bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiative forcing and climate response due to the presence of black carbon in cloud droplets
Authors: Wang Zhili , Zhang Hua , Li Jiangnan , Jing Xianwen , Lu Peng
Published: April 2013

Optical properties of clouds containing black carbon (BC) particles in their water droplets are calculated by using the Maxwell Garnett mixing rule and Mie theory. The obtained cloud optical properties were then applied to an interactive system by coupling an aerosol model with a General Circulation Model. This system is used to investigate the radiative forcing and the equilibrium climate response due to BC in cloud droplets. The simulated global annual mean radiative forcing at the top of the atmosphere due to the BC in cloud droplets is found to be 0.086 W m−2. Positive radiative forcing can be seen in Africa, South America, East and South Asia, and West Europe, with a maximum value of 1.5 W m−2 being observed in these regions. The enhanced cloud absorption is shown to increase the global annual mean values of solar heating rate, water vapor, and temperature, but to decrease the global annual mean cloud fraction. Finally, the global annual mean surface temperature is shown to increase by +0.08 K. The local maximum changes are found to be as low as −1.5 K and as high as +0.6 K. We show there has been a significant difference in surface temperature change in the Southern and Northern Hemisphere (+0.19 K and −0.04 K, respectively). Our results show that this interhemispheric asymmetry in surface temperature change could cause a corresponding change in atmospheric dynamics and precipitation. It is also found that the northern trade winds are enhanced in the Intertropical Convergence Zone (ITCZ). This results in northerly surface wind anomalies which cross the equator to converge with the enhanced southern trade winds in the tropics of Southern Hemisphere. This is shown to lead to an increase (a decrease) of vertical ascending motion and precipitation on the south (north) side of the equator, which could induce a southward shift in the tropical rainfall maximum related to the ITCZ.
Seasonal variations of black carbon observed at the remote mountain site Happo in Japan
Authors: Liu X. , Kondo Y. , Ram K. , Matsui H. , Nakagomi K. , Ikeda T. , Oshima N. , Verma R. L. , Takegawa N. , Koike M. , Kajino M.
Published: April 2013

The emission of black carbon (BC) from East Asia and its long‐range transport strongly influence the mass concentration of BC (MBC) over the western Pacific. However, reliable and long‐term BC data are still limited in this region, especially at elevated altitudes. In this study, we present accurate measurements of MBC using a continuous soot monitoring system at Happo, a remote mountain site at an altitude of about 1.8 km in Japan, from August 2007 to August 2009. The annual average MBC at Happo was about 0.26 ± 0.18 (1σ) µg m−3. The monthly average MBC values exhibited similar seasonal variations during both years, with minimum values in winter. Around 40% of the air sampled at the site was of free tropospheric (FT) origin, with about 10% originating in North China (NC) origin, respectively. The MBC values for FT (0.24 µg m−3) and NC (0.23 µg m−3) air were representative of the MBC values (0.26 µg m−3) at 1.8 km height in the western Pacific, which are strongly influenced by BC emissions in North China. The MBC values calculated using a regional‐scale model reproduced well the MBC observed at Happo. The model predicted that BC transported from northern China alone contributed ~53% to the measured MBC, consistent with trajectory analysis. The comparison of model‐calculated and observed MBC values indicates that the minimum values of MBC in winter were caused by the suppressed upward transport of BC over the Asian continent. Biomass burning in Siberia substantially increased MBC in the spring of 2008.
Tropical Atlantic dust and smoke aerosol variations related to the Madden‐Julian Oscillation in MODIS and MISR observations
Authors: Guo Yanjuan , Tian Baijun , Kahn Ralph A. , Kalashnikova Olga , Wong Sun , Waliser Duane E.
Published: April 2013

In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) fine mode fraction and Multi‐angle Imaging SpectroRadiometer (MISR) nonspherical fraction data are used to derive dust and smoke aerosol optical thickness (τdust and τsmoke) over the tropical Atlantic in a complementary way: due to its wider swath, MODIS has 3–4 times greater sampling than MISR, but MISR dust discrimination is based on particle shape retrievals, whereas an empirical scheme is used for MODIS. MODIS and MISR show very similar dust and smoke winter climatologies. τdust is the dominant aerosol component over the tropical Atlantic, accounting for 40–70% of the total aerosol optical thickness (AOT), whereas τsmoke is significantly smaller than τdust. The consistency and high correlation between these climatologies and their daily variations lends confidence to their use for investigating the relative dust and smoke contributions to the total AOT variation associated with the Madden‐Julian Oscillation (MJO). The temporal evolution and spatial patterns of the τdus anomalies associated with the MJO are consistent between MODIS and MISR: the magnitude of MJO‐realted τdust anomalies is comparable to or even larger than that of the total τ, while the τsmoke anomaly represents about 15% compared to the total, which is quite different from their relative magnitudes to the total τ on the climatological time scale. This suggests that dust and smoke are not influenced by the MJO in the same way. Based on correlation analysis, dust is strongly influenced by the MJO‐modulated trade wind and precipitation anomalies, and can last as long as one MJO phase, whereas smoke is less affected.
The importance of low‐level environmental vertical wind shear to wildfire propagation: Proof of concept
Authors: Kochanski Adam , Jenkins Mary Ann , Sun Ruiyu , Krueger Steven , Abedi Sepideh , Charney Joseph
Published: April 2013

This study is a proof of concept of the sensitivity of grassfire propagation to vertical shear in the near‐surface environmental flow found through four comparative grassfire numerical simulations with a coupled wildfire‐atmosphere model. A unidirectional constant wind field, under neutral atmospheric conditions, no surface friction, Coriolis force or topography, and homogeneous fuel, prescribes the model environment. By using the same surface (at 6.2 m above ground level) wind speed for all simulations, analyses of the results can suggest when the behavior and spread rate of the fire may depend more on the interaction of the fire plume with the shear in the above surface wind or more on the magnitude of the mean upstream surface wind speed at the surface. Three aspects of wildfire behavior are investigated: impact of unidirectional vertical shear on surface flow properties and fire line propagation; variability in fire spread and area burnt due to the evolution of the surface flow; and implications of low‐level vertical wind shear on the prediction of wildfire, especially extreme or erratic, behavior.
An impact origin for hydrated silicates on Mars: A synthesis
Authors: Tornabene Livio L. , Osinski Gordon R. , McEwen Alfred S. , Wray James J. , Craig Michael A. , Sapers Haley M. , Christensen Philip R.
Published: April 2013

Recent Mars‐orbiting spectrometers continue to detect surface materials containing hydrated silicates, particularly clays and amorphous phases (e.g., silica glasses), concentrated within the heavily cratered Noachian highlands crust. This paper provides a review, summary, and synthesis of observations from terrestrial impact structures with current Martian data. It is suggested that numerous and frequent impacts into the volatile‐rich silicate crust of Mars, through direct and indirect impact‐generated mechanisms, represent a plausible hypothesis that can explain the widespread distribution of hydrated silicates in the surface and subsurface of the heavily cratered Noachian highlands crust largely independent of climate. In addition to impact‐generated hydrothermal activity, devitrification, autometamorphism, and the voluminous production of impact “damaged” materials that are susceptible to alteration must be considered. When taken together, a drastically different early climate on Mars, in which water is stable at the surface for extended periods of time, cannot be ruled out; however, it is noted here that these additional impact mechanisms can operate and thereby extend the range of possible alteration settings to include climate conditions that may have been predominately colder and drier. Such a climate would not be dissimilar to the conditions of today, with the important exceptions of a higher geothermal gradient, and punctuated thermal disturbance to the cryosphere and hydrosphere from igneous activity and an exponentially higher impact flux.
Advance directives in the perioperative setting: Managing ethical and legal issues when patient rights and perceived obligations of the healthcare provider conflict
Authors: Williams Stephen P. , Howe Christopher L.
Published: April 2013

Perhaps individual wishes are not always acknowledged or accepted when it comes to end‐of‐life care. This possibility, in conjunction with the experiences of healthcare risk managers, should cause concern in the healthcare risk management community. One particularly concerning issue where a persistent failure to honor a patient's wishes exists is with Do Not Resuscitate (DNR) orders in the perioperative arena. Despite a strong focus on informed consent and advance directives, evidence suggests a number of healthcare organizations either have no policy in place regarding DNR orders during the perioperative period, or, for those organizations that do have a policy, many call for automatic suspension of the DNR order without consultation with the patient. This latter practice poses many ethical, medico‐legal, and regulatory concerns, and healthcare organizations with such a policy in place should strongly consider revisiting this practice.
Over‐Expression of the Overexpressed in Lung Cancer 1 Is Associated With Poor Prognosis in Epithelial Ovarian Cancer
Authors: Jia Changru , Li Xia , Sun Huaping , Sui Lihua
Published: April 2013

Background

The overexpressed in lung cancer 1 (OLC1), a novel tumor associated gene, is upregulated in several carcinomas. The purpose of this study was to determine whether increased expression of OLC1 is associated with epithelial ovarian carcinoma (EOC) that diagnosed in patients.

Methods

OLC1 expression was assayed in 20 normal ovarian and 139 ovarian cancer's specimens by Western blotting and immunohistochemical staining (IHC). Univariate and multivariate analysis were performed to determine the association between OLC1 expression and prognosis.

Results

Western blotting analysis demonstrated that OLC1 was overexpressed in ovarian cancers, and immunohistochemistry results revealed that 63 patients had increased level of OLC1. The 5‐year overall survival (OS) rates of patients with high OLC1 expression and low OLC1 expression were 24.8% and 75.2%, respectively (hazard ratio: 21.43, 95% CI: 2.54, 7.12, P < 0.0001). The 5‐year progression‐free survival (PFS) rates were 30.1% for patients in the high‐expression group and 69.9% for patients in the low OLC1 expression group (hazard ratio: 17.04, 95% CI: 0.33, 5.96, P < 0.0001).

Conclusions

OLC1 over‐expression is an important factor in epithelial ovarian carcinoma prognosis and can be a potential biomarker for ovarian carcinoma. J. Surg. Oncol. 2013 9999:XX–XX. © 2013 Wiley Periodicals, Inc. J. Surg. Oncol. 2013;107:847–852. © 2013 Wiley Periodicals, Inc.
Clinicopathologic Significance of Putative Stem Cell Marker, CD44 and CD133, in Human Gastric Carcinoma
Authors: CHEN SHI , HOU JING‐HUI , FENG XING‐YU , ZHANG XIAO‐SHI , ZHOU ZHI‐WEI , YUN JING‐PING , CHEN YING‐BO , CAI MU‐YAN
Published: April 2013

Background and Objectives

CD44 and CD133 have been reported as putative stem cell markers. However, the clinicopathologic significance of CD44 and CD133 expression in patients with gastric carcinoma (GC) has not been clearly elucidated.

Methods

Immunohistochemistry (IHC) was performed to investigate the CD44 and CD133 expression in gastric carcinomas and normal mucosal tissues. Receiver operating characteristic (ROC) curve analysis, spearman's rank correlation, Kaplan–Meier plots, and Cox proportional hazards regression model were used to analyze the data.

Results

The highly expressed CD44 and CD133 were observed in 27/152 (17.7%) and 64/152 (42.1%) of GCs and in 4/60 (6.7%) and 15/60 (25.0%) normal gastric mucosal tissues, respectively (P < 0.05, Fisher's exact test). High expression of CD44 was significantly correlated with tumor poorer differentiation, presence of distant metastasis, advanced TNM stage, and tumor relapse; and high expression of CD133 was positively associated with tumor invasion depth, presence of distant metastasis and advanced TNM stage. More importantly, high‐expressed CD44 and CD133 were both associated with shorter survival as evidenced by univariate and multivariate analysis.

Conclusions

Our study introduces high expression of CD44 and CD133 as adverse independent prognostic factors in GC patients. The combined CD44 and CD133 expression may become a useful tool for identifying patients with different clinical outcomes. J. Surg. Oncol. 2013;107:799–806. © 2013 Wiley Periodicals, Inc.
Is click chemistry attractive for separation sciences?
Authors: Marechal Audrey , El‐Debs Racha , Dugas Vincent , Demesmay Claire
Published: April 2013

Trends inLCfocus on dedicated separation developments spanning different fields of applications ranging from sample preparation to miniaturization. Chromatographic performances result from the porous media, its implantation inside the “column,” and its surface functionalization. Because molecular interactions govern chromatographic phenomena, surface functionalization is still a hot research topic. Besides standard approaches for surface functionalization, the use of new surface chemistry reactions opens new perspectives. Click chemistry belongs to this new class of chemical reactions, characterized by its specificity, compatibility with aqueous media, and high reaction yields. In this frame, we review the use of click chemistry reactions in chromatographic sciences. In a first part, we present click chemistry with a specific focus on its implementation in stationary phases. The use of these new clicked materials is detailed and discussed with respect to the chromatographic mode.
Amphiphilic Polypeptides as a Bifunctional Template in the Mineralization of Calcium Carbonate at the Air/Water Interface
Authors: Cao Heng , Lin Guoqiang , Yao Jinrong , Shao Zhengzhong
Published: April 2013

A well‐defined amphiphilic polypeptide, poly(glutamic acid)22‐block‐poly(alanine)8(PGlu22‐b‐PAla8), which plays the roles of both soluble (functional) additive and insoluble (structural) matrix, is employed to mediate the mineralization of CaCO3at the air/water interface. X‐ray diffraction (XRD) and Raman spectroscopy, for example, show that the polymorph of CaCO3particles obtained is calcite. The observations from SEM and TEM suggest that PGlu22‐b‐PAla8initiates the amorphous precursor phase and heterogeneous nucleation of CaCO3at the air/water interface, while temporarily stabilizes the gelatinous precursors as a process‐directing agent; nevertheless, the initial concentration of Ca2+controls the procedure of crystallization and the final morphology of CaCO3particles. Such “bifunctional” amphiphilic‐polypeptide‐regulated mineralization at the air/water interface may be applied to the synthesis of many kinds of symmetrical inorganic/organic hybrids.

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In Vitro Evaluation of Combined Sulfated Silk Fibroin Scaffolds for Vascular Cell Growth
Authors: Liu Haifeng , Ding Xili , Bi Yanxue , Gong Xianghui , Li Xiaoming , Zhou Gang , Fan Yubo
Published: April 2013

A combined sulfated silk fibroin scaffold is fabricated by modifying a knitted silk scaffold with sulfated silk fibroin sponges. In vitro hemocompatibility evaluation reveals that the combined sulfated silk fibroin scaffolds reduce platelet adhesion and activation, and prolong the activated partial thromboplastin time (APTT), thrombin time (TT), and prothrombin time (PT). The response of porcine endothelial cells (ECs) and smooth muscle cells (SMCs) on the scaffolds is studied to evaluate the cytocompatibility of the scaffolds. Vascular cells are seeded on the scaffolds and cultured for 2 weeks. The scaffolds demonstrate enhanced EC adhesion, proliferation, and maintenance of cellular functions. Moreover, the scaffolds inhibit SMC proliferation and induce expression of contractile SMC marker genes.

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Poloxamine–Cyclodextrin–Simvastatin Supramolecular Systems Promote Osteoblast Differentiation of Mesenchymal Stem Cells
Authors: Simões Susana M. N. , Veiga Francisco , Torres‐Labandeira Juan J. , Ribeiro Ana Cristina F. , Concheiro Angel , Alvarez‐Lorenzo Carmen
Published: April 2013

Osteogenic/osteoinductive systems combine simvastatin, poloxamine Tetronic 908 (T908) and α‐cyclodextrins (αCDs) in a supramolecular network that enhances the solubility/stability of the simvastatin hydroxy acid form and synergistically promotes osteoblast differentiation. Incorporation of 5% αCD transforms dilute T908 solutions (as low as 2% copolymer) into gels, enhances the osteoinductive activity of T908, and provides simvastatin sustained release for more than one week, which results in higher and more prolonged alkaline phosphatase (ALP) activity. The performance of the intrinsically osteoinductive polypseudorotaxane scaffold can be easily tuned by modifying the concentrations of T908, αCD, and simvastatin in a certain range of values. Moreover, the use of affordable, stable materials that can be sterilized applying a conventional method make the supramolecular gels advantageous candidates as scaffolds to be applied in the critical defect using minimally invasive techniques.

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Roles of the Gac‐Rsm pathway in the regulation of phenazine biosynthesis in Pseudomonas chlororaphis 30‐84
Authors: Wang Dongping , Lee Sung‐Hee , Seeve Candace , Yu Jun Myoung , Pierson Leland S. , Pierson Elizabeth A.
Published: April 2013

The GacS/GacA two‐component regulatory system activates the production of secondary metabolites including phenazines crucial for biological control activity in Pseudomonas chlororaphis 30‐84. To better understand the role of the Gac system on phenazine regulation, transcriptomic analyses were conducted by comparing the wild‐type strain to a gacA mutant. RNA‐seq analysis identified 771 genes under GacA control, including many novel genes. Consistent with previous findings, phenazine biosynthetic genes were significantly downregulated in a gacA mutant. The transcript abundances of phenazine regulatory genes such as phzI, phzR, iopA, iopB, rpoS, and pip also were reduced. Moreover, the transcript abundance of three noncoding RNAs (ncRNAs) including rsmX, rsmY, and rsmZ was significantly decreased by gacA mutation consistent with the presence of consensus GacA‐binding sites associated with their promoters. Our results also demonstrated that constitutive expression of rsmZ from a non‐gac regulated promoter resulted in complete restoration of N‐acyl‐homoserine lactone (AHL) and phenazine production as well as the expression of other gac‐dependent secondary metabolites in gac mutants. The role of RsmA and RsmE in phenazine production also was investigated. Overexpression of rsmE, but not rsmA, resulted in decreased AHL and phenazine production in P. chlororaphis, and only a mutation in rsmE bypassed the requirement for GacA in phenazine gene expression. In contrast, constitutive expression of the phzI/phzR quorum sensing system did not rescue phenazine production in the gacA mutant, indicating the direct posttranscriptional control by Gac on the phenazine biosynthetic genes. On the basis of these results, we propose a model to illustrate the hierarchic role of phenazine regulators modulated by Gac in the control of phenazine production. The transcriptomic analysis also was used to identify additional genes regulated by GacA that may contribute to the biological control capability of strain 30‐84.
Wage‐setting Decisions on Newly Hired Employees: Survey Evidence from Colombian Firms
Authors: Iregui Ana María , Melo Ligia Alba , Ramírez María Teresa
Published: April 2013

This paper uses a survey on wage formation applied to 1305 Colombian firms to study wage‐setting decisions of newly hired employees. The survey indicates that wages of the newly hired are based mainly on a predefined wage structure. This may help to explain, in part, the presence of downward nominal wage rigidities in the Colombian formal labour market, since firms are unwilling to differentiate the pay of new hires from the wages of existing workers. Using multinomiallogitmodels, we find that firm size and the share of temporary workers increase the relative risk of using a predefined internal structure over bargaining between employee and employer when setting the wages of the newly hired employees. Copyright © 2013 John Wiley & Sons, Ltd.
Clinical and posturographic correlates of falling in Parkinson's disease
Authors: Johnson Liam , James Ian , Rodrigues Julian , Stell Rick , Thickbroom Gary , Mastaglia Frank
Published: April 2013

Various clinical tests and balance scales have been used to assess postural stability and the risk of falling in patients with idiopathic Parkinson's disease (IPD). Quantitative posturography allows a more objective assessment but the findings in previous studies have been inconsistent and few studies have investigated which posturographic measures correlate best with a history of falling. The purpose of this study was to determine the efficacy of clinical tests, balance scales, and stable‐platform posturography in detecting postural instability and discriminating between fallers and non‐fallers in a home‐dwelling PD cohort. Forty‐eight PD subjects (Hoehn & Yahr stage 1–3) and 17 age‐matched controls had the following assessments: Activities‐specific Balance Confidence scale, Berg Balance Scale, Unified Parkinson's Disease Rating Scale (UPDRS) (motor), pull‐test, timed up‐and‐go, static posturography, and dynamic posturography to assess multidirectional leaning balance. Of the clinical assessments, all but the pull‐test were closely correlated with a history of falling. Static posturography discriminated between PD fallers and controls but not between PD fallers and non‐fallers, whereas dynamic posturography (reaction time, velocity, and target hit‐time) also discriminated between fallers and non‐fallers. Our findings suggest that this combination of clinical and posturographic measures would be useful in the prospective assessment of falls risk in PD patients. A further prospective study is now required to assess their predictive value. © 2013 Movement Disorder Society
Head injury and risk of Parkinson disease: A systematic review and meta‐analysis
Authors: Jafari Siavash , Etminan Mahyar , Aminzadeh Farhad , Samii Ali
Published: April 2013

Head trauma has been implicated in the etiopathogenesis of Parkinson's disease (PD). We performed a meta‐analysis to investigate the association between head trauma and the risk of developing PD. We included observational studies if they (1) clearly defined PD, (2) defined head trauma leading to concussion, and (3) presented odds ratios (ORs) and 95% confidence intervals (CIs) or provided data to compute these statistics. Random effect model was used to estimate the pooled, adjusted OR. Heterogeneity between studies was evaluated with the Q test and the I2 statistic. We conducted a sensitivity analysis to assess the influence of each study and repeated the analysis by excluding the studies with the largest weights. We used funnel plot to assess the presence of publication bias. After reviewing more than 636 article titles, 34 articles were selected for full review. In total, 22 studies (19 case–control studies, 2 nested case–control studies, and 1 cohort study) were included in the meta‐analysis. The pooled OR for the association of PD and head trauma was 1.57 (95% CI, 1.35–1.83). The results of our meta‐analysis indicate that a history of head trauma that results in concussion is associated with a higher risk of developing PD. © 2013 Movement Disorder Society
QF‐PCR as a substitute for karyotyping of cytotrophoblast for the analysis of chorionic villi: advantages and limitations from a cytogenetic retrospective audit of 44,727 first‐trimester prenatal diagnoses
Authors: Grati Francesca R. , Malvestiti Francesca , Grimi Beatrice , Gaetani Elisa , Di Meco Anna Maria , Trotta Anna , Liuti Rosaria , Chinetti Sara , Dulcetti Francesca , Ruggeri Anna Maria , Agrati Cristina , Frascoli Giuditta , Milani Silvia , De Toffol Simona , Martinoni Lorenza , Paganini Silvia , Marcato Livia , Maggi Federico , Simoni Giuseppe
Published: April 2013

Objectives

Karyotyping on chorionic villous samples (CVS) includes the analysis of both cytotrophoblast (STC) and mesenchyme (LTC). This approach requires complex laboratory organization and trained technicians. The introduction of quantitative fluorescent polymerase chain reaction (QF‐PCR) instead of conventional karyotyping in low‐risk pregnancies opened its application in CVS analysis. Discordant QF‐PCR and CVS cytogenetic results were reported, and strategies for CVS analysis were introduced to minimize this risk. The possibility to substitute the STC with QF‐PCR was reported. The aim of this study is to evaluate benefits and limitations of the approach QF‐PCR + LTC compared with the traditional method STC + LTC and to quantify the associated risks of false results.

Method

This study is based on a retrospective cytogenetic audit of CVS results (n = 44 727) generated by the STC + LTC analytic approach. False‐negative risks related to true fetal mosaicism type IV, imprinting syndromes and maternal contamination in LTC were calculated.

Results

Compared with STC + LTC, QF‐PCR + LTC approach is associated with a cumulative false‐negative risk of ~1/3100–1/4400. Costs and reporting time of STC in a high‐throughput cytogenetic lab are similar to a CE‐IVD marked QF‐PCR analysis.

Conclusions

These results should be clearly highlighted in the pre‐test counseling and extensively discussed with the couple prior to testing for informed consent. © 2013 John Wiley & Sons, Ltd.
Stimuli‐responsive star polymers
Authors: Kuckling Dirk , Wycisk Agnes
Published: April 2013

Stimuli‐responsive star polymers gain more and more interest over the last decades due to their unique properties compared to their linear counterparts. The branched structure for instance has influence on the responsive behavior of these polymers. This review offers an overview of stimuli‐responsive star polymers generated by different polymerization techniques, e.g. anionic and controlled radical polymerization (CRP). Beside conventional branched homopolymers different other types like block copolymers, miktoarm star copolymers, core crosslinked star polymers (CCS) and comb polymers are also presented. Furthermore their responsive behavior in solution or immobilized on a substrate, and their applications are outlined. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2980–2994
Biomimetic design of amphiphilic polycations and surface grafting onto polycarbonate urethane film as effective antibacterial agents with controlled hemocompatibility
Authors: Khan Musammir , Feng Yakai , Yang Dazhi , Zhou Wei , Tian Hong , Han Ying , Zhang Li , Yuan Wenjie , Zhang Jin , Guo Jintang , Zhang Wencheng
Published: April 2013

The synthetic polycations are ideal candidates as antimicrobial agents, because they resemble natural antimicrobial peptides, but to render hemocompatibility to these materials is a great challenge. Herein, we used 2‐(tert‐butyl‐aminoethyl) methacrylate (TBAEMA), to synthesize its homopolymer and pegylated random and diblock copolymers with polyethyleneglycol methacrylate (PEGMA, Mn = 360 Da) by single‐electron transfer–living radical polymerization (SET‐LRP). In the second step, the secondary amino groups in the precursor polymers were quaternized with iodomethane and bromohexane, to obtain three series of quaternized polymers. The antimicrobial properties of these quaternized polymers were evaluated against Escherichia coli (E. coli), by studying the minimum inhibitory concentrations (MICs) which ranged between 32 and 200 mg L−1 and showed higher values for the quaternized random than the diblock copolymers. In addition to, we have also demonstrated the grafting of these polycations onto polycarbonate urethane film surfaces, which showed good killing efficacy against E. coli. Furthermore, the hemolysis of these materials was investigated against human red blood cells, which indicated that except the quaternized homopolymers that showed highest hemolysis, all other amphiphilic polycations exhibited very low hemolytic activity. Therefore, our designed materials with controlled structures and functionality, synthesized from cheaply available resources could serve as useful agents in the field of biomedicines and implantable materials. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3166–3176
Brush macro‐RAFT agent mediated dispersion polymerization of styrene in the alcohol/water mixture
Authors: Xiao Xin , He Shangjin , Dan Meihan , Su Yang , Huo Fei , Zhang Wangqing
Published: April 2013

Dispersion RAFT polymerization of styrene in the alcohol/water mixture mediated with the brush macro‐RAFT agent of poly[poly(ethylene oxide) methyl ether vinylphenyl‐co‐styrene] trithiocarbonate [P(mPEGV‐co‐St)‐TTC] with similar molecular weight but different chemical composition is investigated. Well‐controlled RAFT polymerization including an initial slow homogeneous polymerization and a subsequent fast heterogeneous polymerization at almost complete monomer conversion is achieved. The molecular weight of the synthesized block copolymer increases linearly with the monomer conversion, and the polydispersity is relatively narrow (PDI < 1.3). The RAFT polymerization kinetics is dependent on the chemical composition in the brush macro‐RAFT agents, and those with high content of hydrophobic segment lead to fast RAFT polymerization. The growth of the block copolymer nano‐objects during the RAFT polymerization is explored, and various block copolymer nano‐objects such as nanospheres, worms, vesicles and large‐compound‐micelle‐like particles are prepared. The parameters such as the chemical composition in the brush macro‐RAFT agent, the chain length of the solvatophobic block, the concentration of the feeding monomer and the solvent character affecting the size and morphology of the block copolymer nano‐objects are investigated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3177–3190
Flutiform, a new steroid/long‐acting beta‐agonist inhaler
Authors: Chaplin Steve , Thomson Neil
Published: April 2013

Flutiform is a new inhaled steroid/long‐acting beta‐agonist combination containing fluticasone and formoterol. Here, the authors give details of the clinical trial results regarding its efficacy and safety and discuss its place in the treatment of asthma.
Heterogeneous integration of hexagonal boron nitride on bilayer quasi‐free‐standing epitaxial graphene and its impact on electrical transport properties
Authors: Hollander Matthew J. , Agrawal Ashish , Bresnehan Michael S. , LaBella Michael , Trumbull Kathleen A. , Cavalero Randal , Snyder David W. , Datta Suman , Robinson Joshua A.
Published: April 2013

We present a comprehensive study on the integration of hexagonal boron nitride (h‐BN) with epitaxial graphene (EG) and bilayer hydrogen intercalated EG. Charged impurity scattering is the dominant scattering mechanism for as‐grown and h‐BN coated graphene. Use of h‐BN dielectrics leads to a 2.6× improvement in Hall mobility relative to HfO2 by introducing less charged impurities and negligible additional remote surface optical scattering beyond that introduced by the substrate. Temperature dependent mobility measurement is used to link the surface morphology of the silicon carbide substrate (i.e., step‐edge density) with charge carrier transport, showing that significant degradation in mobility can result from increased remote charged impurity as well as remote surface optical scattering at the SiC step‐edges. Furthermore, we demonstrate that the integration of h‐BN with EG and bilayer graphene presents unique challenges compared to previous works on exfoliated graphene, where the benefits of h‐BN as a dielectric is highly dependent on the initial quality of the EG. To this end, modeling of the carrier mobility as a function of impurity density is used to identify the regimes where h‐BN dielectrics outperform conventional dielectrics and where they fail to surpass them. Modeling indicates that h‐BN can ultimately lead to a >5× increase in mobility relative to HfO2 dielectrics due to higher energy surface optical phonon (SOP) modes.
Optical magnetic metamaterials based on thick metal film perforated with rectangular nanohole arrays
Authors: Yuan Li , Chen Fuyi
Published: April 2013

The dependence of the optical magnetic property on metal film thickness and the origin of the magnetic property in thick metal (silver) film perforated with rectangular nanohole arrays were investigated using the finite‐difference time‐domain technique. A negative permeability was observed in the thickness range where two hybridized magnetic plasmon polariton resonances are present, and a big negative permeability was observed at certain thickness when the antisymmetric coupling between the electrical current density near the top and bottom film plane with the directions of electrical current density in the plane are present. Two types of antisymmetric coupling of electrical current density in the metal film were found to probably contribute to the permeability.
Spatial variability of liquid cloud and rain: observations and microphysical effects
Authors: Boutle I. A. , Abel S. J. , Hill P. G. , Morcrette C. J.
Published: April 2013

Spatial variability of liquid cloud water content and rainwater content is analysed from three different observational platforms: in situ measurements from research aircraft, land‐based remote sensing techniques using radar and lidar, and spaceborne remote sensing from CloudSat. The variance is found to increase with spatial scale, but also depends strongly on the cloud or rain fraction regime, with overcast regions containing less variability than broken cloud fields. This variability is shown to lead to large biases, up to a factor of 4, in both the autoconversion and accretion rates estimated at a model grid scale of ≈︁40 km by a typical microphysical parametrization using in‐cloud mean values. A parametrization for the subgrid variability of liquid cloud and rainwater content is developed, based on the observations, which varies with both the grid scale and cloud or rain fraction, and is applicable for all model grid scales. It is then shown that if this parametrization of the variability is analytically incorporated into the autoconversion and accretion rate calculations, the bias is significantly reduced.
Handling test length bloat
Authors: Fraser Gordon , Arcuri Andrea
Published: April 2013

The length of test cases is a little investigated topic in search‐based test generation for object‐oriented software, where test cases are sequences of method calls. Although intuitively longer tests can achieve higher overall code coverage, there is always the threat of bloat – a complex phenomenon in evolutionary computation, where the length abnormally grows over time. In this paper, we show that bloat indeed also occurs in the context of test generation for object‐oriented software. We present different techniques to overcome the problem of length bloat, and evaluate all possible combinations of these techniques using different starting lengths for the search. Experiments on a set of difficult search targets, selected from several open source and industrial projects, show that controlling bloat with the appropriate techniques can significantly improve the search performance. Copyright © 2013 John Wiley & Sons, Ltd.
ZACUBE‐1 Space Weather Mission: Characterize the SuperDARN HF Radar Antenna Array at SANAE‐IV
Authors: Van Zyl R. R. , Visser D. F. , Cilliers P. J. , Opperman B. D. L.
Published: April 2013

Key Points

SuperDarn characterization

CubeSat mission
Ensemble forecasting of coronal mass ejections using the WSA‐ENLIL with CONED Model
Authors: Emmons D. , Acebal A. , Pulkkinen A. , Taktakishvili A. , MacNeice P. , Odstrcil D.
Published: April 2013

The combination of the Wang‐Sheeley‐Arge (WSA) coronal model, ENLIL heliospherical model version 2.7, and CONED Model version 1.3 (WSA‐ENLIL with CONED Model) was employed to form ensemble forecasts for 15 halo coronal mass ejections (halo CMEs). The input parameter distributions were formed from 100 sets of CME cone parameters derived from the CONED Model. The CONED Model used image processing along with the bootstrap approach to automatically calculate cone parameter distributions from SOHO/LASCO imagery based on techniques described by Pulkkinen et al. (2010). The input parameter distributions were used as input to WSA‐ENLIL to calculate the temporal evolution of the CMEs, which were analyzed to determine the propagation times to the L1Lagrangian point and the maximum Kpindices due to the impact of the CMEs on the Earth's magnetosphere. The Newell et al. (2007) Kpindex formula was employed to calculate the maximum Kpindices based on the predicted solar wind parameters near Earth assuming two magnetic field orientations: a completely southward magnetic field and a uniformly distributed clock‐angle in the Newell et al. (2007) Kpindex formula. The forecasts for 5 of the 15 events had accuracy such that the actual propagation time was within the ensemble average plus or minus one standard deviation. Using the completely southward magnetic field assumption, 10 of the 15 events contained the actual maximum Kpindex within the range of the ensemble forecast, compared to 9 of the 15 events when using a uniformly distributed clock angle.
Extended study of extreme geoelectric field event scenarios for geomagnetically induced current applications
Authors: Ngwira Chigomezyo M. , Pulkkinen Antti , Wilder Frederick D. , Crowley Geoffrey
Published: April 2013

Geomagnetically induced currents (GIC) flowing in man‐made ground technological systems are a direct manifestation of adverse space weather. Today, there is great concern over possible geomagnetically induced current effects on power transmission networks that can result from extreme space weather events. The threat of severe societal consequences has accelerated recent interest in extreme geomagnetic storm impacts on high‐voltage power transmission systems. As a result, extreme geomagnetic event characterization is of fundamental importance for quantifying the technological impacts and societal consequences of extreme space weather. This article reports on the global behavior of the horizontal geomagnetic field and the induced geoelectric field fluctuations during severe/extreme geomagnetic events. This includes (1) an investigation of the latitude threshold boundary, (2) the local time dependency of the maximum induced geoelectric field, and (3) the influence of the equatorial electrojet (EEJ) current on the occurrence of enhanced induced geoelectric fields over ground stations located near the dip equator. Using ground‐based and satellite‐borne Defense Meteorological Satellite Program measurements, this article confirms that the latitude threshold boundary is associated with the movements of the auroral oval and the corresponding auroral electrojet current system, which is the main driver of the largest perturbations of the ground geomagnetic field at high latitudes. In addition, we show that the enhancement of the EEJ is driven by the penetration of high‐latitude electric fields and that the induced geoelectric fields at stations within the EEJ belt can be an order of magnitude larger than that at stations outside the belt. This has important implications for power networks located around the electrojet belt and confirms that earlier observations by Pulkkinen et al. (2012) were not isolated incidences but rather cases that can occur during certain severe geomagnetic storm events.
Space weather impacts on satellites and forecasting the Earth's electron radiation belts with SPACECAST
Authors: Horne R. B. , Glauert S. A. , Meredith N. P. , Boscher D. , Maget V. , Heynderickx D. , Pitchford D.
Published: April 2013

Satellites can be damaged by high energy charged particles in the Earth's radiation belts and during solar energetic particle (SEP) events. Here we review the growing reliance on satellite services, new vulnerabilities to space weather, and previous events that have led to loss of service. We describe a new European system to forecast the radiation belts up to 3 h ahead, which has three unique features: first, it uses physics‐based models, which include wave‐particle interactions; second, it provides a forecast for the whole outer radiation belt including geostationary, medium, and slot region orbits; third, it is a truly international effort including Europe, United States, and Japan. During the 8–9 March 2012 storm and SEP event, the models were able to forecast the >800 keV electron flux to within a factor of 2 initially, and later to within a factor of 10 of the GOES data. Although ACE and GOES data became unreliable during the SEP event, the system continued forecasting without interruption using ground‐based magnetometers. A forecast of the 24 h electron fluence >2 MeV is used to provide a risk index for satellite operators. We show that including wave‐particle interactions for L* > 6.5 improves the agreement with GOES data substantially and that a fast inward motion of the magnetopause to L* < 8 is related to rapid loss of relativistic electrons at geostationary orbit. Thus, we suggest that better wave‐particle models and better coupling between the solar wind and the models of the magnetopause and radiation belts should lead to better forecasting.
An operational software tool for the analysis of coronagraph images: Determining CME parameters for input into the WSA‐Enlil heliospheric model
Authors: Millward G. , Biesecker D. , Pizzo V. , de Koning C. A.
Published: April 2013

Coronal mass ejections (CMEs)—massive explosions of dense plasma that originate in the lower solar atmosphere and propagate outward into the solar wind—are the leading cause of significant space weather effects within Earth's environment. Computational models of the heliosphere such as WSA‐Enlil offer the possibility of predicting whether a given CME will become geo‐effective and, if so, the likely time of arrival at Earth. To be meaningful, such a forecast model is dependent upon accurately characterizing key parameters for the CME, notably its speed and direction of propagation, and its angular width. Studies by Zhao et al. (2002) and Xie et al. (2004) suggest that these key CME parameters can be deduced from geometric analysis of the elliptical “halo” forms observed in coronagraph images on spacecraft such as the Solar and Heliospheric Observatory (SOHO) and which result from a CME whose propagation is roughly toward or away from the observer. Both studies assume that the CME presents a circular cross‐section and maintains a constant angular width during its radial expansion, the so called “cone model.” Development work at the NOAA Space Weather Prediction Center (SWPC) has been concerned with building and testing software tools to allow forecasters to determine these CME parameters routinely within an operational context, a key aspect of transitioning the WSA‐Enlil heliospheric model into operations at the National Weather Service. We find “single viewpoint” cone analysis, while a useful start, to be highly problematic in many real‐world situations. In particular, it is extremely difficult to establish objectively the correct ellipse that should be applied to a given halo form and that small changes in the exact ellipse chosen can lead to large differences in the deduced CME parameters. The inaccuracies in the technique are particularly evident for analysis of the “nearly circular” elliptical forms which result from CMEs that are propagating directly toward the observer and are therefore the most likely to be geo‐effective. In working to resolve this issue we have developed a new three‐dimensional (3‐D) graphics‐based analysis system which seeks to reduce inaccuracies by analyzing a CME using coronagraph images taken concurrently by SOHO and also by the two Solar TErrestrial RElations Observatory (STEREO) spacecraft, which provide additional viewing locations well away from the Sun‐Earth line. The resulting “three view” technique has led to the development of the CME Analysis Tool (CAT), an operational software system in routine use at the SWPC as the primary means to determine CME parameters for input into the WSA‐Enlil model. Results from the operational WSA‐Enlil system are presented: utilizing CAT to provide CME input parameters, we show that, during the first year of operations at SWPC, the WSA‐Enlil model has forecasted the arrival of CMEs at Earth with an average error 7.5 h.
An empirical model of ground‐level geomagnetic perturbations
Authors: Weimer D. R.
Published: April 2013

A new empirical model for predicting ground‐level geomagnetic perturbations has been developed. This model is based on global measurements of the magnetic field at multiple stations in the Northern Hemisphere collected over an 8 year period, along with the simultaneous measurements of the interplanetary magnetic field (IMF). Variations in ionospheric conductivity are implicitly contained in the measurements used in the model's construction, including the solar F10.7 index. Provided with the IMF, solar wind velocity, dipole tilt angle (for season), and F10.7 index, this model computes all three vector components of the magnetic perturbations at specified locations. The model results are consistent with the corresponding maps of the ionospheric electric potential. Interestingly, maps of the vertical component have patterns that resemble maps of the overhead, ionospheric field‐aligned currents. Comparisons of model calculations with measurements at different locations show very good results, particularly at low frequencies. There are random variations at higher frequencies that are not reproduced well with the model, but they tend to occur in proportion to the predicted levels. This model could be useful for providing regional forecasts of geomagnetic activity with an approximately 1 h lead time.
NOAA's Space Weather Prediction Center Releases Two New Products
Authors: Rutledge R. , Steenburgh R. , Viereck R. , Onsager T.
Published: April 2013

Key Points

The NWS SWPC released two new forecast products

Forecasts will be in more frequent and more easily understood manner

Information is at an appropriate level to meet the sophistication of the users
Extreme Space Weather—A Report Published by the UK Royal Academy of Engineering
Authors: Cannon Paul S.
Published: April 2013

Key Points

A solar superstorm will not be catastrophic

A UK Space Weather Board should be set up