bluuebunny/crossref_metadata_2025 huggingface dataset:
Preoperative “group and save” in lumbar microdiscectomy: is it necessary?
Authors: Saxena Ankur , Eljamel Sam
Published: September 2011

Object

“Group and save” (type and screen) is commonly requested preoperatively in lumbar microdiscectomy. On average, less than 100 ml of blood is lost during lumbar microdiscectomy, and blood transfusion guidelines and resuscitation practice recommend that no transfusion would be required in almost all healthy patients with less than 750 ml of blood loss. The authors performed an audit of 319 consecutive lumbar microdiscectomies to determine if the practice of group and save can be justified. A telephone survey of the United Kingdom (UK) neurosurgical units to establish current UK neurosurgical practice was also conducted.

Methods

A telephone survey of all UK neurosurgical units and an audit of all patients who underwent primary lumbar microdiscectomy at our institution over a period of 2 consecutive years was performed. The health records of all patients were retrieved and critically reviewed. Information about hemoglobin measurements before and after surgery, group and save, and blood transfusion were collected.

Results

Thirty-two UK neurosurgical units were surveyed by telephone, with a 100% response rate. Group and save was commonly performed prior to lumbar microdiscectomy in 28 units (87.5%). The records of 319 consecutive patients who underwent lumber microdiscectomy were reviewed. All patients had group and save prior to lumbar microdiscectomy. No patient required a blood transfusion during or after surgery. The mean decrease in hemoglobin concentration was 0.8 g/dl in 121 patients who had postoperative hemoglobin measurements.

Conclusions

Blood transfusion and hemoglobin decrease following lumbar microdiscectomy is exceptionally rare. Group and save and postoperative hemoglobin measurements are therefore nonessential in all patients undergoing lumbar microdiscectomy, with potentially significant cost savings from not performing these tests.
Rapid change of tundra snow hardness in Alaska
Authors: Sugiura Konosuke , Yang Daqing , Ohata Tetsuo
Published: September 2011

Abstarct

To understand the formation of hard snow in the field and its relationship to the physical parameters of snow surfaces, we carried out snowpack observations at a flat and snow-covered field in Barrow, Alaska. These observations were performed in the middle of winter and included two drifting snow events. After the end of each drifting snow event, the minimum snow surface density increased slightly with time and there was a rapid increase in the minimum snow surface hardness. There was no rain during our observations. Therefore, the strong bonds among the snow surface particles were not due to melting and refreezing; they formed because of hardening during water-vapor transport under a temperature gradient and also by exposure of the inner snow layer through erosion. As a consequence, the snow formed a hard surface following the drifting snow events.
Initial results of the SeaRISE numerical experiments with the models SICOPOLIS and IcIES for the Greenland ice sheet
Authors: Greve Ralf , Saito Fuyuki , Abe-Ouchi Ayako
Published: September 2011

Abstarct

SeaRISE (Sea-level Response to Ice Sheet Evolution) is a US-led multi-model community effort to predict the likely range of the contribution of the Greenland and Antarctic ice sheets to sea-level rise over the next few hundred years under global warming conditions. The Japanese ice-sheet modelling community is contributing to SeaRISE with two large-scale, dynamic/thermodynamic models: SICOPOLIS and IcIES. Here we discuss results for the Greenland ice sheet, obtained using both models under the forcings (surface temperature and precipitation scenarios) defined by the SeaRISE effort. A crucial point for meaningful simulations into the future is to obtain initial conditions that are close to the observed state of the present-day ice sheet. This is achieved by proper tuning during model spin-up from the last glacial/interglacial cycle to today. Experiments over 500 years indicate that both models are more sensitive (exhibit a larger rate of ice-sheet mass loss) to future climate warming (based on the A1B emission scenario) than to a doubling in the basal sliding speed. Ice-sheet mass loss varies between the two models by a factor of ~2 for sliding experiments and a factor of ~3 for climate-warming experiments, highlighting the importance of improved constraints on the parameterization of basal sliding and surface mass balance in ice-sheet models.
Wet-snow instabilities: comparison of measured and modelled liquid water content and snow stratigraphy
Authors: Mitterer Christoph , Hirashima Hiroyuki , Schweizer Jürg
Published: September 2011

Abstarct

Wet-snow avalanches are difficult to forecast, as the change from stable to unstable snow conditions occurs rapidly in a wet snowpack, often in response to water production and movement. Snow stratigraphy plays a vital role in determining flux behaviour. Capillary barriers or melt–freeze crusts can impede and divert water horizontally over large areas and thus may act as a failure layer for wet-snow avalanches. We present a comparison of measured and modelled liquid water content, θw, and snow stratigraphy during periods of wet-snow instabilities. Special attention is given to the reproducibility of capillary barriers, ponding of water on melt–freeze crusts and the timing of first wetting and of water arrival at the bottom of the snowpack, because these factors are believed to play a major role in the formation of wet-snow avalanches. In situ measurements were performed in the vicinity of automatic weather stations or close to recent wet-snow avalanches in order to compare them with model results. The simulations are based on two different water flux models incorporated within the 1-D snow-cover model SNOWPACK. The comparison of the two model runs with observed θw and stratigraphy revealed that both water-transport models reproduced the ponding of water on melt–freeze crusts. However, in both models melt–freeze crusts were transformed to normal melt forms earlier than observed in nature, so still existing ponding was not captured by the models. Only one of the models was able to reproduce capillary barriers in agreement with observations. The time of the first wetting at the surface was well predicted, but the simulated arrival time of the wetting front at the bottom of the snowpack differed between the simulations; it was either too early or too late compared with the observation.
Iceberg-capsize tsunamigenesis
Authors: MacAyeal Douglas R. , Abbot Dorian S. , Sergienko Olga V.
Published: September 2011

Calving from the floating termini of outlet glaciers and ice shelves is just the beginning of an interesting chain of events that can subsequently have important impacts on human life and property. Immediately after calving, many icebergs capsize (roll over by 90°) due to the instability of their initial geometry. As icebergs melt and respond to the cumulative effects of ocean swell, they can also reorient their mass distribution by further capsize and fragmentation. These processes release gravitational potential energy and can produce impulsive large-amplitude surface-gravity waves known as tsunamis (a term derived from the Japanese language). Iceberg-capsize tsunamis in Greenland fjords can be of sufficient amplitude to threaten human life and cause destruction of property in settlements. Iceberg-capsize tsunamis may also have a role in determining why some ice shelves along the Antarctic Peninsula disintegrate ‘explosively’ in response to general environmental warming. To quantify iceberg tsunami hazards we investigate iceberg-capsize energetics, and develop a rule relating tsunami height to iceberg thickness. This rule suggests that the open-water tsunami height (located far from the iceberg and from shorelines where the height can be amplified) has an upper limit of 0.01H where H is the initial vertical dimension of the iceberg.
Records of sea-ice extent and air temperature at the Sea of Okhotsk from an ice core of Mount Ichinsky, Kamchatka
Authors: Matoba Sumito , Shiraiwa Takayuki , Tsushima Akane , Sasaki Hirotaka , Muravyev Yaroslav D.
Published: September 2011

Abstarct

The Sea of Okhotsk is the southernmost area in the Northern Hemisphere where seasonal sea ice is produced every year. The formation of sea ice drives thermohaline circulation in the Sea of Okhotsk, and this circulation supports the high productivity in the region. However, recent reports have indicated that sea-ice production in the Sea of Okhotsk is decreasing, raising concern that the decreased sea ice will affect not only circulation but also biological productivity in the sea. To reconstruct climatic changes in the Sea of Okhotsk region, we analyzed an ice core obtained from Ichinskaya Sopka (Mount Ichinsky), Kamchatka. We assumed that the remarkable negative peaks of δD in the ice core were caused by expansion of sea ice in the Sea of Okhotsk. Melt feature percentage (MFP), which indicates summer snowmelt, showed high values in the 1950–60s and the mid-1990s–2000s. The high MFP in the 1950–60s was assumed to be caused by an increase in cyclone activity reaching Kamchatka during a negative period of the Pacific Decadal Oscillation index, and that in the 1990–2000s may reflect the increase in solar irradiation during a positive period of the summer Arctic Oscillation index.
Estimation of the electrostatic charge of individual blowing-snow particles by wind tunnel experiment
Authors: Omiya Satoshi , Sato Atsushi , Kosugi Kenji , Mochizuki Shigeto
Published: September 2011

Abstarct

There are some reports on the measurement of the charge-to-mass ratio of blowing-snow particles, but there are few studies concerned with individual snow-particle charge. We measured the charge-to-mass ratios using snow particles selected according to size, and discussed individual charges. Experiments were conducted in a cryogenic wind tunnel. Charge-to-mass ratios measured in our experiment were all negative and their absolute values tended to increase with a decrease in particle diameter. Individual snow-particle charges were calculated from the average of particle diameter distributions. The charges were all approximated by the power function of diameter at each temperature. Assuming that the coefficient of these approximations is a function of air temperature, we could easily predict the individual snow-particle charge.
‘Sticky spots’ and subglacial lakes under ice streams of the Siple Coast, Antarctica
Authors: Sergienko Olga V. , Hulbe Christina L.
Published: September 2011

Abstarct

Locations of subglacial lakes discovered under fast-moving West Antarctic ice streams tend to be associated with topographic features of the subglacial bed or with areas that have strong variations in basal conditions. Inversion of ice-stream surface velocity indicates that basal conditions under ice streams can be highly variable and that there can be widespread regions where basal traction is high. To seek an explanation for why lakes appear to be sited near areas with high basal traction, we use numerical models to simulate ice-stream dynamics, thermodynamics and subglacial water flow. We demonstrate that the ice flow over high basal traction areas produces favourable conditions for the ponding of meltwater. Energy dissipation associated with ice sliding over a region with high basal traction constitutes a water source supplying a lake, and ice-thickness perturbations induced by ice flow over variable traction create local minima in hydraulic potential. Variations in thermodynamic processes caused by such ice flow could be responsible for limiting the horizontal extent of the subglacial lakes.
Changes in glacier dynamics under the influence of proglacial lake formation in Rhonegletscher, Switzerland
Authors: Tsutaki Shun , Nishimura Daisuke , Yoshizawa Takeshi , Sugiyama Shin
Published: September 2011

Abstarct

To investigate the impact of proglacial lake formation on the dynamics and evolution of glaciers, we measured the ice motion of the terminal part of Rhonegletscher, Switzerland, where a lake formed in 2005. In 2009, the flow velocity near the terminus was >20 m a−1. One of the survey stakes tripled its velocity between 2006 and 2007. Since the lake water pressure was consistently close to the ice overburden pressure, it is likely that the high subglacial water pressure enhanced the basal ice motion. The estimated flow velocity due to ice shearing was negligibly small; almost 100% of the horizontal velocity near the terminus was caused by basal sliding. The longitudinal strain rate was large, 0.064 a–1, indicating that much of the glacier thinning was due to ice dynamics. The region of ice flotation adjacent to the lake expanded between 2008 and 2009 as a result of glacier thinning. Accordingly, a huge uplift of the surface was observed in 2009. It is clear from the vertical ice motion as well as visual observations that the marginal part of the glacier began to float. The ice-thinning rate in the studied area from 2008 to 2009 was 3.4 ma–1, larger than previous estimates.
Chemical characteristics of the snow pits at Murododaira, Mount Tateyama, Japan
Authors: Watanabe Koichi , Saito Yukiko , Tamura Syoko , Sakai Yuki , Eda Nagisa , Aoki Mikiko , Kawabuchi Manami , Yamada Hirotsugu , Iwai Ayumi , Kawada Kunio
Published: September 2011

Abstarct

Measurements of the chemical composition of the snow pits at Murododaira (2450m a.s.l.), Mount Tateyama, near the coast of the Japan Sea in central Japan, were performed each spring from 2005 through 2008. The mean concentrations of nssSO42– and NO3– are higher than those in snowpack in the 1990s. The pH and nssCa2+ were usually high in the upper parts of 2–3m of snow deposited in the spring, when Asian dust (Kosa) particles are frequently transported. High concentrations of nssSO42– were detected in both the spring and winter layers. The high-nssCa2+ layers usually contained high concentrations of nssSO42–. The results show that not only Kosa particles but also air pollutants might have been transported long-range from the continent of Asia. The concentrations of peroxides were high in the new snow (precipitation particles) and granular snow (coarse grain, melt forms) layers. The peroxide concentrations in the snow layers were negatively correlated with the nssCa2+ concentrations. High peroxide concentrations may be preserved in granular snow layers having low concentrations of nssCa2+.
Geodetic mass balance of Azarova glacier, Kodar mountains, eastern Siberia, and its links to observed and projected climatic change
Authors: Shahgedanova M. , Popovnin V. , Aleynikov A. , Stokes C.R.
Published: September 2011

Abstarct

The Kodar mountains in eastern Siberia accommodate 30 small, cold-based glaciers with a combined surface area previously estimated at ~19 km2. Very little is known about these glaciers, which were first surveyed in the late 1950s. In this paper, we use terrestrial photogrammetry to calculate changes in the surface area, elevation, volume and geodetic mass balance of Azarova glacier between 1979 and 2007 and relate these to meteorological data from nearby Chara weather station (1938–2007). The glacier surface area declined by 20±6.9% and the surface lowered by an average of 20±1.8m (mean thinning 0.71 ma–1), resulting in a strongly negative cumulative and average mass balance of –18±1.6mw.e. and –640±60mm w.e. a–1, respectively. The July–August air temperature increased at a rate of 0.036˚Ca–1 between 1979 and 2007, and the 1980–2007 period was on average ~1˚C warmer than 1938–79. In comparison to the 1961–90 period, regional climate projections for the A2 and B2 CO2 emission scenarios developed using the PRECIS regional climate model indicate that summer temperatures will increase by 2.6–4.7˚C and 4.9–6.2˚C, respectively, during the 2071–2100 period. The annual total of solid precipitation will increase by 20% under the B2 scenario but is projected to decline by 3% under the A2 scenario. Azarova glacier exhibits high sensitivity to climatic warming due to its low elevation and exposure to comparatively high summer temperatures. Further summer warming and a decline in solid precipitation projected under the A2 scenario will force Azarova glacier to retreat further, but the impact of an increase in solid precipitation projected under the B2 scenario is more uncertain and requires further investigation before a more conclusive prediction can be made.
Glaciers, snow and ski tourism in Austria’s changing climate
Authors: Fischer Andrea , Olefs Marc , Abermann Jakob
Published: September 2011

Abstarct

This study illustrates the relevance of cryospheric changes for, and their impact on, ski tourism in Austria. The results of several case studies on snow reliability, snow production and mass balance in glacier ski resorts in the Ötz and Stubai valleys are summarized. Climate data from Obergurgl (1936ma.s.l.) in the Ötz valley are analyzed with respect to the amount and duration of natural snow cover and the possibility of snow production. A case study on Mittelbergferner focuses on the impacts of glacial recession on a ski resort and possible adaptation measures. From long-term glacier inventory and short-term mass-balance data, the effect of operating ski resorts on glaciers is investigated. At Obergurgl, the probability of both snow cover and snow production is >80% from December to March and decreases significantly in the months before and after this peak season. The interannual variability of snow cover and production is low during the main season and higher in other months. Year-to-year differences are larger than any long-term trend. Glacier ski resorts must adapt to shrinking glacial area and falling glacier surface. Covering the glacier with textiles reduces ablation by 60% and results in significantly less volume loss than on uncovered parts of the glacier. Neither the mass-balance comparison between groomed and ungroomed areas nor the comparison of long-term volume changes between 10 ski resort glaciers and 100 surrounding glaciers showed evidence for an impact of the operation of ski resorts on the glaciers.
Variations of glacial lakes and glaciers in the Boshula mountain range, southeast Tibet, from the 1970s to 2009
Authors: Wang Weicai , Yao Tandong , Yang Xiaoxin
Published: September 2011

Abstarct

Catastrophic floods originating from glacial lake outbursts have recently become one of the primary natural hazards in the southeastern Tibetan Plateau. Here we report observations of glacial lake expansions and glacier recessions in the Boshula mountain range, southeast Tibet, derived from multitemporal remote-sensing images and digital elevation models during the period from the 1970s to 2009. The area of glacial lakes has expanded from 10.96 ± 0.1 km2 in the 1970s to 10.96±0.1km2 in 2009. Specifically, the area of moraine-dammed lakes has increased by 26.8%. From the 1970s to 2009, the glacierized area in the Boshula mountain range shrank by 12.7% (21.2 km2). Increasing mean summer air temperature was the main cause for the glacier recession and lake expansion from the 1970s to 2001, while the combination of increased summer temperature and decreased summer precipitation led to accelerated glacier recession after 2001. Climate warming and ongoing deglaciation play important roles in the expansion of moraine-dammed lakes, calling for intensified monitoring to properly address the hazard potential in the study area.
Present weather-sensor tests for measuring drifting snow
Authors: Bellot Hervé , Trouvilliez Alexandre , Naaim-Bouvet Florence , Genthon Christophe , Gallée Hubert
Published: September 2011

Abstarct

In Antarctica, blowing snow accounts for a major component of the surface mass balance near the coast. Measurements of precipitation and blowing snow are scarce, and therefore collected data would allow testing of numerical models of mass flux over this region. A present weather station (PWS), Biral VPF730, was set up on the coast at Cap Prud’homme station, 5 km from Dumont d’Urville (DDU), principally to quantify precipitation. Since we expected to be able to determine blowing-snow fluxes from the PWS data, we tested this device first on our experimental site, the Lac Blanc pass. An empirical calibration was made with a snow particle counter. Although the physics of the phenomenon was not well captured, the flux outputs were better than those from FlowCapts. The first data from Antarctica were reanalyzed. The new calibration seems to be accurate for estimating the high blowing-snow flux with an interrogation of the precipitation effects.
Seasonal variations of snow chemistry at NEEM, Greenland
Authors: Kuramoto Takayuki , Goto-Azuma Kumiko , Hirabayashi Motohiro , Miyake Takayuki , Motoyama Hideaki , Dahl-Jensen Dorthe , Steffensen Jørgen Peder
Published: September 2011

Abstarct

We conducted a pit study in July 2009 at the NEEM (North Greenland Eemian Ice Drilling) deep ice-coring site in northwest Greenland. To examine the seasonal variations of snow chemistry and characteristics of the drill site, we collected snow/firn samples from the wall of a 2 m deep pit at intervals of 0.03 m and analyzed them for electric conductivity, pH, Cl–, NO3–, SO42–, CH3SO3– (MSA), Na+, K+, Mg2+, Ca2+ and stable isotopes of water (δ18O and δD). Pronounced seasonal variations in the stable isotopes of water were observed, which indicated that the snow had accumulated regularly during the past 4 years. Concentrations of Na+, Cl– and Mg2+, which largely originate from sea salt, peaked in winter to early spring, while Ca2+, which mainly originates from mineral dust, peaked in late winter to spring, slightly later than Na+, Cl– and Mg2+. Concentrations of NO3– showed double peaks, one in summer and the other in winter to spring, whereas those of SO42– peaked in winter to spring. The winter-to-spring concentrations of NO3– and SO42– seem to have been strongly influenced by anthropogenic inputs. Concentrations of MSA showed double peaks, one in spring and the other in late summer to autumn. Our study confirms that the NEEM deep ice core can be absolutely dated to a certain depth by counting annual layers, using the seasonal variations of stable isotopes of water and those of ions. We calculated the annual surface mass balance for the years 2006–08. The mean annual balance was 176 mm w.e., and the balances for winter-to-summer and summer-to-winter halves of the year were 98 and 78 mm, respectively. Snow deposition during the winter-to-summer half of the year was greater than that during the summer-to-winter half by 10–20mm for all three years covered by this study.
Massacre by the Book: Amritsar and the Rules of Public-Order Policing in Britain and India
Authors: Doyle Mark
Published: September 2011

In the immediate aftermath of the 1919 killings at Amritsar, where British forces commanded by Reginald Dyer gunned down hundreds of unarmed Indians at an illegal demonstration, debate centered on whether Dyer's actions were typical or atypical of British behavior in India. While British commentators generally regarded this violence as aberrant and ‘un-British,’ Indian nationalists and some British observers saw the killings as merely an unusually naked manifestation of the generalized violence of British imperialism. This article offers a re-examination of the Amritsar killings by placing Dyer's behaviour within the context of the rules governing public-order policing in both India and Britain. While broadly agreeing that the killings were part of a pattern of state violence in British India, it argues that the killings were not carried out in opposition to the rule of law but were, in fact, authorized by the law. In both Britain and India, the rules of public-order policing gave police and military commanders the power to use deadly force in dispersing crowds and by remaining deliberately vague about when such force should be used. The restraint of state violence in Britain came about through the vigilance of the press and Parliament, but in India state violence against large crowds was much more common due to fewer external checks. The killings at Amritsar did not violate the rule of law, therefore, but they did expose a profound difference between Britain and India in how that law was enacted.
On Various Ways of Measuring Pro-Poor Growth
Authors: Deutsch Joseph , Silber Jacques
Published: September 2011

This paper examines three possible approaches to pro-poor growth. The first one assumes that the poverty line remains constant in real terms over time. The second perspective examines the case where the poverty line is equal to half the median of the income distribution but assumes that such a poverty line is determined exogenously. Finally we also propose a third type of decomposition of the change in poverty, one which is obtained when the poverty line is assumed to be endogenous.

In addition, whatever the assumption made concerning the poverty line, we take both a relative and an absolute approach to inequality measurement when defining pro-poor growth. With a relative approach to pro-poor growth it is assumed that inequality does not to vary when all incomes are multiplied by a constant whereas, with an absolute approach to pro-poor growth, inequality is supposed not to vary when an equal sum is added to all incomes. The empirical illustration covers the period 1990–2006 in Israel and the analysis is based on the use of the FGT poverty index. It turns out that the assumptions made concerning the way the poverty line is defined and the choice between a relative and an absolute approach to pro-poor growth greatly affect the results. As a whole however growth was pro-rich in Israel during the 1990–2006 period.
Microphysical simulations of new particle formation in the upper troposphere and lower stratosphere
Authors: English J. M. , Toon O. B. , Mills M. J. , Yu F.
Published: September 2011

Abstract. Using a three-dimensional general circulation model with sulfur chemistry and sectional aerosol microphysics (WACCM/CARMA), we studied aerosol formation and microphysics in the upper troposphere and lower stratosphere (UTLS) as well as the middle and upper stratosphere based on three nucleation schemes (two binary homogeneous schemes and an ion-mediated scheme related to one of the binary schemes). Simulations suggest that ion-mediated nucleation rates in the UTLS are 25 % higher than its related binary scheme, but that the rates predicted by the two binary schemes vary by two orders of magnitude. None of the nucleation schemes is superior at matching the limited observations available at the smallest sizes. However, it is found that coagulation, not nucleation, controls number concentration at sizes greater than approximately 10 nm. Therefore, based on this study, processes relevant to atmospheric chemistry and radiative forcing in the UTLS are not sensitive to the choice of nucleation schemes. The dominance of coagulation over other microphysical processes in the UTLS is consistent with other recent work using microphysical models. Simulations using all three nucleation schemes compare reasonably well to observations of size distributions, number concentration across latitude, and vertical profiles of particle mixing ratio in the UTLS. Interestingly, we find that we need to include Van der Waals forces in our coagulation scheme to match the UTLS aerosol concentrations. We conclude that this model can reasonably represent sulfate microphysical processes in the UTLS, and that the properties of particles at atmospherically relevant sizes appear to be insensitive to the details of the nucleation scheme. We also suggest that micrometeorites, which are not included in this model, dominate the aerosol properties in the upper stratosphere above about 30 km.
Acid-yield measurements of the gas-phase ozonolysis of ethene as a function of humidity using Chemical Ionisation Mass Spectrometry (CIMS)
Authors: Leather K. E. , McGillen M. R. , Cooke M. C. , Utembe S. R. , Archibald A. T. , Jenkin M. E. , Derwent R. G. , Shallcross D. E. , Percival C. J.
Published: September 2011

Abstract. Gas-phase ethene ozonolysis experiments were conducted at room temperature to determine formic acid yields as a function of relative humidity (RH) using the integrated EXTreme RAnge chamber-Chemical Ionisation Mass Spectrometry technique, employing a CH3I ionisation scheme. RHs studied were <1, 11, 21, 27, 30 % and formic acid yields of (0.07 ± 0.01) and (0.41 ± 0.07) were determined at <1 % RH and 30 % RH respectively, showing a strong water dependence. It has been possible to estimate the ratio of the rate coefficient for the reaction of the Criegee biradical, CH2OO with water compared with decomposition. This analysis suggests that the rate of reaction with water ranges between 1 × 10−12–1 × 10−15 cm3 molecule−1 s−1 and will therefore dominate its loss with respect to bimolecular processes in the atmosphere. Global model integrations suggest that this reaction between CH2OO with water may dominate the production of HC(O)OH in the atmosphere.
Atmospheric Cluster Dynamics Code: a flexible method for solution of the birth-death equations
Authors: McGrath M. J. , Olenius T. , Ortega I. K. , Loukonen V. , Paasonen P. , Kurtén T. , Kulmala M. , Vehkamäki H.
Published: September 2011

Abstract. The Atmospheric Cluster Dynamics Code (ACDC) is presented and explored. This program was created to study the first steps of atmospheric new particle formation by examining the formation of molecular clusters from atmospherically relevant molecules. The program models the cluster kinetics by explicit solution of the birth–death equations, using an efficient computer script for their generation and the MATLAB ode15s routine for their solution. Through the use of evaporation rate coefficients derived from formation free energies calculated by quantum chemical methods for clusters containing dimethylamine or ammonia and sulphuric acid, we have explored the effect of changing various parameters at atmospherically relevant monomer concentrations. We have included in our model clusters with 0–4 base molecules and 0–4 sulfuric acid molecules for which we have commensurable quantum chemical data. The tests demonstrate that large effects can be seen for even small changes in different parameters, due to the non-linearity of the system. In particular, the temperature and sticking probabilities both have a large impact on all clusters, while the boundary effects (allowing clusters to grow to sizes beyond the largest cluster that the code keeps track of, or forbidding such processes), coagulation sink terms, non-monomer collisions, and monomer concentrations can all have significant effects. Removal of coagulation sink terms prevented the system from reaching the steady state when all the initial cluster concentrations were set to the default value of 1 m−3, which is probably an effect caused by studying only relatively small cluster sizes.
Determination of field scale ammonia emissions for common slurry spreading practice with two independent methods
Authors: Sintermann J. , Ammann C. , Kuhn U. , Spirig C. , Hirschberger R. , Gärtner A. , Neftel A.
Published: September 2011

Abstract. At a cropland and a grassland site field scale ammonia (NH3) emissions from slurry application were determined simultaneously by two approaches based on (i) eddy covariance (EC) flux measurements using high temperature Chemical Ionisation Mass Spectrometry (HT-CIMS) and on (ii) backward Lagrangian Stochastic (bLS) dispersion modelling using concentration measurements by three optical open path Fourier Transform Infrared (FTIR) systems. Slurry was spread on the fields in sequential tracks over a period of one to two hours. In order to calculate field emissions, measured EC/HT-CIMS fluxes were combined with flux footprint analysis of individual slurry spreading tracks to parameterise the NH3 volatilisation with a bi-exponential time dependence. Accordingly, track-resolved concentration footprints for the FTIR measurements were calculated using bLS. A consistency test with concentrations measured by impingers showed very low systematic deviations for the EC/HT-CIMS results (<8%) but larger deviations for the bLS/FTIR results. For both slurry application events, the period during fertilisation and the subsequent two hours contributed by more than 80% to the total field emissions. Averaged over the two measurement methods, the cumulated emissions of the first day amounted to 17 ± 3% loss of applied total ammoniacal nitrogen over the cropland and 16 ± 3% over the grassland field.
Stand age and tree species affect N2O and CH4 exchange from afforested soils
Authors: Christiansen J. R. , Gundersen P.
Published: September 2011

Abstract. Afforestation of former agricultural land is a means to mitigate anthropogenic greenhouse gas emissions. The objectives of this study were (1) to assess the effect of oak (Quercus robur) and Norway spruce (Picea abies [L.] Karst.) stands of different stand ages (13–17 and 40 years after afforestation, respectively) on N2O and CH4 exchange from the soil under these species and (2) identify the environmental factors responsible for the differences in gas exchange between tree species of different ages. N2O and CH4 fluxes (mean ± SE) were measured for two years at an afforested site. No species difference was documented for N2O emission (oak: 4.2 ± 0.7 μg N2O-N m−2 h−1, spruce: 4.0 ± 1 μg N2O-N m−2 h−1) but the youngest stands (1.9 ± 0.3 μg N2O-N m−2 h−1) emitted significantly less N2O than older stands (6.3 ± 1.2 μg N2O-N m−2 h−1). CH4 exchange did not differ significantly between tree species (oak: −8.9 ± 0.9, spruce: −7.7 ± 1) or stand age (young: −7.3 ± 0.9 μg CH4-C m−2 h−1, old: −9.4 ± 1 μg CH4-C m−2 h−1) but interacted significantly; CH4 oxidation in the soil increased with stand age in oak and decreased with age for soils under Norway spruce. We conclude that the exchange of N2O and CH4 from the forest soil undergoes a quick and significant transition in the first four decades after planting in both oak and Norway spruce. These changes are related to (1) increased soil N availability over time as a result of less demand for N by trees in turn facilitating higher N2O production in older stands and (2) decreasing bulk density and increased gas diffusivity in the top soil over time facilitating better exchange of N2O and CH4 with the atmosphere.
Effects of climate variability and functional changes on the interannual variation of the carbon balance in a temperate deciduous forest
Authors: Wu J. , van der Linden L. , Lasslop G. , Carvalhais N. , Pilegaard K. , Beier C. , Ibrom A.
Published: September 2011

Abstract. The net ecosystem exchange of CO2 (NEE) between the atmosphere and a beech forest (Sorø, Denmark) showed significant interannual variation (IAV) over 13 years (1997–2009) of observations. The forest sequestered, on average, 157 g C m−2 yr−1, ranging from a source of 32 to a sink of 344 g C m−2 yr−1 in 1998 and 2008, respectively. The objectives of this study were to evaluate to what extent and at which temporal scale, climatic variability (through direct response) and changes in ecosystem functional properties (through biotic response) regulated the IAV in the ecosystem carbon balance. To address this question, we performed correlation analysis between the carbon fluxes and climate variables at different time scales. The response of CO2 exchange to climatic variability was significantly higher at short time scales and the limiting factors changed intra-annually. Combinations of climate anomalies in different periods of the year either intensified or attenuated the aggregated ecosystem responses, implying that the changing distribution of climate anomalies, in addition to the average climate change, could have stronger impacts on the ecosystem carbon balance in the future. A semi empirical model was used to estimate a set of parameter time series for each of the 13 years, which was considered to represent the functional properties of the ecosystem. The climate and parameter time series were applied factorially by year to quantify their relative importance for the IAV in carbon flux. At an annual time scale, as much as 77 % of the IAV in NEE could be attributed to the variation in both photosynthesis and respiration related model parameters, indicating a strong influence of functional change. The possible causes for the observed functional change could not be addressed with the available dataset. This demonstrates the need for more targeted experiments, such as long-term measurements of leaf nitrogen content. Our approach incorporated seasonal variation in the ecosystem status and demonstrated a significant role of biotic factors on the carbon dynamics in a typical temperate deciduous forest. The method can be applied at other sites to explore ecosystem behaviour across different plant functional types and climate gradients. Further, this approach showed how important it is to incorporate functional change in process based models, which could guide model development and consequently reduce the uncertainties in long-term projection of global ecosystem carbon balance.
The Atmosphere-Ocean General Circulation Model EMAC-MPIOM
Authors: Pozzer A. , Jöckel P. , Kern B. , Haak H.
Published: September 2011

Abstract. The ECHAM/MESSy Atmospheric Chemistry (EMAC) model is coupled to the ocean general circulation model MPIOM using the Modular Earth Submodel System (MESSy) interface. MPIOM is operated as a MESSy submodel, thus the need of an external coupler is avoided. The coupling method is tested for different model configurations, proving to be very flexible in terms of parallel decomposition and very well load balanced. The run-time performance analysis and the simulation results are compared to those of the COSMOS (Community earth System MOdelS) climate model, using the same configurations for the atmosphere and the ocean in both model systems. It is shown that our coupling method shows a comparable run-time performance to the coupling based on the OASIS (Ocean Atmosphere Sea Ice Soil, version 3) coupler. The standard (CMIP3) climate model simulations performed with EMAC-MPIOM show that the results are comparable to those of other Atmosphere-Ocean General Circulation models.
Sediment transport modelling in a distributed physically based hydrological catchment model
Authors: Konz M. , Chiari M. , Rimkus S. , Turowski J. M. , Molnar P. , Rickenmann D. , Burlando P.
Published: September 2011

Abstract. Bedload sediment transport and erosion processes in channels are important components of water induced natural hazards in alpine environments. A raster based distributed hydrological model, TOPKAPI, has been further developed to support continuous simulations of river bed erosion and deposition processes. The hydrological model simulates all relevant components of the water cycle and non-linear reservoir methods are applied for water fluxes in the soil, on the ground surface and in the channel. The sediment transport simulations are performed on a sub-grid level, which allows for a better discretization of the channel geometry, whereas water fluxes are calculated on the grid level in order to be CPU efficient. Several transport equations as well as the effects of an armour layer on the transport threshold discharge are considered. Flow resistance due to macro roughness is also considered. The advantage of this approach is the integrated simulation of the entire basin runoff response combined with hillslope-channel coupled erosion and transport simulation. The comparison with the modelling tool SETRAC demonstrates the reliability of the modelling concept. The devised technique is very fast and of comparable accuracy to the more specialised sediment transport model SETRAC.
Wet snow hazard for power lines: a forecast and alert system applied in Italy
Authors: Bonelli P. , Lacavalla M. , Marcacci P. , Mariani G. , Stella G.
Published: September 2011

Abstract. Wet snow icing accretion on power lines is a real problem in Italy, causing failures on high and medium voltage power supplies during the cold season. The phenomenon is a process in which many large and local scale variables contribute in a complex way and not completely understood. A numerical weather forecast can be used to select areas where wet snow accretion has an high probability of occurring, but a specific accretion model must also be used to estimate the load of an ice sleeve and its hazard. All the information must be carefully selected and shown to the electric grid operator in order to warn him promptly. The authors describe a prototype of forecast and alert system, WOLF (Wet snow Overload aLert and Forecast), developed and applied in Italy. The prototype elaborates the output of a numerical weather prediction model, as temperature, precipitation, wind intensity and direction, to determine the areas of potential risk for the power lines. Then an accretion model computes the ice sleeves' load for different conductor diameters. The highest values are selected and displayed on a WEB-GIS application principally devoted to the electric operator, but also to more expert users. Some experimental field campaigns have been conducted to better parameterize the accretion model. Comparisons between real accidents and forecasted icing conditions are presented and discussed.
2009 Influenza Pandemic Impact on Sick Leave Use in the Veterans Health Administration: Framework for a Health Care Provider–Based National Syndromic Surveillance System
Authors: Schult Tamara M. , Awosika Ebi R. , Hodgson Michael J. , Martinello Richard A.
Published: September 2011

Objective:To determine relations between sick leave use and the 2009 novel influenza A (H1N1) influenza pandemic among clinical and nonclinical staff in the Veterans Health Administration (VHA).

Methods:Aggregate sick leave use for all VHA employees was monitored in near-real time during the 2009 H1N1 influenza pandemic and compared with historical data from 2004 to 2008. The ratio of sick leave use between clinical and nonclinical staff was examined. An autoregressive integrated moving average model was used to assess whether the pandemic had a significant effect on sick leave use.

Results:The H1N1 influenza pandemic was associated with a significant effect on sick leave use in the VHA during the second wave of the pandemic. During this wave, the ratio of clinical to nonclinical sick leave use changed; clinical staff began taking more leave than nonclinical staff for 3 successive 2-week pay periods, with ratio measures of 1.004, 1.018, and 1.011, respectively. Using an autoregressive integrated moving average model with a pulse variable representing the pandemic, there was a significant effect on sick leave use. The average hours of sick leave used per full-time equivalent staff member per month increased by 0.3904 hours (P= .003) for clinical staff and 0.3898 hours (P= .01) for nonclinical staff over previous months during the first month of the second pandemic wave.

Conclusions:Work loss associated with a pandemic is an important indicator of disease activity and may be a more sensitive indicator of emerging strains than deaths. Monitoring sick leave use in near real time in a large national health care system may be an important early indicator of pandemic severity with practical implications that should be considered in addition to more traditional measures of influenza epidemic and pandemic severity.

(Disaster Med Public Health Preparedness. 2011;5:S235-S241)
Impact of the Northridge Earthquake on the Mental Health of Veterans: Results From a Panel Study
Authors: Dobalian Aram , Stein Judith A. , Heslin Kevin C. , Riopelle Deborah , Venkatesh Brinda , Lanto Andrew B. , Simon Barbara , Yano Elizabeth M. , Rubenstein Lisa V.
Published: September 2011

Objective:The 1994 earthquake that struck Northridge, California, led to the closure of the Veterans Health Administration Medical Center at Sepulveda. This article examines the earthquake's impact on the mental health of an existing cohort of veterans who had previously used the Sepulveda Veterans Health Administration Medical Center.

Methods:From 1 to 3 months after the disaster, trained interviewers made repeated attempts to contact participants by telephone to administer a repeated measures follow-up design survey based on a survey that had been done preearthquake. Postearthquake data were obtained on 1144 of 1800 (64%) male veterans for whom there were previous data. We tested a predictive latent variable path model of the relations between sociodemographic characteristics, predisaster physical and emotional health measures, and postdisaster emotional health and perceived earthquake impact.

Results:Perceived earthquake impact was predicted by predisaster emotional distress, functional limitations, and number of health conditions. Postdisaster emotional distress was predicted by preexisting emotional distress and earthquake impact. The regression coefficient from earthquake impact to postearthquake emotional distress was larger than that of the stability coefficient from preearthquake emotional distress. Postearthquake emotional distress also was affected indirectly by preearthquake emotional distress, health conditions, younger age, and lower socioeconomic status.

Conclusions:The postdisaster emotional health of veterans who experienced greater earthquake impact would have likely benefited from postdisaster intervention, regardless of their predisaster emotional health. Younger veterans and veterans with generally poor physical and emotional health were more vulnerable to greater postearthquake emotional distress. Veterans of lower socioeconomic status were disproportionately likely to experience more effects of the disaster because they had more predisaster emotional distress, more functional limitations, and a greater number of health conditions. Because many veterans use non–Department of Veterans Affairs (VA) health care providers for at least some of their health needs, future disaster planning for both VA and non-VA providers should incorporate interventions targeted at these groups.

(Disaster Med Public Health Preparedness. 2011;5:S220-S226)
Changes in hand bone mineral density and the association with the level of disease activity in patients with rheumatoid arthritis: Bone mineral density measurements in a multicenter randomized clinical trial
Authors: Dirven L. , Güler‐Yüksel M. , de Beus W. M. , Ronday H. K. , Speyer I. , Huizinga T. W. J. , Dijkmans B. A. C. , Allaart C. F. , Lems W. F.
Published: September 2011

Objective

To determine if metacarpal bone mineral density (mBMD) gain occurs in patients with rheumatoid arthritis (RA). If mBMD loss is driven by inflammation, we expect to find mBMD gain in patients who are in remission.

Methods

mBMD was measured by digital x‐ray radiogrammetry in consecutive radiographs of 145 patients with RA with either continuous high disease activity (HDA; Disease Activity Score [DAS] >2.4), low disease activity (LDA; 1.6 ≥ DAS ≤ 2.4), or continuous clinical remission (CR; DAS <1.6) during a 1‐year observation period. The association of mBMD changes with disease activity was investigated with multinomial regression analysis. Next, clinical variables associated with mBMD gain were identified.

Results

Mean change in mBMD in CR patients was −0.03%, compared to −3.13% and −2.03% in HDA and LDA patients, respectively (overall, P < 0.001). Of the patients in CR, 32% had mBMD loss (less than or equal to −4.6 mg/cm2/year), compared to 62% and 66% of the patients with HDA or LDA, respectively, whereas 26% of the patients in CR had mBMD gain (≥4.6 mg/cm2/year), compared to 2% of the patients with HDA and 5% of the patients with LDA. Patients in CR had a higher chance of having mBMD gain, compared with LDA and HDA (relative risk [RR] 14.9, 95% confidence interval [95% CI] 3.0–18.7 and RR 4.7, 95% CI 1.2–6.3, respectively). CR, hormone replacement therapy, and lower age were significant independent predictors of mBMD gain.

Conclusion

In RA, mBMD gain occurs primarily in patients in continuous (≥1 year) CR and rarely in patients with continuous HDA or LDA. This suggests that mBMD loss is driven by inflammation.