bluuebunny/crossref_metadata_2025 huggingface dataset:
Endocrine and morphological perspectives in testicular descent
Authors: Hutson John M , Baker Marilyn L , Griffiths Amanda L , Momose Yoshitaka , Goh Day Way , Middlesworth William , Yun Zhou Bai , Cartwright Elizabeth
Published: March 2009

Before sexual differentiation occurs at seven weeks, the urological ridges develop in the embryo. These contain the primitive gonads, the mesonephros (embryonic kidneys) and the paired Wolffian (mesonephric) ducts, along with the Müllerian (paramesonephric) ducts. The fundamental mechanism of fetal sexual development was elucidated by Alfred Jost and is determined by the development of the gonad: where testes form in response to the testis-determining gene, and the male testicular hormones cause development of the male phenotype. If ovaries develop or the gonads are absent, female secondary sex characteristics are produced. Recently, the cloning of the putative human testis-determining gene on the Y-chromosome was reported. Assuming this is the true controller of testicular development, an understanding of the initiation of sexual differentiation at the genetic level should emerge in the near future. Of great importance will be the isolation of the testis-determining gene product and identification of other genes that it regulates.
Diagnosis of inherited disease before implantation
Authors: Handyside Alan H
Published: March 2009

The diagnosis of inherited disease in affected embryos before implantation is now possible using in vitro fertilization (IVF), embryo biopsy and DNA analysis. This enables pregnancies to be established with unaffected embryos following transfer to the uterus avoiding the possibility of terminating a pregnancy diagnosed as affected later in gestation. Pregnancies have been established with female embryos in women carrying X-linked recessive genetic defects affecting boys by identifying the sex of embryos either by DNA amplification of Y-specific sequences or by dual fluorescent in situ hybridization (FISH) with X- and Y-specific probes to interphase nuclei. The predominant ΔF508 deletion causing cystic fibrosis (CF) has also been detected by DNA amplification from single cells and the first pregnancy and birth of a child successfully screened for a single gene defect achieved. The prospects for applying preimplantation diagnosis to other chromosomal and single gene defects are reviewed.
Nd-YAG laser hysteroscopic surgery: endometrial ablation, partial endometrial ablation and myomectomy
Authors: Donnez J , Nisolle M
Published: March 2009

Hysteroscopy was first reported by Pantaleoni in 1869. He used a 12 mm diameter straight tube that was inserted into the uterine cavity with a concave mirror to reflect light into the uterus. Today, there are two main types of endoscopes in use: (1) the rigid endoscopie panoramic hysteroscope and (2) the flexible hysteroscope.
Pulsatile gonadotrophin-releasing hormone (GnRH) treatment in hypogonadotrophic amenorrhoea
Authors: Braat Didi DM
Published: March 2009

Following the isolation, and subsequent synthesis of the decapeptide gonadotrophin-releasing hormone (GnRH) in the laboratories of Schally and Guillemin in 1971, a more physiological treatment for hypogonadotrophic women became available. It was not, however, until 1980 that a successful, pulsatile mode of administration was established.
Corpus luteum function and regression
Authors: Behrman Harold R , Endo Toshiaki , Aten Raymond F , Musicki Biljana
Published: March 2009

Several conclusions can be drawn from a review of the formation, function and regression of the corpus luteum. Ovulation and luteinization encompass degenerative and growth changes. Inflammatory conditions associated with ovulation lead to the breakdown of the follicle wall and the membrana granulosa, along with initial damage to theca and granulosa cells. The early corpus luteum is, therefore, a tissue in stress. Thus, one view of the corpus luteum is that it, like the phoenix, rises from the inflammatory ashes of the postovulatory follicle to exist briefly and to be consumed by a similar process at regression. The luteinization process is associated with parenchymal cell hypertrophy and matrix remodelling, which appear to be regulated by IGFs and androgens, and with angiogenesis, which is induced mostly by bFGF. High levels of functional activity of the corpus luteum are regulated by control at the level of the LH receptor, whose activation leads to the translocation of cholesterol into the cell and mitochondria for conversion to steroids. Functional luteal regression can be considered as another inflammatory-like condition with apparent activation of the immune system, along with cytokine, reactive oxygen, and eicosanoid production. Structural luteolysis is subsequently invoked that leads to matrix dissolution and cellular degeneration. It is perhaps not surprising that the invocation of immune activation, which causes the production of DNA-damaging reactive oxygen species and cytotoxic cytokines each cycle, may increase the risk of pathologies. One example may be ovarian cancer which appears to be associated with the use of fertility-enhancing drugs and associated with the number of ovulations in a woman's lifetime.
Cytogenetics of tumours of the female reproductive tract
Authors: Dal Cin Paola , Van Den Berghe Herman
Published: March 2009

Tumours of the reproductive tract present with a great variety and diversity in males as well as in females. They originate from tissues which belong to different embryonic sheets or stem cells, and may appear at various ages, including younger age groups. Some are under hormonal control or influence, others may have a strong environmental component. It is becoming increasingly clear that in tumours, one or more molecular lesions at the DNA level are the causative factor. Their specificity may be very high and may also determine, in part, the phenotype and histology of the proliferation. Discovery of the genes involved was made possible by previous identification of chromosome changes typically occurring in certain tumours.
Role of cytokines in endometrium and at the fetomaternal interface
Authors: Tabibzadeh S
Published: March 2009

Cytokines were first recognized as factors involved in the immune responses. However, emerging evidence suggests that cytokines serve as the unanimous language through which cells in organ systems as diverse as hypothalamus to endometrium communicate. Evidence for the participation of these factors in the normal function of the endometrium and uteroplacental unit and development of the embryo is being recognized. This review will highlight the significant insight gained over the past several years for the role of cytokines in the field of reproductive biology. Major emphasis will be placed on interleukins, tumour necrosis factor-α, transforming growth factors, colony stimulating factors and interferon-gamma.
Fertility-promoting laparoscopically-directed procedures
Authors: Munro Malcolm G , Gomel Victor
Published: March 2009

Fertility-promoting procedures are among the most frequently performed laparoscopic procedures. Some of the procedures have a relatively long history, with good documentation of technique, efficacy and effectiveness. On the other hand, many are experimental, in development or relatively new and lacking supportive clinical data.
Endometrial protein PP14: a new test of endometrial function?
Authors: Chard T , Olajide F
Published: March 2009

The human endometrium produces a number of proteins which are at least partly specific to that tissue. Two of these proteins have been the subject of much recent work. They were originally called ‘placental protein 12’ and ‘placental protein 14’ (PP12 and PP14) because they were isolated by Hans Bohn from extracts of whole placentae. However, it is now clear that they arise from the maternal endometrium (decidua) rather than the fetal trophoblast. Placental protein 12 has been shown to be identical to the insulin-like growth factor binding protein-1 (IGFBP-1). It is produced in many normal tissues and its measurement probably does not provide a specific index of endometrial function. By contrast, PP14 is detectable only in ‘reproductive’ tissues and, in theory, might be an excellent clinical test of endometrial function.
Trophoblast invasion
Authors: Pijnenborg R
Published: March 2009

The establishment of a pregnancy depends upon mechanisms of forming close contacts between embryonic/fetal and maternal tissues. The starting point is the attachment of the blastocyst to the uterine wall, and this critical step is followed by a series of different morphogenetic events leading to placentation. These processes depend on the invasive properties of extra-embryonic trophectoderm-derived cells that show their highest expression in species with haemochorial placentation, i.e. Insectivores, rodents, and primates including the human. In this review we will concentrate upon the human with occasional reference to other species.
Genes and phenotypes of the human Y chromosome
Authors: Schafer Alan J
Published: March 2009

By 1959 it was recognized that the gene (or genes) responsible for initiating the human male phenotype were carried on the Y chromosome. But in subsequent years, few phenotypes were associated with the Y chromosome. Recently, using molecular techniques combined with classical genetics, the Y chromosome has been the focus of intensive and productive investigation. Some of the findings are unexpected and have extended our understanding of the functions of the human Y chromosome. The notion that the Y chromosome is largely devoid of genes is changing. At the present, over 20 Y chromosome genes or pseudogenes have been identified or cloned, a number that is rapidly increasing. A high proportion of Y chromosome sequences have been found to be related to X chromosome sequences: the assembly of a complete physical map of the Y chromosome euchromatic region (believed to carry all of the genes) has shown 25% of the region studied to have homology to the X chromosome.3 Several X-homologous genes are located in the X and Y chromosome pairing regions, an area predicted to have shared homology. Surprisingly, some of the Y-encoded genes that lie outside of the X and Y pairing region share high sequence similarity, and in at least one case, functional identity, with genes on the X chromosome.
The role of sperm creatine kinase in the assessment of male fertility
Authors: Huszar Gabor
Published: March 2009

The lack of reliable methods to assess sperm fertilizing potential has been a long-standing problem for infertile couples and for their physicians. The most widely used tests, the measurements of sperm concentrations, motility, velocity and morphology in the ejaculate, are of limited utility. Indeed, following intrauterine insemination, a treatment that compensates for low motile sperm concentrations, there were no significant differences found in semen parameters among those who did or did not achieve pregnancies. Other available assays probing for selected sperm functions, such as membrane integrity, acrosome enzyme activity, bovine cervical mucus penetration test, zona-free hamster oocyte penetration test and sperm binding to various carbohydrates,10–13have all failed thus far to consistently predict male fertility. It became increasingly obvious that there was a need to identify cellular markers of sperm quality and fertilizing potential.
Hormone replacement therapy for osteoporosis: clinical and pathophysiological aspects
Authors: Compston JE
Published: March 2009

The pathogenetic role of oestrogen deficiency in osteoporosis was first postulated by Fuller Albright in 1941 and has subsequently become well established. Hormone replacement therapy prevents menopausal bone loss and is the only treatment which has convincingly been shown to reduce fracture risk at both the spine and hip. The mechanisms by which oestrogens affect bone, however, are poorly understood and many aspects of treatment remain ill-defined, in particular with respect to the duration of therapy and its long-term risks and benefits.
Randomized trials assessing calcium supplementation in healthy children: relationship between industry sponsorship and study outcomes
Authors: Nkansah Nancy , Nguyen Thao , Iraninezhad Hoda , Bero Lisa
Published: March 2009

Objective

To explore the relationship between industry sponsorship of Ca supplementation studies in healthy children and study outcomes.

Design

An electronic search for published randomized controlled trials (RCT) was conducted. We collected data on study design features aimed at reducing bias, statistical significance of results, authors’ conclusions and financial sponsorship of study. We used Fischer’s exact test to examine associations between sponsorship and study results and conclusions.

Subjects

Healthy children between the ages of 9 and 18 years.

Results

Nineteen trials met our inclusion criteria. Seventeen out of nineteen studies reported a statistically significant improvement of supplementation on bone mineral density. Subjects in eight of the seventeen studies had a baseline daily Ca intake of 800–1300 mg. There was no significant association between study design features and the results or conclusions of the studies. Three studies received government funding, two of which (66·7 %) concluded in favour of additional supplementation. Sixteen studies were either industry-funded or had mixed industry funding, thirteen (81·3 %) of which had a conclusion supporting Ca supplementation in children. There was no significant association between study sponsorship and authors’ conclusions.

Conclusions

The majority of RCT assessing the effects of Ca supplementation in healthy children are industry-funded and support Ca supplementation. The clinical significance of the outcomes measured in Ca supplementation studies should be considered when examining associations between study design and results. Further non-industry funded research is needed to thoroughly assess the impact of funding on authors’ conclusions in nutrition research.
Incidence and duration of severe wasting in two African populations
Authors: Garenne Michel , Willie Douladel , Maire Bernard , Fontaine Olivier , Eeckels Roger , Briend André , Van den Broeck Jan
Published: March 2009

Objective

The present study aimed to compare two situations of endemic malnutrition among <5-year-old African children and to estimate the incidence, the duration and the case fatality of severe wasting episodes.

Design

Secondary analysis of longitudinal studies, conducted several years ago, which allowed incidence and duration to be calculated from transition rates. The first site was Niakhar in Senegal, an area under demographic surveillance, where we followed a cohort of children in 1983–5. The second site was Bwamanda in the Democratic Republic of Congo, where we followed a cohort of children in 1989–92. Both studies enrolled about 5000 children, who were followed by routine visits and systematic anthropometric assessment, every 6 months in the first case and every 3 months in the second case.

Results

Niakhar had less stunting, more wasting and higher death rates than Bwamanda. Differences in cause-specific mortality included more diarrhoeal diseases, more marasmus, but less malaria and severe anaemia in Niakhar. Severe wasting had a higher incidence, a higher prevalence and a more marked age profile in Niakhar. However, despite the differences, the estimated mean durations of episodes of severe wasting, calculated by multi-state life table, were similar in the two studies (7·5 months). Noteworthy were the differences in the prevalence and incidence of severe wasting depending on the anthropometric indicator (weight-for-height Z-score ≤–3.0 or mid upper-arm circumference <110 mm) and the reference system (National Center for Health Statistics 1977, Centers for Disease Control and Prevention 2000 or Multicentre Growth Reference Study 2006).

Conclusions

Severe wasting appeared as one of the leading cause of death among under-fives: it had a high incidence (about 2 % per child-semester), long duration of episodes and high case fatality rates (6 to 12 %).
Neighbourhood ethnic composition and diet among Mexican-Americans
Authors: Reyes-Ortiz Carlos A , Ju Hyunsu , Eschbach Karl , Kuo Yong-Fang , Goodwin James S
Published: March 2009

Objectives

We explore the association between a neighbourhood’s ethnic composition and the foods and nutrients consumed by Mexican-Americans.

Design

Cross-sectional survey of a large national sample, from the Third National Health and Nutrition Examination Survey (1988–94), was linked to the 1990 Census. The outcomes were food frequencies and serum levels of micronutrients. The variable of interest was percentage of Mexican-Americans at the census tract level.

Setting

United States.

Subjects

A total of 5306 Mexican-American men and women aged 17–90 years.

Results

Increased percentage of Mexican-Americans at the census tract level was associated with less consumption of fruits, carrots, spinach/greens and broccoli and with lower serum levels of Se, lycopene, α-carotene, vitamin C and folate. By contrast, increased percentage of Mexican-Americans at the census tract level was associated with more consumption of corn, tomatoes, hot red chilli peppers and legumes such as beans, lentils or chickpeas.

Conclusions

An increased percentage of Mexican-Americans at the census tract level was associated with less consumption of selective foods (e.g. some fruits, broccoli) and low levels of serum Se or vitamin C, but it was associated with more consumption of other foods (e.g. legumes, tomatoes, corn products) that may have positive effects on health in this population.
Experimental evidence for statistical scaling and intermittency in sediment transport rates
Authors: Singh Arvind , Fienberg Kurt , Jerolmack Douglas J. , Marr Jeffrey , Foufoula‐Georgiou Efi
Published: March 2009

Understanding bed load transport fluctuations in rivers is crucial for development of a transport theory and for choosing a sampling interval for “mean” transport rates. Field‐scale studies lack sufficient resolution to statistically characterize these fluctuations, while laboratory experiments are limited in scale and hence cannot be directly compared to field cases. Here we use a natural‐scale laboratory channel to examine bed load transport fluctuations in a heterogeneous gravel substrate under normal flow conditions. The novelty of our approach is the application of a geometrical/statistical formalism (called the multifractal formalism), which allows characterization of the “roughness” of the series (depicting the average strength of local abrupt fluctuations in the signal) and the “intermittency” (depicting the temporal heterogeneity of fluctuations of different strength). We document a rougher and more intermittent behavior in bed load sediment transport series at low‐discharge conditions, transitioning to a smoother and less intermittent behavior at high‐discharge conditions. We derive an expression for the dependence of the probability distribution of bed load sediment transport rates on sampling interval. Our findings are consistent with field observations demonstrating that mean bed load sediment transport rate decreases with sampling time at low‐transport conditions and increases with sampling time at high‐transport conditions. Simultaneous measurement of bed elevation suggests that the statistics of sediment transport fluctuations are related to the statistics of bed topography.
Analysis of the time‐averaged properties of sediment motion in a local scour process
Authors: Radice Alessio , Porta Giovanni , Franzetti Silvio
Published: March 2009

We examined the kinematics of sediment particles in the proximity of a vertical plate attached to the side wall of a pressurized duct. The laboratory phenomenon investigated was archetypal of local scour near bridge abutments in covered rivers. We conducted a clear‐water scour experiment where we measured the temporal evolution of the local erosion depth; the latter was found to follow a logarithmic trend. The concentration and velocity of the moving particles were measured on the basis of digital movies taken at various evolution stages of the process. The spatial pattern of the sediment motion showed that the action of the principal vortex system becomes progressively more evident with the general lowering of the sediment transport intensity detected as the scour hole increases in time. Furthermore, the phenomenology of local sediment transport was analyzed; key findings of the research include (1) the time‐averaged values of the sediment transport rate are linked with those of concentration and velocity through relationships which are almost invariant, regardless of the experimental time and of the location within the scour hole; (2) intermittency and irregularity of the sediment fluxes increase as their mean intensity decreases; (3) the relative weight of the temporal fluctuations of concentration and velocity in the time‐mean sediment transport activity is significant throughout the entire process. Potential implications of the present results for the modeling of local scour processes in pressurized‐flow conditions are discussed. The considerations made are likely to have analogous applicability to local scour with a free surface, since the large‐scale evolutions of the erosion depth in the two conditions may not be greatly different. Given the qualitative analogy of the present findings with earlier ones obtained for one‐dimensional bed load, it is suggested that similar considerations may hold also for the small‐scale modeling of a wider class of sediment transport processes.
Evolution of the Cenozoic carbon cycle: The roles of tectonics and CO2 fertilization
Authors: Li Gaojun , Ji Junfeng , Chen Jun , Kemp David B.
Published: March 2009

Cenozoic carbon fluxes associated with rock weathering, sediment burial, and volcanic degassing are calculated from the mass balance equations coupling marine isotopic records of carbon (both organic and inorganic), strontium, and osmium. The result is confirmed by the good match between modeled carbonate sedimentation rates and carbonate sedimentation rates previously integrated from ocean basins worldwide. The coevolution between weathering and burial of carbonate suggests that marine carbonate accumulation was regulated mainly by the recycling of carbonate rocks, which mediated the bicarbonate ion concentration of the oceans. A reduction in CO2 effusion to the atmosphere caused by reduced volcanic degassing from 52 to 15 Ma and tectonically enhanced organic rock exhumation since 15 Ma is also observed. These changes in CO2 effusion are balanced by concomitant changes in CO2 sequestration by silicate weathering and organic carbon burial. Importantly, we demonstrate a clear decoupling of modeled silicate weathering rates from global climate over the last ∼15 Ma. This observation is inconsistent with temperature‐mediated mineral dissolution acting as the key mechanism facilitating the CO2 silicate weathering feedback process. However, we instead observe a clear coupling (positive correlation) between modeled silicate weathering, organic carbon burial, and atmospheric CO2 concentration. We suggest that CO2 fertilization effects on terrestrial biomass productivity and plant weathering could have represented a major negative feedback process helping to balance atmospheric CO2, at least during the Cenozoic ice house periods.
ACRIM‐gap and TSI trend issue resolved using a surface magnetic flux TSI proxy model
Authors: Scafetta Nicola , Willson Richard C.
Published: March 2009

The ACRIM‐gap (1989.5–1991.75) continuity dilemma for satellite TSI observations is resolved by bridging the satellite TSI monitoring gap between ACRIM1 and ACRIM2 results with TSI derived from Krivova et al.'s (2007) proxy model based on variations of the surface distribution of solar magnetic flux. ‘Mixed’ versions of ACRIM and PMOD TSI composites are constructed with their composites' original values except for the ACRIM gap, where Krivova modeled TSI is used to connect ACRIM1 and ACRIM2 results. Both ‘mixed’ composites demonstrate a significant TSI increase of 0.033 %/decade between the solar activity minima of 1986 and 1996, comparable to the 0.037 % found in the ACRIM composite. The finding supports the contention of Willson (1997) that the ERBS/ERBE results are flawed by uncorrected degradation during the ACRIM gap and refutes the Nimbus7/ERB ACRIM gap adjustment Fröhlich and Lean (1998) employed in constructing the PMOD.
Vertical mixing at intermediate depths in the Arctic boundary current
Authors: Lenn Y. D. , Wiles P. J. , Torres‐Valdes S. , Abrahamsen E. P. , Rippeth T. P. , Simpson J. H. , Bacon S. , Laxon S. W. , Polyakov I. , Ivanov V. , Kirillov S.
Published: March 2009

Microstructure and hydrographic observations, during September 2007 in the boundary current on the East Siberian continental slope, document upper ocean stratification and along‐stream water mass changes. A thin warm surface layer overrides a shallow halocline characterized by a ∼40‐m thick temperature minimum layer beginning at ∼30 m depth. Below the halocline, well‐defined thermohaline diffusive staircases extended downwards to warm Atlantic Water intrusions found at 200–800 m depth. Observed turbulent eddy kinetic energy dissipations are extremely low (ε < 10−6 W m−3), such that double diffusive convection dominates the vertical mixing in the upper‐ocean. The diffusive convection heat fluxes FHdc ∼1 W m−2, are an order of magnitude too small to account for the observed along‐stream cooling of the boundary current. Our results implicate circulation patterns and the influence of shelf waters in the evolution of the boundary current waters.
Modeling of outer radiation belt electrons by multidimensional diffusion process
Authors: Xiao Fuliang , Su Zhenpeng , Zheng Huinan , Wang Shui
Published: March 2009

In this study, we develop a new code which uses a hybrid finite difference (HFD) method to solve a 2‐D bounce‐averaged energy–pitch angle diffusion equation in the outer radiation belts. We implement the numerical algorithm by adopting a split operator technique, an implicit scheme for dealing with diagonal diffusion coefficients, and an alternative direction implicit scheme for off‐diagonal (or cross) diffusion coefficients. We show that our code HFD can successfully overcome the unstable problem when the large and rapidly varying cross diffusion coefficients are included. Particularly, we examine whether resonant interactions with obliquely propagated whistler mode chorus and hiss waves result in a net acceleration or loss of relativistic electrons in the outer radiation belt L = 4.5. Numerical simulations show that chorus waves can yield significant acceleration of relativistic electrons, while hiss waves are primarily responsible for scattering equatorially mirroring electrons toward the loss cone.
Introduction to special section on Large Geomagnetic Storms
Authors: Gopalswamy N.
Published: March 2009

Solar cycle 23 witnessed the accumulation of rich data sets that reveal various aspects of geomagnetic storms in unprecedented detail both at the Sun where the storm‐causing disturbances originate and in geospace where the effects of the storms are directly felt. During two recent coordinated data analysis workshops (CDAWs) the large geomagnetic storms (Dst ≤ −100 nT) of solar cycle 23 were studied in order to understand their solar, interplanetary, and geospace connections. This special section grew out of these CDAWs with additional contributions relevant to these storms. Here I provide a brief summary of the results presented in the special section.
Structure and downstream evolution of the Agulhas Current system during a quasi‐synoptic survey in February–March 2003
Authors: Casal Tânia G. D. , Beal Lisa M. , Lumpkin Rick , Johns William E.
Published: March 2009

The Agulhas Undercurrent Experiment took place in February–March 2003 off the east coast of South Africa and consisted of four sections of hydrographic and velocity data across the Agulhas Current between 30 and 36°S and connecting offshore sections that formed three closed boxes. An inverse model was applied to the quasi‐synoptic data, and results show that the net mass transport at the historical 32°S section had a considerably higher transport of 100 ± 9 Sv than earlier estimates. This high transport falls within the peak‐to‐peak variability obtained previously from a current meter time series. Several mesoscale cyclonic eddies extending down to intermediate depths were sampled during the survey; in particular, a strong, locally formed shear edge eddy was found inshore of the Agulhas Current at 36°S. Offshore eddies were found to drive considerable onshore‐offshore fluxes, resulting in highly variable Agulhas transports from one section to another. After attempting to account for and remove the influence of these eddies on the Agulhas transport, the downstream growth of the Agulhas Current is found to be consistent with the Sverdrup transport variation, within errors. To account for the total magnitude of the Agulhas transport, fluxes from both the Indonesian Throughflow and Indian Ocean overturning must also be taken into account. There is no clear evidence from this study for a significant contribution of inertial recirculation to the Agulhas within this latitude range.
Regional ground‐level ozone trends in the context of meteorological influences across Canada and the eastern United States from 1997 to 2006
Authors: Chan Elton
Published: March 2009

Meteorologically adjusted trends for different ozone averaging metrics (including daily maximum 1 h, daily maximum 8 h average, daily average, daytime average, nighttime average, daily minimum 8 h average, and monthly 5th percentile of ozone mixing ratios) were investigated in different regions of Canada and the United States over the time period 1997–2006. The spatiotemporal variability of the May–September daily ozone mixing ratios from 97 nonurban ozone measurement sites in Canada and the United States was examined to establish regions of common variability using rotated principal component analysis (R‐PCA). This was followed by modeling multiple sites within the PCA‐derived regions for all months using generalized linear mixed models. Most regions in southeastern Canada and the eastern United States showed statistically significant decreasing trends in the daily maximum 8 h average ranging from 0.53 ± 0.2 to 2.7 ± 0.86%/a, whereas significant increasing trends of 0.44 ± 0.37%/a and 0.98 ± 0.76%/a were found in Atlantic and Pacific Canada, respectively. In southeastern Canada and the eastern United States, the rates of decrease of the meteorologically adjusted regional trends associated with low ozone levels were slower than those of high levels. However, the rates of increase in the Atlantic and Pacific coastal regions associated with low levels were faster than those of high levels. These results are consistent with decreasing NOx and nonmethane hydrocarbon emissions in southeastern Canada and the eastern United States starting in the early 2000s and a hypothesized widespread increase due to the rising hemispheric background ozone.
Which surface atmospheric variable drives the seasonal cycle of sea surface temperature over the global ocean?
Authors: Kara A. B. , Wallcraft A. J. , Hurlburt H. E. , Loh W.‐Y.
Published: March 2009

The impact of near‐surface atmospheric variables used in driving the seasonal cycle of climatological mean sea surface temperature (SST) is quantified over the global ocean. The six atmospheric variables are air temperature, vapor mixing ratio, wind speed, precipitation, net shortwave radiation, and net longwave radiation, the first (last) three just above (at) the sea surface. Atmospherically forced ocean general circulation model (OGCM) simulations with no data assimilation are performed using monthly and annual means of those variables under the assumption that variations in climatological monthly SSTs are driven by atmospheric variables. SSTs resulting from these simulations are compared with those from a satellite‐based field to determine the impact of each atmospheric variable. Large spatial variability is found in the order of impact (most to least) of six atmospheric variables. In general, the SST seasonal cycle is driven primarily by shortwave radiation at midlatitudes, but wind speed is the major controlling variable in the Indian Ocean. Precipitation has almost no significant influence on monthly SST. Overall, shortwave radiation is the most influential variable controlling the seasonal cycle of SST over 34.3% of the global ocean. Wind speed is the second most important variable (27.2%). In tropical regions and the Arabian Sea, sources other than the atmospheric thermal forcing are found to play a significant role in regulating the SST seasonal cycle.
CALIPSO observations of wave‐induced PSCs with near‐unity optical depth over Antarctica in 2006–2007
Authors: Noel V. , Hertzog A. , Chepfer H.
Published: March 2009

Ground‐based and satellite observations have hinted at the existence of polar stratospheric clouds (PSCs) with relatively high optical depths, even if optical depth values are hard to come by. This study documents a type II PSC observed from spaceborne lidar, with visible optical depths up to 0.8. Comparisons with multiple temperature fields, including reanalyses and results from mesoscale simulations, suggest that intense small‐scale temperature fluctuations due to gravity waves play an important role in its formation, while nearby observations show the presence of a potentially related type Ia PSC farther downstream inside the polar vortex. Following this first case, the geographic distribution and microphysical properties of PSCs with optical depths above 0.3 are explored over Antarctica during the 2006 and 2007 austral winters. These clouds are rare (less than 1% of profiles) and concentrated over areas where strong winds hit steep ground slopes in the Western Hemisphere, especially over the peninsula. Such PSCs are colder than the general PSC population, and their detection is correlated with daily temperature minima across Antarctica. Lidar and depolarization ratios within these clouds suggest they are most likely ice‐based (type II). Similarities between the case study and other PSCs suggest they might share the same formation mechanisms.
Impact of vegetation coverage on regional water balance in the nonhumid regions of China
Authors: Yang Dawen , Shao Weiwei , Yeh Pat J.‐F. , Yang Hanbo , Kanae Shinjiro , Oki Taikan
Published: March 2009

The growth of vegetation is affected by water availability, while vegetation growth also feeds back to influence regional water balance. A better understanding of the relationship between vegetation state and water balance would help explain the complicated interactions between climate change, vegetation dynamics, and the water cycle. In the present study, the impact of vegetation coverage on regional water balance was analyzed under the framework of the Budyko hypothesis by using data from 99 catchments in the nonhumid regions of China, including the Inland River basin, the Hai River basin, and the Yellow River basin. The distribution of vegetation coverage on the Budyko curve was analyzed, and it was found that a wetter environment (higher P/E0) had a higher vegetation coverage (M) and was associated with a higher evapotranspiration efficiency (E/E0). Moreover, vegetation coverage was related not only to climate conditions (measured by the dryness index DI = E0/P) but also to landscape conditions (measured by the parameter n in the coupled water–energy balance equation). This suggests that the regional long‐term water balance should not vary along a single Budyko curve; instead, it should form a group of Budyko curves owing to the interactions between vegetation, climate, and water cycle. A positive correlation was found between water balance component (E/P) and vegetation coverage (M) for most of the Yellow River basin and for the Inland River basin, while a negative correlation of M ∼ E/P was found in the Hai River basin. Vegetation coverage was successfully incorporated into an empirical equation for estimating the catchment landscape parameter n in the coupled water–energy balance equation. It was found that interannual variability in vegetation coverage could improve the estimation of the interannual variability in regional water balance.
Formation dry‐out from CO2 injection into saline aquifers: 1. Effects of solids precipitation and their mitigation
Authors: Pruess Karsten , Müller Nadja
Published: March 2009

Injection of CO2 into saline aquifers may cause formation dry‐out and precipitation of salt near the injection well, which may reduce formation porosity, permeability, and injectivity. This paper uses numerical simulation to explore the role of different processes and parameters in the salt precipitation process and to examine injection strategies that could mitigate the effects. The main physical mechanisms affecting the dry‐out and salt precipitation process include (1) displacement of brine away from the injection well by injected CO2, (2) dissolution (evaporation) of brine into the flowing CO2 stream, (3) upflow of CO2 due to gravity effects (buoyancy), (4) backflow of brine toward the injection point due to capillary pressure gradients that oppose the pressure gradient in the CO2‐rich (“gas”) phase, and (5) molecular diffusion of dissolved salt. The different mechanisms operate on a range of spatial scales. CO2 injection at constant rate into a homogeneous reservoir with uniform initial conditions is simulated in 1‐D radial geometry, to resolve multiscale processes by taking advantage of the similarity property, i.e., the evolution of system conditions as a function of radial distance R and time t depends only on the similarity variable R2/t. Simulations in 2‐D vertical cross sections are used to examine the role of gravity effects. We find that counterflow of CO2 and brine can greatly increase aqueous phase salinity and can promote substantial salt precipitation even in formations with low dissolved solids. Salt precipitation can accentuate effects of gravity override. We find that injecting a slug of fresh water prior to commencement of CO2 injection can reduce salt precipitation and permeability loss near the injection well.
Great Lakes Sinkholes: A Microbiogeochemical Frontier
Authors: Biddanda Bopaiah A. , Nold Stephen C. , Ruberg Steven A. , Kendall Scott T. , Sanders T. Garrison , Gray Jefferson J.
Published: March 2009

Recent underwater explorations have revealed unique hot spots of biogeochemical activity at several submerged groundwater vents in Lake Huron, the third largest of the Laurentian Great Lakes. Fueled by venting groundwater containing high sulfate and low dissolved oxygen, these underwater ecosystems are characterized by sharp physical and chemical gradients and spectacularly colorful benthic mats that overlie carbon‐rich sediments. Here, typical lake inhabitants such as fish and phytoplankton are replaced by communities dominated by microorganisms: bacteria and archaea that perform unique ecosystem functions. Shallow, sunlit sinkholes are dominated by photosynthetic microorganisms and processes, while food webs in deep aphotic sinkholes are supported primarily by chemosynthesis.
Communicating Science: Translation and Tangibility
Authors: Johnson Brian
Published: March 2009

Until last summer, I thought communicating science was just a matter of translation. When my friends' eyes glazed over as I explained, for example, how a productivity crisis and planktrophism could have caused the Cretaceous‐Tertiary mass extinction, I thought they simply needed these terms translated.

While cutting through potentially difficult terminology is a key part of communicating science to the public, I now know that it is only the first of two parts. The second part is making one's subject matter tangible. Finding that out was my most important lesson last summer as an AGU‐sponsored fellow in the Mass Media Fellowship program run by the American Association for the Advancement of Science. Understanding this journalistic two‐step has helped me become a better science communicator and comprehend more fully why the Earth sciences fascinate me in the first place.
Cellular and physiological effects of C-peptide
Authors: Hills Claire E. , Brunskill Nigel J.
Published: March 2009

In recent years, accumulating evidence indicates a biological function for proinsulin C-peptide. These results challenge the traditional view that C-peptide is essentially inert and only useful as a surrogate marker of insulin release. Accordingly, it is now clear that C-peptide binds with high affinity to cell membranes, probably to a pertussis-toxin-sensitive G-protein-coupled receptor. Subsequently, multiple signalling pathways are potently and dose-dependently activated in multiple cell types by C-peptide with the resulting activation of gene transcription and altered cell phenotype. In diabetic animals and Type 1 diabetic patients, short-term studies indicate that C-peptide also enhances glucose disposal and metabolic control. Furthermore, results derived from animal models and clinical studies in Type 1 diabetic patients suggest a salutary effect of C-peptide in the prevention and amelioration of diabetic nephropathy and neuropathy. Therefore a picture of Type 1 diabetes as a dual-hormone-deficiency disease is developing, suggesting that the replacement of C-peptide alongside insulin should be considered in its management.
One School District's Experience Working With Speech-Language Pathology Assistants
Authors: Rothwell Gail
Published: March 2009

The Tacoma School District has had a long-term experience working with speech-language pathology assistants (SLPAs). Almost 25 years of experience has given the school district the opportunity to learn how to utilize SLPAs in a positive model. This paper reviews the pros and cons as well as the ethical considerations of working with SLPAs.
Tourism and Quality of Life: Towards a More Critical Approach
Authors: Moscardo Gianna
Published: March 2009

The concept of quality of life (QoL) is implicit in much of the academic literature on tourism impacts. Tourism academics have explored in some detail the contributions that tourism makes to various aspects of the QoL of destination residents. But these explorations have been limited by the social representations that academics hold of tourism. This paper examines those social representations and argues that a more explicit consideration of QoL can help in the development of a better framework for critically analysing tourism impacts. This framework is explored in a qualitative study of social representations of tourism and its impacts on the individual tourist.
Investigating biogenic heterogeneity in coastal sediments with two-dimensional measurements of iron(II) and sulfide
Authors: Robertson David , Welsh David T. , Teasdale Peter R.
Published: March 2009

Environmental context. Microbial respiration generally occurs in distinct layers within coastal sediment, producing high porewater iron or sulfide concentrations, although this layering is dramatically modified by the activities of sediment-dwelling organisms. The present study describes use of a new technique to simultaneously measure two-dimensional concentrations of porewater iron and sulfide at millimetre resolution, allowing the patchiness of patterns of microbial respiration in sediment to be clearly observed. The measurements generally supported a conceptual model predicting the effects of animal burrows and seagrass roots on the porewater iron and sulfide distributions, although the addition of organic matter provided some unexpected observations that require further investigation.
Abstract. One of the most powerful predictive tools in sediment biogeochemistry is the electron acceptor layering model, which describes the order in which oxidised compounds are reduced by successions of respiring microbial populations, and how this layering is influenced by benthic macro-organism activity. However, techniques allowing convenient determination of heterogeneous distributions of reduced substances, such as iron(II) and sulfide, have been lacking. A combined diffusive gradients in thin films–diffusive equilibrium in thin films technique was used to quantitatively measure the two-dimensional iron(II) and sulfide distributions at high resolution in the vicinity of various sediment features, including macrofauna burrows, particulate organic matter and macrophyte roots. Substantial heterogeneity was observed for both analytes in all probes, especially in the vicinity of seagrass roots and particulate organic matter. Measured distributions tended to follow the general patterns predicted by the tertiary electron acceptor layering model. However, there was unexpected overlap of sulfide and iron(II) distributions at the millimetre to centimetre scale in several samples from different sediments, notably the more complex sediments containing particulate organic matter and seagrass roots. The cause of such overlap is unclear and further study is necessary to elucidate how such distributions can occur.
Perchlorate in an urban lawn environment
Authors: Munster Jennie , Hanson Gilbert N.
Published: March 2009

Environmental context. The extent of perchlorate contamination in our environment is inadequately known. We examined perchlorate content in precipitation, soil water, soil cores and grass clippings in an urban lawn environment. Our results show that perchlorate is present in the lawn environment at concentrations that may adversely affect human health.
Abstract. Perchlorate contamination in groundwater is a concern owing to the likelihood that low concentrations of perchlorate may disrupt normal thyroid function. Lawns fertilized with perchlorate-containing fertilizers can adversely affect groundwater. We examined perchlorate concentrations from June 2006 to January 2007 in precipitation, grass clippings, soil cores and soil water at eight lawn environments in Suffolk County, NY, a county where lawns comprise more than 25% of the land use. Measured concentrations in soil waters were as high as 255 μg L–1, with average concentrations of 69 μg L–1 beneath sites treated with organic fertilizer, 1.2 μg L–1 beneath sites treated with chemical fertilizer and 0.34 μg L–1 beneath sites not fertilized. Although concentrations were dependent on the type of fertilizer applied, the patterns of leaching and grass uptake were similar at all sites.
Constraints on the possible atmospheric sources of perchlorate
Authors: Roberts James M.
Published: March 2009

Environmental context. Perchlorate ion is a potentially harmful trace pollutant that can interfere with the proper absorption of iodine by the thyroid gland. Natural, atmospheric chemical sources of perchlorate have been proposed based on isotopic composition of mineral deposits, ground and surface waters. Understanding this natural source is crucial to the formulation of effective mitigation and control strategies.
Abstract. Observations of perchlorate (ClO4–) in a variety of environmental media imply that there is an atmospheric source related to nitrate and ozone photochemistry. Formation of perchlorate from chloride in the atmospheric condensed phase (cloud droplets, aerosol particles) requires considerable oxidation, most likely starting with the conversion to a 0 or +1 oxidation-state compound, a process that has been loosely termed ‘chlorine activation’. There are several features of mid-latitude tropospheric chlorine activation chemistry, insolubility of known precursors, nitryl chloride (ClNO2) and molecular chlorine (Cl2), and rapid and efficient cycling of hypochlorous acid (HOCl) to molecular chlorine, that make these pathways highly improbable candidates for the source of perchlorate. It is more probable that environments such as the chlorine-impacted stratosphere, or arid, high-salt desert regions have the necessary high concentrations of chlorine intermediates that could lead to perchlorate, although the detailed chemical steps are not completely known. Measurements of perchlorate in aerosol particles, and in polar snow, firn and ice cores, as well as further fundamental chemical kinetics studies are recommended.