bluuebunny/crossref_metadata_2025 huggingface dataset:
Body Mass Index and Mortality Risk in Asian Peritoneal Dialysis Patients in Hong Kong—Impact of Diabetes and Cardiovascular Disease Status
Authors: Kiran Verukonda Ravi , Zhu Tong Ying , Yip Terence , Lui Sing Leung , Lo Wai Kei
Published: February 2014

Background

Obesity increases mortality in the general population, but improves survival in hemodialysis patients. In peritoneal dialysis (PD) patients, the reported effect is controversial. We investigated the effect of body mass index (BMI) on patient survival in Asian PD patients.

Methods

The survival of incident Asian PD patients from 2001 to 2008 in a single center in Hong Kong was analyzed retrospectively. Baseline demographic and clinical data were collected from patient records. Patients who had a total Kt/V below 1.7 or who died within 6 months were excluded. The BMI was categorized using the World Health Organization recommendation for Asian populations.

Results

In the 274 study patients [154 men (56%); 138 with diabetes (50.4%); mean age: 63.4 ± 14.6 years; mean BMI: 21.97 ± 3.23 kg/m2; 37 underweight (13.5%); 35 obese (12.8%)], the relative risk (RR) for mortality [adjusted for age, diabetes status, and cardiovascular disease (CVD)] was similar for the normal and overweight groups, but higher for the underweight (RR: 1.909; p = 0.028) and obese groups (RR: 1.799; p = 0.048). The increased mortality in obese patients was more prominent in patients with diabetes (RR: 1.9 vs 1.19 in patients without diabetes; p = 0.074 and 0.76 respectively), and in patients with CVD (RR: 8.895 vs 1.642 in patients without CVD; p = 0.012 and 0.122 respectively).

Conclusions

In Asian PD patients, the relationship between BMI and mortality was U-shaped, with higher mortality in the underweight and obese patients. The negative impact of obesity was more prominent in patients with diabetes and CVD.
Approach to the Metabolic Implications of Peritoneal Dialysis in Acute Kidney Injury
Authors: Góes Cassiana Regina , Berbel Marina Nogueira , Balbi Andre Luis , Ponce Daniela
Published: February 2014

During the 1970s and 1980s, peritoneal dialysis (PD) was widely accepted as the standard treatment for acute kidney injury (AKI). However, advances in the techniques of extra-corporeal blood purification gradually reduced its use, making PD an underused modality in this context. Although PD for AKI is an underutilized modality worldwide, it is frequently used in developing countries because of its lower cost and minimal infrastructure requirements. Recent studies have shown that PD administered continuously through a flexible catheter and cycler is an effective treatment in AKI because it ensures adequate fluid status and metabolic control. However, the use of PD in AKI has several limitations, such as the need for an intact peritoneal cavity and, in emergency situations such as severe fluid overload and severe hyperkalemia, an efficacy that is lower than that with extracorporeal blood purification techniques. Metabolic, infectious, and mechanical disorders related to PD are also limitations.

Among the metabolic complications of PD are hyperglycemia, hypernatremia, protein loss into the dialysate, and hypercatabolism. Hyperglycemia is caused by the use of dialysate containing high concentrations of glucose. Hypernatremia is a result of short dialysate dwell times during the rapid exchanges of high-volume PD. Protein loss into the dialysate can reach 48 g daily, worsening the nutrition status of patients already depleted by AKI. Severe hypercatabolism caused by PD remains controversial and occurs because PD methods cannot provide an adequate dialysis dose for AKI patients.

Few studies have assessed the metabolic implications of PD in AKI patients. Evaluation of these implications is relatively simple, imposes no additional costs, and can provide information about the severity of the disease. Evaluation could also guide the selection of therapeutic, dialytic, and nutrition measures, preventing metabolic complications. The present manuscript describes the metabolic implications of PD and reviews the literature on how to prevent metabolic complications.
Encapsulating Peritoneal Sclerosis in the Era of a Multi-Disciplinary Approach Based on Biocompatible Solutions: The Next-Pd Study
Authors: Nakayama Masaaki , Miyazaki Masanobu , Honda Kazuho , Kasai Kenji , Tomo Tadashi , Nakamoto Hidetomo , Kawanishi Hideki
Published: February 2014

Introduction

Encapsulating peritoneal sclerosis (EPS) is a serious complication of peritoneal dialysis (PD). Over the past decade in Japan, a multidisciplinary approach has been adopted to minimize the incidence and improve outcomes of EPS. This strategy includes planned PD discontinuation for high-risk patients and the introduction of biocompatible solutions. This study examined the current clinical status of EPS in representative PD centers in Japan.

Design, setting, participants and measurements

Patients ( n = 1,338) from 55 PD centers in Japan who were using neutral-pH solutions from the initiation of therapy (mean age, 62 years; median PD duration, 32 months; concomitant use of icodextrin, 35.2%; PD and hemodialysis combination therapy, 12.2%) were assessed every 6 months to ascertain the reasons for PD discontinuation and the development of EPS development. Outcomes were also recorded. The study period was from November 2008 to March 2012.

Results

There were 727 patients who discontinued PD, including 163 deaths. Among all causes of PD withdrawal except for death, planned PD discontinuation to avoid EPS was utilized in 58 cases (7.1% in total). The strategy was increasingly utilized in proportion to the duration of PD: 0.5% for patients undergoing PD for < 3 years, 0.6% for patients undergoing PD for 5 years, 14.7% for patients undergoing PD for 8 years, and 35.5% for patients undergoing PD for > 8 years. Fourteen patients developed EPS (three cases after PD), which corresponded with an overall incidence of 1.0%. The incidence according to the duration of PD was 0.3% for PD < 3 years, 0.6% for PD = 5 years, 2.3% for PD = 8 years, and 1.2% for PD > 8 years. In terms of therapy, 11 patients were treated with prednisolone (PSL), and surgical enterolysis was utilized in two cases. Complete remission of abdominal symptoms was achieved in twelve patients (85.7%), and three died due to EPS (mortality rate of 21.4%).

Conclusions

Use of the multidisciplinary approach described above reduces the risk of the development of EPS according to PD duration. In cases of de novo EPS cases in Japan, this strategy can also attenuate the clinical course of the condition.
Manipulation of nanoparticles of different shapes inside a scanning electron microscope
Authors: Polyakov Boris , Vlassov Sergei , Dorogin Leonid M , Butikova Jelena , Antsov Mikk , Oras Sven , Lõhmus Rünno , Kink Ilmar
Published: February 2014

In this work polyhedron-like gold and sphere-like silver nanoparticles (NPs) were manipulated on an oxidized Si substrate to study the dependence of the static friction and the contact area on the particle geometry. Measurements were performed inside a scanning electron microscope (SEM) that was equipped with a high-precision XYZ-nanomanipulator. To register the occurring forces a quartz tuning fork (QTF) with a glued sharp probe was used. Contact areas and static friction forces were calculated by using different models and compared with the experimentally measured force. The effect of NP morphology on the nanoscale friction is discussed.
QUALITATIVE ANALYSIS OF OPERATIONAL STRATEGY WITH REFURBISHMENT OF METALWORKS OF ENGINEERING STRUCTURES
Authors: Gorokhov Yevhen , Gubanov Vadim , Pchelnikov Sergey , Mushchanov Vladimir
Published: February 2014

The design of engineering structures with metalwork is supposed that corresponding way of operations can support the load-bearing capacity. Because of peculiarities of engineering structures, namely, inaccessibility of a lot of nodes without application of special erection equipment, heavy labour input, etc. – such kind of operation is complicated and sometimes is not carried out. The paper deals with the problems of designing and maintenance of engineering structures with metalwork with specified longevity on the basis of the offered reference methods of principal interaction of designing and maintenance phases.
Modeling of Inclusion by Genetic Algorithms
Authors: Hamou Reda Mohamed , Amine Abdelmalek , Rahmouni Ali , Lokbani Ahmed Chaouki , Simonet Michel
Published: February 2014

The Cyclodextrins are of particular interest and importance in the field of inclusion and the formation of molecular complex. The aim of this work is to search by various techniques, among others: the molecular docking, the inclusion techniques, and complexations (Tail-Thread, Thread-Thread, Tail-Tail) of conformations (geometric parameters) to form inclusion complexes of beta-cyclodextrin with triphenylphosphine using an evolutionary optimization method in this case the Genetic Algorithms. The results are satisfactory. Software was designed to find an elite generation that represents the most stable complexes (minimum energy). This energy has been a determining factor and was chosen as fitness function (fitness) of the genetic algorithm.
The Impact of Perceived Desirability and Perceived Feasibility on Entrepreneurial Intention among Undergraduate Students in Sri Lanka: An Extended Model
Authors: Dissanayake DMNSW
Published: February 2014

Particularly, at the outset the researcher writes that, the insight of conducting and model specification for the study was gained from, Guerrero, Rialp, & Urbano, (2006). Due to the proven validity of intention based models to assess entrepreneurial intention and the non-validity of assessing entrepreneurial intention based on psychological characteristics, general dispositions, and personality traits and demographic factors, the researcher investigates the most appropriate model specification to assess entreprnenurial intention which is named as Krueger and Brazeal’s Entrepreneurial Potential Model. Particularly, the study was conducted in the University of Kelaniya, Sri Lanka, among the undergraduates of the Department of Commerce and Financial Management. Multiple regression analysis of the study was used to prove the stated hypothesis of the study and the researcher concludes that behavioral beliefs, self efficacy and credibility affect significantly towards the entrepreneurial intention within the selected undergraduates. Finally, the researcher suggests the prerequisite of conducting qualitative assessment in this regard and suggests some actions to implement to strengthen new venture creation in Sri Lanka.DOI: http://dx.doi.org/10.4038/kjm.v2i1.6543 Kelaniya Journal of Management Vol.2(1) 2013:39-57
Lease Accounting Disclosure Practice of Non Bank Financial Institutions (NBFIs) in Sri Lanka: A Lessor’s Perspective
Authors: Aruppala Dilini , Thilakarathne PMC
Published: February 2014

Non Bank Financial Institutions (NBFIs) have become prominent alongside with banking and finance sector. The major business of most NBFIs in Sri Lanka is leasing. Lease accounting is a form-driven standard. The Institute of Chartered Accountants of Sri Lanka (ICASL) introduced the revised accounting standard LKAS 17: Leases with effective from January 1, 2012. This research investigated the present state of accounting for lease in Sri Lanka as per the revised standard. An analytical review was done as per the standard and compliance with the stipulated disclosure requirements. All the Non Banking Financial Institutions which engage in leasing business and listed in the Colombo Stock Exchange were considered in this research. The methodology follows the content analysis which is consistent with Nasreen & Jahan (2007). The findings of this research indicate that the degree of correspondence between the standard as per LKAS: 17 and actual reporting by the leasing companies in Sri Lanka is considerably at a satisfactory level.DOI: http://dx.doi.org/10.4038/kjm.v2i1.6544 Kelaniya Journal of Management Vol.2(1) 2013:58-91
Entrepreneurial orientation and business performance of small and medium scale enterprises of Western Province in Sri Lanka
Authors: Wijetunge WADS , Pushpakumari MD
Published: February 2014

The economic growth of developing countries can be sustained by the expansion of private sector, as they are the engine of growth. Many scholars have argued that Entrepreneurial Orientation is one of the salient factors which contribute to the performance of SMEs. However, the recent literature provides contradictory findings about the relationship between Entrepreneurial Orientation and performance. Accordingly this study aimed at investigating the level of Entrepreneurial Orientation (EO) of owner(s)/manager(s) of SMEs and the relationship between EO and business performance of manufacturing SMEs in Western province. This study adopted deductive approach and used both descriptive and inferential statistical tools in analyzing the collected data. Findings revealed that the Entrepreneurial Orientation (EO) among owner/managers of manufacturing SMEs in Western province is at high level. Among the dimensions of EO, innovativeness shows high influence on business performance.DOI: http://dx.doi.org/10.4038/kjm.v2i2.6550 Kelaniya Journal of Management Vol.2(2) 2013:51-67
A dosimetric study of volumetric modulated arc therapy planning techniques for treatment of low-risk prostate cancer in patients with bilateral hip prostheses
Authors: Rana Suresh B. , Pokharel Shyam
Published: February 2014

Background and Purpose: Recently, megavoltage (MV) photon volumetric modulated arc therapy (VMAT) has gained widespread acceptance as the technique of choice for prostate cancer patients undergoing external beam radiation therapy. However, radiation treatment planning for patients with metallic hip prostheses composed of high-Z materials can be challenging due to (1) presence of streak artifacts from prosthetic hips in computed tomography dataset, and (2) inhomogeneous dose distribution within the target volume. The purpose of this study was to compare the dosimetric quality of VMAT techniques in the form of Rapid Arc (RA) for treating low-risk prostate cancer patient with bilateral prostheses. Materials and Methods: Three treatment plans were created using RA techniques utilizing 2 arcs (2-RA), 3 arcs (3-RA), and 4 arcs (4-RA) for 6 MV photon beam in Eclipse treatment planning system. Each plan was optimized for total dose of 79.2 Gy prescribed to the planning target volume (PTV) over 44 fractions. All three RA plans were calculated with anisotropic analytical algorithm. Results : The mean and maximum doses to the PTV as well as the homogeneity index among all three RA plans were comparable. The plan conformity index was highest in the 2-Arc plan (1.19) and lowest in the 4-Arc plan (1.10). In comparison to the 2-RA technique, the 4-RA technique reduced the doses to rectum by up to 18.8% and to bladder by up to 7.8%. In comparison to the 3-RA technique, the 4-RA technique reduced the doses to rectum by up to 14.6% and to bladder by up to 3.5%. Conclusion: Based on the RA techniques investigated for a low-risk prostate cancer patient with bilateral prostheses, the 4-RA plan produced lower rectal and bladder dose and better dose conformity across the PTV in comparison with the 2-RA and 3-RA plans.
Serum zinc as a prognostic indicator in locally advanced cancer cervix patients receiving chemo-irradiation: A pilot study
Authors: Tiwari Vivek , Shukla Piyush , Gupta Gourav
Published: February 2014

Objective: To evaluate the prognostic significance of serum Zinc (S.Zn) in locally advanced cancer cervix (LACC) patients treated with chemo-irradiation. Materials and Methods: S.Zn values in 34 females with histopathologically (HP) proven LACC (>/= stage II B) were prospectively measured using atomic absorption spectrophotometer pre- and post-treatment. Thirty-four age- and sex-matched healthy individuals were also evaluated for the parameter during the course of the study. After completion of treatment, the patients were divided into 2 groups based on the response, 1 - Complete response (CR) and 2 - Partial/No response (PR/NR). These groups were compared based on the observations of the studied parameter. Results: The mean post-treatment S.Zn values were significantly higher in group 1 as compared to group 2 (P < 0.05). Conclusion: In our study, patients achieving CR had higher mean levels of S.Zn compared to patients achieving PR/NR. We advocate further in-depth studies to evaluate the role of S.Zn in the prognosis of LACC patients treated with chemo-irradiation.
Study of socio‑demographic determinants of esophageal cancer at a tertiary care teaching hospital of Western Maharashtra, India
Authors: Giri Purushottam A. , Singh Kailash K. , Phalke Deepak B.
Published: February 2014

Background: Esophageal cancer has a peculiar geographical distribution and shows marked differences in incidence within a particular geographical region. Presently, as there seems little prospect of early detection of this cancer, an understanding of the etiological factors may suggest opportunities for its primary prevention. Objectives: The present study was carried out to find out the socio-demographic determinants of esophageal cancer in a tertiary care teaching hospital of western Maharashtra, India. Materials and Methods: A retrospective hospital record-based study was carried out for the period of five years (2007-2011) in the department of Radiotherapy of Pravara Rural Hospital, Loni, western Maharashtra, India. A total of 5879 patients were diagnosed with cancer, of them, 207 (3.52%) patients had esophageal cancer. Data was collected on the basis of the patients′ record in the hospital and analyzed in the form of percentage and proportions whenever appropriate. Results: Out of total 5879 patients who were diagnosed with cancer during the five studied years, 207 (3.52%) patients had esophageal cancer, of which 121 (58.46%) were males and 86 (41.54%) were females, which show predominance of males over females. Most of the patients (28.50%) belonged to lower class, while only 9.66% were from upper class. Majority of the patients (54.14%) had a history of tobacco chewing, followed by smoking (cigarette, bidi, or both) in 36.94% and alcohol in 21.65%. Conclusion: The present study shows that esophageal cancer constitutes 3.52% of cancer cases. There is a need to screen the high-risk group of people, improve socio-economic status, and efforts must be made to introduce a set of preventive measures that have the potential to significantly reduce the burden of disease and to help bridge the gap between research and public awareness.
Effect of Propionibacterium acidipropionici P169 on growth performance and rumen metabolism of beef cattle fed a corn- and corn dried distillers’ grains with solubles-based finishing diet
Authors: Narvaez N. , Alazzeh A. Y. , Wang Y. , McAllister T. A.
Published: February 2014

Narvaez, N., Alazzeh, A. Y., Wang, Y. and McAllister, T. A. 2014. Effect of Propionibacterium acidipropionici P169 on growth performance and rumen metabolism of beef cattle fed a corn- and corn dried distillers’ grains with solubles-based finishing diet. Can. J. Anim. Sci. 94: 363–369. A growth and metabolism experiment was conducted to evaluate the effect of Propionibacterium acidipropionici P169 on feedlot steers fed a corn- and corn dried distillers' grains with soluble (DDGS)-based finishing diet. Steers (40 non-cannulated and 8 ruminally cannulated) were divided into two groups and administered 10 g head−1 d−1 of maltodextrin containing 1×1011 colony-forming units (CFU) of P169 or the same amount of carrier (Control), top-dressed once daily upon feeding. Feed intake, growth rate and feed efficiency were determined over 115 d. For cannulated steers, ruminal pH was monitored continuously for 5 d during the second week of each month over the entire feeding period with rumen samples collected 3 h after feeding on days 1 and 5. Molar proportions of butyrate, branched-chain volatile fatty acids (VFA) and NH3-N concentration increased (P<0.01) with P169, whereas total VFA, molar proportions of propionate, the acetate:propionate ratio, and lactate concentration did not differ (P>0.05) between treatments. P169 had a limited effect on ruminal pH as duration and area under the curve both at pH 5.5 and 5.2 as well as frequency of acute ruminal acidosis bouts were similar (P>0.05) for both groups. Compared with control steers, steers fed P169 had more (P<0.05) bouts of subacute ruminal acidosis (SARA). All steers had similar (P>0.05) feed intake, growth rate, feed efficiency and carcass characteristics, except for longissiumus muscle area, being less (P<0.05) for P169 steers than controls. Supplementing P169 to beef cattle fed a corn- and corn DDGS-based finishing diet had no effect on growth performance of beef cattle or ruminal pH and increased the bouts of SARA.
Nitrogen fixation, hydrogen production and N2O emissions
Authors: Flynn Bryan , Graham Amanda , Scott Neal , Layzell David B. , Dong Zhongmin
Published: February 2014

Flynn, B., Scott, N. and Dong, Z. 2014. Nitrogen fixation, hydrogen production and N2O emissions. Can. J. Plant Sci. 94: 1037–1041. H2 is a by-product of the nitrogenase reaction. Exposure to H2 is linked to increased N2O production, increased CO2 fixation and plant growth promotion in soil. The effects of H2 exposure on soil were observed using controlled H2 gas treatments and field trials with legumes. In field trials, increased N2O production was observed in soil adjacent to legume nodules and inoculation of H2-oxidizing isolates led to increased N2O emissions in corn fields. Many H2-oxidizing isolates tested positive for key denitrification genes, indicating a connection between H2 uptake and N2O emissions. H2 treatment significantly increased copy number of the nitrite reductase (nirK) gene suggesting increased denitrification as the source of N2O. There was also a significant increase in copy number and expression of the RubisCO (cbbL) gene in soil. H2-oxidizing bacterial isolates (JM63 and JM162a) were found to promote plant growth, increasing tiller number and yield in spring wheat and barley. Combined results of T-RFLP and 16S rDNA clone libraries analysis revealed bacterial community structure changes in response to H2 treatment, primarily with increases to the Gammaproteobacteria and Betaproteobacteria groups. The results of these studies help provide a better understanding of the soil bacterial community's responses to H2 exposure and may lead to the development of a commercially viable plant growth promoting inoculant.
The Use of Ultrasonography for the Guidance of Epidural Analgesia in Obstetric Anesthesia
Authors: Plavsic Sanja Kupesic , Teissler Hana , Lozano Claudia
Published: February 2014

This review article describes the development of the use of ultrasound guidance for neuraxial blocks in obstetric anesthesia. Current evidence of the clinical utility and application, basic lumbar spine sonoanatomy and practical clinical approach of the ultrasound-guided technique for neuraxial blocks are presented and discussed. Suggested curriculum is intended to prepare anesthesiology residents for application of ultrasound guidance in epidural analgesia and obstetric anesthesia.

How to cite this article

Teissler H, Lozano C, Kupesic Plavsic S. The Use of Ultrasonography for the Guidance of Epidural Analgesia in Obstetric Anesthesia. Donald School J Ultrasound Obstet Gynecol 2014;8(1):44-51.
Obstetrics and Gynecology Ultrasound Fellowship: Experience of Dubrovnik International University Fellowship Program in Dubai
Authors: Honemeyer Ulrich , Sungler Paul , Grobler Diana , John Lorraine Natasha
Published: February 2014

In this article, we review a 4-year experience (2009-2013) with a Postgraduate Fellowship Program in Advanced obstetrics and gynecology Ultrasound under the Academic Mentorship of Dubrovnik International University (DIU), Croatia. The fellowship was conducted in Dubai, Welcare Mediclinic Hospital, and an Academic Teaching Hospital of DIU. Since 2009, we completed four master diploma courses with 38 graduates from the Middle East, Africa and Asia. The concept of the fellowship program did not require internship in our institution and allowed postgraduate students to remain in their professional and private environment. Each fellowship lasted for one year, including six teaching modules of 9 days every other month. The modules consisted of lectures given by international faculty and handson in the hospital, in the field of ultrasound in obstetrics and gynecology. The number of participants was limited to twelve in one course. At the end of the fellowship, students had to pass a written, oral and practical examination and hand over a logbook of a minimum of 50 sonographic case documentations. We give detailed account of the fellowship program, medicolegal and administrative specifics, course-related problems and their solutions from the nursing perspective, and describe the organizational challenges.

How to cite this article

Kurjak A, Honemeyer U, Sungler P, Grobler D, John LN. Obstetrics and Gynecology Ultrasound Fellowship: Experience of Dubrovnik International University Fellowship Program in Dubai. Donald School J Ultrasound Obstet Gynecol 2014;8(1):52-59.
Drivers of diel and regional variations of halocarbon emissions from the tropical North East Atlantic
Authors: Hepach H. , Quack B. , Ziska F. , Fuhlbrügge S. , Atlas E. L. , Krüger K. , Peeken I. , Wallace D. W. R.
Published: February 2014

Abstract. Methyl iodide (CH3I), bromoform (CHBr3) and dibromomethane (CH2Br2), which are produced naturally in the oceans, take part in ozone chemistry both in the troposphere and the stratosphere. The significance of oceanic upwelling regions for emissions of these trace gases in the global context is still uncertain although they have been identified as important source regions. To better quantify the role of upwelling areas in current and future climate, this paper analyzes major factors that influenced halocarbon emissions from the tropical North East Atlantic including the Mauritanian upwelling during the DRIVE expedition. Diel and regional variability of oceanic and atmospheric CH3I, CHBr3 and CH2Br2 was determined along with biological and physical parameters at six 24 h-stations. Low oceanic concentrations of CH3I from 0.1–5.4 pmol L−1 were equally distributed throughout the investigation area. CHBr3 and CH2Br2 from 1.0 to 42.4 pmol L−1 and to 9.4 pmol L−1, respectively were measured with maximum concentrations close to the Mauritanian coast. Atmospheric CH3I, CHBr3, and CH2Br2 of up to 3.3, 8.9, and 3.1 ppt, respectively were detected above the upwelling, as well as up to 1.8, 12.8, and 2.2 ppt at the Cape Verdean coast. While diel variability in CH3I emissions could be mainly ascribed to oceanic non-biological production, no main driver was identified for its emissions over the entire study region. In contrast, biological parameters showed the greatest influence on the regional distribution of sea-to-air fluxes of bromocarbons. The diel impact of wind speed on bromocarbon emissions increased with decreasing distance to the coast. The height of the marine atmospheric boundary layer (MABL) influenced halocarbon emissions via its influence on atmospheric mixing ratios. Oceanic and atmospheric halocarbons correlated well in the study region, and in combination with high oceanic CH3I, CHBr3 and CH2Br2 concentrations, local hot spots of atmospheric halocarbons could solely be explained by marine sources. This conclusion is in contrast to previous studies that hypothesized elevated atmospheric halocarbons above the eastern tropical Atlantic to be mainly originated from the West-African continent.
A review of sea-spray aerosol source functions using a large global set of sea salt aerosol concentration measurements
Authors: Grythe H. , Ström J. , Krejci R. , Quinn P. , Stohl A.
Published: February 2014

Abstract. Sea-spray aerosols (SSA) are an important part of the climate system because of their effects on the global radiative budget – both directly as scatterers and absorbers of solar and terrestrial radiation, and indirectly as cloud condensation nuclei (CCN) influencing cloud formation, lifetime, and precipitation. In terms of their global mass, SSA have the largest uncertainty of all aerosols. In this study we review 21 SSA source functions from the literature, several of which are used in current climate models. In addition, we propose a~new function. Even excluding outliers, the global annual SSA mass produced spans roughly 3–70 Pg yr−1 for the different source functions, for particles with dry diameter Dp < 10 μm, with relatively little interannual variability for a given function. The FLEXPART Lagrangian particle dispersion model was run in backward mode for a large global set of observed SSA concentrations, comprised of several station networks and ship cruise measurement campaigns. FLEXPART backward calculations produce gridded emission sensitivity fields, which can subsequently be multiplied with gridded SSA production fluxes in order to obtain modeled SSA concentrations. This allowed us to efficiently and simultaneously evaluate all 21 source functions against the measurements. Another advantage of this method is that source-region information on wind speed and sea surface temperatures (SSTs) could be stored and used for improving the SSA source function parameterizations. The best source functions reproduced as much as 70% of the observed SSA concentration variability at several stations, which is comparable with "state of the art" aerosol models. The main driver of SSA production is wind, and we found that the best fit to the observation data could be obtained when the SSA production is proportional to U103.5, where U10 is the source region averaged 10 m wind speed. A strong influence of SST on SSA production, with higher temperatures leading to higher production, could be detected as well, although the underlying physical mechanisms of the SST influence remains unclear. Our new source function with wind speed and temperature dependence gives a global SSA production for particles smaller than Dp < 10 μm of 9 Pg yr−1, and is the best fit to the observed concentrations.
Constraints on ship NOx emissions in Europe using GEOS-Chem and OMI satellite NO2 observations
Authors: Vinken G. C. M. , Boersma K. F. , van Donkelaar A. , Zhang L.
Published: February 2014

Abstract. We present a top-down ship NOx emission inventory for the Baltic Sea, the North Sea, the Bay of Biscay and the Mediterranean Sea based on satellite-observed tropospheric NO2 columns of the Ozone Monitoring Instrument (OMI) for 2005–2006. We improved the representation of ship emissions in the GEOS-Chem chemistry transport model, and compared simulated NO2 columns to consistent satellite observations. Relative differences between simulated and observed NO2 columns have been used to constrain ship emissions in four European seas (the Baltic Sea, the North Sea, the Bay of Biscay and the Mediterranean Sea) using a mass-balance approach, and accounting for non-linear sensitivities to changing emissions in both model and satellite retrieval. These constraints are applied to 39 % of total top-down European ship NOx emissions, which amount to 0.96 Tg N for 2005, and 1.0 Tg N for 2006 (11–15% lower than the bottom-up EMEP ship emission inventory). Our results indicate that EMEP emissions in the Mediterranean Sea are too high (by 60%) and misplaced by up to 150 km, which can have important consequences for local air quality simulations. In the North Sea ship track, our top-down emissions amount to 0.05 Tg N for 2005 (35% lower than EMEP). Increased top-down emissions were found for the Baltic Sea and the Bay of Biscay ship tracks, with totals in these tracks of 0.05 Tg N (131% higher than EMEP) and 0.08 Tg N for 2005 (128% higher than EMEP), respectively. Our study explicitly accounts for the (non-linear) sensitivity of satellite retrievals to changes in the a priori NO2 profiles, as satellite observations are never fully independent of model information (i.e. assumptions on vertical NO2 profiles). Our study provides for the first time a space-based, top-down ship NOx emission inventory, and can serve as a framework for future studies to constrain ship emissions using satellite NO2 observations in other seas.
Validation of the Aura High Resolution Dynamics Limb Sounder geopotential heights
Authors: Smith L. L. , Gille J. C.
Published: February 2014

Abstract. Global satellite observations from the EOS Aura spacecraft's High Resolution Dynamics Limb Sounder (HIRDLS) of temperature and geopotential height (GPH) are discussed. The accuracy, resolution and precision of the HIRDLS version 7 algorithms are assessed and data screening recommendations are made. Comparisons with GPH from observations, reanalyses and models including European Center for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis, Goddard Earth Observing System Model (GEOS) version 5, and EOS Aura Microwave Limb Sounder (MLS) illustrate the HIRDLS GPH have a precision ranging from 2 m to 30 m and an accuracy of ±100 m. Comparisons indicate HIRDLS GPH may have a slight low bias in the tropics and a slight high bias at high latitudes. Geostrophic winds computed with HIRDLS GPH qualitatively agree with winds from other data sources including ERA-Interim, NCEP and GEOS-5.
Using palaeo-climate comparisons to constrain future projections in CMIP5
Authors: Schmidt G. A. , Annan J. D. , Bartlein P. J. , Cook B. I. , Guilyardi E. , Hargreaves J. C. , Harrison S. P. , Kageyama M. , LeGrande A. N. , Konecky B. , Lovejoy S. , Mann M. E. , Masson-Delmotte V. , Risi C. , Thompson D. , Timmermann A. , Tremblay L.-B. , Yiou P.
Published: February 2014

Abstract. We present a selection of methodologies for using the palaeo-climate model component of the Coupled Model Intercomparison Project (Phase 5) (CMIP5) to attempt to constrain future climate projections using the same models. The constraints arise from measures of skill in hindcasting palaeo-climate changes from the present over three periods: the Last Glacial Maximum (LGM) (21 000 yr before present, ka), the mid-Holocene (MH) (6 ka) and the Last Millennium (LM) (850–1850 CE). The skill measures may be used to validate robust patterns of climate change across scenarios or to distinguish between models that have differing outcomes in future scenarios. We find that the multi-model ensemble of palaeo-simulations is adequate for addressing at least some of these issues. For example, selected benchmarks for the LGM and MH are correlated to the rank of future projections of precipitation/temperature or sea ice extent to indicate that models that produce the best agreement with palaeo-climate information give demonstrably different future results than the rest of the models. We also explore cases where comparisons are strongly dependent on uncertain forcing time series or show important non-stationarity, making direct inferences for the future problematic. Overall, we demonstrate that there is a strong potential for the palaeo-climate simulations to help inform the future projections and urge all the modelling groups to complete this subset of the CMIP5 runs.
Salinity changes in the Agulhas leakage area recorded by stable hydrogen isotopes of C37 alkenones during Termination I and II
Authors: Kasper S. , van der Meer M. T. J. , Mets A. , Zahn R. , Sinninghe Damsté J. S. , Schouten S.
Published: February 2014

Abstract. At the southern tip of Africa, the Agulhas Current reflects back into the Indian Ocean causing so-called "Agulhas rings" to spin off and release relatively warm and saline water into the South Atlantic Ocean. Previous reconstructions of the dynamics of the Agulhas Current, based on paleo-sea surface temperature and sea surface salinity proxies, inferred that Agulhas leakage from the Indian Ocean to the South Atlantic was reduced during glacial stages as a consequence of shifted wind fields and a northwards migration of the subtropical front. Subsequently, this might have led to a buildup of warm saline water in the southern Indian Ocean. To investigate this latter hypothesis, we reconstructed sea surface salinity changes using alkenone δD, and paleo-sea surface temperature using TEXH86 and UK'37, from two sediment cores (MD02-2594, MD96-2080) located in the Agulhas leakage area during Termination I and II. Both UK'37 and TEXH86 temperature reconstructions indicate an abrupt warming during the glacial terminations, while a shift to more negative δDalkenone values of approximately 14‰ during glacial Termination I and II is also observed. Approximately half of the isotopic shift can be attributed to the change in global ice volume, while the residual isotopic shift is attributed to changes in salinity, suggesting relatively high salinities at the core sites during glacials, with subsequent freshening during glacial terminations. Approximate estimations suggest that δDalkenone represents a salinity change of ca. 1.7–1.9 during Termination I and Termination II. These estimations are in good agreement with the proposed changes in salinity derived from previously reported combined planktonic Foraminifera δ18O values and Mg/Ca-based temperature reconstructions. Our results confirm that the δD of alkenones is a potentially suitable tool to reconstruct salinity changes independent of planktonic Foraminifera δ18O.
Background albedo dynamics improve simulated precipitation variability in the Sahel region
Authors: Vamborg F. S. E. , Brovkin V. , Claussen M.
Published: February 2014

Abstract. Using the general circulation model ECHAM5–JSBACH forced by observed sea surface temperatures (SSTs) for the 20th century, we investigate the role of vegetation and land surface albedo dynamics in shaping rainfall variability in the Sahel. We use two different land surface albedo schemes, one in which the albedo of the canopy is varying and one in which the albedo changes of the surface below the canopy are also taken into account. The SST forcing provides the background for simulating the observed decadal signal in Sahelian rainfall, though the response to SST forcing only is not strong enough to fully capture the observed signal. The introduction of dynamic vegetation leads to an increase in interannual variability of the rainfall, and gives rise to an increased number of high-amplitude rainfall anomaly events. The dynamic background albedo leads to an increased persistence of the rainfall anomalies. The increase in persistence means that the difference between the dry and the wet decades is increased compared to the other simulations, and thus more closely matching the observed absolute change between these two periods. These results highlight the need for a consistent representation of land surface albedo dynamics for capturing the full extent of rainfall anomalies in the Sahel.
Spatially resolved information on karst conduit flow from in-cave dye tracing
Authors: Lauber U. , Ufrecht W. , Goldscheider N.
Published: February 2014

Abstract. Artificial tracers are powerful tools for investigating karst systems. Tracers are commonly injected into sinking streams or dolines, while springs serve as monitoring sites. The obtained flow and transport parameters represent mixed information from the vadose, epiphreatic and phreatic zones (that is, the aquifer remains a black box). Accessible active caves constitute valuable but underexploited natural laboratories to gain detailed insights into the hydrologic functioning of the aquifer. Two multi-tracer tests in the catchment of a major karst spring (Blautopf, Germany) with injections and monitoring in two associated water caves aimed at obtaining spatially and temporally resolved information on groundwater flow in different compartments of the system. Two tracers were injected into the caves to characterize the hydraulic connections between them and with the spring. Two injections at the land surface, far from the spring, aimed at resolving the aquifer's internal drainage structure. Tracer breakthrough curves were monitored by field fluorimeters in caves and at the spring. Results demonstrate the dendritic drainage structure of the aquifer. It was possible to obtain relevant flow and transport parameters for different sections of this system. The highest mean flow velocities (275 m h−1) were observed in the near-spring epiphreatic section (open-channel flow), while velocities in the phreatic zone (pressurized flow) were one order of magnitude lower. Determined conduit water volumes confirm results of water balances and hydrograph analyses. In conclusion, experiments and monitoring in caves can deliver spatially resolved information on karst aquifer heterogeneity and dynamics that cannot be obtained by traditional investigative methods.
Climate-driven interannual variability of water scarcity in food production potential: a global analysis
Authors: Kummu M. , Gerten D. , Heinke J. , Konzmann M. , Varis O.
Published: February 2014

Abstract. Interannual climatic and hydrologic variability has been substantial during the past decades in many regions. While climate variability and its impacts on precipitation and soil moisture have been studied intensively, less is known on subsequent implications for global food production. In this paper we quantify effects of hydroclimatic variability on global "green" and "blue" water availability and demand in global agriculture, and thus complement former studies that have focused merely on long-term averages. Moreover, we assess some options to overcome chronic or sporadic water scarcity. The analysis is based on historical climate forcing data sets over the period 1977–2006, while demography, diet composition and land use are fixed to reference conditions (year 2000). In doing so, we isolate the effect of interannual hydroclimatic variability from other factors that drive food production. We analyse the potential of food production units (FPUs) to produce a reference diet for their inhabitants (3000 kcal cap−1 day−1, with 80% vegetal food and 20% animal products). We applied the LPJmL vegetation and hydrology model to calculate the variation in green-blue water availability and the water requirements to produce that very diet. An FPU was considered water scarce if its water availability was not sufficient to produce the diet (i.e. assuming food self-sufficiency to estimate dependency on trade from elsewhere). We found that 24% of the world's population lives in chronically water-scarce FPUs (i.e. water is scarce every year), while an additional 19% live under occasional water scarcity (water is scarce in some years). Among these 2.6 billion people altogether, 55% would have to rely on international trade to reach the reference diet, while for 24% domestic trade would be enough. For the remaining 21% of the population exposed to some degree of water scarcity, local food storage and/or intermittent trade would be enough to secure the reference diet over the occasional dry years.
Monitoring recent variations of the surface displacements of eight Nyainqêntanglha glaciers
Authors: Shi J. , Menenti M.
Published: February 2014

Abstract. A polythermal glacier is one of the dominant types of glacier that is distributed widely in the transition zone of the monsoon and continental climates of the Tibetan Plateau. However, the study of the glacier dynamics of this type of glacier in most of the glaciated area is still limited owing to the remoteness of the mountains, and issues related to high altitude. Theoretically, the surface displacement of a polythermal glacier has strong variations both in the spatial and temporal scales. We chose eight typical polythermal type glaciers (Zhadang Glacier, Panu Glacier, Lalong Glacier, Tangse No. 2 Glacier, Xibu Glacier, Lisheng Glacier, Guila Glacier, and Guren Glacier) in the Nyainqêntanglha Mountains, the south of Nam Co Lake, Tibetan Plateau for a case study. In this study, we monitored the ice surface displacements of these glaciers for nearly two decades from 1993 to 2009 by using the feature-tracking method. The ice displacement measurements with sub-pixel accuracy were recorded over the entire areas of the Zhadang, Panu, Lalong, Tangse No. 2, Xibu, Lisheng, Guila, and Guren glaciers during this period. Through the comparison of ice surface displacements between 1993–2003 and 2003–2009, we found that the change of the displacements are observed in most areas of these studied glaciers, especially in the ablation zones. The magnitude of this change is about −51%, except in the Xibu Glacier (+24%), in terms of the average of the total displacements. The surface displacements that were extracted by spaceborne optical imagery are promising for potential detection of the mechanics of polythermal glaciers in the Nyainqêntanglha Mountains.
Interpreting and analyzing King Tide in Tuvalu
Authors: Lin C.-C. , Ho C.-R. , Cheng Y.-H.
Published: February 2014

Abstract. The spatial and temporal distribution of sea-level rise has the potential to cause regional flooding in certain areas, and low-lying island countries are severely at risk. Tuvalu, an atoll country located in the southwest Pacific Ocean, has been inundated by this regional flooding for decades. Tuvaluans call this regional flooding phenomenon King Tide, a term not clearly defined, blaming it for loss of life and property in announcing their intention to migrate. In this study, we clarified and interpreted King Tide, and analyzed the factors of King Tide in Tuvalu. Using tide gauge and topographical data, we estimated that 3.2 m could be considered the threshold of King Tide, which implied half of the island of Tuvalu was flooded with seawater. This threshold is consistent with the finding of the National Oceanic and Atmospheric Administration that King Tide events occur once or twice a year. We surveyed 28 King Tide events to analyze the factors of regional flooding. Tide gauge and satellite altimeter data from 1993 to 2012 were cross-validated and indicated that the King Tide phenomenon is significantly related to the warm-water effect. Warm water contributed to the King Tide phenomenon by an average of 5.1% and a maximum of 7.8%. The height of King Tide is affected by the combined factors of spring tide, storm surge, climate variability, and, significantly, by the warm-water effect.
Automated classification of the atmospheric circulation patterns that drive regional wave climates
Authors: Pringle J. , Stretch D. D. , Bárdossy A.
Published: February 2014

Abstract. Wave climates are fundamental drivers of coastal vulnerability and changing trends in wave height, period and direction can severely impact coastlines. In a diverse storm environment, the changes in these parameters are difficult to detect and quantify. Since wave climates are linked to atmospheric circulation patterns an automated and objective classification scheme was developed to explore links between synoptic scale circulation patterns and wave climate variables, specifically wave heights. The algorithm uses a set of objective functions based on wave heights to guide the classification. Fuzzy rules define classification types that are used to detect locally high and low pressure anomalies through a process of simulated annealing. The optimized classification focuses on extreme wave events. The east coast of South Africa was used as a case study. The results show that three dominant patterns drive extreme wave events. The circulation patterns exhibit some seasonality with one pattern present throughout the year. Some 50–80% of the extreme wave events are explained by these three patterns. It is evident that strong low pressure anomalies east of the country drive a wind towards the KwaZulu-Natal coastline which results in extreme wave conditions. We conclude that the methodology can be used to link circulation patterns to wave heights within a diverse storm environment. The circulation patterns agree with qualitative observations of wave climate drivers. There are applications to the assessment of coastal vulnerability and the management of coastlines worldwide.