slavery
Authors: Farr James
Published: May 2008

This essay systematically reformulates an earlier argument about Locke and new world slavery, adding attention to Indians, natural law, and Locke's reception. Locke followed Grotian natural law in constructing a just-war theory of slavery. Unlike Grotius, though, he severely restricted the theory, making it inapplicable to America. It only fit resistance to “absolute power” in Stuart England. Locke was nonetheless an agent of British colonialism who issued instructions governing slavery. Yet they do not inform his theory—or vice versa. This creates hermeneutical problems and raises charges of racism. If Locke deserves the epithet “racist,” it is not for his having a racial doctrine justifying slavery. None of this makes for a flattering portrait. Locke's reputation as the champion of liberty would not survive the contradictions in which new world slavery ensnared him. Evidence for this may be found in Locke's reception, including by Southern apologists for slavery.
Gender-Specific Factors Associated With Community Substance Abuse Treatment Utilization Among Incarcerated Substance Users
Authors: Staton-Tindall Michele , Havens Jennifer R. , Oser Carrie B. , Prendergast Michael , Leukefeld Carl
Published: May 2008

This article describes the independent correlates of preincarceration community substance abuse treatment utilization for male and female offenders currently participating in prison-based treatment. As part of the National Institute on Drug Abuse—funded Criminal Justice Drug Abuse Treatment Studies cooperative agreement, this protocol was implemented by four collaborating research centers. Males with a history of treatment utilization were more likely to be older, to have used crack, and to have had a greater number of arrests, and they were less likely to be arrested for a violent charge. Females with previous treatment were more likely to have been hospitalized for a health condition and were significantly more likely to have lived with someone else before prison rather than in their own home. These findings suggest that factors associated with preincarceration treatment utilization differ by gender, which may have important implications for correctional-based treatment assessment, reentry planning, and transitional case management.
Self-Reported Vision, Upper/Lower Limb Disability, and Fall Risk in Older Adults
Authors: Steinman Bernard A.
Published: May 2008

The purpose of this study was to examine independent and interactive roles of self-reported vision status and upper and lower limb disability as predictors of falls in people 65 and older. Data from the 2002 and 2004 panels of the Health and Retirement Study were analyzed using binary logistic regression. Results indicated a reduced or eliminated role of vision status after upper and lower limb disabilities were controlled. Gender differences were found with respect to health conditions that predicted falls; however, vision status was not found to have a moderating influence on upper and lower limb disability in predicting falls for men or women. Implications for exercise programs designed for older people with visual impairments are discussed.
Students' Opinions Regarding Their Individualized Education Program Involvement
Authors: Agran Martin , Hughes Carolyn
Published: May 2008

Despite national interest in promoting self-determination and active involvement in individualized education program (IEP) planning, available data suggest that many students have little involvement in these activities. Findings on the extent to which students are provided opportunities to be involved in IEP development and to receive self-determination instruction have been based on parent and teacher input, with little input provided by students. In this study, researchers piloted a tool that asked students with intellectual and other disabilities to provide input on their involvement in IEP development and their opportunities to learn self-determination strategies. Findings reveal that although the majority of students reported receiving some instruction on one or more self-determination strategies, few students were provided instruction in having an active role in the IEP process.
An Intersectional Analysis of Sexual Harassment in Housing
Authors: Tester Griff
Published: May 2008

Research on sexual harassment in the workplace is extensive, yet research on sexual harassment in housing is extremely limited. In this study, the author qualitatively analyzes 60 cases of sexual harassment in rental housing to expand on recent research addressing this topic by examining the forms and processes of housing-related sexual harassment in more detail, with a particular focus on class and race. This study reveals that sexual coercion is the most common form of sexual harassment for women in housing. It also demonstrates the intersections of race, gender, and class in shaping this harassment. Landlords used their institutional authority in the housing context and racialized gender stereotypes to exploit tenants'economic vulnerabilities and sexually coerce them. Landlords also used these strategies to defend themselves against complaints of harassment.
Gall, Gallantry, and the Gallows
Authors: Linders Annulla , Van Gundy-Yoder Alana
Published: May 2008

In this article, the authors examine how the debate over women's executions during the nineteenth and early twentieth century funneled and in various ways processed the contrary demands of gender and capital justice. They show how encounters with capital punishment both reflected and reinforced dominant interpretations of womanhood and as such contributed to the intricate web of normative strictures that affected all women at the time. At the same time, however, the often heated debates that accompanied such cases pried open some of the contradictions inherent in the dominant interpretations and, as a result, came to challenge the boundaries that separated not only women from men but also women from each other. Rather than viewing gender as a unidirectional influence on capital punishment, the authors argue that gender is best approached as an evolving social category that gets reconstructed, modified, and transformed whenever it is implicated in social practices and public debates.
The Transnational Traffic in Human Body Parts
Authors: Geis Gilbert , Brown Gregory C.
Published: May 2008

Organized criminal syndicates, notable for their adaptability to opportunities offered by changing social and market conditions, have become involved in the transnational trade in human organs. The complexity of such operations, however, has to date restricted organized crime groups to a limited segment of the worldwide trafficking in human body parts. This article offers evidence indicating that the fear of the theft of body parts plays a prominent part in communities where poverty and victimization are widespread. The horror of involuntary bodily mutilation feeds into scripts that tend to exaggerate organized crime's role in such activities.
Revolving Doors?
Authors: Etzion Dror , Davis Gerald F.
Published: May 2008

This article analyzes the movement of personnel among elite positions in business and government, contrasting the staffing patterns at higher rungs of the executive branch during the Clinton and G. W. Bush administrations. We find that the Bush administration recruited far more heavily from among corporate officers and directors than did the Clinton administration, particularly when staffing ambassadorships. We also find that both administrations served as springboards for subsequent corporate board appointments. There were relatively few patterns with respect to industry or geography, with the exception of the military: All but one of the Joint Chiefs of Staff at the turn of the millennium ended up serving on the board of a military contractor after completing their government service.
A Cluster Analysis of Personality Style in Adults With ADHD
Authors: Robin Arthur L. , Tzelepis Angela , Bedway Marquita
Published: May 2008

Objective: The purpose of this study was to use hierarchical linear cluster analysis to examine the normative personality styles of adults with ADHD. Method: A total of 311 adults with ADHD completed the Millon Index of Personality Styles, which consists of 24 scales assessing motivating aims, cognitive modes, and interpersonal behaviors. Results: The sample was randomly divided into half, and independent hierarchical linear cluster analyses were performed on each half to identify replicable clusters. A three-cluster solution was selected, and two of the clusters were replicated across the independent analyses. Participants in Cluster 1 manifested more polarized, negative motivating aims, cognitive modes, and interpersonal behaviors than participants in Cluster two. Conclusion: Hierarchical linear cluster analyses identified two very different personality styles in a sample of adults with ADHD, with implications for clinicians and future research. (J. of Att. Dis. 2008; 12(3) 254-263)