bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment of tinnitus with transcutaneous electrical nerve stimulation improves patients' quality of life
Authors: Aydemir G , Tezer M S , Borman P , Bodur H , Unal A
Published: March 2006

Objectives: Tinnitus can adversely affect patients' quality of life. Transcutaneous electrical nerve stimulation (TENS) may be effective in the management of tinnitus. No study has investigated the efficacy of TENS for the management of tinnitus by means of quality of life measures. In this study, we evaluated the efficacy of TENS for the management of tinnitus symptoms by using the visual analogue scale (VAS), tinnitus handicap inventory test, Nottingham health profile (NHP) and short form-36 (SF-36) questionnaires.

Methods: Twenty-two patients were included in this study (male/female, 16/6; mean age, 48.04 ± 15.57 years). Nine patients had unilateral and 13 patients had bilateral tinnitus.

Results: After TENS, improvement measured by VAS was only marginally significant (p = 0.059). However, after TENS, there were statistically significant improvements regarding tinnitus severity scores, tinnitus handicap inventory scores, NHP fatigue, social isolation and emotional problems scores, and many parameters measured by the SF-36 (physical functioning, general health, vitality, social functioning, role limitations due to emotional problems, and mental health)(p < 0.05).

Conclusion: Transcutaneous electrical nerve stimulation is a useful method to improve the quality of life of patients with tinnitus.
Thyroid surgery and recurrent laryngeal nerve monitoring
Authors: Bailleux S , Bozec A , Castillo L , Santini J
Published: March 2006

Recurrent laryngeal nerve paralysis is a much-dreaded complication of thyroid surgery.

Objective: To study the feasibility and the reliability of a recurrent laryngeal nerve monitoring technique.

Materials and methods: This was a prospective study including 36 patients proposed for thyroid surgery with recurrent laryngeal nerve monitoring. They underwent post-operative fibre-optic laryngeal examination and speech therapist consultation.

Results: Our technique of nerve monitoring showed a 98 per cent sensitivity and 86 per cent specificity.

Conclusions: Recurrent laryngeal nerve monitoring is a feasible and reliable technique. It can be used to avoid bilateral nerve injury and to increase the surgeon's confidence but not to replace a systematic nerve identification and a careful dissection.
Development of China's Overland Transportation Links with Central, South-west and South Asia
Authors: Garver John W.
Published: March 2006

The development of China's western regions was for a long time hampered by the difficult terrain of the area and its distance from the sea and hence maritime commerce. However China now has the fiscal wherewithal to invest in modern transportation technology and build railways and roads to link its west to the oceans. These networks will bring an acceleration of rates of development in the west to bring it more nearly in line with the east, and are a manifestation of China's economic rise. A second dimension is that the new lines of transportation will be bearers of Chinese influence to Central, South-west and South Asia. Trade flows and inter-dependencies will develop, and China's role in the regions to its west and south-west will increase.
Powershed Politics: Yunnan Hydropower under Great Western Development
Authors: Magee Darrin
Published: March 2006

This article uses hydropower development on the Lancang (upper Mekong River) and Nu (upper Salween River) as a lens for exploring institutional change and decision-making processes among governmental units and hydropower companies under the Great Western Development campaign. Scholars of the campaign tend to focus on central government policies and individual provinces' responses, and on the campaign's role as a central-state-strengthening project aimed at curbing regionalist tendencies. Large-scale hydropower development in Yunnan, however, is a complex affair involving national and provincial power companies, regional grids and governmental units at many levels. Conceptualizing Yunnan as the “powershed” of Guangdong, I argue that the Western Development campaign paves the way for increasingly strong interprovincial linkages between Guangdong and Yunnan that are not necessarily central-state-strengthening, and that consideration of such linkages should be fundamental to any attempt to understand the impacts of China's western development.
Privatization and Its Discontents in Chinese Factories
Authors: Chen Feng
Published: March 2006

Based on fieldwork in a city in central China, this study shows that, with an aggressive implementation of privatization schemes, labour struggles have emerged in which moral economy demands are increasingly permeated by “class consciousness.” Privatization activates workers' “class consciousness,” an idea that has become embedded in their minds through several decades' immersion in socialist (and anti-capitalist) ideology. For them, anti-privatization is politically defensible. It provides them with motivation, opportunity and an action-frame for class-conscious mobilization in Chinese factories. However, while workers' current efforts to base their demand on socialist rhetoric might be strategic, it seems to have trapped labour struggle in a direction that is unlikely to produce any significant positive outcomes for them, as the transition to the market is irreversible.
The Production of the Chiang Kai-shek Personality Cult, 1929–1975
Authors: Taylor Jeremy E.
Published: March 2006

One of the most visible features of Nationalist rule on Taiwan throughout the period of martial law (1948–87) was the promotion of a personality cult focused on the figure of Chiang Kai-shek. This article is an examination of the ways in which the disparate elements which made up this cult were produced. It considers how the cult reflected a political culture which originated in the Nanjing decade and the subsequent war years, yet which adapted to the realities of post-war exile in Taiwan. This study suggests that whilst the Chiang personality cult was promoted by the central government (and by Chiang himself) it was quasi-official organizations and individuals who were primarily responsible for the production of its written, visual and monumental texts.
Graduate Unemployment: Dilemmas and Challenges in China's Move to Mass Higher Education
Authors: Bai Limin
Published: March 2006

China's recent upsurge in graduate unemployment has specific causes relating to economic development, education policy-making, and reforms in the economy as well as in higher education. With a focus on graduate unemployment, this study looks at the historical and socio-economic conditions for China's move to raise the level of participation in higher education, the rationale behind the 1999 decision to accelerate the pace of expansion in the tertiary education sector, and the impact of this rapid expansion on society, and on graduate employment in particular. Martin Trow's theory is adopted as a theoretical framework within which the dilemmas and challenges of China's mass higher education movement are analysed. Through examining the relationship between the development of higher education and economic growth, this report questions whether China's higher education sector should have expanded and continue to expand on such a large scale.
Relationship between bovine oocyte morphology and in vitro developmental potential
Authors: Nagano Masashi , Katagiri Seiji , Takahashi Yoshiyuki
Published: March 2006

We investigated the relationship between the morphology of oocytes collected from small antral follicles and their developmental capacity. Immature oocytes were classified into seven groups and cultured in vitro for maturation (IVM), fertilization (IVF) and development to blastocysts (IVC). After IVF, sperm penetration and normal fertilization rates were higher in the oocytes whose cytoplasm appeared brown. The rate of polyspermy was highest in the oocytes whose cytoplasm was black. After IVC, the rates of cleavage and of development to the blastocyst stage were also higher in the brown oocytes. Although the oocytes with dark clusters in a pale cytoplasm showed lower cleavage rates, cleaved zygotes had high developmental rates the same as the oocytes with a brown cytoplasm. Transmission electron microscopy showed that the oocytes with a pale or black cytoplasm had organelles arranged differently from other oocytes before IVM. Most of the oocytes with a brown and homogeneous cytoplasm or small diameter had the characteristics of immature cytoplasm (large clusters of cortical granules) even after IVM. On the other hand, the brown oocytes with a dark zone at the periphery or with dark clusters showed the same arrangement of organelles as in vivo matured oocytes. The oocytes with a pale or black cytoplasm appeared to be degenerating and/or ageing. In conclusion, a dark ooplasm indicates an accumulation of lipids and good developmental potential, while a light-coloured ooplasm indicates a low density of organelles and poor developmental potential. A black ooplasm indicates ageing and low developmental potential.
Contribution of spermatozoal centrosomes to the microtubule-organizing centre in Antarctic minke whale (Balaenoptera bonaerensis)
Authors: Kobayashi Toshihiro , Amemiya Kazue , Takeuchi Kana , Tsujioka Tomomi , Tominaga Keiichiro , Hirabayashi Masumi , Ishikawa Hajime , Fukui Yutaka , Hochi Shinichi
Published: March 2006

Using an interspecies microinsemination assay with bovine oocytes, it was examined whether centrosomes of Antarctic minke whale spermatozoa function as the microtubule-organizing centre (MTOC). Bull and rat spermatozoa were used as positive and negative controls, respectively. Vitrified-warmed bovine mature oocytes were subjected to immunostaining against α-tubulin 4–6 h after intracytoplasmic injection (ICSI) of 5 mM dithiothreitol-treated spermatozoa. Aster formation occurred from whale spermatozoa (33%) and bull spermatozoa (33%), but very little from rat spermatozoa (3%). Activation treatment for the microinseminated oocytes with 7% ethanol + 2 mM 6-dimethylaminopurine resulted in a similar proportion of oocytes forming a whale sperm aster (35% vs 27% in the non-treated group; 4 h after ICSI) but a significantly larger aster (ratio of aster diameter to oocyte diameter, 0.57 vs 0.30 in the non-treated group). These results indicate that the centrosome introduced into bovine oocytes by whale spermatozoa contributes to the MTOC and that assembly of the microtubule network is promoted by oocyte activation.
Blastocyst development in equine oocytes with low meiotic competence after suppression of meiosis with roscovitine prior to in vitro maturation
Authors: Choi Y.H. , Love L.B. , Varner D.D. , Hinrichs K.
Published: March 2006

This study was conducted to evaluate the in vitro development of equine oocytes with compact cumuli that had been subjected to a period of meiotic suppression with roscovitine before in vitro maturation. In experiment 1, oocytes were recovered from slaughterhouse-derived ovaries and held in M199 + 10% fetal bovine serum containing 66 μM roscovitine with or without an overlay of mineral oil in 5% CO2 in air at 38.2 °C for 16–18 or 24 h. No oocytes treated with roscovitine in the absence of an oil overlay for 16–18 h were maturing, compared with 2–4% of oocytes in other treatments. In experiment 2, oocytes were either fixed immediately after recovery, or were cultured for 18 h in the presence or absence of roscovitine. Oocytes cultured in the absence of roscovitine had a significantly higher rate of meiotic resumption (18%) than was found in the other two treatments (0). In experiment 3, oocytes were matured immediately or after 16–18 h culture with roscovitine. Maturation rates were similar between oocytes previously treated with roscovitine (22%) and control oocytes (19%). Mature oocytes were fertilized by intracytoplasmic sperm injection and then cultured, with or without oviductal epithelial cells, for 7.5 days. There was no significant effect of roscovitine treatment on blastocyst development. Development to blastocyst of roscovitine-treated oocytes in DMEM/F-12 + co-culture (37%) was significantly higher than that of control oocytes in DMEM/F-12 without co-culture (14%). These data indicate that equine oocytes with compact cumuli can be held in roscovitine before maturation without any harmful effect on blastocyst formation.
Inhibitory effects of calcium ionophore pretreatment of porcine oocytes on polyspermic fertilization
Authors: Hayashi T. , Sato H. , Iwata H. , Kuwayama T. , Monji Y.
Published: March 2006

The present study examined the inhibitory effects of various pretreatment concentrations (0–100 μM) of the calcium ionophore A23187 on polyspermic fertilization and then examined the effect of the maturation period and the time between calcium ionophore treatment and fertilization on the inhibitory effect of calcium ionophore on polyspermic fertilization. In experiment 1, a high concentration of calcium ionophore (100 μM) increased the rate of activated oocytes, but the rate of fertilization declined. On the other hand, when oocytes were treated with a low concentration of calcium ionophore (10 μM), monospermic fertilization was significantly increased (10 μM; 31.3%) (p < 0.05). In experiment 2, oocytes were cultured for various times (0, 0.5, 3, 6 h) after calcium ionophore treatment (10 μM) before fertilization. The highest rate of monospermic fertilization was detected in the oocytes cultured for 6 h after calcium ionophore treatment before fertilization. In experiments 3 and 4, we examined the effect of the maturation period (40 h or 44 h) on the rate of fertilization and blastulation of oocytes pretreated with calcium ionophore. The treatment of oocytes with calcium ionophore significantly decreased the rate of polyspermic fertilization regardless of the maturation period (44 h: with calcium ionophore 26.25% vs without 78.8%; 40 h: with calcium ionophore 37.5% vs without 77.5%); however, calcium ionophore treatment increased the rates of monospermic fertilization and blastulation of the oocytes matured for 44 h, but not those matured for 40 h. In conclusion, activation with a low concentration of calcium ionophore (10 μM) and a further 6 h of culture before fertilization improved the rate of monospermic fertilization and blastulation.
Annealing control primer system identifies differentially expressed genes in blastocyst-stage porcine parthenotes
Authors: Lee Hwa Young , Cui Xiang-Shun , Lee Kyung-Ah , Kim Nam-Hyung
Published: March 2006

There is very little information available on stage-specific gene expression during early embryo development, particularly in the pig. Here, we accurately identified the genes that are specifically or prominently expressed in parthenogenetic porcine blastocysts as compared with 2-cell stage embryos. We accomplished this by using a PCR technology regulated by annealing control primers (ACPs). By utilizing 120 ACPs, a total of 46 expressed sequence tags (ESTs) of genes that are differentially expressed in blastocysts as compared with 2-cell stage embryos were cloned and sequenced. The cloned genes or ESTs all exhibited significant sequence similarity with known genes or ESTs of other species. Of the known genes, six genes [renin-binding protein (RNBP), BMDP, solute carrier family 25 (SLC25A6), MTHFD1, TRK-fused gene (TFG), spermidine synthase (SRM)] were selected and their stage-specific expression levels in porcine parthenotes were determined by real-time quantitative polymerase chain reaction at the 1-, 2-, 4-cell, morula and blastocyst stages. While RNBP, BMDP, SLC25A6, MTGFD1 and SRM were highly expressed only at the blastocyst stage, TFG was highly expressed at the 1-cell stage, then declined after genomic activation, high levels of expression being again detected at the morula and blastocyst stages. This analysis suggests that the ACP system is an effective tool for use in the identification of stage-specific genes in small numbers of porcine parthenotes. Examination of the genes differentially expressed in the blastocyst, which we have identified here, will provide insight into the molecular basis of preimplantation development.
The absence of a DNA replication checkpoint in porcine zygotes
Authors: Vackova Irena , Kren Radomir , Loi Pasqualino , Krylov Vladimír , Fulka Josef
Published: March 2006

It has been demonstrated that in the zygotes of some mammals a unique checkpoint controls the onset of DNA replication. Thus, DNA replication begins in the maternal pronucleus only after the paternal pronucleus is fully formed. In our experiments we have investigated whether this checkpoint also operates in porcine zygotes produced either by in vitro fertilization (IVF) or by intracytoplasmic sperm injection (ICSI). Our results show that the onset of DNA replication occurs in the maternal pronucleus even in the presence of an intact sperm head in zygotes produced by ICSI, as well as in polyspermic eggs where some sperm heads are intact or male pronuclei are not yet fully developed. We conclude that in porcine zygotes there is an absence of the DNA replication checkpoint that is typical for some other mammals.
Differential effects of culture and nuclear transfer on relative transcript levels of genes with key roles during preimplantation
Authors: Moreira P.N. , Fernández-Gonzalez R. , Ramirez M.A. , Pérez-Crespo M. , Rizos D. , Pintado B. , Gutiérrez-Adán A.
Published: March 2006

It is well known that the preimplantation culture environment to which embryos are exposed influences the expression of developmentally important genes. Recently, it has been reported that MEMα, a culture medium commonly used for somatic cells, allows high rates of preimplantation development and development to term of mouse somatic cell nuclear transfer (SCNT) embryos. The objective of this study was to compare the differential effects of this medium and of the nuclear transfer procedure on the relative mRNA abundance of several genes with key roles during preimplantation. The relative mRNA levels of nine genes (Glut 1, Glut 5, G6PDH, Bax, Survivin, Gpx 1, Oct4, mTert and IGF2bp1) were quantified at blastocyst stage on cumulus cell cloned embryos cultured in MEMα, as well as on in vivo cultured and MEMα cultured controls. Only three of the nine transcripts analysed (Glut 5, Gpx 1 and Igf2bp1) were significantly down-regulated at blastocyst stage in in vitro produced controls. However, most genes analysed in our MEMα cultured cloned embryos showed altered transcription levels. Interestingly, between cloned and in vitro produced controls only the transcription levels measured for Glut 1 were significantly different. This result suggests that Glut 1 may be a good marker for embryo quality after cumulus cell nuclear transfer.
Do age and extended culture affect the architecture of the zona pellucida of human oocytes and embryos?
Authors: Kilani Suha S. , Cooke Simon , Kan Andrew K. , Chapman Michael G.
Published: March 2006

Advanced female age and extended in vitro culture have both been implicated in zona pellucida (ZP) hardening and thickening. This study aimed to determine the influence of (i) the woman's age and (ii) prolonged in vitro culture of embryos on ZP thickness and density using non-invasive polarized light (LC-PolScope) microscopy. ZP thickness and density (measured as retardance) were determined in oocytes, embryos and blastocysts in women undergoing intracytoplasmic sperm injection (ICSI) in two age groups (older, >38 years; younger, ≤38 years). A total of 193 oocytes from 29 patients were studied. The younger group contained 100 oocytes and the older group 93 oocytes. The ZP was significantly thicker in metaphase II oocytes in the older group compared with the younger group (mean ± SD: 24.1 ± 2.5 μm vs 23.1 ± 3.3 μm; p = 0.01) but ZP density was equal (2.8 ± 0.7 nm). By day 2 of culture, embryos from the two groups had similar ZP thickness (22.2 ± 2.2 μm vs 21.7 ± 1.6 μm; p = 0.28) and density (2.9 ± 0.7 nm vs 2.8 ± 0.8 nm; p = 0.57). For the embryos cultured to blastocyst (older: n = 20; younger: n = 18) ZP thickness was similar in the two groups (19.2 ± 2.7 μm vs 19.1 ± 5.0 μm; p = 0.8) but thinner than on day 2. The older group had significantly denser ZP than the younger group (4.2 ± 0.5 nm vs 3.3 ± 1.0 nm, p < 0.01). Blastocysts from both groups had significantly denser ZP than their corresponding day 2 embryos (older: 4.2 ± 0.5 nm vs 2.9 ± 0.7 nm, p < 0.001; younger: 3.3 ± 1.0 nm vs 2.8 ± 0.8 nm, p = 0.013). It is concluded that there is little relationship between ZP thickness and its density as measured by polarized light microscopy. While ZP thickness decreases with extended embryo culturing, the density of the ZP increases. ZP density increases in both age groups with extended culture and, interestingly, more in embryos from older compared with younger women.
Influence of relative humidity upon pollution and dust during ACE‐Asia: Size distributions and implications for optical properties
Authors: Howell S. G. , Clarke A. D. , Shinozuka Y. , Kapustin V. , McNaughton C. S. , Huebert B. J. , Doherty S. J. , Anderson T. L.
Published: March 2006

An extensive set of aerosol physical and optical measurements was taken over the waters east of Asia during the Aerosol Characterization Experiment‐Asia (ACE‐Asia) project in the spring of 2001. Dust storms upwind of the study area combined with intense pollution plumes from coastal cities yielded an opportunity to examine both types of aerosol, in isolation and as they interacted. Scattering calculated from aerosol size distributions measured with an optical particle counter agreed well with simultaneous nephelometer measurements. We periodically heated sample air to evaporate sulfates and organic material. The change in volume upon heating agreed well with simultaneous measurements of aerosol composition. This volatile material was distributed on dust in rough proportion to surface area. Here we use the particle size and composition data to improve estimates of scattering at ambient humidity and to examine the effects of mixing on the optical properties of both pollution and dust aerosols. The presence of dust results in uptake of soluble and condensible species onto its surface and thereby reduces the mass scattering efficiency of the pollution aerosol by 50% and suppresses the change in scattering due to relative humidity (f(RH)) by up to 35%.
Impacts of Central America gap winds on the SST annual cycle in the eastern Pacific warm pool
Authors: Sun Fengpeng , Yu Jin‐Yi
Published: March 2006

The annual cycle of sea surface temperature (SST) in the eastern Pacific warm pool and its relation to Central America gap winds are examined in this study. Locally enhanced annual harmonics of SST are found underneath the regions where the Tehuantepec and Papagayo gap winds blow. The SSTs underneath the Tehuantepec gap wind undergo larger annual variations than those underneath the Papagayo gap wind. This suggests that the Tehuantepec gap wind has a stronger influence on the annual cycle of SST than the Papagayo gap wind. A series of ocean model experiments are performed to demonstrate the enhancement effect of the gap winds. Further heat budget analyses of the experiments show that the gap winds increase the amplitude of the SST annual cycle primarily by enhancing the vertical entrainment process in the ocean. The thermal forcing effect of the gap winds is less important in modulating the SST annual cycle.
Long‐term behaviour of ENSO: Interactions with the PDO over the past 400 years inferred from paleoclimate records
Authors: Verdon Danielle C. , Franks Stewart W.
Published: March 2006

This study uses proxy climate records derived from paleoclimate data to investigate the long‐term behaviour of the Pacific Decadal Oscillation (PDO) and the El Niño Southern Oscillation (ENSO). During the past 400 years, climate shifts associated with changes in the PDO are shown to have occurred with a similar frequency to those documented in the 20th Century. Importantly, phase changes in the PDO have a propensity to coincide with changes in the relative frequency of ENSO events, where the positive phase of the PDO is associated with an enhanced frequency of El Niño events, while the negative phase is shown to be more favourable for the development of La Niña events.
Detecting the warm core of a hurricane from the Special Sensor Microwave Imager Sounder
Authors: Liu Quanhua , Weng Fuzhong
Published: March 2006

Warm core is a typical structure of hurricanes and typhoons. It is a result of huge release of latent heat from the warm and moist inflow near the surface to form clouds and precipitation during the upward movement. The anomalistic high temperature to the ambient environment and the area of warm core correlate to the precipitation of hurricanes. The larger area and the higher temperature anomaly of the warm core is, the more precipitation from hurricanes is produced. This study uses the fourth channel of the Special Sensor Microwave Imager Sounder (SSMIS) onboard the U.S. Defense Meteorological Satellite Program (DMSP) F16 satellite to study the warm core of hurricanes Katrina and Rita which occurred in the fall of 2005. The channel is sensitive to the atmospheric layer between upper and middle troposphere and the brightness temperature from this channel reflects the effective layer temperature there. By investigating a time series of the satellite observations for hurricanes Katrina and Rita, we show that the warm core strengthens when the hurricanes reach maturity and that the warm core spreads and weakens after the landfall of the hurricanes.
Correlation of airglow temperature and emission rate at Resolute Bay (74.68°N), over four winters (2001–2005)
Authors: Cho Y.‐M. , Shepherd G. G.
Published: March 2006

The rotational temperature and emission rate of the OH (6‐2) Meinel band and the O2 (0‐1) Atmospheric band were monitored with a Spectral Airglow Temperature Imager (SATI), located at Resolute Bay (74.68°N, 94.90°W) since November, 2001. A strong correlation between these two quantities is found in data taken over a single day. This is consistent with previous model and observational results of wave motions in airglow and with model calculations presented here. The same correlation is observed over one month, over one winter and even from winter to winter. This means that similar dynamical processes are involved for perturbations with periods of a few hours or for many days or months. This suggests that all scales of dynamical variations during the polar winter arise from vertical motions, and that the effective source concentration of atomic oxygen at some reference level is remarkably constant.
Changes in global monsoon precipitation over the past 56 years
Authors: Wang Bin , Ding Qinghua
Published: March 2006

Changes in the global monsoon rainfall over land were examined using four sets of rain‐gauge precipitation data sets compiled for the period of 1948–2003 by climate diagnostic groups around the world. Here, we define a global monsoon rain domain according to annual precipitation range, using simple objective criteria; then, we propose metrics for quantifying the intensity of the global monsoon precipitation. The results suggest an overall weakening of the global land monsoon precipitation in the last 56 years, primarily due to weakening of the summer monsoon rainfall in the Northern Hemisphere. However, since 1980, the global land monsoon rainfall has seen no significant trend, which contrasts with the rapid intensification of global warming during the same period. Meanwhile the oceanic monsoon precipitation shows an increasing trend after 1980. The results provide a rigorous test for climate models that will be used in future climate‐change assessment.
Unraveling uncertainties in hydrologic model calibration: Addressing the problem of compensatory parameters
Authors: Clark Martyn P. , Vrugt Jasper A.
Published: March 2006

In a previous paper, Vrugt et al. (2005) presented a combined parameter and state estimation method, entitled SODA, to improve the treatment of input, output, parameter and model structural error during model calibration. The argument for using SODA is that explicit treatment of all sources of uncertainty should result in parameter estimates that closer represent system properties, instead of parameter values that are compensating for input, output and model structural errors. In this study we provide further support for this claim by applying the SODA method to the calibration of a simple 2‐parameter snow model, using data from the Lake Eldora SNOwpack TELemetry (SNOTEL) site in Colorado, USA.
Optimal aperture synthesis radar imaging
Authors: Hysell D. L. , Chau J. L.
Published: March 2006

Aperture synthesis radar imaging has been used to investigate coherent backscatter from ionospheric plasma irregularities at Jicamarca and elsewhere for several years. Phenomena of interest include equatorial spread F, 150‐km echoes, the equatorial electrojet, range‐spread meteor trails, and mesospheric echoes. The sought‐after images are related to spaced‐receiver data mathematically through an integral transform, but direct inversion is generally impractical or suboptimal. We instead turn to statistical inverse theory, endeavoring to utilize fully all available information in the data inversion. The imaging algorithm used at Jicamarca is based on an implementation of the MaxEnt method developed for radio astronomy. Its strategy is to limit the space of candidate images to those that are positive definite, consistent with data to the degree required by experimental confidence limits; smooth (in some sense); and most representative of the class of possible solutions. The algorithm was improved recently by (1) incorporating the antenna radiation pattern in the prior probability and (2) estimating and including the full error covariance matrix in the constraints. The revised algorithm is evaluated using new 28‐baseline electrojet data from Jicamarca.
Three‐dimensional numerical analysis of steady state pumping tests in heterogeneous confined aquifers
Authors: Firmani G. , Fiori A. , Bellin A.
Published: March 2006

We study three‐dimensional steady state flow field generated by a fully penetrating well extracting a constant water discharge from a confined aquifer of constant thickness. The hydraulic conductivity K is modeled as an axisymmetric, stationary random space function, and the flow equation is solved by using the seven‐node finite volume numerical scheme. In view of application in aquifer characterization we analyze how the equivalent conductivity Keq varies as a function of the distance from the extraction well. The numerical simulations showed that the boundary condition at the well exerts a large impact on Keq and that the first‐order solution in σY2 obtained by Indelman et al. (1996) is valid up to σY2 = 0.5. For higher values of σY2 the first‐order solution overestimates Keq with differences that for a given σY2, reduce progressively as the formation becomes more anisotropic. A simple inverse procedure based on Keq, obtained through cross‐well interference, is finally proposed and tested with the objective of estimating the parameters of the geostatistical model of variability of the hydraulic conductivity. A few parametric examples showed that a suitable interpretation of pumping tests can be used to safely estimate parameters such as the geometric mean of the hydraulic conductivity, its variance, and, although with larger uncertainty, the horizontal integral scale, while the inference of the anisotropy ratio is highly uncertain and error prone.
Economic impacts of federal policy responses to drought in the Rio Grande Basin
Authors: Ward Frank A. , Hurd Brian H. , Rahmani Tarik , Gollehon Noel
Published: March 2006

Significant growth in the Rio Grande Basin's demand for water has stressed the region's scarce water supply. This paper presents an analysis of the impacts of severe and sustained drought and of minimum in‐stream flow requirements to support endangered species in the Rio Grande watershed. These impacts are investigated by modeling the physical and institutional constraints within the Rio Grande Basin and by identifying the hydrologic and economic responses of all major water users. Water supplies, which include all major tributaries, interbasin transfers, and hydrologically connected groundwater, are represented in a yearly time step. A nonlinear programming model is developed to maximize economic benefits subject to hydrologic and institutional constraints. Results indicate that drought produces considerable impacts on both agriculture and municipal and industrial (MI) uses in the Rio Grande watershed. In‐stream flow requirements to support endangered species' habitat produce the largest impacts on agricultural water users in New Mexico and Texas. Hydrologic and economic impacts are more pronounced when in‐stream flow requirements dictate larger quantities of water for endangered species' habitat. Higher in‐stream flow requirements for endangered species in central New Mexico cause considerable losses to New Mexico agriculture above Elephant Butte Reservoir and to MI users in Albuquerque, New Mexico. Those same in‐stream flow requirements reduce drought damages to New Mexico agriculture below Elephant Butte Reservoir and reduce the severity of drought damages to MI users in El Paso, Texas. Results provide a framework for formulating federal policy responses to drought in the Rio Grande Basin.
A new equation for shallow groundwater flow over a curved impermeable boundary: Numerical solutions and laboratory tests
Authors: Chapman T. G. , Ong G.
Published: March 2006

The flow of recharge‐induced shallow groundwater over an impermeable boundary is a basic process in hillslope hydrology, which has usually been simplified by taking the boundary as having a constant slope. Previously published equations in curvilinear coordinates have been reduced here to a single equation for shallow groundwater flow over an impermeable boundary with continuous curvature, subject to conditions. The equation has been verified by comparison with a finite difference solution of the steady flow case, and with a range of experimental data from a viscous flow physical model, for both steady and transient flows. The results show that, while the bed profile affects flow depths, it has relatively little impact on the outflow hydrograph. It was found that the outflow is closely approximated by a power relationship with the volume in storage, and this leads to a simple algorithm for predicting the outflow hydrograph under conditions of variable recharge.
Space‐time modeling of soil moisture: Stochastic rainfall forcing with heterogeneous vegetation
Authors: Rodríguez‐Iturbe I. , Isham V. , Cox D. R. , Manfreda S. , Porporato A.
Published: March 2006

The present paper complements that of Isham et al. (2005), who introduced a space‐time soil moisture model driven by stochastic space‐time rainfall forcing with homogeneous vegetation and in the absence of topographical landscape effects. However, the spatial variability of vegetation may significantly modify the soil moisture dynamics with important implications for hydrological modeling. In the present paper, vegetation heterogeneity is incorporated through a two dimensional Poisson process representing the coexistence of two functionally different types of plants (e.g., trees and grasses). The space‐time statistical structure of relative soil moisture is characterized through its covariance function which depends on soil, vegetation, and rainfall patterns. The statistical properties of the soil moisture process averaged in space and time are also investigated. These properties are especially important for any modeling that aggregates soil moisture characteristics over a range of spatial and temporal scales. It is found that particularly at small scales, vegetation heterogeneity has a significant impact on the averaged process as compared with the uniform vegetation case. Also, averaging in space considerably smoothes the soil moisture process, but in contrast, averaging in time up to 1 week leads to little change in the variance of the averaged process.
Electron bridging dihydrogen bond in the imidazole-contained anion derivatives
Authors: Yan Shihai , Bu Yuxiang , Cukier Robert I.
Published: March 2006

The large contact distance of electron bridging dihydrogen bond (EBDB), which is over 2.4Å, is the most prominent characteristic for the imidazole-contained anion derivatives. The elongation of N–H bond and the shortening of H⋯H distance can be observed upon hydration and hydrogenation. Transformation from EBDB to dissociative H2 is convenient upon sequential hydrogenation. The H⋯H distance decreases with the enhancement of the electronegativity of the heavy atom which contacts directly with one of these two hydrogen atoms. NMR shielding of the bonding N varies significantly upon hydration and hydrogenation. The spin-spin coupling constants, JH–H1, is dominated predominantly by the paramagnetic spin-orbit and diamagnetic spin-orbit contributions instead of the Fermi-contact term. Enhancement of electronegativity of the heavy atom leads to the increase of JH–H1 coupling constants. The stabilization is enhanced upon hydration predominantly for the formation of O–H⋯N H bond, while it is reversed upon hydrogenation for the cleavage of big π bond, Π56. Enhancement of the stability is demonstrated by the increase of stabilization energy and vertical electron detachment energy with the electronegativity of the heavy atom. The dominant contributions for the formation of such electron bridging dihydrogen bond are the high polarity of each fragment, large electron density between two fragments, and strong bonding interaction of the bridging electron with H(N) atoms. The H⋯H interaction can be formed by X–Hδ+ and Hδ−–Y polar molecules in Hδ+⋯Hδ− and Hδ+⋯e⋯Hδ+ of two forms.
A Monte Carlo study of the mesophases formed by polar bent-shaped molecules
Authors: Orlandi Silvia , Berardi Roberto , Steltzer Joachim , Zannoni Claudio
Published: March 2006

Liquid crystal phases formed by bent-shaped (or “banana”) molecules are currently of great interest. Here we investigate by Monte Carlo computer simulations the phases formed by rigid banana molecules modeled combining three Gay-Berne sites and containing either one central or two lateral and transversal dipoles. We show that changing the dipole position and orientation has a profound effect on the mesophase stability and molecular organization. In particular, we find a uniaxial nematic phase only for off-center dipolar models and tilted phases only for the one with terminal dipoles.
Development of a lattice-sum method emulating nonperiodic boundary conditions for the treatment of electrostatic interactions in molecular simulations: A continuum-electrostatics study
Authors: Kastenholz Mika A. , Hünenberger Philippe H.
Published: March 2006

Artifacts induced by the application of periodic boundary conditions and lattice-sum methods in explicit-solvent simulations of (bio-)molecular systems are nowadays a major concern in the computer-simulation community. The present article reports a first step toward the design of a modified lattice-sum algorithm emulating nonperiodic boundary conditions, and therefore exempt of such periodicity-induced artifacts. This result is achieved here in the (more simple) context of continuum electrostatics. It is shown that an appropriate modification of the periodic Poisson equation and of its boundary conditions leads to a continuum-electrostatics scheme, which, although applied under periodic boundary conditions, exactly mimics the nonperiodic situation. The possible extension of this scheme to explicit-solvent simulations is outlined and its practical implementation will be described in more details in a forthcoming article.
On the characterization of three state conical intersections: A quasianalytic theory using a group homomorphism approach
Authors: Schuurman Michael S. , Yarkony David R.
Published: March 2006

In this work, degenerate perturbation theory through second order is used to characterize the vicinity of a three state conical intersection. This report extends our recent demonstration that it is possible to describe the branching space (in which the degeneracy is lifted linearly) and seam space (in which the degeneracy is preserved) in the vicinity of a two state conical intersection using second order perturbation theory. The general analysis developed here is based on a group homomorphism approach. Second order perturbation theory, in conjunction with high quality ab initio electronic structure data, produces an approximately diabatic Hamiltonian whose eigenenergies and eigenstates can accurately describe the three adiabatic potential energy surfaces, the interstate derivative couplings, and the branching and seam spaces in their full dimensionality. The application of this approach to the minimum energy three state conical intersection of the pyrazolyl radical demonstrates the potential of this method. A Hamiltonian comprised of the ten characteristic (linear) parameters and over 300second order parameters is constructed to describe the branching space associated with a point of conical intersection. The second order parameters are determined using data at only 30 points. In the vicinity of the conical intersection the energy and derivative couplings are well reproduced and the singularity in the derivative coupling is analyzed.
Multivariable kinetic theory of the first order phase transitions
Authors: Alekseechkin N. V.
Published: March 2006

The problem of calculation of the steady state homogeneous nucleation rate in the multidimensional space of the variables describing a nucleus is considered. Within the framework of the theory proposed, expressions for the nucleation rate and the steady state distribution function of nuclei are derived. The expression for the nucleation rate is invariant with respect to the space dimensionality and, in particular, involves the result of the one-dimensional theory. The distribution function is obtained in the initial, physical variables. In connection with the analysis of restrictions on the current direction, the question of symmetry of the matrix of diffusivities is considered; on the basis of the detailed balance principle it is shown that this matrix is symmetric. The question of normalizing the equilibrium distribution functions is investigated and the physical picture of the equilibrium state is described. The procedure of reducing the multidimensional theory to the one-dimensional one is described.
Temperature dependence of solvation dynamics and anisotropy decay in a protein: ANS in bovine serum albumin
Authors: Sahu Kalyanasis , Mondal Sudip Kumar , Ghosh Subhadip , Roy Durba , Bhattacharyya Kankan
Published: March 2006

Temperature dependence of solvation dynamics and fluorescence anisotropy decay of 8-anilino-1-naphthalenesulfonate (ANS) bound to a protein, bovine serum albumin (BSA), are studied. Solvation dynamics of ANS bound to BSA displays a component (300ps) which is independent of temperature in the range of 278–318K and a long component which decreases from 5800ps at 278K to 3600ps at 318K. The temperature independent part is ascribed to a dynamic exchange of bound to free water with a low barrier. The temperature variation of the long component of solvation dynamics corresponds to an activation energy of 2.1kcalmol−1. The activation energy is ascribed to local segmental motion of the protein along with the associated water molecules and polar residues. The time scale of solvation dynamics is found to be very different from the time scale of anisotropy decay. The anisotropy decays are analyzed in terms of the wobbling motion of the probe (ANS) and the overall tumbling of the protein.
Electronic spectra of heteroatom-containing isoelectronic carbon chains C2nS and C2nCl+ (n=1–5)
Authors: Zhang Jinglai , Wu Wenpeng , Wang Lianbin , Cao Zexing
Published: March 2006

Structures and stabilities of carbon chains C2nS and C2nCl+ (n=1–5) in their ground states have been investigated by the density functional theory and the coupled cluster approach using single and double substitutions. The complete active space self-consistent-field method has been used for geometry optimization of selected excited states in both series. Calculations show that both C2nS (n=1–5) and C2nCl+ (n=3–5) have linear structures in the triplet ground state Σ−3, while C2Cl+ and C4Cl+ have nonlinear structures in the ground state A″3. The vertical transition energies and emission energies by the multiconfigurational second-order perturbation theory in linear clusters C2nS and C2nCl+ exhibit similar size dependences. In comparison with the available experimental observations, the predicted excitation energies for the allowed 2Σ−3←XΣ−3 transitions have an accuracy of no more than 0.24eV. Spin-orbit coupling configuration interaction calculations indicate that the spin-forbidden 2Σ+1←XΣ−3 transition in these species has an oscillator strength with the magnitude of 10−4–10−5, and they may be observable experimentally.
A practical nonlocal model for heat transport in magnetized laser plasmas
Authors: Nicolaï Ph. D. , Feugeas J.-L. A. , Schurtz G. P.
Published: March 2006

A model of nonlocal transport for multidimensional radiation magnetohydrodynamics codes is presented. In laser produced plasmas, it is now believed that the heat transport can be strongly modified by the nonlocal nature of the electron conduction. Other mechanisms, such as self-generated magnetic fields, may also affect the heat transport. The model described in this work, based on simplified Fokker-Planck equations aims at extending the model of G. Schurtz, Ph. Nicolaï, and M. Busquet [Phys. Plasmas 7, 4238 (2000)] to magnetized plasmas. A complete system of nonlocal equations is derived from kinetic equations with self-consistent electric and magnetic fields. These equations are analyzed and simplified in order to be implemented into large laser fusion codes and coupled to other relevant physics. The model is applied to two laser configurations that demonstrate the main features of the model and point out the nonlocal Righi-Leduc effect in a multidimensional case.
Dynamics study of the reaction OH−+C2H2→C2H−+H2O with crossed beams and density-functional theory calculations
Authors: Liu Li , Li Yue , Farrar James M.
Published: March 2006

The proton transfer reaction between OH− and C2H2, the sole reactive process observed over the collision energy range from 0.37to1.40eV, has been studied using the crossed beam technique and density-functional theory (DFT) calculations. The center of mass flux distributions of the product C2H− ions at three different energies are highly asymmetric, characteristic of a direct process occurring on a time scale much less than a rotational period of any transient intermediate. The maxima in the flux distributions correspond to product velocities and directions close to those of the precursor acetylene reactants. The reaction quantitatively transforms the entire exothermicity into internal excitation of the products, consistent with an energy release motif in which the proton is transferred early, in a configuration in which the forming bond is extended. This picture is supported by DFT calculations showing that the first electrostatically bound intermediate on the reaction pathway is the productlike C2H−∙H2O species. Most of the incremental translational energy in the two higher collision energy experiments appears in product translational energy, and provides an example of induced repulsive energy release characteristic of the heavy+light-heavy mass combination.