bluuebunny/crossref_metadata_2025 huggingface dataset:
Mild renal pyelectasis in the second trimester: determination of cut‐off levels for postnatal referral
Authors: Cohen‐Overbeek T. E. , Wijngaard‐Boom P. , Ursem N. T. C. , Hop W. C. J. , Wladimiroff J. W. , Wolffenbuttel K. P.
Published: March 2005

Objective

To establish guidelines for postnatal referral of fetuses presenting with mild pyelectasis in the second trimester of pregnancy.

Methods

In a retrospective study, 87 fetuses with a renal pelvis anteroposterior (RPAP) diameter of ≥ 4 mm and ≤ 10 mm before 28 weeks of gestation were included. All patients had a third‐trimester scan and fetuses with an RPAP diameter of ≥ 10 mm at that stage were referred for postnatal assessment. The family practitioner of all infants with an RPAP of < 10 mm in the third trimester was contacted for follow‐up information. The RPAP diameter most predictive of renal pathology was determined with receiver–operating characteristics (ROC) curve analysis for both the first and second scans.

Results

In 36 of 87 infants, 49 abnormal kidneys were diagnosed. Seven infants required surgery on eight renal tracts. The ROC curves of the first scan, second scan and differences between scans resulted in an area under the curve of 0.60, 0.87 and 0.85, respectively. The sensitivities and specificities for a cut‐off level of 8, 9 and 10 mm at the second scan were 80%, 71% and 61% and 79%, 90% and 93%, respectively. At a cut‐off level of 10 mm, only cases of insignificant minimal dilatation and a case of vesicoureteric reflux (VUR) requiring surgery were not detected.

Conclusion

After establishing a diagnosis of mild pyelectasis before 28 weeks, a second scan is mandatory to determine which infants need postnatal evaluation. A cut‐off level of 8 mm has a low specificity but includes most cases of pathology. A cut‐off level of 10 mm detects most significant pathology; however, VUR may not be detected. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Inverted repeat of a large segment unveiled on the right arm of Saccharomyces cerevisiae chromosome II
Authors: Ohnishi Katsunori , Ono Bun‐ichiro
Published: March 2005

By means of gene disruption analyses, Saccharomyces cerevisiae strain YPH499 was shown to have two, and only two, copies of ATP3 that encodes the γ‐subunit of H+‐dependent ATP synthase and locates on the right arm of chromosome II. Linkage analyses of the two distinguishably marked copies of ATP3 indicated that the distance between them was about 43 cM. Since YBR030W, an ORF proximal to ATP3 by a distance of 17 kbp, was also found to be duplicated, we marked them with two distinguishable nutritional markers, which were also distinguishable from those used for marking the two copies of ATP3, and achieved four‐point linkage analyses; CEN2 marked with an appropriate nutritional marker gene was included as a reference point. And, the following linkage map was deduced: CEN2– [11 cM]–YBR030Wa– [8 cM]–ATP3a–[47 cM]–ATP3b– [55 cM]–YBR030Wb. From this map, we suspected that a segment spanning at least YBR030W–ATP3 would be inversely duplicated on the right arm of chromosome II. We then carried out chromosome fragmentation analyses, using several laboratory strains including YPH499, and obtained data in accord with our speculation for all strains, although the distance between the two copies of ATP3 varied from 48 kbp to 192 kbp among the strains examined. Copyright © 2005 John Wiley & Sons, Ltd.
Mouse polyomavirus mediated effects on the infected cell membrane studied by dielectric spectroscopy
Authors: Bonincontro Adalberto , Melucci-Vigo Gianna , Risuleo Gianfranco
Published: March 2005

The effect of polyomavirus on the infected cell has been investigated by dieclectric spectroscopy. This technique has a great potential in the study of the ion transport properties of the cell membrane. The results presented in this communication suggest a correlation between progression of the viral infection and dielectric features of the infected, cell plasma membrane.
Insulin-like growth factor I enhances the formation of type I collagen in hydrocortisone-treated human osteoblasts
Authors: Jonsson Kenneth B. , Ljunghall Sverker , Karlström Olle , Johansson Anna G. , Mallmin Hans , Ljunggren Östen
Published: March 2005

We have studied the effect of insulin-like growth factor I (IGF-I) on the formation of osteocalcin and type I collagen in isolated human osteoblasts. IGF-I at and above 0.1 nM stimulated the formation of type I collagen as measured by the type I procollagen carboxyterminal peptide (PICP), in human osteoblasts, incubated for 72 hrs in serumfree conditions. The secretion of osteocalcin was not affected by IGF-I while 1,25(OH)2 vitamin D3 significantly enhanced the formation of osteocalcin. When human osteoblast-like cells were incubated with hydrocortisone (1 μM), a significant decrease in the release of both PICP and osteocalcin was seen. Addition of IGF-I to human osteoblasts also treated with hydrocortisone normalized the PICP-formation but did not affect the suppressed osteocalcin-formation. These data indicate that IGF-I reverses selective effects of hydrocortisone on bone.
Significant species‐dependence of P700 redox potential as verified by spectroelectrochemistry: Comparison of spinach and Theromosynechococcus elongatus
Authors: Nakamura Akimasa , Suzawa Tomoyuki , Kato Yuki , Watanabe Tadashi
Published: March 2005

The redox potentials of P700, the primary electron donor of photosystem (PS) I, of spinach and Thermosynechococcus elongatus were determined by means of spectroelectrochemistry with an error range of ±2–3 mV, to find that the redox potential of P700 in T. elongatus is lower by ca. 50 mV as compared with spinach. The shift in the P700 redox potential of PS I core particles prepared by harsh detergent treatments remained to within 10 mV for both organisms. These results show that the 50 mV difference in the P700 redox potential between the two organisms is not a detergent‐induced artifact but reflects an intrinsic property of each PS I.
Research note: amendments to the model for predicting age at sexual maturity for growing pullets of layer strains following changes in photoperiod
Authors: LEWIS P. D. , MORRIS T. R.
Published: March 2005

A model was published by Lewis et al. (2002) to predict the mean age at first egg (AFE) for pullets of laying strains reared under non-limiting environmental conditions and exposed to a single change in photoperiod during the rearing stage. Subsequently, Lewis et al. (2003) reported the effects of two opposing changes in photoperiod, which showed that the first change appears to alter the pullet's physiological age so that it responds to the second change as though it had been given at an earlier age (if photoperiod was decreased), or later age (if photoperiod was increased) than the true chronological age. During the construction of a computer model based on these two publications, it became apparent that some of the components of the models needed adjustment. The amendments relate to (1) the standard deviation (S.D.) used for calculating the proportion of a young flock that has attained photosensitivity, (2) the equation for calculating the slope of the line relating AFE to age at transfer from one photoperiod to another, (3) the equation used for estimating the distribution of AFE as a function of the mean value, (4) the point of no return when pullets which have started spontaneous maturation in response to the current photoperiod can no longer respond to a late change in photoperiod and (5) the equations used for calculating the distribution of AFE when the trait is bimodal.
(Tanz-)Bewegungen als Ausdruck der Lebenseinstellung des Menschen und Einsatzmöglichkeiten in diesem Zusammenhang in der Sozialen Arbeit
Authors: Erdmann-Rajski Katja
Published: March 2005

Zusammenfassung. Ausgangspunkt des Artikels ist der Gedanke, dass Soziale Arbeit immer auch eine Auseinandersetzung damit ist, wie der Mensch sich und seine Umwelt wahrnimmt. Um bei der Diskussion um die Wahrnehmungsweisen des Menschen einen neuen Blickwinkel zu eröffnen, wird hier der Frage nachgegangen, inwieweit (Tanz-)Bewegungen diesbezüglich aufschlussreich (für die Soziale Arbeit) sind. Zunächst werden drei unterschiedliche Bewegungsweisen am Beispiel vom Walzer, von einer Richtung im so genannten Ausdruckstanz und am Charleston beschrieben und analysiert. Dazu werden Interaktionen im Tanz untersucht. Diese beziehen sich darauf, welche Schlüsse sich aus den Bewegungsabläufen während eines Tanzes auf die Erfahrung des eigenen Körpers ziehen lassen und in welcher Weise den Tänzern Raum und Zeit gegenwärtig sind. Weiter wird beschrieben, wie Tänzer miteinander Verbindung aufnehmen und wie sie dabei aufeinander wirken. Dann soll noch untersucht werden, von welcher Person beim Tanz die Aktivität ausgeht, wer somit die Dynamik bestimmt. Anhand dieser Untersuchungen wird anschließend gefragt, ob die unterschiedlichen Bewegungsweisen Tendenzen in den gesellschaftlichen Ordnungsvorstellungen und Wahrnehmungsweisen der Gesellschaft des 20./21. Jahrhunderts erkennen lassen. In einem zweiten Schritt wird die Frage gestellt, wie in der sozialpädagogischen Praxis mit Bewegung und Tanz im Blick auf den Zusammenhang von Bewegungen und Wahrnehmungsweisen gearbeitet werden könnte.
Impact of GPS satellite antenna offsets on scale changes in global network solutions
Authors: Ge M. , Gendt G. , Dick G. , Zhang F. P. , Reigber C.
Published: March 2005

In this paper, we demonstrate that biases in the GPS satellite antenna phase center offsets could lead to scale biases in global network solutions, which change along with the observed satellite constellation. To validate the IGS standard offset values, satellite‐specific offsets are estimated from GPS data and the network solutions are re‐adjusted with these estimates. Both the estimated offsets and the re‐adjusted network scales confirmed that the IGS standard offsets are significantly biased and produce scale changes of more than 1 ppb. From investigations of the offset inhomogeneities among satellites belonging to the same block type, it is strongly recommended that block‐type‐specific offsets used presently as IGS standard should be replaced by satellite‐specific ones.
Separated status of the natural dust plume and polluted air masses in an Asian dust storm event at coastal areas of China
Authors: Zhang Daizhou , Iwasaka Yasunobu , Shi Guangyu , Zang Jiaye , Hu Min , Li Chanyi
Published: March 2005

Asian dust particles usually refer to mineral particles which originate from arid and semiarid areas in the Asian continent and disperse eastward in a wide range in the atmosphere. Their appearances in the downstream marine areas are always accompanied by high concentrations of sulfate and nitrate, suggesting their significance as a medium for pollutant conversion and transportation. However, analysis of particles collected at a coastal site in east China before and after the cold front arrival of a heavy dust–loading low‐pressure system in this study revealed that air masses polluted by anthropogenic emissions from local or regional areas and the natural Asian dust plume from northwest China were in different air parcels. Anthropogenic pollutants were in the prefrontal air while the so‐called Asian dust particles were in the postfrontal air. There was a large amount of anthropogenic mineral particles in the polluted air masses, and the particles were abundant in sulfur, sodium, and calcium, while the so‐called Asian dust particles were very “clean” (meaning lack of anthropogenic pollution). Continuous records of PM10, SO2, and O3 concentrations indicated that the cold front was the boundary layer between the polluted air masses and the clean dust plume. Hence, at the coastal areas the Asian dust plume and polluted air masses did not mix with each other and were separated in two consecutive air parcels by the cold front although they were in the same low‐pressure system. In addition, the analysis also revealed that calcium was not a good indicator for Asian dust from natural sources because the anthropogenic mineral particles contained significant calcium.
On the shape of bottle-brush macromolecules: Systematic variation of architectural parameters
Authors: Rathgeber Silke , Pakula Tadeusz , Wilk Agnieszka , Matyjaszewski Krzysztof , Beers Kathryn L.
Published: March 2005

We measured the form factor of bottle-brush macromolecules under good solvent conditions with small-angle neutron scattering and static light scattering. The systems under investigation are brushes, synthesized via the grafting-from route, built from a poly(alkyl methacrylate) backbone to which poly(n-butyl acrylate) side chains are densely grafted. The aim of our work is to study how the systematic variation of structural parameters such as the side chain length and backbone length change the conformation of the polymer brushes in solution. All spectra can be consistently described by a model, considering the bottle-brush polymers as flexible rods with internal density fluctuations. Parameters discussed are (1) the contour length per main chain monomer lb, (2) the fractal dimension of the side chains Ds, as well as (3) the fractal dimension D, and (4) the Kuhn length λk of the overall brush. lb=0.253±0.008nm is found to be independent of the side chain length and equal to the value found for the bare main chain, indicating a strongly stretched conformation for the backbone due to the presence of the side chains. The fractal dimension of the side chains is determined to be Ds=1.75±0.07 which is very close to the value of 1∕0.588≈1.70 expected for a three-dimensional self-avoiding random walk (3D-SAW) under good solvent conditions. On larger length scales the overall brush appears to be a 3D-SAW itself (D=1.64±0.08) with a Kuhn-step length of λk=70±4nm. The value is independent of the side chain length and 46 times larger than the Kuhn length of the bare backbone (λk=1.8±0.2nm). The ratio of Kuhn length to brush diameter λk∕d⩾20 determines whether lyotropic behavior can be expected or not. Since longer side chains do not lead to more persistent structures, λk∕d decreases from 8 to 4 with increasing side chain length and lyotropic behavior becomes unlikely.
Relativistic effects on the electronic structure and volatility of group-8 tetroxides MO4, where M=Ru, Os, and element 108, Hs
Authors: Pershina V. , Bastug T. , Fricke B.
Published: March 2005

The influence of relativistic effects on properties and volatility of the group-8 tetroxides MO4, where M=Ru, Os, and element 108, Hs, was studied on the basis of results of the fully relativistic (four component) and nonrelativistic density functional theory calculations. Relativistic effects were shown to increase bond strengths and decrease bond lengths in these molecules. They are responsible for a decrease in molecular polarizabilities and an increase in ionization potentials. The effects are much stronger in HsO4 than in the lighter congeners. Relativistic effects were also shown to slightly decrease dispersion interaction energies of RuO4, OsO4, and HsO4 with an inert (quartz or silicon nitride) surface, i.e., they increase volatility of these compounds as studied in the “one-atom-at-a-time” gas-phase chromatography experiments. They do, however, not influence the trend in group 8: both relativistically and nonrelativistically, volatility should change as RuO4<OsO4<HsO4. The reason for that is identical trends in the relativistic and nonrelativistic space distributions of the valence d electrons.
Methodological problems in pressure profile calculations for lipid bilayers
Authors: Sonne Jacob , Hansen Flemming Y. , Peters Günther H.
Published: March 2005

From molecular dynamics simulations of a dipalmitoyl-phosphatidyl-choline (DPPC) lipid bilayer in the liquid crystalline phase, pressure profiles through the bilayer are calculated by different methods. These profiles allow us to address two central and unresolved problems in pressure profile calculations: The first problem is that the pressure profile is not uniquely defined since the expression for the local pressure involves an arbitrary choice of an integration contour. We have investigated two different choices leading to the Irving–Kirkwood (IK) and Harasima (H) expressions for the local pressure tensor. For these choices we find that the pressure profile is almost independent of the contour used, which indicates that the local pressure is well defined for a DPPC bilayer in the liquid crystalline phase. This may not be the case for other systems and we therefore suggest that both the IK and H profiles are calculated in order to test the uniqueness of the profile. The second problem is how to include electrostatic interactions in pressure profile calculations when the simulations are conducted without truncating the electrostatic potential, i.e., using the Ewald summation technique. Based on the H expression for the local pressure, we present a method for calculating the contribution to the lateral components of the local pressure tensor from electrostatic interactions evaluated by the Ewald summation technique. Pressure profiles calculated with an electrostatic potential truncation (cutoff) from simulations conducted with Ewald summation are shown to depend on the cutoff in a subtle manner which is attributed to the existence of long-ranged charge ordering in the system. However, the pressure profiles calculated with relatively long cutoffs are qualitatively similar to the Ewald profile for the DPPC bilayer studied here.
Switching behavior of microcrystalline silicon deposited by hot-wire chemical vapor deposition
Authors: Hu Jian , Stradins Paul , Branz Howard M. , Wang Qi , Huie Brittany , Weinberg-Wolf J. R. , Harley E. C. T. , Wang Keda , Han Daxing
Published: March 2005

We study current-induced changes in electrical and structural properties of a p-type microcrystalline silicon (μc-Si) films sandwiched between two metal contacts. After switching, the resistance decreases from above 1MΩ to below 1kΩ. The voltage–current characteristics show a saturated voltage region where irreversible changes occur gradually. In this region, transient temperature measurements show that film temperature rises considerably. The resistance of the switched state depends strongly on device area, suggesting that structural changes responsible for switching involve a large fraction of the device area. Micro-Raman studies show that film crystallinity increases during switching. This increase in crystallinity may indicate that the electrical switching process involves the formation of percolation paths through an amorphous incubation layer formed during film growth. This switching mechanism is quite different from the metallic filament formation observed in amorphous silicon switches.
Thermal conduction in AlxGa1−xN alloys and thin films
Authors: Liu Weili , Balandin Alexander A.
Published: March 2005

We report on experimental and theoretical investigation of thermal conduction in AlxGa1−xN alloys. A focus of this study is on understanding the effect of the Al mass fraction x and temperature on thermal conductivity in AlxGa1−xN thin films. The thermal conductivity of a set of AlxGa1−xN thin films as well as a pure GaN sample was measured using the differential 3ω technique in the temperature range from 80 to 400 K. Application of the virtual-crystal model allowed us to elucidate the strength of the mass-difference and strain-field-difference phonon scattering in AlxGa1−xN alloy system. The obtained thermal-conductivity temperature dependence indicates the high degree of disorder in the system. The measured variation of the thermal conductivity with the Al fraction x is in good agreement with the theory predictions. The measured data and calculation procedure are useful for evaluating the self-heating effect in AlxGa1−xN/GaN heterostructure field-effect transistors and for the device structure optimization.
Ab initio thermodynamics of MgSiO3 perovskite at high pressures and temperatures
Authors: Oganov Artem R. , Price G. David
Published: March 2005

Using quantum-mechanical simulations based on density-functional perturbation theory, we address the problem of stability of MgSiO3 perovskite to decomposition into MgO and SiO2 at pressures and temperatures of the Earth’s lower mantle. We show that MgSiO3 perovskite (and its post-perovskite phase) is more stable than the mixture of oxides throughout the pressure-temperature regime of the Earth’s mantle. Structural stability and lattice dynamics of phases in the system MgO-SiO2 are discussed.
Space-charge waves in semiconductors excited by static and moving optical interference patterns
Authors: Kleinert P.
Published: March 2005

We consider space-charge waves in semiconductors that are excited by the superposition of optically generated static and moving interference patterns. Induced dc and ac contributions are resonantly enhanced when the spatial and temporal periods of the interference grating match the related quantities of the space-charge wave. Two eigenmodes of the electron-hole system are identified. One of them is excited by the synchronous drift of photogenerated electron-hole pairs with the moving intensity grating. The other one has the character of trap-recharging waves. The amplification of induced dc and ac components provides complementary information about space-charge waves in semiconductors.
Spongelike metal surface generated by laser in the semiconfined configuration
Authors: Lugomer Stjepan , Mihaljević Branka , Peto Gabor , Toth Atilla L. , Horvath Eniko’
Published: March 2005

A porous surface of tantalum and molybdenum plates has been formed by a nanosecond laser-matter interaction in the “semiconfined configuration,” in which the laser plasma is trapped between the target and the transparent cover plate. The evolution of the plasma cloud and the pressure above the surface induce a superheated state in the liquid surface layer. Explosion of the plasma disk and formation of a cylindrical blast wave drive the superheated metastable fluid toward the spinodal, i.e., to the point of absolute thermodynamic instability. Phase explosion of a spinodal fluid occurs through the cascade of bubblings and generates a very porous spongelike surface ∼5–7μm thick (in some cases even ∼10μm), which stays frozen permanently because of ultrafast cooling at the end of the laser pulse. The total area of the porous surface is enlarged ∼104 times at the microscale range. At even larger magnification, a different, nanoscale-type porosity has been observed.
Low-temperature processable inherently photosensitive polyimide as a gate insulator for organic thin-film transistors
Authors: Pyo Seungmoon , Son Hyunsam , Choi Kil-Yeong , Yi Mi Hye , Hong Sung Kwon
Published: March 2005

We have fabricated organic thin-film transistors (OTFTs) on polyethersulfone substrate using low-temperature processable, inherently photosensitive polyimide as the gate insulator and pentacene as the active material. The polyimide was prepared through two-step reaction. The polyimide precursor, poly(amic acid), was prepared from a dianhydride and aromatic diamine through a polycondensation reaction, and subsequently converted to its corresponding polyimide by a chemical imidization. Photolithographic properties of the polyimide are investigated. The pattern resolution of the cured polyimide was about 50μm. The pentacene OTFTs with the patterned polyimide were obtained with a carrier mobility of 0.1cm2∕Vs and ION∕IOFF of 5×105. The OTFT characteristics are discussed in more detail with respect to the electrical properties of the photosensitive polyimide thin film. This low-temperature photopatternable polyimide paves the way for the easy and low-cost fabrication of OTFT arrays without expensive and complicated photolithography and dry etching processes.
Ordering of Si0.55Ge0.45 islands on vicinal Si(001) substrates: Interplay between kinetic step bunching and strain-driven island growth
Authors: Lichtenberger H. , Mühlberger M. , Schäffler F.
Published: March 2005

We synchronized the kinetic and the strain-driven growth instabilities in the SiGe∕Si(001) heterosystem to implement a two-stage self-organization scheme for the fabrication of long-range-ordered SiGe islands. In the first step, a homoepitaxial Si buffer is grown under optimized step-bunching conditions on a 4° miscut Si(001) substrate. In the second step, SiGe is deposited under conditions that yield three-dimensional island growth in registry with the underlying step-bunching template. By varying the deposition temperature of the SiGe layer, the nucleation phase of the islands could be resolved: At 4° miscut along [110] the slope of the step-bunching areas is most favorable for their disintegration into trains of adjacent (1¯05) and (01¯5) facets upon pseudomorphic overgrowth with SiGe. This strain-driven step meandering instability is a precursor of the SiGe islands, which evolve during further coarsening. At high enough deposition temperatures, we find face-centered, rectangular island ordering that is entirely based on self-organization.
Ion-irradiation-induced porosity in GaSb
Authors: Kluth S. M. , Fitz Gerald J. D. , Ridgway M. C.
Published: March 2005

Porosity in GaSb induced by Ga69 ion irradiation has been investigated as a function of implant dose and temperature. Initially pores form in the implanted material which become elongated as they increase in size. With increasing implant dose, the structure continues to evolve into plates and finally a network of nanoscale rods. Swelling to 25 times the original implanted layer thickness has been observed. The temperature dependence of the minimum feature size has been established. The crystalline-to-amorphous and continuous-to-porous transformations proceed simultaneously. We suggest the latter results from the precipitation of interstitials at extended crystalline defects in preference to Frenkel pair recombination as potentially related to anomalous diffusion in GaSb.
Measuring Physical Characteristics of Housing: The Built Environment Site Survey Checklist (BESSC)
Authors: Burton Elizabeth , Weich Scott , Blanchard Martin , Prince Martin
Published: March 2005

Empirical research in the built environment field is hampered by a lack of reliable measurement tools. The authors argue that there is a need for measures of built form that are objective, descriptive, comprehensive, reliable, practical, and address all environmental scales. They outline the development of an instrument to measure physical characteristics of housing for use in a study funded by the Wellcome Trust, on the effects of regeneration on mental health. The Built Environment Site Survey Checklist (BESSC) contains a wide range of items designed to be rated by built environment specialists for individual predetermined ‘housing areas’. The interrater reliability of the BESSC was tested using the κ and weighted κ statistics for categorical variables and item rankings and intraclass correlation coefficients for continuous measures. The majority of the items were found to be reliable and, although the instrument requires further refinement, it offers substantial potential for investigation of the relative merits of alternative urban forms and the generation of research-based design guidance.
Optimizing Public Transit Quality and System Access: The Multiple-Route, Maximal Covering/Shortest-Path Problem
Authors: Wu Changshan , Murray Alan T
Published: March 2005

Public transit service is a promising travel mode because of its potential to address urban sustainability. However, current ridership of public transit is very low in most urban regions—particularly those in the United States. Low transit ridership can be attributed to many factors, among which poor service quality is key. Transit service quality may potentially be improved by decreasing the number of service stops, but this would be likely to reduce access coverage. Improving transit service quality while maintaining adequate access coverage is a challenge facing public transit agencies. In this paper we propose a multiple-route, maximal covering/shortest-path model to address the trade-off between public transit service quality and access coverage in an established bus-based transit system. The model is applied to routes in Columbus, Ohio. Results show that it is possible to improve transit service quality by eliminating redundant or underutilized service stops.
Diffusion and Coalescence of the Houston Metropolitan Area: Evidence Supporting a New Urban Theory
Authors: Dietzel Charles , Oguz Hakan , Hemphill Jeffery J , Clarke Keith C , Gazulis Nicholas
Published: March 2005

The authors build on a recent development in urban geographic theory, providing evidence of an oscillatory behavior in spatiotemporal patterns of urban growth. With the aid of remotely sensed data, the spatial extent of urban areas in the Houston (USA) metropolitan region from 1974 to 2002 was analyzed by spatial metrics. Regularities in the spatial urban growth pattern were identified with temporal periods as short as thirty years by means of spatial metric values, including mean nearest-neighbor distance, mean patch area, total number of urban patches, and mean patch fractal dimension. Through changes in these values, a distinct oscillation between phases of diffusion and coalescence in urban growth was revealed. The results suggest that the hypothesized process of diffusion and coalescence may occur over shorter time periods than previously thought, and that the patterns are readily observable in real-world systems.
Uncertainty in Extrapolations of Predictive Land-Change Models
Authors: Pontius Robert Gilmore , Spencer Joseph
Published: March 2005

This paper gives a technique to extrapolate the anticipated accuracy of a prediction of land-use and land-cover change (LUCC) to any point in the future. The method calibrates a LUCC model with information from the past in order to simulate a map of the present, so that it can compute an objective measure of validation with empirical data. Then it uses that observed measurement of predictive accuracy to anticipate how accurately the model will predict a future landscape. The technique assumes that the accuracy of the model will decay to randomness as the model predicts farther into the future and estimates how fast the decay in accuracy will occur based on prior model performance. Results are presented graphically in terms of percentage of pixels classified correctly so that nonexperts can interpret the accuracy visually. The percentage correct is budgeted by three components: agreement due to chance, agreement due to the predicted quantity of each land category, and agreement due to the predicted location of each land category. The percentage error is budgeted by two components: disagreement due to the predicted location of each land category and disagreement due to the predicted quantity of each land category. Therefore, model users can see the sources of the accuracy and error of the model. The entire analysis is computable for multiple resolutions, so users can see how the results are sensitive to changes in scale. We illustrate the method with an application of the land-use change model Geomod to Central Massachusetts, where the predictive accuracy of the model decays to 90% over fourteen years and to near complete randomness over 200 years.
Phosphorylation of Hdmx mediates its Hdm2- and ATM-dependent degradation in response to DNA damage
Authors: Pereg Yaron , Shkedy Dganit , de Graaf Petra , Meulmeester Erik , Edelson-Averbukh Marina , Salek Mogjiborahman , Biton Sharon , Teunisse Amina F. A. S. , Lehmann Wolf D. , Jochemsen Aart G. , Shiloh Yosef
Published: March 2005

Maintenance of genomic stability depends on the DNA damage response, an extensive signaling network that is activated by DNA lesions such as double-strand breaks (DSBs). The primary activator of the mammalian DSB response is the nuclear protein kinase ataxia–telangiectasia, mutated (ATM), which phosphorylates key players in various arms of this network. The activation and stabilization of the p53 protein play a major role in the DNA damage response and are mediated by ATM-dependent posttranslational modifications of p53 and Mdm2, a ubiquitin ligase of p53. p53's response to DNA damage also depends on Mdm2-dependent proteolysis of Mdmx, a homologue of Mdm2 that represses p53's transactivation function. Here we show that efficient damage-induced degradation of human Hdmx depends on functional ATM and at least three sites on the Hdmx that are phosphorylated in response to DSBs. One of these sites, S403, is a direct ATM target. Accordingly, each of these sites is important for Hdm2-mediated ubiquitination of Hdmx after DSB induction. These results demonstrate a sophisticated mechanism whereby ATM fine-tunes the optimal activation of p53 by simultaneously modifying each player in the process.
Dynamic microcompartmentation in synthetic cells
Authors: Long M. Scott , Jones Clinton D. , Helfrich Marcus R. , Mangeney-Slavin Lauren K. , Keating Christine D.
Published: March 2005

An experimental model for cytoplasmic organization is presented. We demonstrate dynamic control over protein distribution within synthetic cells comprising a lipid bilayer membrane surrounding an aqueous polymer solution. This polymer solution generally exists as two immiscible aqueous phases. Protein partitioning between these phases leads to microcompartmentation, or heterogeneous protein distribution within the “cell” interior. This model cytoplasm can be reversibly converted to a single phase by slight changes in temperature or osmolarity, such that local protein concentrations can be manipulated within the vesicle interior.
Logic functions of the genomic cis-regulatory code
Authors: Istrail Sorin , Davidson Eric H.
Published: March 2005

cis-regulatory modules that control developmental gene expression process the regulatory inputs provided by the transcription factors for which they contain specific target sites. A prominent class of cis-regulatory processing functions can be modeled as logic operations. Many of these are combinatorial because they are mediated by multiple sites, although others are unitary. In this work, we illustrate the repertoire of cis-regulatory logic operations, as an approach toward a functional interpretation of the genomic regulatory code.
Contingent gene regulatory networks and B cell fate specification
Authors: Singh Harinder , Medina Kay L. , Pongubala Jagan M. R.
Published: March 2005

The B cell developmental pathway represents a leading system for the analysis of regulatory circuits that orchestrate cell fate specification and commitment. Considerable progress has been achieved within the past decade in the identification and genetic analysis of various regulatory components. These components include the transcription factors PU.1, Ikaros, Bcl11a, E2A, EBF, and Pax-5, as well as the cytokine receptors Flk2 and IL-7R. Experimental evidence of connectivity among the regulatory components is used to assemble sequentially acting and contingent gene regulatory networks. Transient signaling inputs, self-sustaining positive feedback loops, and crossantagonism among alternate cell fate determinants are key features of the proposed networks that instruct the development of B lymphocyte precursors from hematopoietic stem cells.
A *-closed subalgebra of the Smirnov class
Authors: Garcia Stephan
Published: March 2005

We study real Smirnov functions and investigate a certain

∗
*

-closed subalgebra of the Smirnov class

N
+

N^+

containing them. Motivated by a result of Aleksandrov, we provide an explicit representation for the space

H
p

∩

H
p

¯

H^p \cap \overline {H^p}

. This leads to a natural analog of the Riesz projection on a certain quotient space of

L
p

L^p

for

p
∈
(
0
,
1
)

p \in (0,1)

. We also study a Herglotz-like integral transform for singular measures on the unit circle

∂

D

\partial \mathbb {D}

.
Meromorphic functions and factoriality
Authors: Kucharz W.
Published: March 2005

Let

K
K

be a compact subset of a connected Stein manifold

X
X

. We study algebraic properties of the ring of meromorphic functions on

X
X

without poles in

K
K

.
Homogeneity of powers of spaces and the character
Authors: Arhangel’skii A.
Published: March 2005

A space is said to be power-homogeneous if some power of it is homogeneous. We prove that if a Hausdorff space

X
X

of point-countable type is power-homogeneous, then, for every infinite cardinal

τ
\tau

, the set of points at which

X
X

has a base of cardinality not greater than

τ
\tau

, is closed in

X
X

. Every power-homogeneous linearly ordered topological space also has this property. Further, if a linearly ordered space

X
X

of point-countable type is power-homogeneous, then

X
X

is first countable.
The initial value problem for a third order dispersive equation on the two-dimensional torus
Authors: Chihara Hiroyuki
Published: March 2005

We present the necessary and sufficient conditions for the

L
2

L^2

-well-posedness of the initial problem for a third order linear dispersive equation on the two-dimensional torus. Birkhoff’s method of asymptotic solutions is used to prove necessity. Some properties of a system for quadratic algebraic equations associated to the principal symbol play a crucial role in proving sufficiency.
The converse of the four vertex theorem
Authors: Dahlberg Björn
Published: March 2005

We establish the converse to the four vertex theorem without the positivity condition.
Existence and mapping properties of the wave operator for the Schrödinger equation with singular potential
Authors: Georgiev Vladimir , Ivanov Angel
Published: March 2005

We consider the Schrödinger equation in three-dimensional space with small potential in the Lorentz space

L

3

/

2
,
∞

L^{3/2,\infty }

and we prove Strichartz-type estimates for the solution to this equation. Moreover, using Cook’s method, we prove the existence of the wave operator. In the last section we prove the equivalence between the homogeneous Sobolev spaces

H
˙

s

\dot {H}^s

and

H
˙

V
s

\dot {H}^s_V

in the case

0
≤
s
>

3
2

0 \leq s > \frac {3}{2}

.
Classification of quasifinite modules over Lie algebras of matrix differential operators on the circle
Authors: Su Yucai
Published: March 2005

We prove that an irreducible quasifinite module over the central extension of the Lie algebra of

N
×
N

N\times N

-matrix differential operators on the circle is either a highest or lowest weight module or else a module of the intermediate series. Furthermore, we give a complete classification of indecomposable uniformly bounded modules.
A special case of positivity (II)
Authors: Dutta S.
Published: March 2005

In this note we prove the following special case of Serre’s conjecture on Intersection Multiplicity: Let

(
R
,
m
)

(R,m)

be a regular local ring and let

P
P

,

Q
Q

be two prime ideals such that

ℓ
(
R

/

(
P
+
Q
)
)
>
∞

\ell (R/(P+Q))>\infty

,

dim
⁡
R

/

P
+
dim
⁡
R

/

Q
=
dim
⁡
R

\dim R/P +\dim R/Q=\dim R

and dimension of
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper G Subscript m Baseline left-parenthesis upper R slash upper P right-parenthesis circled-times Subscript upper G Sub Subscript m Subscript left-parenthesis upper R right-parenthesis Baseline upper G Subscript m Baseline left-parenthesis upper R slash upper Q right-parenthesis greater-than 2">

G

m

(
R

/

P
)

⊗

G

m

(
R
)

G

m

(
R

/

Q
)
>
2

G_{m}(R/P)\otimes _{G_{m}(R)}G_{m}(R/Q)>2

. Then
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="chi left-parenthesis upper R slash upper P comma upper R slash upper Q right-parenthesis greater-than-or-equal-to e Subscript m Baseline left-parenthesis upper R slash upper P right-parenthesis e Subscript m Baseline left-parenthesis upper R slash upper Q right-parenthesis">

χ
(
R

/

P
,
R

/

Q
)
≥

e

m

(
R

/

P
)

e

m

(
R

/

Q
)

\chi (R/P,R/Q)\geq e_{m}(R/P) e_{m}(R/Q)

; here

e

m

(
T
)

e_{m}(T)

denotes the Hilbert-Samuel multiplicity for any finitely generated module

T
T

with respect to

m
m

.
Gaussian polynomials and invertibility
Authors: Lucas Thomas
Published: March 2005

The content of a polynomial

f
f

over a commutative ring

R
R

is the ideal

c
(
f
)

c(f)

of

R
R

generated by the coefficients of

f
f

. If

c
(
f
g
)
=
c
(
f
)
c
(
g
)

c(fg)=c(f)c(g)

for each polynomial

g
∈
R
[
x
]

g\in R[x]

, then

f
f

is said to be Gaussian. If

c
(
f
)

c(f)

is an invertible ideal of

R
R

, then

f
f

is Gaussian. An open question has been whether the converse holds for a polynomial whose content is a regular ideal of

R
R

. The main theorem shows slightly more than this; namely, if

c
(
f
)

c(f)

has no nonzero annihilators, then

c
(
f
)
H
o

m
R

(
c
(
f
)
,
R
)
=
R

c(f)Hom_R(c(f),R)=R

.
Differential Subnuclear Localization and Replication Timing of Histone H3 Lysine 9 Methylation States
Authors: Wu Rong , Terry Anna V. , Singh Prim B. , Gilbert David M.
Published: March 2005

Mono-, di-, and trimethylation of specific histone residues adds an additional level of complexity to the range of histone modifications that may contribute to a histone code. However, it has not been clear whether different methylated states reside stably at different chromatin sites or whether they represent dynamic intermediates at the same chromatin sites. Here, we have used recently developed antibodies that are highly specific for mono-, di-, and trimethylated lysine 9 of histone H3 (MeK9H3) to examine the subnuclear localization and replication timing of chromatin containing these epigenetic marks in mammalian cells. Me1K9H3 was largely restricted to early replicating, small punctate domains in the nuclear interior. Me2K9H3 was the predominant MeK9 epitope at the nuclear and nucleolar periphery and colocalized with sites of DNA synthesis primarily in mid-S phase. Me3K9H3 decorated late-replicating pericentric heterochromatin in mouse cells and sites of DAPI-dense intranuclear heterochromatin in human and hamster cells that replicated throughout S phase. Disruption of the Suv39h1,2 or G9a methyltransferases in murine embryonic stem cells resulted in a redistribution of methyl epitopes, but did not alter the overall spatiotemporal replication program. These results demonstrate that mono-, di-, and trimethylated states of K9H3 largely occupy distinct chromosome domains.
Poetry after Auschwitz – Adorno's Dictum
Authors: Hofmann Klaus
Published: March 2005

abstract

Referring to Adorno's ‘dictum’ is a diplomatic way of avoiding the discussion of what Adorno actually wrote. Two phrases, cut out from a compound sentence, are alternately, sometimes concurrently, put forward as his ‘dictum’: ‘To write poetry after Auschwitz is barbaric’; and: ‘It is impossible to write poetry after Auschwitz’. Out of context, both phrases, the latter one in particular, lose the problematic quality conferred on them by the argument put forward in the original text and, beyond that, in the author's writing as a whole. This article endeavours to establish this argumentative context and restore Adorno's verdict to its dialectic matrix.
Germination success of temperate grassland species after passage through ungulate and rabbit guts
Authors: COSYNS E. , DELPORTE A. , LENS L. , HOFFMANN M.
Published: March 2005

Dispersal of endozoochorous seed involves uptake by a herbivore and exposure to different kinds of digestive fluids during passage through the gastrointestinal tract. Assessment of the ecological significance of endozoochory therefore requires examination of the survival rate of seeds during this phase.

A feeding experiment was conducted with seeds of 19 plant species that are important constituents of temperate semi‐natural grasslands and five animal species (two ruminants, two colon fermenters and a caecum fermenter). Mean retention time of germinable seeds was determined and seed characteristics that might affect germination success were examined.

Gut‐passed seeds had a much lower germination success (0–26%) than non‐gut‐passed seeds either sown directly on dung (2–79%) or bare soil (7–89%).

Relative germination success differed considerably between both plant and animal species. This may result from complex, herbivore‐specific interactions between animal behaviour (chewing, digestion) and seed characteristics.

Germination success was positively related to seed longevity and, remarkably, also to seed mass and seed shape. Retention time of germinable seeds varied from c. 12 hours (rabbit) to 72 hours (ungulates), potentially allowing long‐distance seed dispersal. This study highlights both the complex interaction between animal species and seed characteristics and the considerable differences in germination success of gut‐passed seeds, which exist between plant species. The loss of seed germinability after gut passage calls into question the ecological significance of endozoochory, although the costs of other dispersal mechanisms remain to be tested.
A space‐for‐time substitution reveals the long‐term decline in genotypic diversity of a widespread salt marsh plant, Spartina alterniflora, over a span of 1500 years
Authors: TRAVIS STEVEN E. , HESTER MARK W.
Published: March 2005

Clonal populations face a trade‐off between sexual recruitment and vegetative growth and, once established, may undergo continuous declines in genotypic diversity if their sexual recruits make poor competitors. The geological history of delta formation in the Lower Mississippi River Valley was used to age eight S. alterniflora marshes for use in a space‐for‐time substitution ranging over 1500 years, in order to determine the long‐term effects of clonal growth on genotypic diversity in natural populations.

We also predicted that highly heterozygous clones are competitively superior, leading to an increase in the overall level of genetic diversity as a marsh ages and/or to an increasingly positive relationship between clone size and individual heterozygosity, and that the clumping of ramets within clones will occur over increasingly large distances as populations age, while the clumping of genetically related clones will become less pronounced as intraclonal competition begins to obscure the initial effects of localized seedling recruitment.

Using molecular markers to differentiate clones, we documented a decline in clonal richness at the rate of approximately 1% 100 years−1 that was accompanied for the first 300–500 years by an increase in the distance over which clumping of ramets within genets occurred. Older populations, in the 500–1500‐year range, showed evidence of clone fragmentation.

The spatial clustering of kin was observed for only two marshes, and exhibited no clear relationship with marsh age.

Whereas the overall level of genetic diversity was consistent among marshes and showed no clear relationship with marsh age, the relationship between heterozygosity and individual clone size became increasingly pronounced within older marshes.

Our results suggest that under natural conditions S. alterniflora marshes will rarely reach ages sufficient for the loss of all clonal diversity, or for the effects of inbreeding and drift to pose a significant threat to population viability.