bluuebunny/crossref_metadata_2025 huggingface dataset:
Interpretation of capacitance spectra and transit times of single carrier space‐charge limited transport in organic layers with field‐dependent mobility
Authors: Montero José M. , Bisquert Juan , Garcia‐Belmonte Germà , Bolink Henk J. , Barea Eva M.
Published: May 2007

The ac impedance characteristics of a single carrier with space‐charge limited current (SCLC) transport in organic layers with field‐dependent mobility is analyzed, indicating the similarities as well as the differences to the constant mobility case. The model provides capacitance spectra and transit times from different calculation methods, in relation to the electric field distribution in the SCLC regime. It is found that the low frequency capacitance lies in the range 3Cg/4 < Cif < Cg, with respect to the geometric capacitance Cg. An approximated expression for the variation of the transit time with applied bias is derived, in good agreement with exact calculations. Experimental results of capacitance spectra of hole‐only PPV devices indicate the validity of the SCLC model but also show a strong contribution of trapping at low frequencies that overlap the low‐frequency value of the SCLC capacitance. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extrinsic and intrinsic origins of anisotropic magnetoresistance in doped YIG
Authors: Lehmann‐Szweykowska A. , Wojciechowski R. J. , Gehring G. A. , Szamer A. , Wigen P. E. , Micnas R.
Published: May 2007

A microscopic model of Ca:YIG minimal system in the form of a pair of the tetrahedral (d) iron–oxygen clusters, separated by the octahedral (a) cluster, coupled in series to the electrodes, is employed in an interpretation of the experimentally observed intriguing behaviour of anisotropic magnetoresistance (MR). Two possible origins of the anisotropy of MR are viewed. The extrinsic one results from orbital contributions to magnetic moments of the central clusters and reveals itself in the external magnetic field. The intrinsic one is caused by different spin polarisation of the left and the right d clusters with respect to the middle a cluster. The effect is connected with a presence of a compensating hole at one of the tetrahedral clusters. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Partial localization of correlated electrons in an orbitally degenerate narrow band: spin dependent masses, saturated ferromagnetism
Authors: Jędrak Jakub , Spałek Jozef , Zwicknagl Gertrud
Published: May 2007

We have determined the localization threshold in a partially filled and doubly degenerate model of correlated electrons. Particular emphasis is put on a non‐integer band filling n ≥ 1, when the system decomposes into the localized and the itinerant subsystems. A simultaneous transition to the ferromagnetic state is discussed as driven by the Hund's rule coupling combined with the effective field coming from the correlations. Dependence of the quasiparticle mass on the spin direction appears naturally in the spin‐polarized phase and is attributed to the electron correlation effects, as is also a metamagnetic transition in an applied field. Although the main results have been obtained within the saddle point slave‐boson approach, their qualitative features are discussed in general terms, i.e. as a transition from quantum‐mechanical indistinguishability of particles forming the Fermi fluid to a two‐component situation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman spectroscopy of pentyl‐functionalized carbon nanotubes
Authors: Müller M. , Maultzsch J. , Wunderlich D. , Hirsch A. , Thomsen C.
Published: May 2007

We present Raman scattering on carbon nanotubes functionalized with pentyl groups. Studies of the intermediate frequency region and the C–H bond stretching signal along with the D mode show evidence of the addition reaction by Raman spectroscopy. From the resonance profiles of the radial breathing mode (RBM) we assign the chiral indices of the tubes and study the influence of the functionalization on the transition energies, shift and intensity of the RBM signal. The largest effect we observe is on the Raman intensity of the radial breathing mode. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

magnified image

Pentyl–SWNT
Nanoporous Aluminum Oxide Membranes for Filtration and Biofunctionalization
Authors: Thormann Annika , Teuscher Nico , Pfannmöller Monika , Rothe Ulrich , Heilmann Andreas
Published: May 2007

Nanoporous aluminum oxide membranes with high open porosity are prepared by anodic oxidation. Conventional self‐supporting as well as mechanically stabilized nanoporous membranes are produced from aluminum plates and microimprinted aluminum foils, respectively. The mechanically stabilized membranes are characterized by very thin membrane parts stabilized by surrounding thick bridges. The minimal thickness of these thin membranes with open pores on both sides is 1 μm, with a mean pore size of the parallel open pores of 185 nm. With these two kinds of membrane the flow rates for cross filtration can be tuned over a wide range. With the mechanically stabilized membranes, substantially higher flow rates are achieved and experiments that cannot be performed with thicker membranes become possible. The biofunctionalization of the pore walls with archaebacterial tetraether lipids is realized and proved using aminated semiconductor nanocrystals. The lipid layer deposited on the pore walls also changes the filtration properties.
Cluster‐based information processing in wireless sensor networks: an energy‐aware approach
Authors: Tian Yuan , Ekici Eylem , Özgüner Füsun
Published: May 2007

Emerging Wireless Sensor Network (WSN) applications demand considerable computation capacity for in‐network processing in resource limited WSN environments. To achieve the required processing capacity under energy consumption constraints, collaboration among sensors through parallel processing methods emerges as a promising solution. Although such methods have been extensively studied in wired networks of processors, its counterpart for WSNs remains largely unexplored. In this paper, a localized task mapping and scheduling solution for energy‐constrained applications in WSNs, Energy‐constrained Task Mapping and Scheduling (EcoMapS), is presented. EcoMapS guarantees energy consumption constraints while minimizing schedule length. EcoMapS incorporates channel modeling, concurrent task mapping, communication and computation scheduling, and sensor failure handling algorithms. Simulation results show significant performance improvements of EcoMapS over existing mechanisms in terms of minimizing schedule lengths subject to energy consumption constrains. Copyright © 2007 John Wiley & Sons, Ltd.
Generalization of signcryption for resources‐constrained environments
Authors: Han Yiliang
Published: May 2007

Traditional signcryption is not feasible for some information security scenarios, though it is a new cryptographic primitive that simultaneously fulfills both the functions of signature and encryption.Generalized signcryptionis an adaptive primitive which achieves both secrecy and authenticity or provides them respectively by a generic structure. The notions related to generalized signcryption such as syntax, correctness, and security are proposed in the paper. A practical generalized signcryption scheme ECGSC is evaluated carefully also. The formal proofs for the unforgeability and confidentiality of ECGSC in the Random Oracle model are provided. To give a solution for multiple user settings, an efficient multicast scheme is also designed. ECGSC will seamlessly switch to the Elliptic Curve Digital Signature Algorithm (ECDSA) or a provable secure asymmetric encryption scheme when recipient's keys or sender's keys are absent. Compared with other schemes, it saves 9–14% communication costs in the signcryption mode. It also saves 78–82% computational costs. Copyright © 2007 John Wiley & Sons, Ltd.
Functional Diagnostics in Mitochondrial Diseases
Authors: Siciliano Gabriele , Volpi Leda , Piazza Selina , Ricci Giulia , Mancuso Michelangelo , Murri Luigi
Published: May 2007

Mitochondrial diseases (MD) with respiratory chain defects are caused by genetic mutations that determine an impairment of the electron transport chain functioning. Diagnosis often requires a complex approach with measurements of serum lactate, magnetic resonance spectroscopy (MRS), muscle histology and ultrastructure, enzymology, genetic analysis, and exercise testing. The ubiquitous distribution of the mitochondria in the human body explains the multiple organ involvement. Exercise intolerance is a common symptom of MD, due to increased dependence of skeletal muscle on anaerobic metabolism, with an excess lactate generation, phosphocreatine depletion, enhanced free radical production, reduced oxygen extraction and electron flux through the respiratory chain. MD treatment has included antioxidants (vitamin E, alpha lipoic acid), coenzyme Q10, riboflavin, creatine monohydrate, dichloroacetate and exercise training. Exercise is a particularly important tool in diagnosis as well as in the management of these diseases.
Synthesis and Properties of Functionalized Alkylaldonamides
Authors: Piasecki Andrzej , Piłakowska‐Pietras Dorota
Published: May 2007

Application studies of novel saccharide‐type nonionic surfactants were performed. The homolog series of N‐alkyl‐N‐(2‐hydroxyethyl)gluconamides and N‐alkyl‐N‐(2‐hydroxyethyl)glucoheptonamides (alkyl: n‐C10H21, n‐C12H25, and n‐C14H29) were synthesized and their structures were confirmed by means of elemental analysis and 1H‐NMR spectroscopy. The investigations showed that the application of N‐alkyl‐N‐(2‐hydroxyethyl)aldonamides as surfactants in an aqueous media can be limited. This is because of their relatively high Krafft point temperature. However, some variants can be successfully applied in mixtures with an anionic surfactant: sodium salt of n‐dodecyl sulfate (SDS). The addition of SDS causes significant improvement of the Krafft point temperatures. In some cases a synergistic effect was observed, i.e., the Krafft point temperature of the binary mixture was lower that the corresponding values for the solutions containing individual compounds. It is also remarkable, that the aqueous solutions of binary surfactant mixtures were characterized by improved foaming properties, as compared to that of pure SDS.
Pelvic and para‐aortic lymphadenectomy in patients with endometrioid adenocarcinoma of the endometrium
Authors: Geisler J.P. , Linnemeier G.C. , Manahan K.J.
Published: May 2007

Background: The purpose is to determine the rate of lymph node metastases in women with endometrioid adenocarcinoma of the endometrium (EAE) undergoing systematic lymphadenectomy. Methods: Patients (349) underwent a complete pelvic and para‐aortic lymphadenectomy from caudal to the median circumflex to the level of the renal vessels. Results: Grade 1 tumors accounted for 32.7% of the tumors and 31.0% of the positive nodes, grade 2 accounted for 47.3% of the tumors (37.9% of positive nodes), and grade 3 accounted for 20.1% of the tumors and 31.0% of the positive nodes (P > 0.05). Positive nodes were found in 15.8% of grade 1 tumors, 13.3% of grade 2 tumors and 25.7% of grade 3 tumors (P > 0.05). Isolated para‐aortic involvement without pelvic nodal involvement occurred in 29% of patients with positive nodes. Conclusions: When complete lymphadenectomies are performed in EAE, positive lymph nodes (including isolated para‐aortic lymph nodes) are common in all grades.
Prognostic indices with brief and standard CBT for panic disorder: II. Moderators of outcome
Authors: DOW MICHAEL G. T. , KENARDY JUSTIN A. , JOHNSTON DEREK W. , NEWMAN MICHELLE G. , TAYLOR C. BARR , THOMSON AILEEN
Published: May 2007

Background

Despite the growth of reduced therapist-contact cognitive behavioural therapy (CBT) programmes, there have been few systematic attempts to determine prescriptive indicators for such programmes vis-à-vis more standard forms of CBT delivery. The present study aimed to address this in relation to brief (6-week) and standard (12-week) therapist-directed CBT for panic disorder (PD) with and without agoraphobia. Higher baseline levels of severity and associated disability/co-morbidity were hypothesized to moderate treatment effects, in favour of the 12-week programme.

Method

Analyses were based on outcome data from two out of three treatment groups (n=72) from a recent trial of three forms of CBT delivery for PD. The dependent variables were a continuous composite panic/anxiety score and a measure of clinical significance. Treatment×predictor interactions were examined using multiple and logistic regression analyses.

Results

As hypothesized, higher baseline severity, disability or co-morbidity as indexed by strength of dysfunctional agoraphobic cognitions; duration of current episode of PD; self-ratings of panic severity; and the 36-item Short Form Health Survey (SF-36) (Mental component) score were all found to predict poorer outcome with brief CBT. A similar trend was apparent in relation to baseline level of depression. With high and low end-state functioning as the outcome measure, however, only the treatment×agoraphobic cognitions interaction was found to be significant.

Conclusions

While there was no evidence that the above variables necessarily contraindicate the use of brief CBT, they were nevertheless associated with greater overall levels of post-treatment improvement with the 12-week approach.
Two Further Comments on Durkheim's Le Suicide
Authors: Andriessen Karl
Published: May 2007

Abstract. It appears that the publications of Goldney and Schioldann (2000 , 2001a , b , 2002 ) touched a chord, namely, the quality of the basic literature of contemporary suicidology and the usage of certain words and concepts. This paper adds two comments to this discussion. The first comment focuses on the usage of “altruistic,” “egoistic,” and “anomic” suicide. The second is a comment on the reception of Le Suicide.
Circulation and water mass transformation in a model of the Chukchi Sea
Authors: Spall Michael A.
Published: May 2007

The circulation and water mass transformation in a regional ocean‐ice model of the Chukchi Sea are discussed. The model has horizontal resolution of O(4 km), is forced by fluxes derived from daily NCEP reanalysis fields, and has seasonally varying transport, temperature, and salinity imposed at Bering Strait. Many of the observed characteristics of the mean circulation and seasonal cycle in the Chukchi Sea are reproduced. The discussion focuses on: the branching of the inflow transport into pathways following Herald Canyon, Central Channel, and the Alaskan coast; the pattern of ice melt; and the water mass transformation and formation of winter water and hypersaline water. The ice melt pattern and timing is strongly influenced by advection through Bering Strait. High frequency forcing results in a larger region of ice melt, particularly over the shoals and in the northern Chukchi Sea, compared to monthly mean forcing. In the model, the seasonal cycle of salinity in the southern and central Chukchi Sea is dominated by advection through Bering Strait, while local atmospheric forcing and brine rejection are more important north of Herald and Hanna Shoals and in Barrow Canyon. However, since the residence time in the Chukchi Sea is generally less than 1 year, interannual variability in the Bering Strait salinity will be reflected in the salinity across the Chukchi Sea and at Barrow Canyon.
Coupling glacial erosion and tectonics at active orogens: A numerical modeling study
Authors: Tomkin Jonathan H.
Published: May 2007

Climate change indirectly alters the distribution of tectonic uplift at active orogens by modifying the action of surface processes, which in turn alters mountain topography. The impact of alpine glaciation on tectonic activity is explored here. The predictions of previous analytical, critical wedge models are compared with the output of a numerical model that explicitly couples rock uplift produced by convergence with surface erosion. Glacial and fluvial and erosive processes are calculated over a two‐dimensional grid, which uses an ice evolution model to calculate the rate of glacial erosion due to ice sliding. Tectonic uplift is determined by a two‐dimensional finite element convergence model. The simulations performed support the predictions of previous one‐dimensional analytical modeling of fluvially dominated orogens: Increasing precipitation decreases orogen width by the one quarter power. The simulations show that glacially dominated landscapes have similar dependencies. The total glacial erosion yield is determined to be proportional to the glacial coverage, sublinearly dependent on the precipitation rate, and linearly dependent on the glacial erosion constant that relates erosion with sliding speed. Climate also determines the distribution of tectonic uplift in the model. If the equilibrium line altitude (ELA) is high and glacial processes are limited to peak regions, the center of the mountain range experiences the highest rate of rock uplift. Extensive glaciation increases rock uplift rates on the flanks of the range. The style of glacial erosion is also important: A simple glacial buzzsaw does not create the same tectonic response as models that physically simulate glacial erosion. The simulations support the idea that a climate cooling of the magnitude recorded in the late Cenozoic has the potential to more than double the rate of rock uplift in appropriate orogens. The implications of the model are discussed for observations from the Olympic Mountains of Washington State, the Southern Alps of New Zealand, the Alaskan coastal range, and the southern Andes.
Evaluating hot spot–ridge interaction in the Atlantic from regional‐scale seismic observations
Authors: Gaherty James B. , Dunn Robert A.
Published: May 2007

We probe variations in mantle temperature, composition, and fabric along hot spot–influenced sections of the Mid‐Atlantic Ridge (MAR), using surface waves from nearby ridge earthquakes recorded on broadband island‐based seismic stations. We invert frequency‐dependent phase delays from these events to estimate one‐dimensional mean shear velocity and radial shear anisotropy profiles in the upper 200 km of the mantle within two seafloor age intervals: 5–10 Ma and 15–20 Ma. Mean shear velocity profiles correlate with apparent hot spot flux: lithosphere formed near the low‐flux Ascension hot spot is characterized by high mantle velocities, while the MAR near the higher‐flux Azores hot spot has lower velocities. The impact of the high‐flux Iceland hot spot on mantle velocities along the nearby MAR is strongly asymmetric: the lithospheric velocities near the Kolbeinsey ridge are moderately slow, while velocities near the Reykjanes ridge estimated in previous studies are much slower. Within each region the increase in shear velocity with age is consistent with a half‐space cooling model, and the velocity variations observed between Ascension, the Azores, and Kolbeinsey are consistent with approximately ±75° potential‐temperature variation among these sites. In comparison, the Reykjanes lithosphere is too slow to result purely from half‐space cooling of a high‐temperature mantle source. We speculate that the anomalously low shear velocities within the lithosphere produced at the Reykjanes ridge result from high asthenospheric temperatures of +50–75 K combined with ∼12% (by volume) gabbro retained in the mantle due to the imbalance between high hot spot–influenced melt production and relatively inefficient melt extraction along the slow spreading Reykjanes. Radial shear anisotropy in the upper 150 km also indicates an apparent hot spot influence: mantle fabric near Ascension is quite weak, consistent with previous models of anisotropy produced by corner flow during slow seafloor spreading. The fabric near the Azores and the Kolbeinsey ridge is stronger, suggesting that the hot spot increases mantle deformation beyond that produced by slow seafloor spreading in these regions.
Spatiotemporal evolution of aseismic interplate slip between 1996 and 1998 and between 2002 and 2004, in Bungo channel, southwest Japan
Authors: Ozawa Shinzaburo , Suito Hisashi , Imakiire Tetsuo , Murakmi Makoto
Published: May 2007

Interplate aseismic slip in the Bungo channel area, southwest Japan, occurred during 1996–1998 and 2002–2004. We employed a square root information filter following the time‐dependent inversion technique to time series of daily coordinates of global positioning system (GPS) sites. The results show that aseismic interplate slip occurred beneath the southwestern part of Shikoku Island from late 1996, then shifted southwestward to the Bungo channel area from May 1997 to February 1998, and subsided over time with a moment magnitude (Mw) of 7.1. In contrast, the 2002–2004 event shows slip in the area beneath the Bungo channel in an early stage from March 2003 to August 2003. From August 2003 to January 2004, the slip area expanded by around 30 km northeastward to the southwestern part of Shikoku Island and the northern part of the Bungo channel, and then decayed over time with Mw reaching 7.1. In the 2002–2004 event, the start of the northeastward expansion and acceleration of the aseismic slip coincided with the occurrence of a short‐term slow slip event and low‐frequency earthquakes in a deep area. This is a different spatiotemporal evolution from that of the 1996–1998 event, despite having occurred in almost the same area with similar moment magnitudes. A balance of slip deficit and forward aseismic slip on the plate boundary suggests that part of the Bungo channel area releases strain energy mainly by episodic long‐term slow slip events.
A series of cyclonic eddies in the Antarctic Divergence off Adélie Coast
Authors: Aoki Shigeru , Fukai Daisuke , Hirawake Toru , Ushio Shuki , Rintoul Stephen R. , Hasumoto Hiroshi , Ishimaru Takashi , Sasaki Hideharu , Kagimoto Takashi , Sasai Yoshikazu , Mitsudera Humio
Published: May 2007

The spatial and temporal characteristics of cyclonic eddies in the Antarctic Divergence off Adélie Coast are described using repeated in situ observations between 2001 and 2003, satellite observations, and results of a high‐resolution ocean general circulation model. Satellite ocean color images and altimetry clearly revealed a series of cyclonic eddies, with diameters of about 100–150 km that were separated by about 150 km in the zonal direction. The eddies are found at almost the same locations and can be traced for at least two months in the spring‐summer period. Cold and fresh anomalies were found throughout the water column in the cores of the cyclonic eddies. The water properties in the core of the eddies are similar to water found over the continental slope, 150–200 km to the south. The geopotential anomaly of the cold features was smaller than the sea level anomaly detected with satellite altimetry, indicating that significant barotropic flow is associated with the eddies. The Ocean general circulation model for the Earth Simulator (OFES) reproduces a series of cyclonic eddies similar to those observed, including a significant barotropic component. In the model, the series of eddies appear to originate further west over the continental slope region with no consistent phase propagation. The combination of repeat in situ observations, remote sensing and high‐resolution model results confirms the existence of persistent cyclonic eddies near 140°E and suggests the eddies play an important role in the exchange of water across the Antarctic Divergence.
Cold event in the South Atlantic Bight during summer of 2003: Model simulations and implications
Authors: Aretxabaleta Alfredo , Blanton Brian O. , Seim Harvey E. , Werner Francisco E. , Nelson James R. , Chassignet Eric P.
Published: May 2007

A set of model simulations are used to determine the principal forcing mechanisms that resulted in anomalously cold water in the South Atlantic Bight (SAB) in the summer of 2003. Updated mass field and elevation boundary conditions from basin‐scale Hybrid Coordinate Ocean Model (HYCOM) simulations are compared to climatological forcing to provide offshore and upstream influences in a one‐way nesting sense. Model skill is evaluated by comparing model results with observations of velocity, water level, and surface and bottom temperature. Inclusion of realistic atmospheric forcing, river discharge, and improved model dynamics produced good skill on the inner shelf and midshelf. The intrusion of cold water onto the shelf occurred predominantly along the shelf‐break associated with onshore flow in the southern part of the domain north of Cape Canaveral (29° to 31.5°). The atmospheric forcing (anomalously strong and persistent upwelling‐favorable winds) was the principal mechanism driving the cold event. Elevated river discharge increased the level of stratification across the inner shelf and midshelf and contributed to additional input of cold water into the shelf. The resulting pool of anomalously cold water constituted more than 50% of the water on the shelf in late July and early August. The excess nutrient flux onto the shelf associated with the upwelling was approximated using published nitrate‐temperature proxies, suggesting increased primary production during the summer over most of the SAB shelf.
Profiling float measurements of the recirculation gyre south of the Kuroshio Extension in May to November 2004
Authors: Chen Shuiming , Qiu Bo , Hacker Peter
Published: May 2007

During May to November 2004, 20 profiling floats were deployed in the recirculation gyre (RG) region south of the Kuroshio Extension (KE). With the KE and RG being in a stable state, most of these floats remained within the RG, resulting in a large number of satellite position fixes for estimating the velocities at the parking depth (1500 db) and a large number of temperature/salinity profiles for estimating the geostrophic velocities above the parking depth. The flows of the RG at different depths in the upper 1500 db are found to be approximately parallel to each other, with the speed at the surface (35 cm s−1) being about three and a half times larger than that at the parking depth (10 cm s−1). By analyzing the full‐depth conductivity‐temperature‐depth profiles in the RG, in addition to the velocity estimates, we found that the vertical structure of the RG velocity field was dominated by the barotropic and first baroclinic modes. The two modes are combined in such a way that the resulting RG circulates anticyclonically in the same direction from the surface to the bottom and has an anticyclonic bottom velocity on the order of 5 cm s−1. From the barotropic component (depth‐averaged) of the RG velocity field, the RG transport with one standard error is estimated at 101 ± 8 × 106 m3 s−1.
Ammonia sources, transport, transformation, and deposition in coastal New England during summer
Authors: Smith Allen M. , Keene William C. , Maben John R. , Pszenny Alexander A. P. , Fischer Emily , Stohl Andreas
Published: May 2007

During summer 2004, NH3, size‐resolved particulate NH4+, and associated characteristics of surface air were measured continuously on Appledore Island, off the southern Maine coast as part of the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT). NH3 concentrations ranged from <0.6 to 123 nmol m−3 with maxima around local noon and minima near dawn. Particulate NH4+ ranged from 10.3 to 191 nmol m−3. The transport of emissions from intensive agricultural activities in the eastern United States was an important source of total NH3 (NH3 + NH4+) over the Gulf of Maine during summer. Under cleaner northwest flow, total NH3 concentrations were relatively low (median = 50.0 nmol m−3) and partitioned roughly equally between phases; under the more polluted midwest flow, total NH3 concentrations were substantially higher (median = 171 nmol m−3) but dominated by particulate NH4+. Because particulate NH4+ was associated primarily with the highly acidic sub‐μm size fractions with low deposition velocities (median flux = 1.5 μmol m–2 day–1), dry‐deposition fluxes were dominated by the gas phase (median = 6.2 μmol m−2 day−1). Consequently, phase partitioning with pollutant‐derived sulfur aerosol substantially increased both the atmospheric lifetime of total NH3 against dry deposition and the relative importance of removal via wet‐ versus dry‐deposition pathways. Total NH3 accounted for 32% of the dry‐deposition flux of inorganic N to the Gulf of Maine during summer. The combined dry deposition of total NH3 and wet deposition of NH4+ via precipitation contributed 40% of the corresponding total atmospheric N flux.
Aircraft observations of aerosol composition and ageing in New England and Mid‐Atlantic States during the summer 2002 New England Air Quality Study field campaign
Authors: Kleinman Lawrence I. , Daum Peter H. , Lee Yin‐Nan , Senum Gunnar I. , Springston Stephen R. , Wang Jian , Berkowitz Carl , Hubbe John , Zaveri Rahul A. , Brechtel Fred J. , Jayne John , Onasch Timothy B. , Worsnop Douglas
Published: May 2007

Aerosol chemical composition, size distribution, and optical properties were measured during 17 aircraft flights in New England and Middle Atlantic States as part of the summer 2002 New England Air Quality Study field campaign. An Aerodyne aerosol mass spectrometer (AMS) was operated with a measurement cycle of 30 s, about an order of magnitude faster than used for ground‐based measurements. Noise levels within a single measurement period were sub μg m−3. Volume data derived from the AMS were compared with volume measurements from a Passive Cavity Aerosol Spectrometer (PCASP) optical particle detector and a Twin Scanning Electrical Mobility Spectrometer (TSEMS); calculated light scattering was compared with measured values from an integrating nephelometer. The median ratio for AMS/TSEMS volume was 1.25 (1.33 with an estimated refractory component); the median ratio for AMS/nephelometer scattering was 1.18. A dependence of the AMS collection efficiency on aerosol acidity was quantified by a comparison between AMS and PCASP volumes in two high sulfate plumes. For the entire field campaign, the average aerosol concentration was 11 μg m−3. Compared with monitoring data from the IMPROVE network, the organic component made up a large fraction of total mass, varying from 70% in clean air to 40% in high concentration sulfate plumes. In combination with other optical and chemical measurements, the AMS gave information on secondary organic aerosol (SOA) production and the time evolution of aerosol light absorption. CO is taken as a conservative tracer of urban emissions and the ratios of organic aerosol and aerosol light absorption to CO examined as a function of photochemical age. Comparisons were made to ratios determined from surface measurements under conditions of minimal atmospheric processing. In air masses in which the NOx to NOy ratio has decreased to 10%, the ratio of organic aerosol to CO has quadrupled indicating that 75% of the organic aerosol is secondary. Also, the ratio of light absorption to CO has more than doubled, which is interpreted as an equivalent increase in the light absorption efficiency of black carbon due to aerosol ageing.
Performance assessment of the Optical Transient Detector and Lightning Imaging Sensor
Authors: Mach Douglas M. , Christian Hugh J. , Blakeslee Richard J. , Boccippio Dennis J. , Goodman Steven J. , Boeck William L.
Published: May 2007

We describe the clustering algorithm used by the Lightning Imaging Sensor (LIS) and the Optical Transient Detector (OTD) for combining the space‐based observations of lightning pulse data into events, groups, flashes, and areas. Events are single pixels that exceed the LIS/OTD background level during a single frame (2 ms). Groups are clusters of events that occur within the same frame and in adjacent pixels. Flashes are clusters of groups that occur within 330 ms and either 5.5 km (for LIS) or 16.5 km (for OTD) of each other. Areas are clusters of flashes that occur within 16.5 km of each other. The flash data from LIS/OTD are currently being used for lightning and thunderstorm processes and climatological studies; therefore we test how variations in the algorithms for the event‐group and group‐flash clustering affect the flash count for a subset of the LIS and OTD data. We divided the subset into areas with low (1–3), medium (4–15), high (16–63), and very high (64+) flash counts to see how changes in the clustering parameters affect the flash rates in these different sizes of areas. We found that as long as the cluster parameters are within about a factor of two of the current values, the overall flash counts do not change by more than about 20%. Therefore the flash clustering algorithm used by the LIS and OTD sensors are robust and create flash rates that are relatively insensitive to reasonable variations in the clustering algorithms.
Streamflow response to seasonal snow cover mass changes over large Siberian watersheds
Authors: Yang Daqing , Zhao Yuanyuan , Armstrong Richard , Robinson David , Brodzik Mary‐Jo
Published: May 2007

We used remotely sensed weekly snow water equivalent (SWE) data (1988–2000) to investigate streamflow response to seasonal snow cover change in the large Siberian watersheds (the Ob, Yenisei, and Lena basins). We quantified the seasonal cycles and variations of snow cover mass and river streamflow and identified a clear correspondence of river discharge to seasonal snow cover mass change. We also examined and compared the weekly mean streamflow with the weekly basin SWE for the study period. The results revealed a strong relation between the streamflow and snow cover mass change during the spring melt season over the large Siberian watersheds. This relationship provides a practical procedure of using remotely sensed snow cover information for snowmelt runoff estimation over the large northern watersheds. Analyses of extreme (high/low) SWE cases (years) and the associated streamflow conditions indicate an association of high (low) flood peak with high (low) maximum SWE in the Ob and Yenisei basins. Comparative analyses of weekly basin SWE data versus snow cover extent (SCE), peak snowmelt floods, and climatic variables (temperature and winter precipitation) indicate consistency among basin SWE, SCE, and temperature but incompatibility between basin SWE and winter precipitation, particularly for the Lena watershed. The inconsistency suggests uncertainties in determination of basin winter snowfall amounts and limitations in applications of the SWE retrieval algorithm over large watersheds/regions with very different physical characteristics. Overall, the results of this study clearly demonstrate that the weekly SWE data/products derived from microwave remote sensing technology are useful in understanding seasonal streamflow changes in the arctic regions.
Three‐dimensional distribution and evolution of permafrost temperatures in idealized high‐mountain topography
Authors: Noetzli Jeannette , Gruber Stephan , Kohl Thomas , Salzmann Nadine , Haeberli Wilfried
Published: May 2007

Permafrost degradation is regarded as a crucial factor influencing the stability of steep rockwalls in alpine areas. Discernment of zones of fast temperature changes requires knowledge about the temperature distribution and evolution at and below the surface of steep rock. In complex high‐mountain topography, strong lateral heat fluxes result from topography and variable surface temperatures and profoundly influence the subsurface thermal field. To investigate such three‐dimensional effects, numerical experimentation was conducted using typical idealized geometries of high‐mountain topography, such as ridges, peaks, or spurs. The approach combines a surface energy balance model with a three‐dimensional ground heat conduction scheme to investigate belowground temperature distribution and permafrost occurrence in high‐mountain topography. Time‐dependent simulations are based on scenario data gained from regional climate models. Results indicate complex three‐dimensional patterns of temperature distribution and heat flow density below mountainous topography for equilibrium conditions, which are additionally perturbed by transient effects. Permafrost occurs at many locations where temperatures at the surface do not indicate it, e.g., on the south face of ridges or below the edges of a peak. The modeling tools applied have potential for a number of studies in high mountains addressing questions related to permafrost distribution and evolution at depth in real topographies, for instance, the reanalysis of temperature‐related instabilities.
Recovery in culture of viable but nonculturable Vibrio parahaemolyticus: regrowth or resuscitation?
Authors: Coutard François , Crassous Philippe , Droguet Mickaël , Gobin Eric , Colwell Rita R , Pommepuy Monique , Hervio-Heath Dominique
Published: May 2007

The objective of this study was to explore the recovery of culturability of viable but nonculturable (VBNC) Vibrio parahaemolyticus after temperature upshift and to determine whether regrowth or resuscitation occurred. A clinical strain of V. parahaemolyticus Vp5 was rendered VBNC by exposure to artificial seawater (ASW) at 4°C. Aliquots of the ASW suspension of cells (0.1, 1 and 10 ml) were subjected to increased temperatures of 20°C and 37°C. Culturability of the cells in the aliquots was monitored for colony formation on a rich medium and changes in morphology were measured by scanning (SEM) and transmission (TEM) electron microscopy. Samples of VBNC cells were fixed and examined by SEM, revealing a heterogeneous population comprising small cells and larger, flattened cells. Forty-eight hours after temperature upshift to 20°C or 37°C, both elongation and division by binary fission of the cells were observed, employing SEM and TEM, but only in the 10-ml aliquots. The results suggest that a portion of VBNC cells is able to undergo cell division. It is concluded that a portion of VBNC cells of V. parahaemolyticus subjected to cold temperatures remain viable. After temperature upshift, regrowth of those cells, rather than resuscitation of all bacteria of the initial inoculum, appears to be responsible for recovery of culturability of VBNC cells of V. parahaemolyticus. Nutrient in filtrates of VBNC cells is hypothesized to allow growth of the temperature-responsive cells, with cell division occurring via binary fission, but also including an atypical, asymmetric cell division.
The Ultimate Bluff: A Case Study of Partygaming.Com
Authors: Laffey Des
Published: May 2007

June 2005 was to bring online gambling out of the shadows and into the spotlight. PartyGaming, a start-up formed in 1997, launched a flotation (Initial Public Offering) on the London Stock Exchange that valued the firm at £4.64 billion giving it a larger market capitalisation than British Airways. PartyGaming had become the dominant player in the booming online poker market with its PartyPoker brand having over 50% market share. However, this float – as with Internet gambling in general – was not without controversy. While PartyGaming had an online gambling license from the tax haven of Gibraltar, nearly 90% of its revenue came from the United States, where the authorities viewed Internet gambling as illegal and threatened legal action. The complex operations of this truly global firm with bases in London, India, Gibraltar and Canada, the background of its founder Ruth Parasol in Internet pornography and the handling of its flotation also raised concerns from an ethical perspective, with some commentators questioning whether the float should have been allowed at all. These concerns were then confirmed as US legislation to curb online gambling was passed in September 2006, leading to PartyGaming's exit from the US market and an immediate fall of 58% in the share price. This case study analyses the entrepreneurs behind PartyGaming, its growth, the challenges it has faced, the ethical issues it poses and its future prospects. The case draws on theory from e-commerce, strategy and ethics.
Viewpoint: Measuring the effects of wildlife contraception: the argument for comparing apples with oranges
Authors: Kirkpatrick Jay F.
Published: May 2007

There are few wildlife populations existing today that can be supported without some form of management. Wildlife fertility control, as one option, has moved from the research stage to actual application with a number of species, including wild horses, urban deer, captive exotic species and even African elephants, but this approach remains controversial in many quarters. Strident debate has arisen over the possible effects of contraception on behaviour, genetics, stress and even management economics, among other parameters. Part of the debate arises from the fact that critics often fail to recognise that some form of alternative management will be applied, and a second problem arises when critics fail to identify and demand the same concern for the consequences of the alternative management approaches. Thus, any rational debate on the merits or possible effects of contraceptive management of wildlife must also recognise all alternative management approaches and apply the same concern and questions to these alternative approaches – including ‘no management’ – as are currently being applied to fertility control. Only then will the stewards of wildlife be in a position to make wise and informed decisions about management options.
Effects of cobalt/vitamin B12 status in ewes on ovum development and lamb viability at birth
Authors: Mitchell Linda M. , Robinson John J. , Watt Robert G. , McEvoy Thomas G. , Ashworth Cheryl J. , Rooke John A. , Dwyer Cathy M.
Published: May 2007

Scottish Blackface ewes from cobalt-deficient farmland were fed a diet containing 0.06 mg cobalt per kg dry matter from approximately 30 days before embryo recovery/transfer until lambing. Ewes remained untreated (–Co; n = 82) or were given an intraruminal cobalt-containing bolus to compensate for the dietary deficit (+Co; n = 82). Ewes used as embryo donors (–Co, n = 17; +Co, n = 16) were artificially inseminated with semen from a single Suffolk sire. Day 6 embryos obtained from –Co and +Co donors were transferred in singleton to –Co and +Co recipients in a 2 × 2 factorial-designed experiment to determine the effects of cobalt/vitamin B12 status during the periconception period (factor 1) and pregnancy (factor 2) on lamb viability at birth. Mean (± s.e.m.) circulating concentrations of vitamin B12 in –Co and +Co donors at ovum recovery were 182 ± 10 and 1288 ± 64 pmol L–1, respectively (P < 0.001), and the number of corpora lutea per ewe ovulating was 9.9 ± 1.6 and 14.4 ± 1.3, respectively (P < 0.05). Treatment did not affect the proportion of recovered ova that contained >32 cells (viable) or the median stage of development (late morula), but viable ova recovered from –Co v. +Co ewes had a better morphological grade (2.0 ± 0.1 v. 2.20 ± 0.04, respectively; P < 0.01). There was no effect of treatment on the proportion of recipient ewes that became pregnant. Circulating concentrations of vitamin B12 were lower in –Co than +Co ewes during pregnancy (P < 0.001) and at birth in lambs born to –Co ewes compared with those born to +Co ewes (P < 0.001). There was no effect of donor or recipient cobalt/vitamin B12 status on lamb birthweight, neonatal vigour or neonatal rectal temperatures, but lambs derived from +Co v. –Co embryo donors were more active in the first 3 days after birth (P < 0.05). Results show that sub-clinical cobalt/vitamin B12 deficiency reduces ovulatory response in superovulated ewes and that periconception nutrition can affect neonatal lamb behaviour.
Independent sorting-out of thousands of duplicated gene pairs in two yeast species descended from a whole-genome duplication
Authors: Scannell Devin R. , Frank A. Carolin , Conant Gavin C. , Byrne Kevin P. , Woolfit Megan , Wolfe Kenneth H.
Published: May 2007

Among yeasts that underwent whole-genome duplication (WGD),
Kluyveromyces polysporus
represents the lineage most distant from
Saccharomyces cerevisiae
. By sequencing the
K. polysporus
genome and comparing it with the
S. cerevisiae
genome using a likelihood model of gene loss, we show that these species diverged very soon after the WGD, when their common ancestor contained >9,000 genes. The two genomes subsequently converged onto similar current sizes (5,600 protein-coding genes each) and independently retained sets of duplicated genes that are strikingly similar. Almost half of their surviving single-copy genes are not orthologs but paralogs formed by WGD, as would be expected if most gene pairs were resolved independently. In addition, by comparing the pattern of gene loss among
K. polysporus
,
S. cerevisiae
, and three other yeasts that diverged after the WGD, we show that the patterns of gene loss changed over time. Initially, both members of a duplicate pair were equally likely to be lost, but loss of the same gene copy in independent lineages was increasingly favored at later time points. This trend parallels an increasing restriction of reciprocal gene loss to more slowly evolving gene pairs over time and suggests that, as duplicate genes diverged, one gene copy became favored over the other. The apparent low initial sequence divergence of the gene pairs leads us to propose that the yeast WGD was probably an autopolyploidization.
Directed evolution of gene-shuffled IFN-α molecules with activity profiles tailored for treatment of chronic viral diseases
Authors: Brideau-Andersen Amy D. , Huang Xiaojian , Sun Siu-Chi Chang , Chen Teddy T. , Stark Diane , Sas Ian J. , Zadik Linda , Dawes Glenn N. , Guptill Douglas R. , McCord Robert , Govindarajan Sridhar , Roy Ajoy , Yang Shumin , Gao Judy , Chen Yong Hong , Skartved Niels Jørgen Ø. , Pedersen Annette K. , Lin David , Locher Christopher P. , Rebbapragada Indrani , Jensen Anne Dam , Bass Steven H. , Nissen Torben L. Straight , Viswanathan Sridhar , Foster Graham R. , Symons Julian A. , Patten Phillip A.
Published: May 2007

Type I IFNs are unusually pleiotropic cytokines that bind to a single heterodimeric receptor and have potent antiviral, antiproliferative, and immune modulatory activities. The diverse effects of the type I IFNs are of differential therapeutic importance; in cancer therapy, an enhanced antiproliferative effect may be beneficial, whereas in the therapy of viral infections (such as hepatitis B and hepatitis C), the antiproliferative effects lead to dose limiting bone marrow suppression. Studies have shown that various members of the natural IFN-α family and engineered variants, such as IFN-con1, vary in the ratios between various IFN-mediated cellular activities. We used DNA shuffling to explore and confirm the hypothesis that one could simultaneously increase the antiviral and Th1-inducing activity and decrease the antiproliferative activity. We report IFN-α hybrids wherein the ratio of antiviral:antiproliferative and Th1-inducing: antiproliferative potencies are markedly increased with respsect to IFN-con1 (75- and 80-fold, respectively). A four-residue motif that overlaps with the IFNAR1 binding site and is derived by cross breeding with a pseudogene contributes significantly to this phenotype. These IFN-αs have an activity profile that may result in an improved therapeutic index and, consequently, better clinical efficacy for the treatment of chronic viral diseases such as hepatitis B virus, human papilloma virus, HIV, or chronic hepatitis C.