bluuebunny/crossref_metadata_2025 huggingface dataset:
Randomized Clinical Trial of Laparoscopic Versus Open Repair of the Perforated Peptic Ulcer: The LAMA Trial
Authors: Bertleff Mariëtta J. O. E. , Halm Jens A. , Bemelman Willem A. , van der Ham Arie C. , van der Harst Erwin , Oei Hok I. , Smulders J. F. , Steyerberg E. W. , Lange Johan F.
Published: May 2009

Background

Laparoscopic surgery has become popular during the last decade, mainly because it is associated with fewer postoperative complications than the conventional open approach. It remains unclear, however, if this benefit is observed after laparoscopic correction of perforated peptic ulcer (PPU). The goal of the present study was to evaluate whether laparoscopic closure of a PPU is as safe as conventional open correction.

Methods

The study was based on a randomized controlled trial in which nine medical centers from the Netherlands participated. A total of 109 patients with symptoms of PPU and evidence of air under the diaphragm were scheduled to receive a PPU repair. After exclusion of 8 patients during the operation, outcomes were analyzed for laparotomy (n = 49) and for the laparoscopic procedure (n = 52).

Results

Operating time in the laparoscopy group was significantly longer than in the open group (75 min versus 50 min). Differences regarding postoperative dosage of opiates and the visual analog scale (VAS) for pain scoring system were in favor of the laparoscopic procedure. The VAS score on postoperative days 1, 3, and 7 was significant lower (P < 0.05) in the laparoscopic group. Complications were equally distributed. Hospital stay was also comparable: 6.5 days in the laparoscopic group versus 8.0 days in the open group (P = 0.235).

Conclusions

Laparoscopic repair of PPU is a safe procedure compared with open repair. The results considering postoperative pain favor the laparoscopic procedure.
Appraising the Quality of Care in Surgery
Authors: Mayer Erik K. , Chow Andre , Vale Justin A. , Athanasiou Thanos
Published: May 2009

There is currently no validated measurement system available for quality of care assessment in surgery despite all of the inherent benefits of such an approach. A structured quality framework needs to be developed and incorporate measures that are truly reflective of several important dimensions of care within the entire treatment episode. Presently this has been only partially addressed. These measures of quality can be categorized into clinical pathway measures (structure of care, process of care, outcome of care, and economic measures of care) and patient‐reported measures (patient‐reported treatment outcomes, health‐related quality of life measures, and patient satisfaction). Combining these measures to create an overall composite quality score can be made feasible only if it is supported by the use of robust statistical methodology. It is important to use appropriate display of performance data to facilitate provider engagement in quality improvement initiatives. This article was designed to present such a structured approach of a quality framework, which is required to appraise the quality of care in surgery to enhance future quality improvement programmes.
Secondary Procedures for Elbow Flexion Restoration in Late Obstetric Brachial Plexus Palsy
Authors: Terzis Julia K. , Kokkalis Zinon T.
Published: May 2009

Even though total absence of elbow flexion in obstetric brachial plexus palsy (OBPP) is rare, weakness is a frequent problem. Numerous procedures for elbow flexion restoration in late obstetric brachial plexus palsy have been described. In this study, children with OBPP who underwent secondary reconstruction for elbow flexion restoration were studied. A retrospective review of 15 patients (16 elbows) who underwent 16 pedicled and eight free-muscle transfers for elbow flexion restoration was conducted. The mean follow-up period was 8.4±2.9 years (range, 25 months to 12.2 years). The mean age at operation (elbow surgery) was 5.4±1.9 years. The total arc of elbow motion was the result of the active elbow flexion less the flexion contracture. There was significant improvement in biceps muscle power from an average grading of 2.49±0.80 preoperatively to 3.64±0.46 postoperatively ( p<0.001). Thirteen of 16 elbows (81%) achieved good and excellent results (≥M3+); and three elbows (19%) fair results (M3- or M3). The average arc of motion was significantly improved from 36°±25° preoperatively to 94°± 26° postoperatively ( p<0.001). The preoperative and postoperative average elbow flexion contracture was 10.9°±8.9° and 20°±12.2°, respectively. Pedicled and/or free-muscle transfers can significantly improve elbow flexion in late obstetric brachial plexus palsy. Choice of the procedure should be individualized and determined on the basis of the type of paralysis, availability of donor muscles, previous reconstruction, and experience of the surgeon.
Magnetic and Cytotoxicity Properties of La1−xSr
x
MnO3(0 ≤ x ≤ 0.5) Nanoparticles Prepared by a Simple Thermal Hydro-Decomposition
Authors: Daengsakul Sujittra , Thomas Chunpen , Thomas Ian , Mongkolkachit Charusporn , Siri Sineenat , Amornkitbamrung Vittaya , Maensiri Santi
Published: May 2009

This study reports the magnetic and cytotoxicity properties of magnetic nanoparticles of La1−x
Sr
x
MnO3(LSMO) withx = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 by a simple thermal decomposition method by using acetate salts of La, Sr, and Mn as starting materials in aqueous solution. To obtain the LSMO nanoparticles, thermal decomposition of the precursor was carried out at the temperatures of 600, 700, 800, and 900 °C for 6 h. The synthesized LSMO nanoparticles were characterized by XRD, FT-IR, TEM, and SEM. Structural characterization shows that the prepared particles consist of two phases of LaMnO3(LMO) and LSMO with crystallite sizes ranging from 20 nm to 87 nm. All the prepared samples have a perovskite structure with transformation from cubic to rhombohedral at thermal decomposition temperature higher than 900 °C in LSMO samples ofx ≤ 0.3. Basic magnetic characteristics such as saturated magnetization (M
S) and coercive field (H
C) were evaluated by vibrating sample magnetometry at room temperature (20 °C). The samples show paramagnetic behavior for all the samples withx = 0 or LMO, and a superparamagnetic behavior for the other samples havingM
Svalues of ~20–47 emu/g and theH
Cvalues of ~10–40 Oe, depending on the crystallite size and thermal decomposition temperature. Cytotoxicity of the synthesized LSMO nanoparticles was also evaluated with NIH 3T3 cells and the result shows that the synthesized nanoparticles were not toxic to the cells as determined from cell viability in response to the liquid extract of LSMO nanoparticles.
A gastrin‐releasing peptide receptor antagonist stimulates Neuro2a neuroblastoma cell growth: Prevention by a histone deacetylase inhibitor
Authors: Abujamra Ana Lucia , Almeida Viviane R. , Brunetto Algemir L. , Schwartsmann Gilberto , Roesler Rafael
Published: May 2009

Gastrin‐releasing peptide (GRP) acts as an autocrine growth factor for neuroblastoma and other types of cancer, and its cell‐surface receptor, GRPR, is overexpressed in advanced‐stage human neuroblastoma. GRPR knockdown and GRPR antagonism inhibit the growth of experimental neuroblastoma. Here we show that a GRPR antagonist promotes rather than inhibits the growth of neuroblastoma cells. The GRPR antagonist, RC‐3095, at 0.1 nM inhibited, whereas at 100 nM stimulated proliferation of Neuro2a murine neuroblastoma cells in vitro. The stimulatory effects were prevented by the histone deacetylase inhibitor (HDACi), sodium butyrate (NaB). Expression of GRPR mRNA in Neuro2a cells was analyzed by RT‐PCR. These findings provide evidence that a GRPR antagonist can stimulate the growth of cancer cells, and suggest that GRPR might interact with epigenetic mechanisms in regulating neuroblastoma cell growth.
Simulated microgravity induce glutathione antioxidant pathwayin Xenopus laevis embryos
Authors: Rizzo Angela M. , Montorfano Gigliola , Negroni Manuela , Corsetto Paola , Berselli Patrizia , Marciani Paola , Zava Stefania , Berra Bruno
Published: May 2009

Space flights cause a number of patho‐physiological changes. Oxidative damage has been demonstrated in astronauts after space flights. Oxidative stress is due to an imbalance between production of oxidant and antioxidative defence. In embryos of Xenopus laevis, the glutathione system is an inducible antioxidant defence. For this reason, we investigated the effect of gravity deprivation on endogenous antioxidant enzymes in X. laevis embryos developed for 6 days in a Random Positioning Machine. The results show that glutathione content and the activity of antioxidant enzymes increase in RPM embryos, suggesting the presence of a protective mechanism. An induction of antioxidant defence might play an important role for animals to adapt to micro‐gravitational stress, possibly during actual space flights.
Modifications of erythrocyte membrane hydration induced by organic tin compounds
Authors: Żyłka Romuald , Kleszczyńska Halina , Kupiec Justyna , Bonarska‐Kujawa Dorota , Hladyszowski Jerzy , Przestalski Stanislaw
Published: May 2009

A study on the effects of selected organic chlorides of tin on the extent of hydration of the lipid bilayer of erythrocyte ghosts from pig blood is presented. The following compounds were used, dibutyltin dichloride (DBT), tributyltin chloride (TBT), diphenyltin dichloride (DPhT) and triphenyltin chloride (TPhT). The degree of membrane hydration was measured by the ATR FTIR technique, which makes it possible to estimate the level of carbonyl and phosphate group hydration in lipids of membranes. Other measurements were made with a fluorescence technique involving a laurdan probe. Tin organic compounds caused dehydration of the lipid bilayer of ghosts in the region of the carbonyl groups. DBT and TBT produced weak dehydration in the region of the phosphate group, whereas DPhT and TPhT increased hydration. The results allow one to determine the location of organotin compounds within a membrane, and show that TBT penetrates the membrane the deepest and DBT the shallowest. Phenyl tin compounds penetrate membranes to an intermediate depth. The results obtained indicate that the destructive properties of the organometallic compounds depend mostly on their effect on hydration of the membrane.
P53 negatively regulates the transcriptional activity of FOXO3a under oxidative stress
Authors: Miyaguchi Yasuo , Tsuchiya Keita , Sakamoto Kazuichi
Published: May 2009

Transcription factors P53 and FOXO are both activated in response to stresses via protein–protein interactions, leading to events such as cell survival or apoptosis. To clarify the mechanisms that regulate FOXO activity, we analyzed the intermolecular interaction of FOXO3a and P53. FOXO3a and P53 interacted in COS‐7 cells, and transcriptional activity of FOXO3a was suppressed by P53, but P53 was not affected by FOXO3a. RT–PCR revealed that expression of the endogenous apoptosis‐inducible genes Bim and Bcl6 was decreased markedly by co‐expression of P53 with them, but expression of p27 and CyclinG2 was not. In addition, treatment with 500 μM H2O2 for 30 min to 1 h to mimic oxidative stress promoted protein binding. Serum deprivation and drug treatment also affected the binding of FOXO3a and P53. These findings suggest that FOXO3a controls cellular function by changing its molecular interaction with P53 to mediate transcription factor activity under stress stimuli.
Detection of c‐Abl kinase‐promoted phosphorylation of Rad51 by specific antibodies reveals that Y54 phosphorylation is dependent on that of Y315
Authors: Popova Milena , Shimizu Hiroko , Yamamoto Ken-ichi , Lebechec Mickael , Takahashi Masayuki , Fleury Fabrice
Published: May 2009

MINT‐7034009: cABL (uniprotkb:P00519) physically interacts (MI:0218) with RAD51 (uniprotkb:Q06609) by pull down (MI:0096)
Concordance rates for cognitive impairment among older African American twins
Authors: Whitfield Keith E. , Kiddoe Jared , Gamaldo Alyssa , Andel Ross , Edwards Christopher L.
Published: May 2009

Background

There is significant attention to the growing elderly African American population and estimating who and how many within this population will be affected by cognitive impairment.

Objective

The etiology of cognitive impairment has not been well studied in African Americans and the contribution of genetic and environmental influences to cognitive impairment is not clear.

Methods

We calculated concordance rates and heritability for cognitive impairment in 95 same‐sexed pairs of African American twins from the Carolina African American Twin Study on Aging (CAATSA). The sample had an average age of 59.6 years (SD = 8.6 years, range 50‐88 years) and 60% were female. The Telephone Interview for Cognitive Status (TICS) was used to assess cognitive impairment with a lower cutoff based on our previous research with African Americans.

Results

Thirteen of the monozygotic (MZ) twins (30.2%) and 9 of the dizygotic (DZ) twins (17.3%) were cognitively impaired. The concordance rate was 72% for MZ and 45% for DZ. We found the heritability for cognitive impairment to be 54%.

Conclusions

The study findings indicate that cognitive impairment is highly heritable, suggesting that genetics may play a relatively large role in the development of cognitive impairment in African American twins.
2009 Alzheimer's disease facts and figures
Authors:   Alzheimer's Association
Published: May 2009

Alzheimer's disease (AD) is the sixth leading cause of all deaths in the United States, and the fifth leading cause of death in Americans aged 65 and older. Whereas other major causes of death have been on the decrease, deaths attributable to AD have been rising dramatically. Between 2000 and 2006, heart‐disease deaths decreased nearly 12%, stroke deaths decreased 18%, and prostate cancer‐related deaths decreased 14%, whereas deaths attributable to AD increased 47%. An estimated 5.3 million Americans have AD; the approximately 200,000 persons under age 65 years with AD comprise the younger‐onset AD population. Every 70 seconds, someone in America develops AD; by 2050, this time is expected to decrease to every 33 seconds. Over the coming decades, the “baby‐boom” population is projected to add 10 million people to these numbers. In 2050, the incidence of AD is expected to approach nearly a million people per year, with a total estimated prevalence of 11 to 16 million people. Significant cost implications related to AD and other dementias include an estimated $148 billion annually in direct (Medicare/Medicaid) and indirect (e.g., decreased business productivity) costs. Not included in these figures is the $94 billion in unpaid services to individuals with AD provided annually by an estimated 10 million caregivers. Mild cognitive impairment (MCI) is an important component in the continuum from healthy cognition to dementia. Understanding which individuals with MCI are at highest risk for eventually developing AD is key to our ultimate goal of preventing AD. This report provides information meant to increase an understanding of the public‐health impact of AD, including incidence and prevalence, mortality, lifetime risks, costs, and impact on family caregivers. This report also sets the stage for a better understanding of the relationship between MCI and AD.
Consumer responses to brand elimination: An attributional perspective
Authors: Mao Huifang , Luo Xueming , Jain Shailendra Pratap
Published: May 2009

While research on innovation and new product development abounds in the literature, studies on firms deleting brands from their portfolio are virtually non‐existent. This paper provides a pioneering examination of how brand elimination might influence consumer evaluations of the firm. As compared to a widely‐held belief that brand elimination would adversely affect firm image, we propose that in situations where brand elimination can be viewed as the firm's effort to improve performance, consumers will rate this action favorably, with concomitant outcomes relating to firm evaluation. These ideas are supported in three studies. Study 1 finds that elimination targeting a weak (vs. strong) brand is more likely to be associated with eliminate‐to‐improve attributions, and consequently, more favorable evaluations. Study 2 shows that explanations provided by the firm (as against explanations generated internally by the consumers) help consumers make positive attributions for elimination targeting a strong brand, but lower evaluations when a weak brand is being eliminated. Study 3 establishes that loyal consumers are more likely to assess the applicability of an ‘eliminate‐to‐improve’ attribution and give favorable evaluations only when the eliminated brand is weak. Non‐loyal consumers in general respond favorably to the elimination, regardless of brand strength. Future directions for brand elimination research are discussed.
Blood types in Bengal cats in the UK
Authors: Gunn-Moore Danièlle A. , Simpson Kerry E. , Day Michael J.
Published: May 2009

Blood samples from 100 adult Bengal cats from the UK were submitted for assessment of blood type using RapidVet-H Feline blood typing cards (dms Laboratories), with further assessment by standard blood typing in a microtitre plate assay when card typing was inconclusive or revealed blood type B or AB. Ninety-eight cats were found to be type A when assessed using the blood typing cards. One cat initially tested as type AB but was found to be type A on testing a second blood sample using the blood typing cards. One cat initially tested as type B but was found to be type A when a second sample was tested by standard blood typing assay. Finding that 100% of the cats were blood type A is in contrast with previous studies that reported 10 Bengal cats to be type A, four to be type AB and one to be type B.
A cohort study on anti-filarial IgG4 and its assessment in good and uncertain MDA-compliant subjects in brugian filariasis endemic areas in southern Thailand
Authors: Jiraamonnimit C. , Wongkamchai S. , Boitano J. , Nochot H. , Loymek S. , Chujun S. , Yodmek S.
Published: May 2009

The prevalence ofBrugia malayiwas surveyed in three highly endemic provinces in southern Thailand as part of an ongoing evaluation of the effectiveness of two rounds of mass drug administration (MDA). Prior to MDA IV, and thereafter every 6 months up to 18 months, including MDA V at 12 months, nocturnal blood sampling was assayed for microfilaria (mf) and IgG4 antibodies in 200 subjects from Nakorn Srithammarat and Surathani provinces. From an additional 300 subjects from Narathiwatt province, daytime blood was also examined for IgG4 antibodies for 1 year. Subjects who tested positive, with reciprocal IgG4 titres above 100, were dichotomized in the ‘good compliant’ or ‘uncertain compliant’ groups. Stool samples were examined for intestinal parasites from all 500 subjects simultaneously. Only two subjects (1%) tested positive for mf, while 98 subjects (19.6% of 500) tested positive for IgG4. In general, the good drug-compliant subjects were less likely to exhibit the IgG4 response than subjects in the uncertain compliant group. Only six subjects (1.2%) exhibited lymphoedema while 68 subjects (13.6%) had a total of 105 parasitic infections, with female instances of protozoan infections exceeding male instances of helminth infections. It was concluded that the two MDA rounds were highly successful in not only in reducing mf to negligible levels but also in lowering antifilarial IgG4 titres in the good compliant subjects. The IgG4 assay is a sensitive and cost-effective surveillance tool for the early detection of brugian infections that is not contingent on nocturnal blood collections.
A theory of contracts for strong service compliance
Authors: BRAVETTI MARIO , ZAVATTARO GIANLUIGI
Published: May 2009

We investigate, in a process algebraic setting, a new notion of correctness for service compositions, which we callstrong service compliance: composed services are strong compliant if their composition is both deadlock and livelock free (this is the traditional notion of compliance), and whenever a message can be sent to invoke a service, it is guranteed to be ready to serve the invocation. We also define a new notion of refinement, calledstrong subcontract pre-order, suitable for strong compliance: given a composition of strong compliant services, we can replace any service with any other service in subcontract relation while preserving the overall strong compliance. Finally, we present a characterisation of the strong subcontract pre-order by resorting to the theory of a (should) testing pre-order.
Fast direct solvers for integral equations in complex three-dimensional domains
Authors: Greengard Leslie , Gueyffier Denis , Martinsson Per-Gunnar , Rokhlin Vladimir
Published: May 2009

Methods for the solution of boundary integral equations have changed significantly during the last two decades. This is due, in part, to improvements in computer hardware, but more importantly, to the development of fast algorithms which scale linearly or nearly linearly with the number of degrees of freedom required. These methods are typically iterative, based on coupling fast matrix-vector multiplication routines with conjugate-gradient-type schemes. Here, we discuss methods that are currently under development for the fast, direct solution of boundary integral equations in three dimensions. After reviewing the mathematical foundations of such schemes, we illustrate their performance with some numerical examples, and discuss the potential impact of the overall approach in a variety of settings.
Spatial dynamics of water management in irrigated agriculture
Authors: Muralidharan Daya , Knapp Keith C.
Published: May 2009

Irrigated agriculture provides 40% of worldwide food supplies but uses large amounts of scarce freshwater and contributes to environmental degradation. At the very core of this problem lie decisions made by irrigators subject to biophysical relations. This research develops a microeconomic model of irrigation management taking into account the dynamics of plant growth over the season, spatial variability in infiltration of applied irrigation water, and fundamental principles from subsurface hydrology. The analysis shows that spatial variability in water infiltration common to traditional irrigation systems increases both applied irrigation water and deep percolation flows by very substantial amounts compared to uniform infiltration. The analysis demonstrates that efficient irrigation management can significantly reduce both applied water and deep percolation at relatively low costs, at least up to a certain level. A long‐run analysis of optimal irrigation systems including capital costs indicates that traditional furrow systems are economically efficient over a wide range of water prices and deep percolation costs. Overall, the results indicate that optimal irrigation management can achieve significant resource conservation and pollution control with low loss in agricultural net benefits and without land retirement, investment in capital‐intensive systems, or crop switching.
Patterns inpCO2in boreal streams and rivers of northern Quebec, Canada
Authors: Teodoru Cristian R. , del Giorgio Paul A. , Prairie Yves T. , Camire Martine
Published: May 2009

Here we examine the patterns in carbon dioxide partial pressure (pCO2) measured in a number of small boreal streams (<5 km in length) in the northwestern boreal region of Québec during the ice‐free season and compare these to the patterns found in a major river (Eastmain River) and in a tributary in the same region. All systems were consistently supersaturated in CO2(range 450 to 5000μatm) streams having both higher (mean 1850μatm) and more variablepCO2than that of rivers (range 550 to 800μatm). StreampCO2was positively related to DOC concentration and stream segment length, both suggesting a direct influence of the surrounding landscape. Calculated stream water‐air CO2fluxes ranged from 700 to over 3000 mg C m−2d−1, up to 2 orders of magnitude higher than those measured in large rivers and lakes of the same region. Small streams, despite their extremely reduced areal coverage (1% of the aquatic surface), accounted for 25% of the total aquatic C emissions, and the resulting areal stream fluxes were comparable to those measured in different soils or wetlands in the region.
Peridotites from a ductile shear zone within back‐arc lithospheric mantle, southern Mariana Trench: Results of a Shinkai 6500 dive
Authors: Michibayashi K. , Ohara Y. , Stern R. J. , Fryer P. , Kimura J.‐I. , Tasaka M. , Harigane Y. , Ishii T.
Published: May 2009

Two N–S fault zones in the southern Mariana fore arc record at least 20 km of left‐lateral displacement. We examined the eastward facing slope of one of the fault zones (the West Santa Rosa Bank fault) from 6469 to 5957 m water depth using the submersible Shinkai 6500 (YK06‐12 Dive 973) as part of a cruise by the R/V Yokosuka in 2006. The dive recovered residual but still partly fertile lherzolite, residual lherzolite, and dunite; the samples show mylonitic, porphyroclastic, and coarse, moderately deformed secondary textures. Crystal‐preferred orientations of olivine within the peridotites show a typical [100](010) pattern, with the fabric intensity decreasing from rocks with coarse secondary texture to mylonites. The sampled peridotites therefore represent a ductile shear zone within the lithospheric mantle of the overriding plate. Peridotites were probably exposed in association with a tear in the subducting slab, previously inferred from bathymetry and seismicity. Furthermore, although the dive site is located in the fore arc close to the Mariana Trench, spinel compositions within the sampled peridotites are comparable to those from the Mariana Trough back arc, suggesting that back‐arc basin mantle is exposed along the West Santa Rosa Bank fault.
Measured turbulent heat transfer on the northern slope of Mt. Everest and its relation to the south Asian summer monsoon
Authors: Zou Han , Ma Shupo , Zhou Libo , Li Peng , Li Aiguo
Published: May 2009

To understand the heat exchange processes in the Tibetan mountains, the near surface turbulent heat transfers are analyzed based on the observations in the Rongbuk Valley on the northern slope of Mt. Everest during the HEST2006 campaign from June 1 to 29, 2006. The turbulent heat transfers are directed from the surface to the atmosphere in this valley. The averaged total heat flux is 102.1 W/m2, with a Bowen ratio of 2.17. This heat transfers are closely related to the south Asian summer monsoon (SASM) activities, with a large flux of 129.2 W/m2 during the SASM break period and a small flux of 79.8 W/m2 during the active period. The difference between the heat transfers of the two SASM periods is mainly caused by the enlarged sensible heat transfer in the SASM break period.
Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: Observations
Authors: Panday Arnico K. , Prinn Ronald G.
Published: May 2009

During the dry season of 2004–2005 we carried out field measurements of air pollution and meteorology in the Kathmandu Valley, Nepal, a bowl‐shaped urban basin in the Himalayan foothills of Nepal. We measured the trace gases carbon monoxide (CO) and ozone (O3) and particulates (PM10), as well as meteorological variables. In our field observations we noted a very regular pattern of morning and evening peaks in CO and PM10 occurring daily in the valley bottom, interspersed with low values in the afternoons and at night. This pattern occurred even on days with unusual timing of emissions and was influenced by the timing of ventilation from the valley. Meteorological variables showed great day‐to‐day similarity, with a strong westerly wind blowing through the valley from late morning until dusk. We found that the air mass on nearby mountaintops was disconnected from pollution within the valley during the night, but received significant pollution during the morning, when up‐slope flows began. At a pass on the western edge of the valley we found a diurnal switch in wind direction, with an inflow from late morning until late evening, and an outflow during the rest of the time. We found that part of the morning peak in pollution was caused by recirculation of pollutants emitted the night before, which spend the night in elevated layers over the valley.
Global dimming and brightening versus atmospheric column transparency, Europe, 1906–2007
Authors: Ohvril Hanno , Teral Hilda , Neiman Lennart , Kannel Martin , Uustare Marika , Tee Mati , Russak Viivi , Okulov Oleg , Jõeveer Anne , Kallis Ain , Ohvril Tiiu , Terez Edward I. , Terez Galina A. , Gushchin Gennady K. , Abakumova Galina M. , Gorbarenko Ekaterina V. , Tsvetkov Anatoly V. , Laulainen Nels
Published: May 2009

Multiannual changes in atmospheric column transparency based on measurements of direct solar radiation allow us to assess various tendencies in climatic changes. Variability of the atmospheric integral (broadband) transparency coefficient, calculated according to the Bouguer‐Lambert law and transformed to a solar elevation of 30°, is used for two Russian locations, Pavlovsk and Moscow, one Ukrainian location, Feodosiya, and three Estonian locations, Tartu, Tõravere, and Tiirikoja, covering together a 102‐year period, 1906–2007. The comparison of time series revealed significant parallelism. Multiannual trends demonstrate decrease in transparency during the postwar period until 1983/1984. The trend ends with a steep decline of transparency after a series of four volcanic eruptions of Soufriere (1979), Saint Helens (1980), Alaid (1981), and El Chichón (1982). From 1984/1985 to 1990 the atmosphere remarkably restored its clarity, which almost reached again the level of the 1960s. Following the eruption of Mount Pinatubo (June 1991), there was the most significant reduction in column transparency of the postwar period. However, from the end of 1990s, the atmosphere in all considered locations is characterized with high values of transparency. The clearing of the atmosphere (from 1993) evidently indicates a decrease in the content of aerosol particles and, besides the decline of volcanic activity, may therefore be also traced to environmentally oriented changes in technology (pollution prevention), to general industrial and agricultural decline in the territory of the former USSR and Eastern Europe after deep political changes in 1991, and in part to migration of some industries out of Europe.
Formation of ozone and growth of aerosols in young smoke plumes from biomass burning: 2. Three‐dimensional Eulerian studies
Authors: Alvarado Matthew James , Wang Chien , Prinn Ronald G.
Published: May 2009

Global‐scale models of atmospheric chemistry (GACMs) “mix” biomass burning emissions into grid boxes with horizontal scales of 10–200 km. This ignores the complex nonlinear transformations that take place in the young smoke plumes. Here we use a new gas‐ and aerosol‐phase chemistry model called Aerosol Simulation Program (ASP) and a 3‐D Eulerian smoke plume model to simulate the fluid dynamics, radiative transfer, gas‐phase chemistry, and aerosol‐phase chemistry of the Timbavati smoke plume observed during SAFARI 2000. We then compare the results of the 3‐D plume model with those of an Eulerian box model, which is used as an analog for the large grid boxes of GACMs. The 3‐D plume model matched the observed plume injection height but required a large minimum horizontal diffusion coefficient to match the observed horizontal dispersion of the plume. Absorption and scattering by smoke aerosols reduced the modeled photolysis rates in the plume by 10–20%. Increasing the heterogeneous production of HONO and H2SO4 in the model and including uncharacterized organic species using monoterpenes as a proxy compound improves the model‐observation match. Direct measurements of OH in the smoke plumes would be an excellent way to determine if heterogeneous production of HONO is taking place. The automatic dilution of smoke plume emissions into the large grid boxes of global models can result in large errors in predicted concentrations of O3, NOx and aerosol species downwind. We discuss several potential approaches that could reduce these errors.
Properties of individual aerosol particles and their relation to air mass origins in a south China coastal city
Authors: Shi Zongbo , He Kebin , Xue Zhigang , Yang Fumo , Chen Yanju , Ma Yongliang , Luo Jiaojiao
Published: May 2009

Atmospheric particles in urban and rural areas in Shenzhen city were collected in summer and winter 2004. The particles were analyzed using a scanning electron microscope equipped with an energy dispersive X‐ray spectrometer. The fine particles (<1 μm) were categorized into chain‐like, elongated, rounded, and others on the basis of their morphology. Chain‐like particles were likely soot aggregates. In summer and winter, chain‐like particles accounted for 43% and 42% of total particles in the urban area, and 22% and 43% in the rural area, respectively. The elongated particles were mixtures of aged sea salts and ammonium sulfate, suggesting an aqueous phase reaction mechanism, i.e., in‐cloud sulfate formation. Such particles occupied 12% of total particles in the urban area in the summer and were rarely observed in the wintertime samples. The rounded particles were mainly composed of sulfate and/or carbon. Their number concentration in the urban area was more than three times higher in the winter. In addition, we found that air masses from northern inland contained much higher concentrations of particles than those from the ocean. This was particularly evident in the rural area, where concentrations of chain‐like and rounded particles were eight times higher in the continental air masses. These results suggest the strong influence of regional pollution on the particle number concentrations in the coastal city.
A study on the temporal and spatial variability of absorbing aerosols using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument Aerosol Index data
Authors: Li Jing , Carlson Barbara E. , Lacis Andrew A.
Published: May 2009

Absorbing aerosols, especially mineral dust and black carbon, play key roles in climate change by absorbing solar radiation, heating the atmosphere, and contributing to global warming. In this paper, we first examine the consistency of the Aerosol Index (AI) product as measured by the Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) instruments and then analyze these AI data sets to investigate the temporal and spatial variability of UV absorbing aerosols. In contrast to the trend in aerosol optical depth found in the advanced very high‐resolution radiometer data, no obvious long‐term trend in absorbing aerosols is observed from the time series of AI records. The comparison between the mean annual cycle in the two data sets shows that the cycles agree very well both globally and regionally, indicating a consistency between the AI products from TOMS and OMI. Varimax rotated Empirical Orthogonal Function (EOF) analysis of detrended, deseasonalized AI data proves to be successful in isolating major dust and biomass burning source regions, as well as dust transport. Finally, we find that large, individual events, such as the Kuwait oil fire and Australian smoke plum, are isolated in individual higher‐order principal components.
Preservation of benthic foraminifera and reliability of deep‐sea temperature records: Importance of sedimentation rates, lithology, and the need to examine test wall structure
Authors: Sexton Philip F. , Wilson Paul A.
Published: May 2009

Preservation of planktic foraminiferal calcite has received widespread attention in recent years, but the taphonomy of benthic foraminiferal calcite and its influence on the deep‐sea palaeotemperature record have gone comparatively unreported. Numerical modeling indicates that the carbonate recrystallization histories of deep‐sea sections are dominated by events in their early burial history, meaning that the degree of exchange between sediments and pore fluids during the early postburial phase holds the key to determining the palaeotemperature significance of diagenetic alteration of benthic foraminifera. Postburial sedimentation rate and lithology are likely to be important determinants of the paleoceanographic significance of this sediment–pore fluid interaction. Here we report an investigation of the impact of extreme change in sedimentation rate (a prolonged and widespread Upper Cretaceous hiatus in the North Atlantic Ocean) on the preservation and δ18O of benthic foraminifera of Middle Cretaceous age (nannofossil zone NC10, uppermost Albian/lowermost Cenomanian, ∼99 Ma ago) from multiple drill sites. At sites where this hiatus immediately overlies NC10, benthic foraminifera appear to display at least moderate preservation of the whole test. However, on closer inspection, these tests are shown to be extremely poorly preserved internally and yield δ18O values substantially higher than those from contemporaneous better preserved benthic foraminifera at sites without an immediately overlying hiatus. These high δ18O values are interpreted to indicate alteration close to the seafloor in cooler waters during the Late Cretaceous hiatus. Intersite differences in lithology modulate the diagenetic impact of this extreme change in sedimentation rate. Our results highlight the importance of thorough examination of benthic foraminiferal wall structures and lend support to the view that sedimentation rate and lithology are key factors controlling the paleoceanographic significance of diagenetic alteration of biogenic carbonates.
River stage tomography: A new approach for characterizing groundwater basins
Authors: Yeh Tian‐Chyi J. , Xiang Jianwei , Suribhatla Raghavendra M. , Hsu Kuo‐Chin , Lee Cheng‐Haw , Wen Jet‐Chau
Published: May 2009

Data from tomographic surveys make an inverse problem better posed in comparison to the data from a single excitation source. A tomographic survey provides different coverages and perspectives of subsurface heterogeneity: nonfully redundant information of the subsurface. Fusion of these pieces of information expands and enhances the capability of a conventional survey, provides cross validation of inverse solutions, and constrains inherently ill posed field‐scale inverse problems. Basin‐scale tomography requires energy sources of great strengths. Spatially and temporally varying natural stimuli are ideal energy sources for this purpose. In this study, we explore the possibility of using river stage variations for basin‐scale subsurface tomographic surveys. Specifically, we use numerical models to simulate groundwater level changes in response to temporal and spatial variations of the river stage in a hypothetical groundwater basin. We then exploit the relation between temporal and spatial variations of well hydrographs and river stage to image subsurface heterogeneity of the basin. Results of the numerical exercises are encouraging and provide insights into the proposed river stage tomography. Using naturally recurrent stimuli such as river stage variations for characterizing groundwater basins could be the future of geohydrology. However, it calls for implementation of sensor networks that provide long‐term and spatially distributed monitoring of excitation as well as response signals on the land surface and in the subsurface.
Tsunami early warning using earthquake rupture duration
Authors: Lomax Anthony , Michelini Alberto
Published: May 2009

Effective tsunami early warning for coastlines near a tsunamigenic earthquake requires notification within 5–15 minutes. We have shown recently that tsunamigenic earthquakes have an apparent rupture duration, T0, greater than about 50 s. Here we show that T0 gives more information on tsunami importance than moment magnitude, Mw, and we introduce a procedure using seismograms recorded near an earthquake to rapidly determine if T0 is likely to exceed T = 50 or 100 s. We show that this “duration‐exceedance” procedure can be completed within 3–10 min after the earthquake occurs, depending on station density, and that it correctly identifies most recent earthquakes which produced large or devastating tsunamis. This identification forms a complement to initial estimates of the location, depth and magnitude of an earthquake to improve the reliability of tsunami early warning, and, in some cases, may make possible such warning.
Atmospheric effects on cratering efficiency
Authors: Schultz Peter H.
Published: May 2009

Laboratory experiments permit quantifying the effects of an atmosphere on cratering efficiency by hypervelocity impacts. Three separable processes have been identified: ambient atmospheric pressure, aerodynamic drag, and projectile‐atmosphere interactions. The effect of ambient atmosphere can be described by a dimensionless pressure ratio, P/δv2 for a pressure P, target density δ, and impact velocity. The use of a helium atmosphere minimized potential effects of aerodynamic drag (low density) and projectile‐atmosphere interactions (low mach numbers) and revealed a power‐law exponent of −0.23 for the dimensionless pressure term for impacts into pumice. Similar exponents but different degrees of reduced cratering efficiency are observed for targets composed of loose fine‐grained sand, low‐density microspheres, and mixtures of coarse sand with small amounts (<10%) of fine‐grained particulates. Consequently, cratering efficiency in an atmosphere does not appear to depend on material properties of the target (internal angle of friction) but on atmospheric pressure and constituent grain size. Correcting the data for atmospheric pressure allowed testing for the possible role of aerodynamic drag through the use of higher‐density atmospheres (same pressure) and various targets with contrasting ejecta sizes but the same bulk density. The results reveal that the effect of aerodynamic drag deceleration d can be viewed as a correction to gravity g in the dimensionless gravity‐scaling π2 parameter. The derived power law exponent for drag‐controlled crater growth in an atmosphere closely matched the exponent for gravity‐controlled crater growth in a vacuum. If it is further assumed that a combination of pressure and drag jointly limit crater growth, then the empirical power law exponent reasonably matches values derived from dimensional analysis and a coupling parameter theory. After correcting for pressure and drag, systematic offsets of the data remained and appeared to depend on Mach number. The possible role of the supersonic wake trailing the projectile was tested by performing projectile‐less impacts where only the wake was allowed to interact with the target. The colliding projectile wake was found to affect crater scaling in two ways. At low mach numbers, the trailing wake gases augmented cratering efficiency by creating backpressure in the transient cavity; that is, the effect of the projectile wake was decoupled from the impact and could be viewed as a negative ambient pressure. At high mach numbers, the disturbed wake gas became coupled with the impactor, thereby changing the effective size of the energy source. Both effects could be documented in the data and in observed phenomena during impact. These results not only reconcile previous studies where atmospheric pressure effects were found to be minimal but could have potential implications for interpreting the cratering record on planets with atmospheres.
The ionospheric effects of a weak intrinsic magnetic field at Mars
Authors: Shinagawa H. , Cravens T. E.
Published: May 2009

The existence of an intrinsic magnetic field at Mars has yet to be ascertained despite a number of missions to Mars over the last few decades. It is now widely accepted that the thermal pressure of the Martian ionosphere is not large enough to balance the average solar wind dynamic pressure; therefore the ionosphere must be magnetized, either by a solar wind induced field or by an intrinsic field. Shinagawa and Cravens (1989) demonstrated that the behavior of the Martian ionosphere depends on the strength of the intrinsic field. We have improved our earlier model of the Martian ionosphere by allowing the magnetic field to have any direction in the horizontal plane, and we present results of calculations for several different intrinsic magnetic field strengths and directions. When the solar wind dynamic pressure exceeds the Martian ionospheric thermal pressure, the plasma motion is weakly downward throughout the ionosphere for the case of no intrinsic magnetic field, but when the intrinsic and induced fields are in opposite directions, the plasma flow tends to converge toward the current sheet. As a consequence of this convergence, the plasma density is somewhat enhanced near the current sheet, which is located near an altitude of 170 km. The ionosphere above an altitude of about 190 km is not significantly affected by the existence of an intrinsic field as weak as 60 nT. In order to unambiguously determine the magnitude of an intrinsic field on the dayside of Mars, it will be necessary to make magnetic field measurements below an altitude of 200 km.
Comparisons of peak ionosphere pressures at Mars and Venus with incident solar wind dynamic Pressure
Authors: Zhang M. H. G. , Luhmann J. G.
Published: May 2009

Previous calculations of the potential for pressure balance between the solar wind and the ionospheres of the weakly magnetized planets, Mars and Venus, indicated that the maximum or peak ionospheric thermal pressure is sufficient to stand off the solar wind at Venus but not at Mars. In this study we used radio occultation measurements of electron density profiles from Mariner 6 and 7, the Mariner 9 extended mission, and the U.S. Viking orbiters, together with model ion and electron temperature profiles, to derive thermal pressure profiles in the Mars ionosphere. Similarly, Pioneer Venus Orbiter (PVO) radio occultation data and temperature models were used to obtain ionospheric pressure profiles at Venus. Because the radio occultation data give information for both active and quiet phases of the solar cycle, this method allows one to consider how the balance changes between solar minimum and maximum. The comparison of the Mars peak ionosphere pressures with the incident solar wind dynamic pressure suggests that at solar maximum the Mars ionosphere, like that of Venus, should generally be sufficient to balance the incident solar wind pressure. At solar minimum, when the ionosphere is weakest and the solar wind dynamic pressure is highest, only the peak pressures at high solar zenith angles (SZAs) at Mars appear to be strong enough to balance the incident solar wind pressure. This is similar to the situation at Venus at solar minimum. However, due to the lack of radio occultation data for Mars for SZAs less than 45°, we can only infer what happens near the subsolar point. Nevertheless, our results are somewhat contrary to the frequent assumption that the Mars ionosphere is everywhere and always too weak to withstand the incident solar wind dynamic pressure. When one takes into account the SZA dependence of both the incident solar wind pressure and the peak electron density, and the solar cycle variation of the ionosphere, the situations at Mars and Venus appear to be quite similar. Our previous perceptions for Mars may have been colored by the fact that most of the available Mars ionospheric data are from low or moderate solar activity levels.
Possible magnetic experiments on the surface of Mars
Authors: Nielsen O. V. , Johansson T. , Knudsen J. M. , Primdahl F.
Published: May 2009

It is proposed that important magnetic properties of the surface materials on Mars be measured by a simple instrument comprising a flux gate magnetometer and a magnetizing coil. The paper describes the basic construction principles and demonstrates the instrument's usability on a few materials that are expected to be similar to those on Mars. Very small traces of ferromagnetic materials can be detected by the measuring technique. In addition to materials studies, the instrument is suitable for magnetospheric, paleomagnetic, and magnetotelluric sounding measurements.