bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer Law of Tunisia: Promoting Secure E-Commerce Transactions with Electronic Signatures
Authors: Blythe Stephen
Published: September 2006

Tunisia's Electronic Exchanges and Electronic Commerce Law ("ECL") was enacted for the purpose of achieving more security in E-commerce transactions. The ECL provides that: (1) electronic documents may be used to satisfy a statutory requirement for paper documents to be stored for a given period of time; and (2) an electronic signature affixed to an electronic document may be used to satisfy a statutory requirement for an ink signature to be executed on a paper document. The National Agency for Electronic Certification ("NAEC") licenses Certification Authorities ("CA") and regulates their business operations. The purpose of a CA is to verify the authenticity and integrity of an electronic signature that was created by its client—the "subscriber"—and the electronic document it is attached to. The CA issues a certificate to a subscriber containing evidence that her electronic signature was created with a private key that was issued to her by the CA. Tunisia recognizes certificates issued by a foreign CA that has met licensing requirements which are comparable to that of Tunisia. The CA carries potential liability for: the veracity of the information stated in the certificate; ensuring the cryptographic relationship between the private key and the public key (which is used by relying third parties to ascertain the electronic signature's authenticity); and for maintenance of security of the subscriber's private information. The subscriber has potential liability based on her duty to maintain security over the private key and to promptly inform the CA if the private key's security has been compromised. The ECL contains rules governing E-commerce contracts. Furthermore, it has some of the best consumer protections to be found anywhere. For example, Tunisian consumers have a 10-day window of opportunity to back out of the deal after an E-contract has been consummated. This is progressive and commendable; many consumers in Western Europe and North America do not enjoy such a protection. The ECL also contains a list of computer crimes and punishments:fines (up to 10,000 dinars) may be assessed for these infractions, and imprisonment may be imposed against a cyber-seller who uses coercion or trickery against a consumer.
Lost and Found Theories of Law in Early China
Authors: Richey Jeffrey
Published: September 2006

The so-called "Chinese view of law" is but one among many ways of understanding law in early China. Early Chinese thinkers held varied views of law's origins in nature or culture, its relationship to the sacred, and its connection with sagehood. Confucians tended to present law as an artificial and ineffective instrument for the promotion of moral order. In contrast, Mohist and Huang-Lao thinkers consistently viewed law as a natural and effective tool for the moral rectification of society when wielded by the sagely ruler, but differed in their conceptions of the sacred and the nature of the cosmic order. On parle souvent de « La perspective chinoise sur la loi » comme si elle était unique. Cependant, les penseurs chinois anciens avaient plusieurs perspectives différentes sur les origines naturelles ou culturelles des lois et sur leurs rapports avec le sacré et avec la sagesse. Les Confuciens présentaient surtout la loi comme un moyen artificiel et inefficace de promouvoir l'ordre moral. Au contraire—quoique les Mohistes et les Huanglaos aient eu des notions très différentes du sacré et de l'ordre cosmique—les deux voyaient surtout la loi comme un outil naturel et efficace qu'un roi éclairé pouvait utiliser pour rectifier les mœurs.
Ugarit and the Southern Levantine Sea-Ports
Authors: Vidal Jordi
Published: September 2006

The texts studied in this paper show that the extent of the commercial and political relationships between Ugarit and the Phoenician cities, particularly Tyre, was far superior to that of the ties with the Southern Levantine sea-ports. However, the importance of the commercial ties between Ugarit and Ashdod may be de fined using the written sources. In fact, if our interpretation of RS 19.96 is correct, the intensity of the contacts between both cities even led to the establishment of an Ashdodite merchant station in Ugarit, from which their commercial affairs were structured. Les textes étudiés dans le présent article montrent la façon dont Ugarit avait maintenu des rélations commerciales et politiques avec les royaumes phéniciens, spécialement avec Tyr. Ces rélations furent plus intenses que celles maintenues avec les ports du sud du Levant. De toute façon, ces textes constatent les liens commerciaux trés etroit qui auraient existé entre Ugarit et Ashdod. De fait, si nôtre interprétation de RS 19.96 est correcte, l'intensité des contacts entre les deux villes aboutit à l'établissement d'une station commerciale d'Ashdod à Ugarit, station qui fut chargée d'organiser ces relations commerciales.
Retrieval of Hydrometeor Profiles in Tropical Cyclones and Convection from Combined Radar and Radiometer Observations
Authors: Jiang Haiyan , Zipser Edward J.
Published: September 2006

A retrieval algorithm is described to estimate vertical profiles of precipitation ice water content and liquid water content in tropical cyclones and convection over ocean from combined spaceborne radar and radiometer measurements. In the algorithm, the intercept parameter N0s in the exponential particle size distribution for rain, snow, and graupel are adjusted iteratively to minimize the difference between observed brightness temperatures and simulated ones by using a simulated annealing optimization method. Sensitivity tests are performed to understand the effects of the input parameters. The retrieval technique is investigated using the Earth Resources (ER)-2 aircraft Doppler radar and Advanced Microwave Precipitation Radiometer data in tropical cyclones and convection. An indirect validation is performed by comparing the measured and retrieved 50-GHz (independent channel) brightness temperature. The global agreement shows not only the quality of the inversion procedure, but also the consistency of the retrieved parameters with observations. The direct validation of the ice water content retrieval by using the aircraft in situ microphysical measurements indicates that the algorithm can provide reliable ice water content estimates, especially in stratiform regions. In convective regions, the large variability of the microphysical characteristics causes a large uncertainty in the retrieval, although the mean difference between the retrieved ice water content and aircraft-derived ice water content is very small. The ice water content estimated by a radar-only empirical relationship is higher than those retrieved by the combined algorithm and derived by the aircraft in situ observations. The new combined algorithm contains information that should improve ice water content estimates from either radar-only or passive microwave–only measurements. An important caveat for this study is that it concerns precipitation estimates. In this paper, ice and liquid water content should be interpreted as precipitation ice and liquid water content.
The Effect of Local Atmospheric Circulations on Daytime Carbon Dioxide Flux Measurements over a Pinus elliottii Canopy
Authors: Loescher H. W. , Starr G. , Martin T. A. , Binford M. , Gholz H. L.
Published: September 2006

The daytime net ecosystem exchange of CO2 (NEE) was measured in an even-aged slash pine plantation in northern Florida from 1999 to 2001 using the eddy covariance technique. In August 2000, two clear-cuts were formed approximately 1 km west of the study site. A statistical approach was used to determine whether the clear-cuts induced changes in CO2 concentration, wind direction, horizontal and vertical wind speeds, and temperature, as measured by instruments above the plantation canopy and, in turn, whether any such changes affected daytime NEE. The NEE estimates were first transformed so that mean responses to incident radiation and vapor pressure deficit were removed using empirically derived functions for each 30-min period. Prior to the clear-cuts, there were significant interactive effects of CO2 concentration and some wind statistics on NEE at the tower when wind was flowing from the direction of the future clear-cuts. Even in this relatively homogenous forest, with flat topography, the CO2 source strength differed with wind direction prior to the clear-cuts. After the clear-cuts, additional two- and three-way interactive effects became significant during flows from the direction of the clear-cuts. There was also a 16.6% reduction in the integrated measure of daytime NEE over 487 days after the clear-cuts. The results herein suggest that the development of local circulations over the clear-cuts contributed to low-frequency effects on the NEE.
Automatic Detection of Local Cloud Systems from MODIS Data
Authors: Cappelluti G. , Morea A. , Notarnicola C. , Posa F.
Published: September 2006

This paper describes an algorithm that is aimed at the identification of cloudy and clear pixels in Moderate-Resolution Imaging Spectroradiometer (MODIS) images to support earth science and nowcasting applications. The process from geolocated and calibrated data allows one to obtain cloud masks with four clear-sky confidence levels for five different cloud system types. The technique has been developed using the MODIS cloud-mask algorithm heritage, but the threshold tests performed have been executed without comparing solar reflectances and thermal brightness temperatures with thresholds determined in advance, but instead with thresholds carried out from classification methods. The main advantage of this technique is that the thresholds are obtained directly from the images. Seventy-five percent of the spectral signatures (known as end members) derived from the winter images in the detection of the various cloud types and 80% of the summer end members can be considered as being well discriminated. Furthermore, it seems that the end members characterizing the different cloud systems are constant throughout the various seasons of the year (they vary with a confidence level of 60%), whereas those describing clear sky change in a notable manner (the associated confidence level is 99%). The algorithm is able to produce cloud masks pertinent to limited regions at a mesoscale level, which may be a key factor for nowcasting purposes. This work shows that the use of end members and spectral angles, as opposed to spectral thresholds, should be carefully examined because of the fact that it might be simpler or that higher performances may be achieved at a regional scale.
The Synoptic Decomposition of Cool-Season Rainfall in the Southeastern Australian Cropping Region
Authors: Pook Michael J. , McIntosh Peter C. , Meyers Gary A.
Published: September 2006

Daily rainfall during the April–October growing season in a major cropping region of southeastern Australia has been related to particular types of synoptic weather systems over a period of 33 yr. The analysis reveals that cutoff lows were responsible for at least 50% of all growing-season rainfall and accounted for 80% of daily rainfall events exceeding 25 mm per station. The proportion of rainfall contributed by cutoff lows varies throughout the growing season. It is highest in austral autumn and spring (55% and 57%, respectively) and falls to a minimum in July (42%). By way of contrast, the total contribution of all types of frontal systems to growing-season rainfall is about 32%, although the monthly value reaches a maximum of 41% in July when mean cutoff rainfall reaches a minimum. Rainfall associated with fronts is strongly concentrated in the lower range of daily falls (less than 10 mm per station). Frontal rainfall is found to be more consistent from year to year than is cutoff rainfall. The number of cutoff lows per season is highly variable, and there is a significant correlation between the number of cutoff days and atmospheric blocking in the region south of Australia in each month of the growing season. The mean amount of rainfall per cutoff day is also variable and has declined by approximately 0.8 mm over the analysis period. An understanding of the mechanisms controlling year-to-year variability of cutoff rainfall is therefore an important step in improving seasonal forecasts for agriculture in southeastern Australia.
NEOPLANTA: A Short Description of the First Serbian UV Index Model
Authors: Malinovic S. , Mihailovic D. T. , Kapor D. , Mijatovic Z. , Arsenic I. D.
Published: September 2006

A numerical model called “NEOPLANTA” for estimating solar UV irradiance and UV index under cloud-free conditions is being developed and tested at the University of Novi Sad in Serbia. In this paper, the model features, calculation procedure, and input parameters are described. Effects of the absorption of UV radiation by O3, SO2, and NO2 and absorption and scattering by aerosol as well as the air molecules in the atmosphere are included. The performance of the model has been tested with respect to its capability of UV index, which is a weighted integral between 280 and 400 nm of the solar irradiance reaching the ground. For this test 10-day data measured during the spring and summer in 2003, 2004, and 2005 are used. Data are recorded by the Yankee UVB-1 biometer located at the Novi Sad university campus (45.33°N, 19.85°E; 84 m MSL). Error analyses indicate that the modeled values agree well with the observations.
GLACE: The Global Land–Atmosphere Coupling Experiment. Part I: Overview
Authors: Koster Randal D. , Sud Y. C. , Guo Zhichang , Dirmeyer Paul A. , Bonan Gordon , Oleson Keith W. , Chan Edmond , Verseghy Diana , Cox Peter , Davies Harvey , Kowalczyk Eva , Gordon C. T. , Kanae Shinjiro , Lawrence David , Liu Ping , Mocko David , Lu Cheng-Hsuan , Mitchell Ken , Malyshev Sergey , McAvaney Bryant , Oki Taikan , Yamada Tomohito , Pitman Andrew , Taylor Christopher M. , Vasic Ratko , Xue Yongkang
Published: September 2006

The Global Land–Atmosphere Coupling Experiment (GLACE) is a model intercomparison study focusing on a typically neglected yet critical element of numerical weather and climate modeling: land–atmosphere coupling strength, or the degree to which anomalies in land surface state (e.g., soil moisture) can affect rainfall generation and other atmospheric processes. The 12 AGCM groups participating in GLACE performed a series of simple numerical experiments that allow the objective quantification of this element for boreal summer. The derived coupling strengths vary widely. Some similarity, however, is found in the spatial patterns generated by the models, with enough similarity to pinpoint multimodel “hot spots” of land–atmosphere coupling. For boreal summer, such hot spots for precipitation and temperature are found over large regions of Africa, central North America, and India; a hot spot for temperature is also found over eastern China. The design of the GLACE simulations are described in full detail so that any interested modeling group can repeat them easily and thereby place their model’s coupling strength within the broad range of those documented here.
One-Way Coupling of an Atmospheric and a Hydrologic Model in Colorado
Authors: Hay L. E. , Clark M. P. , Pagowski M. , Leavesley G. H. , Gutowski W. J.
Published: September 2006

This paper examines the accuracy of high-resolution nested mesoscale model simulations of surface climate. The nesting capabilities of the atmospheric fifth-generation Pennsylvania State University (PSU)–National Center for Atmospheric Research (NCAR) Mesoscale Model (MM5) were used to create high-resolution, 5-yr climate simulations (from 1 October 1994 through 30 September 1999), starting with a coarse nest of 20 km for the western United States. During this 5-yr period, two finer-resolution nests (5 and 1.7 km) were run over the Yampa River basin in northwestern Colorado. Raw and bias-corrected daily precipitation and maximum and minimum temperature time series from the three MM5 nests were used as input to the U.S. Geological Survey’s distributed hydrologic model [the Precipitation Runoff Modeling System (PRMS)] and were compared with PRMS results using measured climate station data.

The distributed capabilities of PRMS were provided by partitioning the Yampa River basin into hydrologic response units (HRUs). In addition to the classic polygon method of HRU definition, HRUs for PRMS were defined based on the three MM5 nests. This resulted in 16 datasets being tested using PRMS. The input datasets were derived using measured station data and raw and bias-corrected MM5 20-, 5-, and 1.7-km output distributed to 1) polygon HRUs and 2) 20-, 5-, and 1.7-km-gridded HRUs, respectively. Each dataset was calibrated independently, using a multiobjective, stepwise automated procedure. Final results showed a general increase in the accuracy of simulated runoff with an increase in HRU resolution. In all steps of the calibration procedure, the station-based simulations of runoff showed higher accuracy than the MM5-based simulations, although the accuracy of MM5 simulations was close to station data for the high-resolution nests. Further work is warranted in identifying the causes of the biases in MM5 local climate simulations and developing methods to remove them.
Variations in the Summertime Atmospheric Hydrologic Cycle Associated with Seasonal Precipitation Anomalies over the Southwestern United States
Authors: Anderson Bruce T. , Kanamaru Hideki , Roads John O.
Published: September 2006

This paper examines year-to-year variations in the large-scale summertime hydrologic cycle over the southwestern United States using a suite of regional model simulations and surface- and upper-air-based observations. In agreement with previous results, it is found that observed interannual precipitation variations in this region can be subdivided into two spatiotemporal regimes—one associated with rainfall variability over the southwestern portion of the domain centered on Arizona and the other associated with variations over the southeastern portion centered on western Texas and eastern New Mexico. Because of the limited duration of the model simulation data, it is possible to only investigate one positive rainfall season over the Arizona region and one negative rainfall season over the New Mexico region. From these investigations it appears that for the positive rainfall anomalies over Arizona excess seasonal precipitation is balanced by both enhanced evaporation and vertically integrated large-scale moisture flux convergence. Vertical profiles of these terms indicate that the anomalous large-scale moisture flux convergence is actually related to a decrease in the mean large-scale moisture flux divergence aloft; below 800 mb there is a decrease in the mean moisture flux convergence typically found at these levels, which in turn produces anomalous moisture divergence from the region. For the negative rainfall anomalies over New Mexico similar results, but of opposite sign, are found; one exception is that at the lowest levels there is an additional (negative) contribution to the vertically integrated moisture flux convergence anomaly related to a weakening of the mean low-level moisture flux convergence during the low-rainfall year. Further studies using two different model simulations with the same large-scale dynamic forcing but differing initial soil moisture values indicate that similar balances are also found for rainfall anomalies related to surface soil moisture changes within the domain, suggesting that the changes in large-scale moisture flux convergence described above can be attributed to both year-to-year variations in the regional land–atmosphere interactions as well as variations in the large-scale circulation patterns.
Snow Distribution and Melt Modeling for Mittivakkat Glacier, Ammassalik Island, Southeast Greenland
Authors: Mernild Sebastian H. , Liston Glen E. , Hasholt Bent , Knudsen Niels T.
Published: September 2006

A physically based snow-evolution modeling system (SnowModel) that includes four submodels—the Micrometeorological Model (MicroMet), EnBal, SnowPack, and SnowTran-3D—was used to simulate five full-year evolutions of snow accumulation, distribution, sublimation, and surface melt on the Mittivakkat Glacier, in southeast Greenland. Model modifications were implemented and used 1) to adjust underestimated observed meteorological station solid precipitation until the model matched the observed Mittivakkat Glacier winter mass balance, and 2) to simulate glacier-ice melt after the winter snow accumulation had ablated. Meteorological observations from two meteorological stations were used as model inputs, and glaciological mass balance observations were used for model calibration and testing of solid precipitation observations. The modeled end-of-winter snow-water equivalent (w.eq.) accumulation increased with elevation from 200 to 700 m above sea level (ASL) in response to both elevation and topographic influences, and the simulated end-of-summer location of the glacier equilibrium line altitude was confirmed by glaciological observations and digital images. The modeled test-period-averaged annual mass balance was 150 mm w.eq. yr−1, or ∼15%, less than the observed. Approximately 12% of the precipitation was returned to the atmosphere by sublimation. Glacier-averaged mean annual modeled surface melt ranged from 1272 to 2221 mm w.eq. yr−1, of which snowmelt contributed from 610 to 1040 mm w.eq. yr−1. The surface-melt period started between mid-May and the beginning of June, and lasted until mid-September; there were as many as 120 melt days at the glacier terminus. The model simulated a Mittivakkat Glacier recession averaging −616 mm w.eq. yr−1, almost equal to the observed −600 mm w.eq. yr−1.
Diagnosing the Annual Cycle of the Equatorial Undercurrent in the Atlantic Ocean from a General Circulation Model
Authors: Arhan M. , Treguier A. M. , Bourlès B. , Michel S.
Published: September 2006

Ten-year-long output series from a general circulation model forced by daily realistic winds are used to analyze the annual cycle of the Equatorial Undercurrent (EUC) in the Atlantic Ocean. Two well-defined transport maxima are found: One, present during boreal summer and autumn in the central part of the basin, is generally recognized and regarded as a near-equilibrium response to the equatorial easterly trades that culminate in this period. Another one, most pronounced near the western boundary, occurs in April–May when the trades relax. This second maximum is less patent in the observations, but concomitant signals in previously published analyses of the North Brazil Current and surface velocity seasonal variations might be indirect manifestations of its reality. Because this intensification appears at periods when the boundary between the tropical and equatorial gyres nears the equator, the authors relate its existence to wind stress curl variations at subequatorial latitudes. A link between the interannual variability of the spring transport maximum and that of the low-latitude wind stress curl is, indeed, found in the model. This diagnostic approach suggests that two different dynamical regimes shape up the EUC seasonal cycle: in summer and autumn, local forcing by the equatorial zonal wind component and main supply from the ocean interior; in winter and spring, remote forcing by the low-latitude rotational wind component and supply from the western boundary currents.
Circumpolar Deep Water Circulation and Variability in a Coupled Climate Model
Authors: Santoso Agus , England Matthew H. , Hirst Anthony C.
Published: September 2006

The natural variability of Circumpolar Deep Water (CDW) is analyzed using a long-term integration of a coupled climate model. The variability is decomposed using a standard EOF analysis into three separate modes accounting for 68% and 82% of the total variance in the upper and lower CDW layers, respectively. The first mode exhibits an interbasin-scale variability on multicentennial time scales, originating in the North Atlantic and flowing southward into the Southern Ocean via North Atlantic Deep Water (NADW). Salinity dipole anomalies appear to propagate around the Atlantic meridional overturning circulation on these time scales with the strengthening and weakening of NADW formation. The anomaly propagates northward from the midlatitude subsurface of the South Atlantic and sinks in the North Atlantic before flowing southward along the CDW isopycnal layers. This suggests an interhemispheric connection in the generation of the first CDW variability mode. The second mode shows a localized θ−S variability in the Brazil–Malvinas confluence zone on multidecadal to centennial time scales. Heat and salt budget analyses reveal that this variability is controlled by meridional advection driven by fluctuations in the strength of the Deep Western Boundary and the Malvinas Currents. The third mode suggests an Antarctic Intermediate Water source in the South Pacific contributing to variability in upper CDW. It is further found that NADW formation is mainly buoyancy driven on the time scales resolved, with only a weak connection with Southern Hemisphere winds. On the other hand, Southern Hemisphere winds have a more direct influence on the rate of NADW outflow into the Southern Ocean. The model’s spatial pattern of θ−S variability is consistent with the limited observational record in the Southern Hemisphere. However, some observations of decadal CDW θ−S changes are beyond that seen in the model in its unperturbed state.
Wave-Follower Field Measurements of the Wind-Input Spectral Function. Part II: Parameterization of the Wind Input
Authors: Donelan Mark A. , Babanin Alexander V. , Young Ian R. , Banner Michael L.
Published: September 2006

Nearly all of the momentum transferred from wind to waves comes about through wave-induced pressure acting on the slopes of waves: known as form drag. Direct field measurements of the wave-induced pressure in airflow over water waves are difficult and consequently rare. Those that have been reported are for deep water conditions and conditions in which the level of forcing, measured by the ratio of wind speed to the speed of the dominant (spectral peak) waves, is quite weak, U10/cp < 3. The data reported here were obtained over a large shallow lake during the Australian Shallow Water Experiment (AUSWEX). The propagation speeds of the dominant waves were limited by depth and the waves were correspondingly steep. This wider range of forcing and concomitant wave steepness revealed some new aspects of the rate of wave amplification by wind, the so-called wind input source function, in the energy balance equation for wind-driven water waves. It was found that the exponential growth rate parameter (fractional energy increase per radian) depended on the slope of the waves, ak, vanishing as ak → 0. For very strong forcing a condition of “full separation” occurs, where the airflow detaches from the crests and reattaches on the windward face leaving a separation zone over the leeward face and the troughs. In a sense, the outer flow does not “see” the troughs and the resulting wave-induced pressure perturbation is much reduced, leading to a reduction in the wind input source function relative to that obtained by extrapolation from more benign conditions. The source function parameterized on wave steepness and degree of separation is shown to be in agreement with previous field and laboratory data obtained in conditions of much weaker forcing and wave steepness. The strongly forced steady-state conditions of AUSWEX have enabled the authors to define a generalized wind input source function that is suitable for a wide range of conditions.
Simulation of X-Band Rainfall Observations from S-Band Radar Data
Authors: Chandrasekar V. , Lim S. , Gorgucci E.
Published: September 2006

To design X-band radar systems as well as evaluate algorithm development, it is useful to have simultaneous X-band observation with and without the impact of path attenuation. One way to develop that dataset is through theoretical models. This paper presents a methodology to generate realistic range profiles of radar variables at attenuating frequencies, such as X band, for rain medium. Fundamental microphysical properties of precipitation, namely, size and shape distribution information, are used to generate realistic profiles of X band starting with S-band observation. Conditioning the simulation from S band maintains the natural distribution of rainfall microphysical parameters. Data from the Colorado State University’s University of Chicago–Illinois State Water Survey (CHILL) radar and the National Center for Atmospheric Research S-band dual-polarization Doppler radar (S-POL) are used to simulate X-band radar variables. Three procedures to simulate the radar variables and sample applications are presented.
Identification and Removal of Ground Echoes and Anomalous Propagation Using the Characteristics of Radar Echoes
Authors: Cho Yo-Han , Lee Gyu Won , Kim Kyung-Eak , Zawadzki Isztar
Published: September 2006

This paper explores the removal of normal ground echoes (GREs) and anomalous propagation (AP) in ground-based radars using a fuzzy logic approach. Membership functions and their weights are derived from the characteristics of radar echoes as a function of radar reflectivity. The dependence on echo intensity is shown to significantly improve the proper identification of GRE/AP. In addition, the proposed method has a better performance at lower elevation angles. The overall performance is comparable with that from a polarimetric approach and can thus be easily implemented in operational radars.
A Fuzzy Logic Technique for Identifying Nonprecipitating Echoes in Radar Scans
Authors: Berenguer Marc , Sempere-Torres Daniel , Corral Carles , Sánchez-Diezma Rafael
Published: September 2006

Because echoes caused by nonmeteorological targets significantly affect radar scans, contaminated bins must be identified and eliminated before precipitation can be quantitatively estimated from radar measurements.

Under mean propagation conditions, clutter echoes (mainly caused by targets such as mountains or large buildings) can be found in almost fixed locations. However, in anomalous propagation conditions, new clutter echoes may appear (sometimes over the sea), and they may be difficult to distinguish from precipitation returns. Therefore, an automatic algorithm is needed to identify clutter on radar scans, especially for operational uses of radar information (such as real-time hydrology).

In this study, a new algorithm is presented based on fuzzy logic, using volumetric data. It uses some statistics to highlight clutter characteristics (namely, shallow vertical extent, high spatial variability, and low radial velocities) to output a value that quantifies the possibility of each bin being affected by clutter (in order to remove those in which this factor exceeds a certain threshold).

The performance of this algorithm was compared against that of simply removing mean clutter echoes. Satisfactory results were obtained from an exhaustive evaluation of this algorithm, especially in those cases in which anomalous propagation played an important role.
Satellite and VIZ–Radiosonde Intercomparisons for Diagnosis of Nonclimatic Influences
Authors: Christy John R. , Norris William B.
Published: September 2006

Radiosonde datasets of temperature often suffer from discontinuities due to changes in instrumentation, location, observing practices, and algorithms. To identify temporal discontinuities that affect the VIZ/Sippican family of radiosondes, the 1979–2004 time series of a composite of 31 VIZ stations are compared to composites of collocated values of layer temperatures from two microwave sounding unit datasets—the University of Alabama in Huntsville (UAH) and Remote Sensing Systems (RSS). Discontinuities in the radiosonde time series relative to the two satellite datasets were detected with high significance and with similar magnitudes; however, some instances occurred where only one satellite dataset differed from the radiosondes. For the products known as lower troposphere (LT; surface–300 hPa) and midtroposphere (MT; surface–75-hPa layer), significant discontinuities relative to both satellite datasets were found—two cases for LT and four for MT. These are likely associated with changes in the radiosonde system. Three apparent radiosonde discontinuities were also determined for the lower-stratospheric product (LS; 150–15 hPa). Because they cannot be definitely traced to changes in the radiosonde system, they could be the result of common errors in the satellite products. When adjustments are applied to the radiosondes based independently on each satellite dataset, 26-yr trends of UAH (RSS) are consistent with the radiosondes for LT, MT, and LS at the level of ±0.06, ±0.04, and ±0.07 (±0.12, ±0.10, and ±0.10) K decade−1. Also, simple statistical retrievals based on radiosonde-derived relationships of LT, MT, and LS indicate a higher level of consistency with UAH products than with those of RSS.
Singular Vector Analysis for Atmospheric Chemical Transport Models
Authors: Liao Wenyuan , Sandu Adrian , Carmichael Gregory R. , Chai Tianfeng
Published: September 2006

The singular vectors of a chemical transport model are the directions of maximum perturbation growth over a finite time interval. They have proved useful for the estimation of error growth, the initialization of ensemble forecasts, and the optimal placement of adaptive observations. The aim of this paper is to address computational aspects of singular vector analysis for atmospheric chemical transport models. The distinguishing feature of these models is the presence of stiff chemical interactions. A projection approach to preserve the symmetry of the tangent linear–adjoint operator for stiff systems is discussed, and extended to 3D chemical transport simulations. Numerical results are presented for a simulation of atmospheric pollution in East Asia in March 2001. The singular values and the structure of the singular vectors depend on the length of the simulation interval, the meteorological data, the location of the optimization region and the selection of optimization species, the choice of error norms, and the size of the optimization region.
Using Digital Cloud Photogrammetry to Characterize the Onset and Transition from Shallow to Deep Convection over Orography
Authors: Zehnder Joseph A. , Zhang Liyan , Hansford Dianne , Radzan Anshuman , Selover Nancy , Brown Constance M.
Published: September 2006

An automated method for segmenting digital images of orographic cumulus and a simple metric for characterizing the transition from shallow to deep convection are presented. The analysis is motivated by the hypothesis that shallow convection conditions the atmosphere for further deep convection by moistening it and preventing the evaporation of convective turrets through the entrainment of dry air. Time series of convective development are compared with sounding and surface data for 6 days during the summer of 2003. The observations suggest the existence of a threshold for the initiation of shallow convection based on the surface equivalent potential temperature and the saturated equivalent potential temperature above the cloud base. This criterion is similar to that controlling deep convection over the tropical oceans. The subsequent evolution of the convection depends on details of the environment. Surface fluxes of sensible and latent heat, along with the transport of boundary layer air by upslope flow, increase the surface equivalent potential temperature and once the threshold value is exceeded, shallow convection begins. The duration of the shallow convection period and growth rate of the deep convection are determined by the kinematic and thermodynamic structure of the mid- and upper troposphere.
The Sensitivity of Simulated Convective Storms to Variations in Prescribed Single-Moment Microphysics Parameters that Describe Particle Distributions, Sizes, and Numbers
Authors: Cohen Charles , McCaul Eugene W.
Published: September 2006

The sensitivity of cloud-scale simulations of deep convection to variations in prescribed microphysics parameters is studied, using the single-moment scheme in the Regional Atmospheric Modeling System (RAMS) model. Realistic changes were made to the shape parameters in the gamma distributions of the diameters of precipitating hydrometeors and of cloud droplets, in the number concentration of cloud droplets, and in the mean size of the hail and graupel. Simulations were performed with two initial soundings that are identical except for their temperature. The precipitation rate at the ground is not very sensitive to changes in the value of the shape parameter used for all precipitating hydrometeors (rain, hail, graupel, snow, and aggregates) or to the mean size of the hail and graupel, owing to counteracting effects. For example, with a larger shape parameter value, there is a greater production of precipitation by collection of cloud water, but also a larger rate of evaporation of the liquid precipitation. However, with a larger shape parameter value, the greater production of precipitation by collection and the increased evaporation result in more low-level cooling by the downdraft. Specifying larger hail and graupel results in less low-level cooling by the downdraft. The simulation with the cold initial sounding showed a change in storm propagation velocity when the specified sizes of hail and graupel were increased, but this did not occur when the warm initial sounding was used. With a larger shape parameter for cloud water or with a larger number concentration of cloud droplets, there is less autoconversion and less collection of cloud water and, consequently, much less precipitation at the ground and denser cirrus anvils. While the number concentration of cloud droplets can be forecast in some models with parameterized microphysics, at present the shape parameter for cloud water cannot and must, therefore, be carefully selected.
A Finite-Volume Grid Using Multimoments for Geostrophic Adjustment
Authors: Xiao F. , Peng X. D. , Shen X. S.
Published: September 2006

This paper presents a novel finite-volume grid that uses not only the volume-integrated average (VIA) like the traditional finite-volume method, but also the surface-integrated average (SIA) as the model variables. The VIA and SIA are generically called “moments” in the context used here and are carried forward in time separately as the prognostic quantities. With the VIA defined in the control volume while the SIA is on the surface of the control volume, the discretization based on VIA and SIA leads to some new features in the numerical dispersions. A simple formulation using both VIA and SIA for shallow-water equations is presented. The numerical dispersion of the resulting grid, which is denoted as the “M grid,” is discussed with comparisons to the existing ones.
Horizontal Convective Rolls in Cold Air over Water: Buoyancy Characteristics of Coherent Plumes Detected by an Airborne Radar
Authors: Yang Qiong , Geerts Bart
Published: September 2006

Aircraft and airborne cloud radar data are used to describe the vertical structure of the convective boundary layer (CBL) during cold-air outbreaks over Lake Michigan in January 2004. Two days with mesoscale cloud street structure and a day with cellular organization are contrasted. The radar reflectivity and vertical velocity structure of the CBL, as well as the radar-inferred topography of the CBL inversion, are collected along flight legs normal to the cloud streets. High-resolution horizontal and vertical transects of the dual-Doppler airflow field capture horizontal convective roll circulations on one day.

Coherent structures within the CBL are analyzed as echo plumes, updraft plumes, and CBL domes. Only updraft plumes have the characteristics of buoyant thermals. Updrafts are narrower, weaker, and less buoyant on the no-roll day, but the differences in characteristics between two cloud street days are larger than those between the no-roll day and the two cloud street days. The lack of a clear buoyancy signal in echo plumes and under CBL domes is attributed to a temporal phase shift between maximum buoyancy, maximum ice particle size, and maximum overshooting in thermals, and the transience of convective updrafts.
GOES Climatology and Analysis of Thunderstorms with Enhanced 3.9-μm Reflectivity
Authors: Lindsey Daniel T. , Hillger Donald W. , Grasso Louie , Knaff John A. , Dostalek John F.
Published: September 2006

By combining observations from the Geostationary Operational Environmental Satellite (GOES) 3.9- and 10.7-μm channels, the reflected component of the 3.9-μm radiance can be isolated. In this paper, these 3.9-μm reflectivity measurements of thunderstorm tops are studied in terms of their climatological values and their utility in diagnosing cloud-top microphysical structure. These measurements provide information about internal thunderstorm processes, including updraft strength, and may be useful for severe weather nowcasting. Three years of summertime thunderstorm-top 3.9-μm reflectivity values are analyzed to produce maps of climatological means across the United States. Maxima occur in the high plains and Rocky Mountain regions, while lower values are observed over much of the eastern United States. A simple model is used to establish a relationship between 3.9-μm reflectivity and ice crystal size at cloud top. As the mean diameter of a cloud-top ice crystal distribution decreases, more solar radiation near 3.9 μm is reflected. Using the North American Regional Reanalysis dataset, the thermodynamic environment that favors thunderstorms with large 3.9-μm reflectivity values is identified. In the high plains and mountains, environments with relatively dry boundary layers, steep lapse rates, and large vertical shear values favor thunderstorms with enhanced 3.9-μm reflectivity. Thunderstorm processes that lead to small ice crystals at cloud top are discussed, and a possible relationship between updraft strength and 3.9-μm reflectivity is presented.
While We Are Waiting: Imagining and Creating a Safe Drug Supply While We Await the Coming of the Radio Frequency Identification Track-and-Trace System
Authors: Ling Louis
Published: September 2006

This article will discuss the history of the present regulatory regime regarding pharmaceutical wholesaling and will demonstrate the deficiencies of the present system. Next, the article will show that the failings of the present regime are caused by a lack of regulatory diligence and fortitude and that one existing tool, namely, the paper pedigree, if properly used, could curb most of the deficiencies in the system. The article will conclude with concrete recommendations to regulators and the pharmaceutical industry that will make the drug supply safe again.
Multiple Gestation: Side Effects of Antepartum Bed Rest
Authors: Maloni Judith A. , Margevicius Seunghee Park , Damato Elizabeth G.
Published: September 2006

The birth rate for higher order multiples has dramatically increased in recent decades. Multiple gestation pregnancies are considered to be at high obstetric risk. Antepartum bed rest is often prescribed to offset complications despite the lack of evidence for its effectiveness in preventing complications. This longitudinal repeated-measures study identified side effects of antepartum bed rest treatment for 31 hospitalized women with twin or triplet gestation. Maternal weight gain and infant birth weight were recorded. Antepartum stressors were measured by the Antepartum Stressors Hospital Inventory, and depressive symptoms were measured by the Center for Epidemiologic Studies Depression Scale (CES-D). Antepartum and post-partum side effects of bed rest were also assessed by the Antepartum and Postpartum Symptom Checklists. The weekly rate of maternal weight gain during hospitalization was significantly less than recent recommendations for multiple gestation weight gain (t =– 2.14,p = .04). Infant birth weights were appropriate for gestational age. There were fewer than expected small-for-gestational-age infants. Concerns regarding family status and separation from family were the major antepartum stressors. Women reported a high number of symptoms during bed rest (M= 22), which did not significantly change across 2 weeks. CES-D scores for depressive symptoms were high on antepartum hospital admission. Postpartum symptoms were initially high but had significantly declined by 6 weeks: F(1, 27)= 15.68, p = .00. These findings suggest that interventions are needed to reduce antepartum maternal weight loss, stress, physiologic and psychosocial symptoms, and depressive symptoms, as well as reduce postpartum symptoms of maternal morbidity.
Thrombin stimulation of p38 MAP kinase in human platelets is mediated by ADP and thromboxane A2 and inhibited by cGMP/cGMP-dependent protein kinase
Authors: Begonja Antonija Jurak , Geiger Jörg , Rukoyatkina Natalia , Rauchfuss Steffen , Gambaryan Stepan , Walter Ulrich
Published: September 2006

p38 MAP kinase in human platelets is activated by platelet agonists including thrombin, thromboxane A2 (TxA2), ADP, and others. However, both upstream mechanisms of p38 MAP kinase activation, and their downstream sequelae, are presently controversial and essentially unclear. Certain studies report sequential activation of cGMP-dependent protein kinase (PKG) and p38/ERK pathways by platelet agonists, leading to integrin activation and secretion, whereas others establish an essential role of Src/ERK-mediated TxA2 generation for fibrinogen receptor activation in human platelets. Here, we show that ADP secreted from platelet-dense granules, and subsequent activation of P2Y12 receptors, as well as TxA2 release are important upstream mediators of p38 MAP kinase activation by thrombin. However, p38 MAP kinase activation did not significantly contribute to calcium mobilization, P-selectin expression, αIIbβ3 integrin activation, and aggregation of human platelets in response to thrombin. Finally, PKG activation did not stimulate, but rather inhibited, p38 MAP kinase in human platelets.
A key role for STIM1 in store operated calcium channel activation in airway smooth muscle
Authors: Peel Samantha E , Liu Bo , Hall Ian P
Published: September 2006

Background

Control of cytosolic calcium plays a key role in airway myocyte function. Changes in intracellular Ca2+ stores can modulate contractile responses, modulate proliferation and regulate synthetic activity. Influx of Ca2+ in non excitable smooth muscle is believed to be predominantly through store operated channels (SOC) or receptor operated channels (ROC). Whereas agonists can activate both SOC and ROC in a range of smooth muscle types, the specific trigger for SOC activation is depletion of the sarcoplasmic reticulum Ca2+ stores. The mechanism underlying SOC activation following depletion of intracellular Ca2+ stores in smooth muscle has not been identified.

Methods

To investigate the roles of the STIM homologues in SOC activation in airway myocytes, specific siRNA sequences were utilised to target and selectively suppress both STIM1 and STIM2. Quantitative real time PCR was employed to assess the efficiency and the specificity of the siRNA mediated knockdown of mRNA. Activation of SOC was investigated by both whole cell patch clamp electrophysiology and a fluorescence based calcium assay.

Results

Transfection of 20 nM siRNA specific for STIM1 or 2 resulted in robust decreases (>70%) of the relevant mRNA. siRNA targeted at STIM1 resulted in a reduction of SOC associated Ca2+ influx in response to store depletion by cyclopiazonic acid (60%) or histamine but not bradykinin. siRNA to STIM2 had no effect on these responses. In addition STIM1 suppression resulted in a more or less complete abrogation of SOC associated inward currents assessed by whole cell patch clamp.

Conclusion

Here we show that STIM1 acts as a key signal for SOC activation following intracellular Ca2+ store depletion or following agonist stimulation with histamine in human airway myocytes. These are the first data demonstrating a role for STIM1 in a physiologically relevant, non-transformed endogenous expression cell model.