bluuebunny/crossref_metadata_2025 huggingface dataset:
Antioxidant activity of ultrasonic extracts of leek Allium porrum L.
Authors: Mladenovic Jelena , Maskovic Pavle , Pavlovic Rados , Radovanovic Blaga , Acamovic-Djokovic Gordana , Cvijovic Milica
Published: May 2011

This study was aimed at evaluating the antioxidant activity and efficacy of
the ethanolic extract of the ultrasonic extracts of leek Allium porrum L.
Ethanolic (50%; v/v) extracts of edible leek parts (stem and leaf) were
prepared by ultrasound-assisted extraction, which was followed by evaluation
of total phenols, flavonoids and antioxidant activity. Total phenols were
determined using the modified Folin-Ciocalteu method. Antioxidant activity
was assessed by scavenging the stable free radical
2,2-diphenyl-1-picrylhydrazyl (DPPH). The results of antioxidant activity
were compared with control antioxidants: vitamin C and BHT. The higher
content of phenols (69.46 mg GAE/g dry extract) and flavonoids (33.53 mg CE/g
dry extract) was found in the ethanolic extract of leek stem. The measured
values of IC50 were 98.90 g/ml and 61.05 g/ml for the ethanolic extract of
leek leaf and stem, respectively.
Effect of prophylactic pastes containing active ingredients on the enamel-bracket bond strength of etch-and-rinse and self-etching systems
Authors: Al-Twaijri Sarah , Viana Grace , Bedran-Russo Ana K.
Published: May 2011

Objective:

To evaluate the effect of prophylactic pastes containing active ingredients such as amorphous calcium phosphate (ACP), fluoride, or a combination of both on the enamel-bracket tensile bond strength.

Materials and Methods:

Human molars were randomly divided into four groups (N  =  40) according to the type of prophylactic pastes: control (no active ingredients), paste containing fluoride, paste containing ACP, and paste containing both fluoride and ACP. After prophylaxis, 20 brackets per group were bonded using an etch-and-rinse bonding technique (37% phosphoric acid and Ortho solo), and the other remaining 20 brackets were bonded using a self-etch bonding technique (Clearfil S3Bond). Samples were tested for tensile strength 24 hours after bonding using a universal testing machine. Data were analyzed using analysis of variance (ANOVA) and Student's t-test with significance level at .05.

Results:

The mean tensile bond strength varied between 3.043 (ACP) and 9.232 (control) MPa. The etch-and-rinse bonding technique was significantly affected by pastes containing active ingredients (P < .001). The self-etching system was not significantly affected by different pastes (P > .05).

Conclusions:

Cleaning enamel surfaces with prophylactic pastes that contain ACP and/or fluoride, prior to orthodontic bonding, resulted in a statistically significant decrease in the tensile bond strength of etch-and-rinse bonding technique.
A comparison of resistance to sliding of self-ligating brackets under an increasing applied moment
Authors: Pliska Benjamin T. , Beyer John P. , Larson Brent E.
Published: May 2011

Objective:

To test the null hypotheses that at clinically relevant amounts of applied moment, there are no differences in the amount of resistance to sliding (RS) between self-ligating (SL) and conventionally ligated (CL) brackets on both stainless steel (SS) and nickel-titanium (NT) archwire.

Materials and Methods:

Three different SL brackets and one CL bracket, all 0.022″ slot, were tested on a custom-built device to simulate canine retraction mechanics in the second-order dimension. The setup allowed for simultaneous and continuous measurement of RS and applied moment at the bracket-archwire interface. The brackets tested were Damon3, In-Ovation R, Smartclip, and Victory, all of which were tested with 0.019″ × 0.025″ SS and NT archwires. The RS at calculated moments of 2000 g-mm and 4000 g-mm was determined and compared between the various brackets and both archwire types. Descriptive measures, analysis of variance, and Tukey-Kramer post-test comparisons were used to calculate results.

Results:

All brackets displayed a greater amount of RS with NT than with SS archwires. At the higher moment levels (4000 g-mm), no significant reduction in RS was found between CL and SL brackets on both SS and NT archwires. At lower levels of applied moment (2000 g-mm), reductions in RS of 18% (42.7 g) and 18% (38.5 g) were found between the CL bracket and the best performing SL bracket on NT and SS, respectively.

Conclusion:

At low values of applied moment, some statistical differences were found; however, in general, the differences in RS amongst the various SL and CL brackets tested may not be clinically relevant.
On a generalized Stokes problem
Authors: Mácha Václav
Published: May 2011

We deal with a generalization of the Stokes system. Instead of the Laplace operator, we consider a general elliptic operator and a pressure gradient with small perturbations. We investigate the existence and uniqueness of a solution as well its regularity properties. Two types of regularity are provided. Aside from the classical Hilbert regularity, we also prove the Hölder regularity for coefficients in VMO space.
Red cabbage anthocyanins may protect blood plasma proteins and lipids
Authors: Kolodziejczyk Joanna , Saluk-Juszczak Joanna , Posmyk Malgorzata , Janas Krystyna , Wachowicz Barbara
Published: May 2011

The present in vitro study was designed to examine the antioxidative activity of red cabbage anthocyanins (ATH) in the protection of blood plasma proteins and lipids against damage induced by oxidative stress. Fresh leaves of red cabbage were extracted with a mixture of methanol/distilled water/0.01% HCl (MeOH/H2O/HCl, 50/50/1, v/v/w). Total ATH concentration [µM] was determined with cyanidin 3-glucoside as a standard. Phenolic profiles in the crude red cabbage extract were determined using the HPLC method. Plasma samples were exposed to 100 µM peroxynitrite (ONOO−) or 2 mM hydrogen peroxide (H2O2) in the presence/absence of ATH extract (5–15 µM); oxidative alterations were then assessed. Pre-incubation of plasma with ATH extract partly reduced oxidative stress in plasma proteins and lipids. Dose-dependent reduction of both ONOO− and H2O2-mediated plasma protein carbonylation was observed. ATH extract partly inhibited the nitrative action of ONOO−, and significantly decreased plasma lipid peroxidation caused by ONOO− or H2O2. Our results demonstrate that anthocyanins present in red cabbage have inhibitory effects on ONOO− and H2O2-induced oxidative stress in blood plasma components. We suggest that red cabbage ATH, as dietary antioxidants, should be considered as potentially usable nutraceuticals in the prevention of oxidative stress-related diseases.
Nonfusion stabilization of the degenerative lumbar spine
Authors: Maleci Alberto , Sambale Rafael Donatus , Schiavone Michele , Lamp Franz , Özer Fahir , von Strempel Archibald
Published: May 2011

Object

The goal of this study was to assess whether a stable but nonrigid nonfusion implant can stabilize the spine in degenerative diseases and also prevent instability following decompression. Instrumented spondylodesis is a recognized surgical treatment in degenerative disease of the lumbar spine. However, pain can develop at the bone graft donor site and the operative trauma can be very stressful in elderly patients, and it is suspected that there may be increased degenerative changes in the adjacent segments. In 2002, a nonrigid but rotationally stable pedicle screw and rod system was introduced, which could be used without additional fusion (referred to hereafter as the Cosmic system).

Methods

A total of 139 patients with degenerative disease of the lumbar spine underwent spinal stabilization with the Cosmic system without additional spondylodesis. Seventy patients had an additional decompression. The minimum follow-up was 2 years. The perioperative course, the clinical results, and the erect anteroposterior and lateral radiographs were recorded and compared with the preoperative data. The data were obtained from 6 different spine centers in Europe and documented on an Internet platform.

Results

The Oswestry Disability Index score improved from 48.9% to 22.5%, and the visual analog scale score decreased from 7.3 to 2.5. Lumbar lordosis did not change, nor did the adjacent disc height. Eleven patients underwent revision, 4 of them for implant failure. Of the 139 patients, 110 assessed the result as excellent, very good, or good; 24 as fair; and 5 as poor. A total of 122 patients would undergo surgery again. There were no significant differences between patients with or without an additional decompression.

Conclusions

The Cosmic system is a stable but nonrigid posterior nonfusion system. Implant complications are low and the clinical outcome is good. Longer follow-up is necessary to confirm the 2-year results.
Clinical outcome of leukemia patients with intracranial hemorrhage
Authors: Chern Joshua J. , Tsung Andrew J. , Humphries William , Sawaya Raymond , Lang Frederick F.
Published: May 2011

Object

Intracranial hemorrhage (ICH) is a frequent complication found in leukemia patients with thrombocytopenia. At the University of Texas MD Anderson Cancer Center, when a leukemia patient is found to have ICH, a platelet transfusion is generally recommended until 50,000/μl is reached. The authors examine the feasibility and outcome of their intervention strategy in this study.

Methods

Records were reviewed from 76 consecutive leukemia patients with newly diagnosed ICH at the University of Texas MD Anderson Cancer Center from January 1, 2007, to December 31, 2009. Variables of interest included age, platelet count at presentation, leukemia subtype, history of trauma, Glasgow Coma Scale score at presentation, whether the 50,000/μl goal was reached after transfusion, and whether the patient was a transfusion responder (platelet count increase > 2000/μl/unit transfused). Outcome parameters were mortality rates at 72 hours and 30 days and imaging-documented hemorrhage progression.

Results

Thrombocytopenia was prevalent at the time of presentation (68 of 76 patients had platelet levels < 50,000/μl at presentation). Despite an aggressive transfusion protocol, only 24 patients reached the 50,000/μl target after an average of 16 units of transfusion. Death due to ICH occurred in 15 patients within the first 72 hours (mortality rate 19.7%). Death correlated with the presenting Glasgow Coma Scale score (p = 0.0075) but not with other transfusion-related parameters. A significant mortality rate was again observed after 30 days (32.7%). The 30-day mortality rate, however, was largely attributable to non-ICH related causes and correlated with patient age (p = 0.032) and whether the patient was a transfusion responder (p = 0.022). Reaching and maintaining a platelet count > 50,000/μl did not positively correlate with the 30-day mortality rate (p = 0.392 and 0.475, respectively).

Conclusions

Platelet transfusion in the setting of ICH in leukemia patients is undoubtedly necessary, but whether the transfusion threshold should be 50,000/μl remains unclear. Factors other than thrombocytopenia likely contribute to the overall poor prognosis.
Safety of microvascular decompression for trigeminal neuralgia in the elderly
Authors: Rughani Anand I. , Dumont Travis M. , Lin Chih-Ta , Tranmer Bruce I. , Horgan Michael A.
Published: May 2011

Object

Microvascular decompression (MVD) offers an effective and durable treatment for patients suffering from trigeminal neuralgia (TN). Because the disorder has a tendency to occur in older persons, the risks of surgical treatment in the elderly have been a topic of recent interest. To date, evidence derived from several small retrospective and a single prospective case series has suggested that age does not increase the complication rate associated with surgery. Using a large national database, the authors aimed to study the impact of age on in-hospital complications following MVD for TN.

Methods

Using the Nationwide Inpatient Sample (NIS) for the 10-year period from 1999 to 2008, the authors selected all patients who underwent MVD for TN. The primary outcome of interest was the in-hospital mortality rate. Secondary outcomes of interest were cardiac, pulmonary, thromboembolic, cerebrovascular, and wound complications as well as the duration of hospital stay, total hospital charges, and discharge location. An elderly cohort of patients was first defined as those 65 years of age and older and then redefined as those 75 years and older.

Results

A total of 3273 patients who underwent MVD for TN were identified, having a median age of 57 years. Within this sample, 31.5% were 65 years and older and 10.7% were 75 years and older. The in-hospital mortality rate was 0.68% for patients 65 years or older (p = 0.0087) and 1.16% for those 75 years or older (p = 0.0026). In patients younger than 65 years, the in-hospital mortality rate was 0.13% (3 deaths among 2241 patients). As analyzed using the chi-square test (for both 65 and 75 years as the age cutoff) and the Pearson rank correlation coefficient, the risk of cardiac, pulmonary, thromboembolic, and cerebrovascular complications was higher in older patients (that is, those 65 and older and those 75 and older), but the risks of wound complications and CNS infection were not. The risk of any in-hospital complication occurring in a patient 65 years and older was 7.36% (p < 0.0001) and 10.0% in those 75 years and older (p < 0.0001). There was no difference in the total hospital charges associated with age. The duration of the hospital stay was longer in older patients, and the likelihood of discharge home was lower in older patients.

Conclusions

Microvascular decompression for TN in the elderly population remains a reasonable surgical option. However, based on data from a large national database, authors of the present study suggest that complications do tend to gradually increase in tandem with an advanced age. While age does not act as a risk factor in isolation, it may serve as a convenient surrogate for complication rates. The authors hope that this information can be of use in guiding older patients through decisions for the surgical treatment of TN.
Phase I/IIa trial of autologous formalin-fixed tumor vaccine concomitant with fractionated radiotherapy for newly diagnosed glioblastoma
Authors: Muragaki Yoshihiro , Maruyama Takashi , Iseki Hiroshi , Tanaka Masahiko , Shinohara Chie , Takakura Kintomo , Tsuboi Koji , Yamamoto Tetsuya , Matsumura Akira , Matsutani Masao , Karasawa Katsuyuki , Shimada Katsunori , Yamaguchi Naohito , Nakazato Yoichi , Sato Keiki , Uemae Youji , Ohno Tadao , Okada Yoshikazu , Hori Tomokatsu
Published: May 2011

Object

The objective of the present study was analysis of results of the prospective clinical trial directed toward the evaluation of therapeutic efficacy of the administration of autologous formalin-fixed tumor vaccine (AFTV) concomitant with fractionated radiotherapy in cases of newly diagnosed glioblastoma multiforme.

Methods

Twenty-four patients were enrolled into the clinical trial, while 2 cases were excluded from the final analysis of results. The treatment protocol included aggressive tumor resection, fractionated radiotherapy up to a total dose of 60 Gy, and 3 concomitant courses of AFTV administered with an interval of one week at the late stage of irradiation. Two delayed-type hypersensitivity (DTH) tests were done—one 48 hours before the initial course of vaccination (DTH-1) and one 2 weeks after the third (DTH-2). All but one of the patients received salvage therapy at the time of tumor progression. The defined primary end point was overall survival; secondary end points were progression-free survival and safety of concomitant treatment.

Results

The median duration of overall survival was 19.8 months (95% CI 13.8–31.3 months). The actuarial 2-year survival rate was 40%. The median duration of progression-free survival was 7.6 months (95% CI 4.3–13.6 months). Overall survival showed a statistically significant association with recursive partitioning analysis class (p < 0.05); progression-free survival showed a statistically significant association with p53 staining index (p < 0.05) and size of DTH-2 response (p < 0.001). AFTV injection concomitant with fractionated radiotherapy was well tolerated by all patients and in no case did treatment-related adverse effects exceed Grade 1 toxicity; adverse effects were limited to local erythema, induration, and swelling at the site of injection.

Conclusions

The results of this study demonstrate that AFTV treatment concomitant with fractionated radiotherapy may be effective in patients with newly diagnosed glioblastoma. Further clinical testing is warranted.
Minimum 5-year follow-up results of skipped pedicle screw fixation for flexible idiopathic scoliosis
Authors: Hwang Chang Ju , Lee Choon-Ki , Chang Bong-Soon , Kim Min-Seok , Yeom Jin S. , Choi Jin-Man
Published: May 2011

Object

The aim of this study was to evaluate after more than 5 years the outcome of surgical treatment for flexible idiopathic scoliosis using skipped pedicle screw fixation.

Methods

For patients with spine curves < 90° and flexibility > 20%, pedicle screws had been inserted into every other segment on the corrective side and 2–4 screws per curve had been inserted on the supportive side. The authors analyzed the results in 57 patients, including the correction rate of coronal curvature and rotational deformity, correction loss, sagittal balance, complications, blood loss, operation time, and implant costs.

Results

The mean Cobb angle was 54° preoperatively and 17° immediately after surgery (69% correction). At the last follow-up, the mean Cobb angle was 18° (2% correction loss). Rotation of the apical vertebra was corrected by 50% on average and showed only a 6% correction loss at the last follow-up. None of the patients had problems in maintaining sagittal balance. An adding-on phenomenon was detected in 4 patients (7%). Twelve of 14 patients with coronal decompensation showed improvement after surgery, whereas postoperative decompensation developed in 3 patients. Four patients had implant failures, and 4 had postoperative infections. The mean blood loss during surgery was 832 ml, and the mean operation time was 167 minutes. Compared with conventional methods, the authors' method used up to 48% fewer screws.

Conclusions

Skipped pedicle screw fixation of flexible idiopathic scoliosis showed satisfactory results. This method has several advantages, including reduced blood loss, shorter operation time, and reduced cost.
Idiopathic hypertrophic spinal pachymeningitis
Authors: Ranasinghe Moksha G. , Zalatimo Omar , Rizk Elias , Specht Charles S. , Reiter G. Timothy , Harbaugh Robert E. , Sheehan Jonas
Published: May 2011

Spinal idiopathic hypertrophic pachymeningitis (IHP) is a rare, chronic, nonspecific, granulomatous inflammatory disorder of the dura with unknown etiology. It can cause a localized or diffuse thickening of the dura mater with compression of the spinal canal and possible myelopathic symptoms. The authors report 3 consecutive cases of spinal IHP with a review of the literature. The diagnosis of spinal IHP was based on biopsy and pathological confirmation. Typical MR imaging findings suggestive of spinal IHP were noted in all cases. The clinical course may be marked by deterioration despite conservative therapy and may require surgical intervention to prevent irreversible neurological damage. Therefore, prompt diagnosis and institution of proper treatment is critical.
Chemometric Analysis of the Amino Acid Requirements of Antioxidant Food Protein Hydrolysates
Authors: Udenigwe Chibuike C. , Aluko Rotimi E.
Published: May 2011

The contributions of individual amino acid residues or groups of amino acids to antioxidant activities of some food protein hydrolysates were investigated using partial least squares (PLS) regression method. PLS models were computed with amino acid composition and 3-z scale descriptors in the X-matrix and antioxidant activities of the samples in the Y-matrix; models were validated by cross-validation and permutation tests. Based on coefficients of the resulting models, it was observed that sulfur-containing (SCAA), acidic and hydrophobic amino acids had strong positive effects on scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and H2O2 radicals in addition to ferric reducing antioxidant power. For superoxide radicals, only lysine and leucine showed strong positive contributions while SCAA had strong negative contributions to scavenging by the protein hydrolysates. In contrast, positively-charged amino acids strongly contributed negatively to ferric reducing antioxidant power and scavenging of DPPH and H2O2 radicals. Therefore, food protein hydrolysates containing appropriate amounts of amino acids with strong contribution properties could be potential candidates for use as potent antioxidant agents. We conclude that information presented in this work could support the development of low cost methods that will efficiently generate potent antioxidant peptide mixtures from food proteins without the need for costly peptide purification.
A Multi-Sensor Approach to Examining the Distribution of Total Suspended Matter (TSM) in the Albemarle-Pamlico Estuarine System, NC, USA
Authors: Miller Richard L. , Liu Cheng-Chien , Buonassissi Christopher J. , Wu An-Ming
Published: May 2011

For many coastal waters, total suspended matter (TSM) plays a major role in key biological, chemical and geological processes. Effective mapping and monitoring technologies for TSM are therefore needed to support research investigations and environmental assessment and management efforts. Although several investigators have demonstrated that TSM or suspended sediments can be successfully mapped using MODIS 250 m data for relatively large water bodies, MODIS 250 m data is of more limited use for smaller estuaries and bays or aquatic systems with complex shoreline geometry. To adequately examine TSM in the Albemarle-Pamlico Estuarine System (APES) of North Carolina, the large-scale synoptic view of MODIS and the higher spatial resolution of other sensors are required. MODIS, Landsat 7 ETM+ and FORMOSAT-2 remote sensing instrument (RSI) data were collected on 8 November, 24 November and 10 December, 2010. Using TSM images (mg/L) derived from MODIS 250 m band 1 (620–670 nm) data, Landsat 7 ETM+ 30 m band 3 (630–690 nm) and FORMOSAT-2 RSI 8 m band 3 (630−690 nm) atmospherically corrected images were calibrated to TSM for select areas of the APES. There was a significant linear relationship between both Landsat 7 ETM+ (r2 = 0.87, n = 599, P < 0.001) and FORMOSAT-2 RSI (r2 = 0.95, n = 583, P < 0.001) reflectance images and MODIS-derived TSM concentrations, thus providing consistent estimates of TSM at 250, 30 and 8 m pixel resolutions. This multi-sensor approach will support a broad range of investigations on the water quality of the APES and help guide sampling schemes of future field campaigns.
Construction of cyclic enones via gold-catalyzed oxygen transfer reactions
Authors: Liu Leping , Xu Bo , Hammond Gerald B
Published: May 2011

During the last decade, gold-catalyzed reactions have become a tour de force in organic synthesis. Recently, the gold-, Brønsted acid- or Lewis acid-catalyzed oxygen transfer from carbonyl to carbon–carbon triple bond, the so-called alkyne–carbonyl metathesis, has attracted much attention because this atom economical transformation generates α,β-unsaturated carbonyl derivatives which are of great interest in synthetic organic chemistry. This mini-review focuses on the most recent achievements on gold-catalyzed oxygen transfer reactions of tethered alkynones, diynes or alkynyl epoxides to cyclic enones. The corresponding mechanisms for the transformations are also discussed.
Du compromis au sacrifice : le concept du deuil au fil du siècle
Authors: Lombard Marjorie
Published: May 2011

Résumé Problématique : Il s’agit d’éclairer, au regard d’une mouvance théorique, un concept largement utilisé, parfois même « vulgarisé »: le deuil. L’organisation du point de vue : C’est au passage de la revue de la littérature, que nous catégoriserons nos propos en quatre sillages principaux, sous l’éclairage d’un autre concept: celui de l’exil. Tout d’abord, depuis Freud jusqu’aux théories de ses disciples et successeurs principalement basées sur les notions de « travail » et de « processus ». Ensuite, nous concentrerons notre approche sur la vision d’un philosophe contemporain qui aborde davantage l’intériorité de l’endeuillé: quelles transformations s’emparent du sujet au-delà de la perte? Enfin, nous étayerons notre parcours des théories lacaniennes dont les recherches mettent en lumière le lien unique qui lie le mort au survivant. Conclusion : Nous pourrions admettre que l’endeuillé se trouverait condamné au remplacement chez Freud, au renoncement chez Longneaux, tandis qu’il le serait au sacrifice chez Allouch.
La mort en face : réactions immédiates des enfants et adolescents confrontés à la mort d'un proche
Authors: Romano Hélène
Published: May 2011

Résumé Lors des interventions médicales d’urgence, les enfants témoins des secours sont rarement la préoccupation des adultes, qu’ils s’agissent des sauveteurs ou des proches. Pourtant les enfants sont bien là et ne sont pas préservés de l’impact traumatique de la mort en direct. À travers une étude prospective concernant 87 enfants, nous avons souhaité analyser les réactions immédiates des enfants confrontés à la mort d’un de leur proche, afin d’améliorer leur prise en charge par les équipes médicales et limiter les facteurs de survictimisation.
Fin de vie et loi Leonetti
Authors: Mauro Cynthia
Published: May 2011

Résumé Considérer la fin de vie c’est entre autre reconnaître la ou les souffrances et apporter la possibilité d’une réponse contenante, sécurisante ou soulageante par la mise en place de moyens matériels et humains spécialisés. Face au mourant, face au renvoie à notre propre mortalité, face au désarroi éprouvé, face à la peur éprouvante du souffrir, quel sens donnons-nous à notre accompagnement en tant que citoyens, en tant que proches, en tant qu’accompagnants, en tant que soignants? Quel cadre éthique et juridique nous permet aujourd’hui de considérer ces souffrances dans le respect de l’humanité et de la dignité de l’Autre dans un altruisme sincère?
Resonant Tunneling of Fast Solitons through Large Potential Barriers
Authors: Abou Salem Walid K. , Sulem Catherine
Published: May 2011

We rigorously study the resonant tunneling of fast solitons through large potential barriers for the nonlinear Schrödinger equation in one dimension. Our approach covers the case of general nonlinearities, both local and Hartree (nonlocal).
$G_\delta$ ideals of compact sets
Authors: Solecki Sławomir
Published: May 2011

We investigate the structure of Gδ ideals of compact sets. We define a class of Gδ ideals of compact sets that, on the one hand, avoids certain phenomena present among general Gδ ideals of compact sets and, on the other hand, includes all naturally occurring Gδ ideals of compact sets. We prove structural theorems for ideals in this class, and we describe how this class is placed among all Gδ ideals. In particular, we establish a result representing ideals in this class via the meager ideal. This result is analogous to Choquet's theorem representing alternating capacities of order ∞ via Borel probability measures. Methods coming from the structure theory of Banach spaces are used in constructing important to us examples of Gδ ideals outside of our class.
Scalar curvature and connected sums of self-dual 4-manifolds
Authors: Kalafat Mustafa
Published: May 2011

Under a reasonable vanishing hypothesis, Donaldson and Friedman proved that the connected sum of two self-dual Riemannian 4-Manifolds is again self-dual. Here we prove that the same result can be extended over to the positive scalar curvature case. So that this is an analogue of the classical theorem of Gromov-Lawson and Schoen-Yau in the self-dual category. The proof is based on the twistor theory.
Conformal harmonic forms, Branson–Gover operators and Dirichlet problem at infinity
Authors: Aubry Erwann , Guillarmou Colin
Published: May 2011

For odd dimensional Poincaré–Einstein manifolds

(X^{n_+1},g)

, we study the set of harmonic

k

-forms (for

k< n/2

) which are

C^m

(with

m ∈ ℕ

) on the conformal compactification

\bar X

of

X

. This is infinite dimensional for small

m

but it becomes finite dimensional if

m

is large enough, and in one-to-one correspondence with the direct sum of the relative cohomology

H^k(\bar X,∂\bar X)

and the kernel of the Branson–Gover [3] differential operators

(L_k,G_k)

on the conformal ifinity

(∂\bar X, [h_0])

. In a second time we relate the set of

C^{n-2k+1}(Λ^k(\bar X))

forms in the kernel of

d + δ_g

to the conformal harmonics on the boundary in the sense of [3], providing some sort of long exact sequence adapted to this setting. This study also provides another construction of Branson–Gover differential operators, including a parallel construction of the generalization of

Q

-curvature for forms.
Hidden structures in the class of convex functions and a new duality transform
Authors: Artstein-Avidan Shiri , Milman Vitali
Published: May 2011

Our main intension in this paper is to demonstrate how some seemingly purely geometric notions can be presented and understood in an analytic language of inequalities and then, with this understanding, can be defined for classes of functions and reveal new and hidden structures within these classes. One main example which we discovered is a new duality transform for convex non-negative functions on

ℝ^n

attaining thevalue

0

at the origin (which we called “geometric convex functions”). This transform, together with the classical Legendre transform, are essentially the only existing duality relations on this class of functions. Using these dualities we show that the geometric constructions of Support and Minkowski–functional may be extended, in a unique way, to the class of geometric log-concave functions, revealing hidden geometric structures on this class of functions.
On NIP and invariant measures
Authors: Hrushovski Ehud , Pillay Anand
Published: May 2011

We study forking, Lascar strong types, Keisler measures and definable groups, under an assumption of
NIP
(not the independence property), continuing aspects of the paper [16]. Among key results are (i) if

p = \mathrm{tp}(b/A)

does not fork over

A

then the Lascar strong type of

b

over

A

coincides with the compact strong type of

b

over

A

and any global nonforking extension of

p

is Borel definable over

\mathrm{bdd}(A)

, (ii) analogous statements for Keisler measures and definable groups, including the fact that

G^{000} = G^{00}

for

G

definably amenable, (iii) definitions, characterizations and properties of “generically stable” types and groups, (iv) uniqueness of invariant (under the group action) Keisler measures on groups with finitely satisfiable generics, (v) a proof of the compact domination conjecture for (definably compact) commutative groups in

o

-minimal expansions of real closed fields.
Fields with analytic structure
Authors: Cluckers Raf , Lipshitz Leonard
Published: May 2011

We present a unifying theory of fields with certain classes of analytic functions, called fields with analytic structure. Both real closed fields and Henselian valued fields are considered. For real closed fields with analytic structure,
o
-minimality is shown. For Henselian valued fields, both the model theory and the analytic theory are developed. We give a list of examples that comprises, to our knowledge, all principal, previously studied, analytic structures on Henselian valued fields, as well as new ones. The
b
-minimality is shown, as well as other properties useful for motivic integration on valued fields. The paper is reminiscent of [Denef, van den Dries,
p-adic and real subanalytic sets
. Ann. of Math. (2)
128
(1988) 79–138], of [Cohen, Paul J.
Decision procedures for real and p-adic fields
. Comm. Pure Appl. Math.
22
(1969)131–151], and of [Fresnel, van der Put,
Rigid analytic geometry and its applications
. Progress in Mathematics,
218
Birkhäuser (2004)], and unifies work by van den Dries, Haskell, Macintyre, Macpherson, Marker, Robinson, and the authors.
Modeling the Frozen-In Anticyclone in the 2005 Arctic Summer Stratosphere
Authors: Allen D. R. , Douglass A. R. , Manney G. L. , Strahan S. E. , Krosschell J. C. , Trueblood J. V. , Nielsen J. E. , Pawson S. , Zhu Z.
Published: May 2011

Abstract. Immediately following the breakup of the 2005 Arctic spring stratospheric vortex, a tropical air mass, characterized by low potential vorticity (PV) and high nitrous oxide (N2O), was advected poleward and became trapped in the easterly summer polar vortex. This feature, known as a "Frozen-In Anticyclone (FrIAC)", was observed in Earth Observing System (EOS) Aura Microwave Limb Sounder (MLS) data to span the potential temperature range from ~580 to 1100 K (~25 to 40 km altitude) and to persist from late March to late August 2005. This study compares MLS N2O observations with simulations from the Global Modeling Initiative (GMI) chemistry and transport model, the GEOS-5/MERRA Replay model, and the Van Leer Icosahedral Triangular Advection (VITA) isentropic transport model to elucidate the processes involved in the lifecycle of the FrIAC, which is here divided into three distinct phases. During the "spin-up phase" (March to early April), strong poleward flow resulted in a tight isolated anticyclonic vortex at ~70–90° N, marked with elevated N2O. GMI, Replay, and VITA all reliably simulated the spin-up of the FrIAC, although the GMI and Replay peak N2O values were too low. The FrIAC became trapped in the developing summer easterly flow and circulated around the polar region during the "anticyclonic phase" (early April to the end of May). During this phase, the FrIAC crossed directly over the pole between 7 and 14 April. The VITA and Replay simulations transported the N2O anomaly intact during this crossing, in agreement with MLS, but unrealistic dispersion of the anomaly occurred in the GMI simulation due to excessive numerical mixing of the polar cap. The vortex associated with the FrIAC was apparently resistant to the weak vertical shear during the anticyclonic phase, and it thereby protected the embedded N2O anomaly from stretching. The vortex decayed in late May due to diabatic processes, leaving the N2O anomaly exposed to horizontal and vertical wind shears during the "shearing phase" (June to August). The observed lifetime of the FrIAC during this phase is consistent with timescales calculated from the ambient horizontal and vertical wind shear. Replay maintained the horizontal structure of the N2O anomaly similar to MLS well into August. Isentropic simulations using VITA also captured the horizontal structure of the FrIAC during this phase, but small-scale structures maintained by VITA are problematic and show that important mixing processes are absent from this single-level simulation.
Anthropogenic aerosols may have increased upper tropospheric humidity in the 20th century
Authors: Bister M. , Kulmala M.
Published: May 2011

Abstract. Recent simulations of deep convection with a spectral microphysics cloud model show that an increase in aerosol concentration can have a significant effect on the nature of convection with more ice precipitation and less warm rain in polluted air. The cloud lifetime and the area covered by cloud anvils of deep convection are also larger for polluted air. Therefore, it is possible that the increase of anthropogenic aerosols in most of the 20th century has increased humidity and perhaps also cloudiness in the mid- to upper troposphere. Satellite data of upper tropospheric relative humidity in 1979–1997 and observed changes in cloudiness support this hypothesis. As changes in upper tropospheric humidity strongly affect longwave radiation, it is possible that anthropogenic aerosols have had a significant warming effect in addition to their other known effects on radiation.
Inversion of long-lived trace gas emissions using combined Eulerian and Lagrangian chemical transport models
Authors: Rigby M. , Manning A. J. , Prinn R. G.
Published: May 2011

Abstract. We present a method for estimating emissions of long-lived trace gases from a sparse global network of high-frequency observatories, using both a global Eulerian chemical transport model and Lagrangian particle dispersion model. Emissions are derived in a single step after determining sensitivities of the observations to initial conditions, the high-resolution emissions field close to observation points, and larger regions further from the measurements. This method has the several advantages over inversions using one type of model alone, in that: high-resolution simulations can be carried out in limited domains close to the measurement sites, with lower resolution being used further from them; the influence of errors due to aggregation of emissions close to the measurement sites can be minimized; assumptions about boundary conditions to the Lagrangian model do not need to be made, since the entire emissions field is estimated; any combination of appropriate models can be used, with no code modification. Because the sensitivity to the entire emissions field is derived, the estimation can be carried out using traditional statistical methods without the need for multiple steps in the inversion. We demonstrate the utility of this approach by determining global SF6 emissions using measurements from the Advanced Global Atmospheric Gases Experiment (AGAGE) between 2007 and 2009. The global total and large-scale patterns of the derived emissions agree well with previous studies, whilst allowing emissions to be determined at higher resolution than has previously been possible, and improving the agreement between the modeled and observed mole fractions at some sites.
Characterization of gas station emissions during the CAREBeijing 2008 field study
Authors: Zheng J. , Zhu T. , Zhang R. , Wang M. , Chang C.-C. , Shao M. , Hu M.
Published: May 2011

Abstract. A proton transfer-reaction mass spectrometer (PTR-MS) onboard a mobile laboratory was used to conduct emission measurements at eight gas stations in Beijing during the CAREBeijing 2008 campaign. Benzene, toluene, C8-, C9-aromatics, methanol, MTBE, butenes and pentenes were the major volatile organic compounds (VOCs) detected during the measurements. An inter-comparison between the PTR-MS and an on-line GC/MS/FID system was also conducted and the result showed good agreement between the two instruments (Interception < 0.08 ppbv, 0.72 < Slope < 0.95, and R2 > 0.92). A Gaussian point source plume model was applied to evaluate the VOCs emission rates. The results showed that on average about 4.5 mt of gasoline were emitted from gas stations in Beijing per day. The estimated emission factor (EF) for gas stations due to refueling processes was about 0.5 kg t−1, which was significantly lower than a value of 2.49 kg t−1 obtained in 2002, indicating a successful implementation of vapor recovery system in the gas stations of Beijing. On average, about 18 ppbv of benzene has been detected at one gas station, twice as much as the US Environmental Protection Agency (EPA) recommended safe chronic exposure level and implying a potential public health concern. MTBE and aromatics were found to be the major antiknocking additives used in gasoline supplied in Beijing. Our results reveal that emissions from gas stations represent an important source for VOCs in megacity Beijing and need to be properly included in emission inventories to assess their roles in photochemical ozone production and secondary organic aerosol formation. Furthermore, promoting methanol-blended fuel in Beijing can be an effective way to reduce toxic air pollutants emission.
Variations in time and space of trace metal aerosol concentrations in urban areas and their surroundings
Authors: Moreno T. , Querol X. , Alastuey A. , Reche C. , Cusack M. , Amato F. , Pandolfi M. , Pey J. , Richard A. , Prévôt A. S. H. , Furger M. , Gibbons W.
Published: May 2011

Abstract. Using an unprecedentedly large geochemical database, we compare temporal and spatial variations in inhalable trace metal background concentrations in a major city (Barcelona, Spain) and at a nearby mountainous site (Montseny) affected by the urban plume. Both sites are contaminated by technogenic metals, with V, Pb, Cu, Zn, Mn, Sn, Bi, Sb and Cd all showing upper continental crust (UCC) normalised values >1 in broadly increasing order. The highest metal concentrations usually occur during winter at Barcelona and summer in Montseny. This seasonal difference was especially marked at the remote mountain site in several elements such as Ti and Rare Earth Elements, which recorded campaign maxima, exceeding PM10 concentrations seen in Barcelona. The most common metals were Zn, Ti, Cu, Mn, Pb and V. Both V and Ni show highest concentrations in summer, and preferentially fractionate into the finest PM sizes (PM1/PM10 > 0.5) especially in Barcelona, this being attributed to regionally dispersed contamination from fuel oil combustion point sources. Within the city, hourly metal concentrations are controlled either by traffic (rush hour double peak for Cu, Sb, Sn, Ba) or industrial plumes (morning peak of Ni, Mn, Cr generated outside the city overnight), whereas at Montseny metal concentrations rise during the morning to a single, prolonged afternoon peak as contaminated air transported by the sea breeze moves into the mountains. Our exceptional database, which includes hourly measurements of chemical concentrations, demonstrates in more detail than previous studies the spatial and temporal variability of urban pollution by trace metals in a given city. Technogenic metalliferous aerosols are commonly fine in size and therefore potentially bioavailable, emphasising the case for basing urban background PM characterisation not only on physical parameters such as mass but also on sample chemistry and with special emphasis on trace metal content.
Spatial dependence of magnetopause energy transfer: Cluster measurements verifying global simulations
Authors: Palmroth M. , Laitinen T. V. , Anekallu C. R. , Pulkkinen T. I. , Dunlop M. , Lucek E. A. , Dandouras I.
Published: May 2011

Abstract. We investigate the spatial variation of magnetopause energy conversion and transfer using Cluster spacecraft observations of two magnetopause crossing events as well as using a global magnetohydrodynamic (MHD) simulation GUMICS-4. These two events, (16 January 2001, and 26 January 2001) are similar in all other aspects except for the sign of the interplanetary magnetic field (IMF) y-component that has earlier been found to control the spatial dependence of energy transfer. In simulations of the two events using observed solar wind parameters as input, we find that the GUMICS-4 energy transfer agrees with the Cluster observations spatially and is about 30 % lower in magnitude. According to the simulation, most of the the energy transfer takes place in the plane of the IMF (as previous modelling results have suggested), and the locations of the load and generator regions on the magnetopause are controlled by the IMF orientation. Assuming that the model results are as well in accordance with the in situ observations also on other parts of the magnetopause, we are able to pin down the total energy transfer during the two Cluster magnetopause crossings. Here, we estimate that the instantaneous total power transferring through the magnetopause during the two events is at least 1500–2000 GW, agreeing with ε scaled using the mean magnetopause area in the simulation. Hence the combination of the simulation results and the Cluster observations indicate that the ε parameter is probably underestimated by a factor of 2–3.
Drought-associated changes in climate and their relevance for ecosystem experiments and models
Authors: De Boeck H. J. , Verbeeck H.
Published: May 2011

Abstract. Drought periods can have important impacts on plant productivity and ecosystem functioning, but climatic conditions other than the lack of precipitation during droughts have never been quantified and have therefore not been considered explicitly in both experimental and modeling studies. Here, we identify which climatic characteristics deviate from normal during droughts and how these deviations could affect plant responses. Analysis of 609 years of daily data from nine Western European meteorological stations reveals that droughts in the studied region are consistently associated with more sunshine (+45 %), increased mean (+1.6 °C) and maximum (+2.8 °C) air temperatures and vapour pressure deficits that were 51 % higher than under normal conditions. These deviations from normal increase significantly as droughts progress. Using the process-model ORCHIDEE, we simulated droughts consistent with the results of the dataset analysis and compared water and carbon exchange of three different vegetation types during such natural droughts and droughts in which only the precipitation was affected. The comparison revealed contrasting responses: carbon loss was higher under natural drought in grasslands, while increased carbon uptake was found especially in decidious forests. This difference was attributed to better access to water reserves in forest ecosystems which prevented drought stress. This demonstrates that the warmer and sunnier conditions naturally associated with droughts can either improve growth or aggravate drought-related stress, depending on water reserves. As the impacts of including or excluding climatic parameters that correlate with drought are substantial, we propose that both experimental and modeling efforts should take into account other environmental factors than merely precipitation.
Rapid transfer of photosynthetic carbon through the plant-soil system in differently managed species-rich grasslands
Authors: De Deyn G. B. , Quirk H. , Oakley S. , Ostle N. , Bardgett R. D.
Published: May 2011

Abstract. Plant-soil interactions are central to short-term carbon (C) cycling through the rapid transfer of recently assimilated C from plant roots to soil biota. In grassland ecosystems, changes in C cycling are likely to be influenced by land use and management that changes vegetation and the associated soil microbial communities. Here we tested whether changes in grassland vegetation composition resulting from management for plant diversity influences short-term rates of C assimilation and transfer from plants to soil microbes. To do this, we used an in situ 13C-CO2 pulse-labelling approach to measure differential C uptake among different plant species and the transfer of the plant-derived 13C to key groups of soil microbiota across selected treatments of a long-term plant diversity grassland restoration experiment. Results showed that plant taxa differed markedly in the rate of 13C assimilation and concentration: uptake was greatest and 13C concentration declined fastest in Ranunculus repens, and assimilation was least and 13C signature remained longest in mosses. Incorporation of recent plant-derived 13C was maximal in all microbial phosopholipid fatty acid (PLFA) markers at 24 h after labelling. The greatest incorporation of 13C was in the PLFA 16:1ω5, a marker for arbuscular mycorrhizal fungi (AMF), while after 1 week most 13C was retained in the PLFA18:2ω6,9 which is indicative of assimilation of plant-derived 13C by saprophytic fungi. Our results of 13C assimilation and transfer within plant species and soil microbes were consistent across management treatments. Overall, our findings suggest that plant diversity restoration management may not directly affect the C assimilation or retention of C by individual plant taxa or groups of soil microbes, it can impact on the fate of recent C by changing their relative abundances in the plant-soil system. Moreover, across all treatments we found that plant-derived C is rapidly transferred specifically to AMF and decomposer fungi, indicating their consistent key role in the cycling of recent plant derived C.