bluuebunny/crossref_metadata_2025 huggingface dataset:
Holocene evolution of mud depocentres on a high-energy, low-accumulation shelf (NW Iberia)
Authors: Lantzsch Hendrik , Hanebuth Till J.J. , Bender Vera B.
Published: August 2009

The high-energy, low-accumulation NW Iberian shelf features three confined Holocene mud depocentres. Here, we show that the evolution of such depocentres follows successive steps. The flooding of inner shelf zones and river catchment areas by the late deglacial sea-level rise provided the precondition for shelf mud deposition. Following this, the Holocene deceleration of the sea-level rise caused a rapid refill of the accommodation space within river valleys. Subsequently, the export of major amounts of fines was initiated. The initial onset and loci of shelf mud deposition were related to deposition-favouring conditions in mid-shelf position or to the presence of morphological highs, which act as sediment traps by providing protection against stronger hydrodynamic energy. The detailed reconstruction of the Holocene depocentre evolution shows for the first time that the expansion of such shelf mud deposits cannot only occur by linear growth off the associated sediment source. Rather, they might develop around centres that are fully disconnected from the source of original sediment supply, and expand later into specific directions. Based on these differences and on the connection of the individual mud depocentres to the material source we propose a conceptual subdivision of the group “mid-shelf mud depocentres”.
Religious Competition and Ethnic Mobilization in Latin America: Why the Catholic Church Promotes Indigenous Movements in Mexico
Authors: TREJO GUILLERMO
Published: August 2009

This article suggests that a society's religious market structure can explain whether religion is “the opium of the people” or a major source of dissident secular mobilization. I present a simple model explaining why under monopolistic conditions, Catholic clergy in Latin America ignored the religious and social needs of poor rural indigenous parishioners but, when confronted by the expansion of U.S. mainline Protestantism, became major institutional promoters of rural indigenous causes. Catholic indigenous parishioners empowered by competition demanded the same benefits their Protestant neighbors were receiving: social services, ecclesiastic decentralization, and the practice of religion in their own language. Unable to decentralize ecclesiastic hierarchies, and facing a reputation deficit for having sided with rich and powerful elites for centuries, Catholic clergy stepped into the secular realm and became active promoters of indigenous movements and ethnic identities; they embraced the cause of the Indians as a member retention strategy and not in response to new doctrinal ideas emanating from Vatican II. Drawing on an original data set of indigenous mobilization in Mexico and on life histories and case studies, I provide quantitative and qualitative evidence of the causal effect of religious competition on the creation of the social bases for indigenous ethnic mobilization.
The effect of dairy foods on CHD: a systematic review of prospective cohort studies
Authors: Gibson Robert A. , Makrides Maria , Smithers Lisa G. , Voevodin Melanie , Sinclair Andrew J.
Published: August 2009

There is interest in the degree to which fats in dairy foods contribute to CHD. We undertook a systematic review to investigate the effect of dairy consumption on CHD using prospective cohort studies. A systematic search of electronic databases identified studies relating dairy food intake in adulthood to episodes or death from CHD, IHD and myocardial infarction. Included studies were assessed for quality based on study methodology, validity of dietary assessment, success of follow-up, standardised assessment of CHD, IHD or myocardial infarction end points and appropriateness of statistical adjustment. Data from twelve cohorts involving >280 000 subjects were included. Most studies had follow-up of >80 %, adjusted statistically for three or more confounders and used standard criteria to determine end points. About half the studies used a validated FFQ, administered the FFQ more than once or had follow-up of >20 years. Fewer than half the studies involved subjects representative of the general population. Four of the twelve cohorts found no association between dairy intake and CHD. Eight studies reported varying relationships between different dairy foods and CHD or differential associations based on race, sex or over time. Although dairy foods contribute to the SFA composition of the diet, this systematic review could find no consistent evidence that dairy food consumption is associated with a higher risk of CHD. This could be due to the limited sensitivity of the dietary assessment methods to detect an effect of a single food in a mixed diet on complex clinical outcomes.
Diet and deprivation in pregnancy
Authors: Haggarty Paul , Campbell Doris M. , Duthie Susan , Andrews Katherine , Hoad Gwen , Piyathilake Chandrika , McNeill Geraldine
Published: August 2009

Deprivation is associated with poor pregnancy outcome but the role of nutrition as a mediating factor is not well understood. We carried out a prospective cohort study of 1461 singleton pregnancies in Aberdeen, UK during 2000–6. We measured nutrient intake and supplement use, B vitamin and homocysteine status, birth weight, gestational age, neonatal treatment and socio-economic deprivation status. Women in the most deprived deciles were approximately 6 years younger and half as likely to take folic acid supplements periconceptually as the least deprived mothers. Deprivation was associated with low blood folate, high homocysteine and diets low in protein, fibre and many of the vitamins and minerals. The diets of the more deprived women were also characterised by low intakes of fruit, vegetables and oily fish and higher intakes of processed meat, fried potatoes, crisps and snacks. Deprivation was related to preterm birth (OR 1·14 (95 % CI 1·03, 1·25); P = 0·009) and whether the baby required neonatal treatment (OR 1·07 (95 % CI 1·01, 1·14); P = 0·028). Low birth weight was more common in women consuming diets low in vitamin C (OR 0·79 (95 % CI 0·64, 0·97); P = 0·028), riboflavin (OR 0·77 (95 % CI 0·63, 0·93); P = 0·008), pantothenic acid (OR 0·79 (95 % CI 0·65, 0·97); P = 0·023) and sugars (OR 0·78 (95 % CI 0·64, 0·96); P = 0·017) even after adjustment for deprivation index, smoking, marital status and parity. Deprivation in pregnancy is associated with diets poor in specific nutrients and poor diet appears to contribute to inequalities in pregnancy outcome. Improving the nutrient intake of disadvantaged women of childbearing age may potentially improve pregnancy outcome.
Cystatin C levels in plasma and peripheral blood mononuclear cells among hyperhomocysteinaemic subjects: effect of treatment with B-vitamins
Authors: Tobin Kari Anne R. , Holven Kirsten B. , Retterstøl Kjetil , Strøm Ellen , Ose Leiv , Aukrust Pål , Nenseter Marit S.
Published: August 2009

Homocysteine has been related to increased risk of CVD. Matrix degradation and inflammation may be involved in this link between hyperhomocysteinaemia and CVD. Recent studies suggest that cystatin C can modulate matrix degradation and inflammation. The present study measured cystatin C at protein (plasma) and mRNA levels (peripheral blood mononuclear cells (PBMC)) in hyperhomocysteinaemic individuals (n 37, female seven and male thirty, aged 20–70 years) before and after B-vitamin supplementation for 3 months in a randomised, placebo-controlled double-blind trial. In a cross-sectional study, seventeen of the hyperhomocysteinaemic subjects were age- and sex-matched to healthy controls (n 17). Our main findings were: (i) as compared with controls, hyperhomocysteinaemic subjects tended to have higher plasma concentrations of cystatin C and lower mRNA levels of cystatin C in PBMC; (ii) compared with placebo, treatment of hyperhomocysteinaemic individuals with B-vitamins significantly increased plasma levels of cystatin C and mRNA levels of cystatin C in PBMC; (iii) while plasma levels of cystatin C were positively correlated with plasma levels of TNF receptor-1, mRNA levels of cystatin C in PBMC were inversely correlated with this TNF parameter. Taken together, our findings suggest that disturbed cystatin C levels may be a characteristic of hyperhomocysteinaemic individuals, potentially related to low-grade systemic inflammation in hyperhomocysteinaemic subjects, and that B-vitamins may modulate cystatin C levels in these individuals.
Ultrahigh-density deuterium of Rydberg matter clusters for inertial confinement fusion targets
Authors: Holmlid L. , Hora H. , Miley G. , Yang X.
Published: August 2009

Clusters of condensed deuterium of densities up to 1029cm−3in pores in solid oxide crystals were confirmed from time-of-flight mass spectrometry measurements. Based on these facts, a schematic outline and possible conclusions of expectable generalizations are presented, which may lead to a simplification of laser driven fusion energy including new techniques for preparation of targets for application in experiments of the NIF type, but also for modified fast igniter experiments using proton or electron beams or side-on ignition of low compressed solid fusion fuel.
Recent clinical trials in diabetes – implications for managing older patients
Authors: Hawthorne GC , Yarnall AJ
Published: August 2009

The prevalence of type 2 diabetes is set to increase, and with it the complications associated with diabetes. Since 2007 there have been a number of significant trials that may change the way we think about treating people with diabetes, especially our older patients. These trials include the Steno-2 trial, UKPDS legacy trial, ADVANCE, ACCORD and VADT. These trials are reviewed in detail in this article, including the implications for the patients we treat. Recent work assessing the effect of HbA1c on cognitive function and the effects of hypoglycaemia are also discussed. We conclude with suggestions for targets for glycated haemoglobin level based on NICE guidance.
Handling of water and electrolytes in the healthy old
Authors: Alvarez Gregori Joaquin-A. , Macías Núñez Juan-F.
Published: August 2009

This paper reviews the handling of water and electrolytes by the ageing kidney and the clinical consequences in everyday clinical practice. Normal physiology in the adult kidney is discussed, followed by description of the main physiological changes (adaption) that occur as the kidney ages. Clearly, successful management of the elderly patient requires a knowledge of these changes, which result in: (i) increased tendency for volume depletion and dehydration; (ii) decreased ability to tolerate a volume load; (iii) increased propensity for potassium disturbances (hypo- and hyperkalaemia); (iv) diminished production of renin and blunted physiological response to the effects of aldosterone and antidiuretic hormone; (v) increased tendency to lower levels of phosphate; and (vi) tendency for the development of hypocalcaemia and hypomagnesaemia. A brief review of the role of extracellular fluid volume depletion and other factors contributing to acute renal failure in elderly patients is also presented.
Abuse of people with dementia
Authors: Selwood Amber , Cooper Claudia
Published: August 2009

People with dementia are particularly vulnerable to abuse. It is inherently difficult to study as it is a hidden offence, perpetrated against vulnerable people with memory impairment, by those on whom they depend. In the general population, 6% of older people have experienced abuse in the last month and this rises to approximately 25% in vulnerable populations such as people with dementia. We know that various factors in the carer and the care recipient can predispose to a higher rate of abuse and this knowledge can be harnessed to try and improve prevention. There are also valid and reliable scales available to help detect abuse in vulnerable older adults. All health and social care professionals have a responsibility to act on any suspicion or evidence of significant abuse or neglect in order to ensure that appropriate management is taken.
Virtual simulation and treatment verification–merits and demerits: experience at Sindh Institute of Urology and Transplantation (SIUT), Pakistan
Authors: Tunio Mutahir , Rafi Mansoor , Maqbool Aamir , Haque Asdarul
Published: August 2009

Background: The rapid changes in practice of radiotherapy have taken place over the past 5 years in Pakistan. With advent of computed tomography simulator, and multileaf collimators–assisted linear accelerators and electronic portal imaging system, few centres in Pakistan have switched from conventional radiotherapy to modern computer-based technology. Our hospital is first centre in Pakistan which is using virtual simulation since March 2006. We present our experience with list of merits and demerits.

Design: Retrospective study.

Patient collection: Medical records of all patients who received radiotherapy in our centre were reviewed. Parameters included were type of malignancy, type radiotherapy (curative/palliative), simulation and planning process time and the displacement of the beam-axis from the planning isocentre in clinical situations during three-dimensional conformal radiotherapy using electronic portal imaging device (EPID). Data were collected on written proforma. Percentages, frequencies, measures of central tendency and dispersion were calculated using SPSS version 17.0.

Results: A total of 289 patients were treated from March 2006 to November 2008. Transitional cell carcinoma of urinary bladder was most common malignancy seen (42.4%) followed by prostate (28.62%) and renal cell carcinoma (14.14%). Of these 34.26% patients were treated on curative basis. The virtual simulation process could be completed in an average time of 5 min (SD 3.5). Under many cases, the treatment portals could be designed and the patient marked in one session. The displacements were recorded for 43 portals for early prostate cancer using an EPID system. The mean displacement was found 2.44 ± 0.8 mm in x (transverse), y (craniocaudal), and z (anteroposterior) directions during treatment. Standard deviation (SD) was 0.87 (90% CI 2.21–2.66). Average number of portals taken was 10 (6–27) per treatment session.

Conclusion: Computer-based simulation and treatment over conventional methods is appropriate for curative patients, achieving more accurate tumour localisation, sparing normal organs at risk, reduced field sizes and a film free environment; however efforts are required to achieve maximum immobilisation during treatment.
Clinical oral examinations: assessment of competence in radiation therapy
Authors: Leech Michelle , Craig A. , Poole C. , Broderick M. , Ni Chuinneagain S. , Coffey M. , Byrne J.
Published: August 2009

Matching assessment strategies to learning outcomes in radiation therapy education is of the utmost importance. Assessing clinical competence requires that ‘competence’ be clearly defined prior to the start of any clinical programme. In this article, we report on our experience in using clinical oral examinations in assessing competence in second year undergraduate radiation therapy students. The shortcomings of clinical oral examinations such as ‘leaking’ of the agenda are addressed and more positive attributes, such as increased collaboration between academic and clinical radiation therapists are discussed.
Palliative radiotherapy: modelling and evaluating the impact of factors in the treatment times and workload of orthovoltage units–a pilot study
Authors: Donaghey S.L.
Published: August 2009

Patients treated with palliative intent present a complex issue for radiotherapy departments in terms of their specific care needs, treatment times, and the productivity of orthovoltage resources. This study seeks to evaluate and quantify patient-related factors, treatment times, and to assess tools and data for future utilisation by radiotherapy departments. A modified Basic Treatment Equivalent (BTE) methodology was chosen, with stopwatch timings taken of treatments on orthovoltage units, over a 4-week period at two radiotherapy departments. Data collected included patient-related, treatment and equipment factors to assess their relative or specific effects on treatment times. Analysis considered the differences in data sets, significance and correlation. Forty-three fractions of treatment were recorded, across a range of treatment sites. The number of fields and delivery of first fractions/plan and treat episodes were found to result in significant differences in treatment time. The use of equipment, age and performance status were not found to be influential. Pain and skin viability symptoms had the greatest impact on treatment times–with these themselves being influenced by the impact of number of fields treated and first fractions. A full study should now be undertaken with a view to design a new equivalence model for the effective assessment of orthovoltage productivity.
Radiation therapists and the Internet: a perspective from Australia
Authors: Shanahan Madeleine
Published: August 2009

The Internet is an important information source for health practitioners; yet little is known of how radiation therapists (RTs) are currently using this vast information resource for their professional learning. In 2007, a four-page postal survey was sent to a random sample of 1,142 Medical Radiation Science practitioners with a response rate of 32.8%, which included 76 RTs. This paper reports and analyses the questionnaire responses from RTs on the use of the Internet to update their professional knowledge and issues affecting accessibility to the Internet in the workplace. This research provides an initial data set on the professional use of Internet-based tools and resources by Australian RTs. It has been shown that the Internet is an important information source widely used by RTs as they search the Internet (89%), access specific web pages (85%), use e-mail (84%) and listservs (49%) to update their professional knowledge. Although all RTs reported Internet access within their workplace, a number of factors have been identified which at present limit accessibility of current quality health and medical information through the Internet to RTs. A large number of RTs were unaware of Internet-based resources, such as Cochrane Library (48%) and GoogleScholar (42%), which support evidence-based practice (EBP) and research. RTs in teaching environments had greater access to computers with Internet access than their colleagues in non-teaching environments (p = 0.044). More RTs in the private sector (22%) reported they had ‘no’ access to the Internet in their workplace than their public sector colleagues (4%, p = 0.037). In addition, RTs in metropolitan workplaces had greater access to protected time during work hours for professional reading or study than their non-metropolitan colleagues (p = 0.000). These issues of non-uniformity of resources across workplaces and knowledge gaps within the profession must be addressed so that all RTs can avail themselves of high quality resources available through the Internet that support them in implementing EBP and meeting the mandatory requirement of updating their professional knowledge.
Correlation between mean lethal dose and organ weight
Authors: Akber Syed F. , Kehwar Than S.
Published: August 2009

The assessment of mean lethal dose (Do) with organ weight in human organs yields a correlation coefficient of 0.94. Results indicate that as the organ weight increases, the Do decreases.
10 Years of Functional Foods in Europe
Authors: Walter Paul
Published: August 2009

In 1999, the Scientific Concepts of Functional Foods in Europe: Consensus Document was published. In the last ten years the main emphasis of progress has been in the following areas: Functions of Food: It has become very clear that a large part of the known functions of vegetables, fruits and grains are not only due to the well known vitamins and minerals, but that a large variety of other non-nutritive biologically active compounds in these foods have also specific actions on human health. An increasing number of these food ingredients are now known. Claims relevant to Functional Foods: In a European Commission Concerted Action lead by ILSI Europe, the Assessment of Scientific Support for Claims on Foods (PASSCLAIM) led to criteria to assess the scientific evidence to support claims on foods. The relative strengths and limitations of types of scientific approaches and data that are relevant to different health and disease states as well as providing guidance on the interpretation of the criteria are also described. Legislation: The new European Regulation on Nutrition and Health Claims made on Foods entered into force on January 19, 2007. The regulation sets out conditions for their use, establishes a system for their scientific evaluation, and will create European lists of authorised claims. This process will be the most important development for the acceptance of foods with special functions in Europe.
Consumer Demand for Personalized Nutrition and Functional Food
Authors: Roosen Jutta , Bruhn Maike , Mecking Rebecca-Ariane , Drescher Larissa S.
Published: August 2009

New developments in nutrigenetic research and the European regulation 1924/2006 on health claims have spurred interest in developing and marketing functional food designed for personalized nutrition. Personalized nutrition uses genetic information regarding a person’s health risk profile. Specifically adapted nutrition recommendations are claimed to help reducing disease risk. An internet survey was conducted in December 2007 using a sample of 452 randomly selected adults in Germany. The survey instrument assesses if consumers would be willing to participate in genetic risk profiling, if they are interested in personalized nutrition advice and if they desire functional food products adapted to their individual nutrigenetic profile. In addition, we estimate the acceptance of functional food products designed to reduce the risk of cardio-vascular diseases. Consumers have a positive attitude towards the testing of their genetic profile to be used in nutrient advice. About 45 % of the sample would agree to such a test and like to obtain a personalized advice on nutrition. Similarly, more than 40 % of the sample showed a positive willingness to buy the proposed functional food products. Given these results, the concept of personalized nutrition seems promising. However, several challenges remain regarding targeted nutrition advice and food marketing.
Importance of Vitamin D and Calcium at Older Age
Authors: Bischoff-Ferrari Heike A. , Staehelin Hannes B.
Published: August 2009

We review the potential of vitamin D for the prevention of falls and fractures. Evidence from randomized-controlled trials will be reviewed for both endpoints, as well as epidemiologic data that correlates higher 25-hydroxyvitamin D status with better bone and muscle health. This review summarizes the compelling dual benefit of vitamin D on bone and muscle health, a concept that is unique and important for optimal fracture prevention at higher age. We will review sources of vitamin D and calcium and also outline why calcium supplementation alone may not contribute to fracture prevention at higher age. This review concludes that vitamin D at a dose of at least 800 IU per day should be provided to all postmenopausal women and everybody starting at age 60 for optimal bone and muscle health. In combination with a vitamin D supplement, dairy products may be an optimal source of calcium at higher age as milk provides both calcium and protein.
On the character and distribution of lower‐frequency radio emissions at Saturn and their relationship to substorm‐like events
Authors: Jackman C. M. , Lamy L. , Freeman M. P. , Zarka P. , Cecconi B. , Kurth W. S. , Cowley S. W. H. , Dougherty M. K.
Published: August 2009

With the arrival of the Cassini spacecraft at Saturn in July 2004, there have been quasi‐continuous observations of Saturn kilometric radiation (SKR) emissions. Exploration of the nightside magnetosphere has revealed evidence of plasmoid‐like magnetic structures and other phenomena indicative of the Kronian equivalent of terrestrial substorms. In general, there is a good correlation between the timing of reconnection events and enhancements in the auroral SKR emission. Eight of nine reconnection events studied occur at SKR phases where the SKR power would be expected to be rising with time. Thus, while the recurrence rate of substorm‐like events at Saturn is likely much longer than the planetary rotation timescale, the events are favored to occur at a particular phase of the rotation. We show three examples in each of which the SKR spectrum extends to lower frequencies than usual. This can be interpreted as an expansion of the auroral particle acceleration region to higher altitudes along magnetic field lines as a direct consequence of an increase in the magnetosphere‐ionosphere current density driven by substorm‐like events. We then conduct a survey of such low‐frequency extensions during the equatorial orbits of 2005–2006 and place some constraints on visibility of these radio emissions.
Nighttime ionospheric D region: Equatorial and nonequatorial
Authors: Thomson Neil R. , McRae Wayne M.
Published: August 2009

Nighttime ionospheric D region parameters are found to be generally well modeled by the traditional H′ and β as used by Wait and by the U.S. Navy in their Earth‐ionosphere VLF radio waveguide programs. New comparisons with nonequatorial, mainly all‐sea VLF path observations reported over several decades are shown to be consistent with the previously determined height H′ ∼ 85.0 km and sharpness β ∼ 0.63 km−1. These paths include NPM (Hawaii) to Washington, D. C., Omega Hawaii and NLK (Seattle) to Japan, NWC (N.W. Australia) to Madagascar, and NBA (Panama) to Colorado. In marked contrast, transequatorial path observations (even when nearly all‐sea) are found to be often not well modeled: for example, for Omega Japan and JJI (Japan) to Dunedin, New Zealand, the observed amplitudes are markedly lower than those which would be expected from H′ ∼ 85.0 km and β ∼ 0.63 km−1, or any other realistic values of H′ and β. Other transequatorial observations compared with modeling include NWC to Japan, Omega Hawaii to Dunedin, and NPM (Hawaii) to Dunedin. It is suggested that the effects of irregularities in the equatorial electrojet may extend down into the nighttime D region and so account for the observed equatorial VLF perturbations through scattering or mode conversion.
September 2005 Manda Hararo‐Dabbahu rifting event, Afar (Ethiopia): Constraints provided by geodetic data
Authors: Grandin R. , Socquet A. , Binet R. , Klinger Y. , Jacques E. , de Chabalier J.‐B. , King G. C. P. , Lasserre C. , Tait S. , Tapponnier P. , Delorme A. , Pinzuti P.
Published: August 2009

We provide a new set of complementary geodetic data for the 2005 rifting event of Afar (Ethiopia). Interferometric synthetic aperture radar and subpixel correlations of synthetic aperture radar and SPOT images allow us to deduce 3‐D surface displacement unambiguously. We determine the geometry of the dike and neighboring magma chambers and invert for the distribution of opening of the dike, as well as slip on rift border faults. The volume of the 2005 dike (1.5–2.0 km3) is not balanced by sufficient volume loss at Dabbahu and Gabho volcanoes (0.42 and 0.12 km3, respectively). Taking into account the deflation of a suspected deep midsegment magma chamber simultaneously to dike intrusion produces a smoother opening distribution along the southern segment. Above the dike, faults slipped by an average 3 m, yielding an estimated geodetic moment of 3.5 × 1019 Nm, one order of magnitude larger than the cumulative seismic moment released during the earthquake swarm. Between Dabbahu and Ado'Ale volcanic complexes, significant opening occurred on the western side of the dike. The anomalous location of the dike at this latitude, offset to the east of the axial depression, may explain this phenomenon. A two‐stage intrusion scenario is proposed, whereby rifting in the northern Manda Hararo Rift was triggered by magma upwelling in the Dabbahu area, at the northern extremity of the magmatic segment. Although vigorous dike injection occurred during the September 2005 event, the tectonic stress deficit since the previous rifting episode was not fully released, leading to further intrusions in 2006–2009.
Non–double‐couple mechanisms of microearthquakes induced by hydraulic fracturing
Authors: Šílený Jan , Hill David P. , Eisner Leo , Cornet Francois H.
Published: August 2009

We have inverted polarity and amplitude information of representative microearthquakes to investigate source mechanisms of seismicity induced by hydraulic fracturing in the Carthage Cotton Valley, east Texas, gas field. With vertical arrays of four and eight three‐component geophones in two monitoring wells, respectively, we were able to reliably determine source mechanisms of the strongest events with the best signal‐to‐noise ratio. Our analysis indicates predominantly non–double‐couple source mechanisms with positive volumetric component consistent with opening cracks oriented close to expected hydraulic fracture orientation. Our observations suggest the induced events are directly the result of opening cracks by fluid injection, in contrast to many previous studies where the seismicity is interpreted to be primarily shearing caused by pore pressure diffusion into the surrounding rock or associated with shear stresses created at the hydraulic fracture tip.
An assessment of corrections for eddy covariance measured turbulent fluxes over snow in mountain environments
Authors: Reba Michele L. , Link Timothy E. , Marks Danny , Pomeroy John
Published: August 2009

Snow‐covered complex terrain is an extremely important runoff‐generating landscape in high‐altitude and high‐latitude environments, yet it is often considered nonviable for eddy covariance measurements of turbulent fluxes. Turbulent flux data are useful for evaluating the coupled snow cover mass and energy balance that control snow ablation and melt. In particular, detailed, multiseason analyses of eddy covariance data postprocessing requirements and resulting data quality for hydrological analyses in open and sheltered mountain sites have not been conducted. These analyses are needed since these landscapes typify those that generate snowmelt runoff in the mountain west of North America. Eddy covariance measurements taken from exposed hilltop and sheltered subcanopy snow research sites during three snow seasons underwent rigorous postprocessing and data quality assessments. Procedures included data filtering, air density corrections, sensor heating, axis rotation, and exclusion of nonstationary data. Data quality analysis showed that 77% of the sensible heat flux data and 95% of the latent heat flux data were of high quality. There was little interannual variability over three seasons in quality or improvements due to postprocessing results. A comparison of summary data based on a 30‐min averaging period to postprocessed high‐resolution flux data found that the postprocessed sensible heat fluxes were up to 14% less than the summary fluxes for the snow season. The results indicated that application of unattended eddy covariance techniques at these sites was viable, but the full suite of corrections and postprocessing are advisable to obtain flux observations of sufficient reliability for snow hydrology calculations.
Stochastic analysis of unsaturated flow with probabilistic collocation method
Authors: Li Weixuan , Lu Zhiming , Zhang Dongxiao
Published: August 2009

In this study, we present an efficient approach, called the probabilistic collocation method (PCM), for uncertainty analysis of flow in unsaturated zones, in which the constitutive relationship between the pressure head and the unsaturated conductivity is assumed to follow the van Genuchten‐Mualem model. Spatial variability of soil parameters leads to uncertainty in predicting flow behaviors. The aim is to quantify the uncertainty associated with flow quantities such as the pressure head and the effective saturation. In the proposed approach, input random fields, i.e., the soil parameters, are represented via the Karhunen‐Loeve expansion, and the flow quantities are expressed by polynomial chaos expansions (PCEs). The coefficients in the PCEs are determined by solving the equations for a set of carefully selected collocation points in the probability space. To illustrate this approach, we use two‐dimensional examples with different input variances and correlation scales and under steady state and transient conditions. We also demonstrate how to deal with multiple‐input random parameters. To validate the PCM, we compare the resulting mean and variance of the flow quantities with those from Monte Carlo (MC) simulations. The comparison reveals that the PCM can accurately estimate the flow statistics with a much smaller computational effort than the MC.
Northward field excursions in Saturn's magnetotail and their relationship to magnetospheric periodicities
Authors: Jackman C. M. , Arridge C. S. , McAndrews H. J. , Henderson M. G. , Wilson R. J.
Published: August 2009

We present results from an investigation of Cassini encounters with Saturn's magnetotail current sheet, using magnetic field and plasma data. In the first of two intervals shown, small periodic changes in the north‐south component of the magnetic field are matched by periodic density enhancements associated with the plasma sheet center. In the second interval, a large plasmoid signature is observed set against a background of small‐scale current sheet motions. We interpret the quasi‐periodic small field deflections and density enhancements as large‐scale wave‐like motion of the current sheet. We stress that plasmoid signatures are of a clearly different character and occur much less frequently.
Interactions between tropospheric chemistry and climate model temperature and humidity biases
Authors: O'Connor F. M. , Johnson C. E. , Morgenstern O. , Collins W. J.
Published: August 2009

Temperature and humidity climatologies from the Met Office Hadley Centre climate model, HadGAM1, show a strong cold bias of up to 5 K in the extra‐tropical upper troposphere/lower stratosphere and a dry bias of up to 20% in the tropical lower and mid troposphere. Removing the temperature bias alone has little effect on tropospheric ozone or methane lifetime. Removing the humidity bias alone causes a reduction in both the global annual mean tropospheric ozone burden of greater than 2% and the methane lifetime of 3.6–4.2%. The impact of removing both biases together is similar to that of removing the humidity bias alone. The choice of reanalysis product (ERA‐40 or NCEP) to calculate the biases does not greatly affect the results. Radiative feedback from ozone and methane reduced some of the climate model biases without any significant change to the performance of the chemistry.
Global MHD simulation of the geomagnetic sudden commencement on 21 October 1999
Authors: Kim K.‐H. , Park K. S. , Ogino T. , Lee D.‐H. , Sung S.‐K. , Kwak Y.‐S.
Published: August 2009

Recently, Shinbori et al. (2004) examined the electric field variations associated with geomagnetic sudden commencements (SC) by using data from the Akebono satellite in the inner magnetosphere (L < 5) and reported the following characteristics of the SC‐associated electric field variations. (1) The electric field shows a bipolar change. (2) The initial excursion of the electric field tends to be directed westward. (3) The electric field amplitude does not show a dependence on magnetic local time. By using a global three‐dimensional MHD simulation model, we examine how and where such SC‐associated electric field variations are established. In our study, we used the SC event that occurred on 21 October 1999, which was caused by a sudden increase in the solar wind dynamic pressure from ∼3 to ∼13 nPa. The solar wind and interplanetary magnetic field conditions observed from the Wind satellite near GSM (x, y, z) ∼ (22, −62, 20) RE are used as the simulation input parameters. The numerical simulation shows that inward flow is first excited near local noon and then flow vortex is generated near the flankside as the solar wind discontinuity is passing over the magnetosphere. Thus, the convection electric field variations change with local time. The vortical structure has a duration of 3–4 min and propagates with a flow speed of ∼75% of the solar wind speed. The electric fields associated with flow vortices show a bipolar structure. We suggest that the flow vortex in our simulation is associated with the main impulse of SC and that the SC‐associated electric fields observed at Akebono are due to the convection electric field.
Using lidar remote sensing and support vector machines to classify fire disturbance legacies in a Florida oak scrub landscape
Authors: Angelo James , Duncan Brean , Weishampel John
Published: August 2009

Background/Question/Methods

Ecologists have long emphasized the reciprocal interactions between spatial pattern and ecological processes in the creation of landscape mosaics. While an enormous amount of recent research has focused on the quantification of spatial patterns, efforts to infer process from pattern have been hindered by the presence of multi-scale, often confounding, drivers of pattern in many landscapes. At the mesoscale, Holling’s extended keystone hypothesis posits that spatially contagious disturbances such as fire are the dominant pattern-generating processes. To test this hypothesis, we used fire history data and discrete, small-footprint lidar remote sensing acquired over a 22 sq. km landscape of oak scrub in the Kennedy Space Center/Merritt Island National Wildlife Refuge area on the east-central coast of Florida. We binned the lidar return data into 1 m vertical height intervals for each 5 m x 5 m horizontal cell. Since community structure tends to recover by 7 years post-fire, we tested for significant differences between recently-burned (< 7 years) and unburned (≥ 7 years) patches with multivariate analysis of variance. To predict the burn status of each cell, we then used distribution-free, nonlinear support vector machine (SVM) classifiers, which have proven to be highly accurate for complex pattern recognition problems.

Results/Conclusions

We detected statistically significant differences in vegetation structure between burned and unburned patches for all of the dominant land cover types (upland non-forested, upland forested, wetland hardwood forest, and non-forested wetlands) in the study area. Initially, we obtained a predicted error rate of approximately 34% from the SVM classifier; by averaging the binned lidar data over a moving window of increasing size, however, we achieved substantial reductions in the predicted error rate for the SVM classifier. The optimal window size of 100 m x 100 m yielded a predicted misclassification rate of approximately 3%, an order of magnitude lower than the error rate obtained on the same data using a logistic regression classifier. These results suggest that, as predicted by the extended keystone hypothesis, fire disturbance is a dominant pattern-generating process at the patch scale in this oak scrub landscape. Furthermore, these results indicate that it is possible to use vertical vegetation structure, as represented by the binned lidar data, to predict burn status with a high level of accuracy. While our study employed a simple binary classification scheme, future research will focus on using SVM regression techniques to predict burn status with finer-grained classes of time since fire.
Residential irrigation as a driver of urban bird communities
Authors: Schleder Bradley , Katti Madhusudan , Wallace Sarah
Published: August 2009

*Background/Question/Methods*

The demand for fresh water has largely outpaced supply both globally and locally with current water management policies unable to meet the needs of urban, agricultural, and industrial activities. Irrigation is one of the many anthropogenic uses of water and is arguably the most important maintenance factor in a landscape. This is particularly true in an arid climate, such as the Central Valley of California. Urban residents' decisions about the design and maintenance of their landscapes affect bird species richness. Published research indicates that these decisions are also affected by the residents' socioeconomic status. However, the driver of this relationship remains unknown. This paper uses data from the Fresno Bird Count, a citizen science organization, to test the hypothesis that neighborhood socioeconomic status influences residential irrigation regimes, which influences plant cover, in turn influencing bird diversity and abundance. A random sampling grid containing 460 points are used as locations for five minute point counts for the Fresno Bird Count ("fresnobirds.org":http://fresnobirds.org/). Socioeconomic data has been obtained from the U.S. Census and irrigation regimes from the city of Fresno. Aerial imagery and ground sampling on point count locations are used for characterizing habitat.

*Results/Conclusions*

Preliminary analysis of the first year of data (2008) supports this hypothesis and reveals a north/south gradient of bird diversity paralleling the socioeconomic gradient of Fresno. This paper will present results from a more comprehensive analysis of data including the spring 2009 bird census. Policies in the U.S. regarding the distribution and cost of water are changing in response to increased water demands, and the city of Fresno is about to undergo such a change. In 2013 a policy of metered water is scheduled to begin, which is predicted to increase water conservation by residents due to an increase in it overall cost. In addition to examining coupled socio-ecological drivers of urban diversity, this study will be the first part of a Before After Control Impact experiment taking advantage of the planned implementation of metering the cost of water use. The results can help guide the city in improving its management of urban habitat and biodiversity.
Root production and methane dynamics: Impact of wetland functional group diversity and composition
Authors: Schultz Rachel , Bouchard Virginie , Frey Serita
Published: August 2009

Background/Question/Methods

The loss of biodiversity worldwide has prompted a close investigation of the link between diversity and ecosystem functions. Most experimental studies have looked at the relationship between grassland plant diversity and aboveground productivity. Less is known about other ecosystems or how diversity affects belowground processes. Our objective was to investigate the link between plant community (diversity and composition) and key belowground processes such as root biomass production and CH4 dynamics in wetland ecosystems. We hypothesized that 1) root biomass would increase with functional group diversity due to complementarity and 2) the sediment pool of CH4 would decrease with diversity due to increased CH4 oxidation facilitated by root biomass. Four plant functional groups (facultative annuals, obligate annuals, reeds and tussocks) were planted in controlled mesocosms to represent five levels of functional diversity and every combination of functional groups at each diversity level. Unplanted mesocosms served as the zero diversity treatment. At peak biomass in 2007, porewater samplers were used to extract water at 5, 15, and 25 cm. The samples were frozen prior to headspace analysis of CH4 and CO2. Porewater was also analyzed for DOC. Afterward, we took soil cores from each mesocosm at 0-10 cm, 10-20 cm and 20-30 cm to determine the root biomass in each depth.

Results/Conclusions

Root biomass increased with functional diversity (F 3, 71 = 2.78, P < 0.05), however only the lowest diversity treatment had significantly lower root biomass than the highest diversity level; 150.6 ± 24.94 (SE) g DW m-2 and 307.2 ± 49.9 g DW m-2, respectively. At each depth, root biomass increased with diversity (P < 0.01), and root biomass at 0-10 cm >10-20 cm >20-30 cm. The facultative annual and obligate annual functional groups had significantly less root biomass than the other functional groups and combinations (P < 0.001). Porewater concentrations of CH4 did not significantly differ between functional group combinations or diversity levels (P > 0.05). However, CH4 was positively correlated with depth (F 1, 194 =19.75, P < 0.001), CO2 concentration (F 1, 194 = 42.94, P < 0.001) and DOC (F 1,194 = 4.98, P < 0.001) and was not correlated with root biomass (P > 0.05). Since this data is from the first year of sampling following mesocosm establishment, the insignificant relationship between root biomass and CH4 in the sediment pool may indicate that the microbial processes were influenced more by starting soil conditions than plant-mediated conditions.
Effects of habitat, microsite and seed density on recruitment limitation in native scrubland and scrub undergoing restoration
Authors: Stephens Elizabeth , Quintana-Ascencio Pedro , Beg Maliha
Published: August 2009

Background/Questions/Methods

Recruitment influences population and community dynamics by determining the replacement of older individuals, decreasing population expansion and reducing/excluding a species from a community. There is insufficient information on the relative importance of mechanisms affecting seed availability and how interactions between recruitment limitation, other life history stages and environmental variables affect plant demography. Seed availability is pertinent to restoration projects, in which the establishment of native plant populations is a priority. We hypothesize that seed and seedling dynamics are affected by seed production, predation, and microsite characteristics, which may differ among habitats with different human disturbance. We compared seed production, and will evaluate seed predation and seedling establishment of two opportunistic native herb species (Chamaecrista fasciculata, Balduina angustifolia) in disturbed scrub and native rosemary scrub. We predicted that these species would have higher seed production and seedling establishment in the disturbed scrub, and that seed removal may differ in the two areas due to contrasting suites of animal species. We expect seed density to further influence the extent of animal-mediated seed removal and germination success.

Results/Conclusions

B. angustifolia was found to produce significantly more seed heads in disturbed scrub than in native scrub, while there was no significant difference in C. fasciculata seed pod production between the habitat types. Preliminary evidence indicated that seedling number increases with seed density. However, lower observed germination probabilities compared to expected estimates (binomial probabilities) in locations with > 7 seeds suggested increasing density dependence with seed density for C. fasciculata. Germination for this species was not significantly different between habitats in our precursory trial. Our work suggests that seed dynamics affect population persistence and should be considered during management of Florida scrub.