bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel mucoadhesive polysaccharide isolated from Bletilla striata improves the intraocular penetration and efficacy of levofloxacin in the topical treatment of experimental bacterial keratitis
Authors: Wu Xiang-gen , Xin Meng , Chen Hao , Yang Li-na , Jiang Hao-ran
Published: August 2010

Objectives

The objective of the present study was to evaluate a novel mucoadhesive polymer extracted from Bletilla striata for ocular delivery of 0.5% levofloxacin in rabbits, and to determine its improved efficacy against experimental keratitis.

Methods

B. striata polysaccharide (BsP) was subjected to cell cytotoxicity and ferning tests. The pharmacokinetics and bioavailability of topically applied 0.5% levofloxacin-BsP eye drops was investigated and compared with 0.5% levofloxacin eye drops (Cravit). Experimental Staphylococcus aureus keratitis was induced and treated with levofloxacin or levofloxacin-BsP eye drops.

Key findings

BsP markedly increased the proliferative capacity of a human corneal endothelial cell line. The ferning test showed that BsP exhibited optimal performance as a tear fluid. The polysaccharides significantly increased intra-aqueous penetration and corneal accumulation in rabbits. Treatment with levofloxacin-BsP reduced the number of organisms more significantly than eye drops containing levofloxacin alone.

Conclusions

BsP appears to be a promising candidate as a vehicle for topical ophthalmic drug delivery, especially for antibiotics.
Induction of apoptosis and cell cycle arrest in L-1210 murine lymphoblastic leukaemia cells by (2E)-3-(2-naphthyl)-1-(3′-methoxy-4′-hydroxy-phenyl)-2-propen-1-one
Authors: Pedrini Fernanda Spezia , Chiaradia Louise Domeneghini , Licínio Marley Aparecida , De Moraes Ana Carolina Rabello , Curta Juliana Costa , Costa Aline , Mascarello Alessandra , Creczinsky-Pasa Tânia Beatriz , Nunes Ricardo José , Yunes Rosendo Augusto , Santos-Silva Maria Cláudia
Published: August 2010

Objectives

New compounds with biological targets and less cytotoxicity to normal cells are necessary for cancer therapy. In this work ten synthetic chalcones derived from 2-naphtaldehyde were evaluated for their cytotoxic effect in murine acute lymphoblastic leukemia cells L-1210.

Methods

A series of ten chalcones derived from 2-naphtaldehyde and corresponding acetophenones were prepared by aldolic condensation, using methanol as solvent under basic conditions, at room temperature for 24 h. The cell viability was determined by MTT colorimeter method. The cell cycle phase analysis was carried out by flow cytometry after propidium iodide staining. The apoptosis induction was assessed by exposure to phosphatidylserine (ANNEXIN V-FITC). Cytometric analysis was performed to evaluate the expression of p53, Bcl-2 and Bax protein. The caspase-3 expression was studied by immunoblotting analysis.

Key findings

A preliminary screening of a series of ten chalcones derived from 2-naphtaldehyde showed that chalcone 8, (2E)-3-(2-naphtyl)-1-(3′-methoxy-4′-hydroxy-phenyl)-2-propen-1-one, had the highest cytotoxic effect (IC50 of 54 µm), but not in normal human lymphocytes. To better understand the cytotoxic mechanism of chalcone 8, its effect on cell cycle and apoptosis was assessed. Our results showed that chalcone 8 caused cell cycle arrest in the G2/M phase and a significant increase in the proportion of cells in the subG0/G1 phase. Our results also demonstrated that chalcone 8 promoted a modification in Bax : Bcl-2 ratio and increased p53 expression and caspase-3 activation.

Conclusions

The studied chalcone 8 has cytotoxic effect against L-1210 lymphoblastic leukaemic cells, and this effect is associated with increase of p-53 and Bax expression.
Vasorelaxant effect of Valeriana edulis ssp. procera (Valerianaceae) and its mode of action as calcium channel blocker
Authors: Estrada-Soto Samuel , Rivera-Leyva Julio , Ramírez-Espinosa Juan José , Castillo-España Patricia , Aguirre-Crespo Francisco , Hernández-Abreu Oswaldo
Published: August 2010

Objectives

The aim was to evaluate the relaxant effect of extracts from Valeriana edulis and determine the possible mechanism of action of the hexanic extract as vasorelaxant agent.

Methods

Extracts from rhizomes obtained by maceration (hexanic (HEVe), dichloromethanic (DEVe), methanolic (MEVe) and hydroalcoholic (HAEVe) (3.03–500 µg/ml)) were evaluated on aortic rat rings with and without endothelium.

Key findings

Extracts induced a significant concentration-dependent and endothelium-independent relaxation on isolated rat aorta pre-contracted with noradrenaline (0.1 µm). HEVe, the most potent extract (0.15–50 µg/ml), induced relaxation in aortic rings pre-contracted with KCl (80 mm), with an IC50 value of 34.61 ± 1.41 µg/ml and Emax value of 85.0 ± 4.38%. Pretreatment with HEVe (30 µg/ml) also inhibited contractile responses to noradrenaline and CaCl2. HEVe (9.98 ± 2.0 µg/ml) reduced noradrenaline-induced transient contraction in Ca2+-free solution, and inhibited contraction induced by KCl (80 mm). In endothelium-denuded rings, the vasorelaxant effect of HEVe was not modified by 1-H-[1,2,4]-oxadiazolo-[4,3a]-quinoxalin-1-one (1 µm), tetraethylammonium (5 mm), glibenclamide (10 µm) or 2-aminopyridine (100 µm).

Conclusions

Our results suggest that HEVe induces relaxation through an endothelium-independent pathway, involving blockade of Ca2+ channels, and this effect could be related to the presence of valepotriates.
Anti-inflammatory and anticancer compounds isolated fromVentilago madraspatanaGaertn.,Rubia cordifoliaLinn. andLantana camaraLinn.
Authors: Ghosh Subhalakshmi , Das Sarma Madhushree , Patra Amarendra , Hazra Banasri
Published: August 2010

Objectives

The aim was to search for anti-inflammatory and anticancer compounds from three medicinal plants, viz. Ventilago madraspatana Gaertn., Rubia cordifolia Linn. and Lantana camara Linn.

Methods

The NO• scavenging potential of selected plant extracts was determined on LPS/IFN-γ activated murine peritoneal macrophage cultures, and iNOS and COX-2 expression was evaluated by Western blot analysis. Bio-assay guided fractionation yielded four compounds: physcion and emodin from V. madraspatana, 1-hydroxytectoquinone from R. cordifolia, and oleanonic acid from L. camara. The anti-inflammatory activity of these compounds was tested through the carrageenan-induced rat-paw oedema model. They were then tested against a murine tumour (Ehrlich ascites carcinoma), and three human cancer cell lines, namely A375 (malignant skin melanoma), Hep2 (epidermoid laryngeal carcinoma) and U937 (lymphoma).

Key findings

All four compounds dose dependently inhibited NO• through suppression of iNOS protein without affecting macrophage viability. Physcion and emodin caused 65–68% reduction of oedema volume at 40 mg/kg, which validated their in-vivo anti-inflammatory effect. 1-hydroxytectoquinone and oleanonic acid exhibited promising cytotoxicity against A375 cells.

Conclusions

Ethnomedical reports on these traditional medicinal plants have been rationalised through an insight into the anti-inflammatory as well as anticancer potential of four constituents, characterised to be prospective candidates for designing novel therapeutic agents.
Towards the development of a rapid, portable, surface enhanced Raman spectroscopy based cleaning verification system for the drug nelarabine
Authors: Corrigan Damion K , Salton Neale A , Preston Chris , Piletsky Sergey
Published: August 2010

Objectives

Cleaning verification is a scientific and economic problem for the pharmaceutical industry. A large amount of potential manufacturing time is lost to the process of cleaning verification. This involves the analysis of residues on spoiled manufacturing equipment, with high-performance liquid chromatography (HPLC) being the predominantly employed analytical technique. The aim of this study was to develop a portable cleaning verification system for nelarabine using surface enhanced Raman spectroscopy (SERS).

Methods

SERS was conducted using a portable Raman spectrometer and a commercially available SERS substrate to develop a rapid and portable cleaning verification system for nelarabine. Samples of standard solutions and swab extracts were deposited onto the SERS active surfaces, allowed to dry and then subjected to spectroscopic analysis.

Key findings

Nelarabine was amenable to analysis by SERS and the necessary levels of sensitivity were achievable. It is possible to use this technology for a semi-quantitative limits test. Replicate precision, however, was poor due to the heterogeneous drying pattern of nelarabine on the SERS active surface. Understanding and improving the drying process in order to produce a consistent SERS signal for quantitative analysis is desirable.

Conclusions

This work shows the potential application of SERS for cleaning verification analysis. SERS may not replace HPLC as the definitive analytical technique, but it could be used in conjunction with HPLC so that swabbing is only carried out once the portable SERS equipment has demonstrated that the manufacturing equipment is below the threshold contamination level.
In-vitro permeation of bevacizumab through human sclera: effect of iontophoresis application
Authors: Pescina Silvia , Ferrari Giulio , Govoni Paolo , Macaluso Claudio , Padula Cristina , Santi Patrizia , Nicoli Sara
Published: August 2010

Objectives

Bevacizumab (Avastin) is a recombinant humanized monoclonal antibody used in ophthalmology (off-label) for the treatment of neovascularization in diseases such as diabetic retinopathy and age-related macular degeneration (wet form). Bevacizumab is currently administrated by repeated intravitreal injection, which can cause severe complications; a non-invasive delivery route is therefore desirable. The passive permeation of bevacizumab through isolated human sclera was evaluated and the iontophoretic technique was explored as a method to enhance its transscleral transport in vitro.

Methods

Bevacizumab was fluorescently labelled using fluorescein isothiocyanate (FITC). Permeation experiments were conducted for 2 h in Franz-type diffusion cells using human sclera as the barrier. The donor compartment contained FITC-bevacizumab (2.5 mg/ml) in phosphate-buffered saline at pH 7.4. In the iontophoretic experiments, a current intensity of 2.3 mA (current density 3.8 mA/cm2) was applied. The permeation samples were analysed with a fluorescence detector (excitation and emission wavelengths were 490 and 520 nm, respectively). The stability of FITC-bevacizumab conjugate was checked by thin layer chromatography.

Key findings

The main finding of this work is that anodal iontophoresis can significantly enhance bevacizumab transport through isolated human sclera (enhancement factor 7.5), even though the drug is essentially uncharged. Due to the relatively constant characteristics of antibodies, these results can probably be extended to other molecules of the same family.

Conclusions

Preliminary results indicate that anodal iontophoresis could be a promising strategy to non-invasively deliver bevacizumab through the sclera. The presence in the eye of other barriers, both static and dynamic, necessitates further evaluation of the technique on more complex ex-vivo and in-vivo models.
Bacopa monniera protects rat heart against ischaemia–reperfusion injury: role of key apoptotic regulatory proteins and enzymes
Authors: Mohanty Ipseeta Ray , Maheshwari Ujjwala , Joseph Daniel , Deshmukh Yeshwant
Published: August 2010

Objectives

Rat isolated hearts were perfused in a Langendorff model to study the cardioprotective effects of Bacopa monniera, a medicinal herb used in the Indian system of medicine, on cardiomyocyte apoptosis and antioxidant status following ischaemia–reperfusion (I-R) injury.

Methods

Forty-eight rats were randomly divided into four groups (12 in each group): sham group (no ischaemia–reperfusion injury), B. monniera control group (orally fed B. monniera at a dose of 75 mg/kg, for three weeks); ischaemia–reperfusion control group(subjected to ischaemia–reperfusion-induced myocardial injury) and B. monniera-treated group (same protocol as ischaemia–reperfusion control group except that rats also fed B. monniera).

Key findings

Post-ischaemic reperfusion injury resulted in significant cardiac necrosis, apoptosis, depression of heart rate, decline in antioxidant status and elevation in lipid peroxidation. Oral administration of B. monniera per se for three weeks to healthy rats caused augmentation of myocardial antioxidants, superoxide dismutase, catalase and glutathione, along with induction of heat shock protein 72 (HSP72). Ischaemia–reperfusion-induced biochemical and histopathological perturbations were significantly prevented by B. monniera (75 mg/kg) pre-treatment. Interestingly, B. monniera also restored the antioxidant network of the myocardium and reduced myocardial apoptosis, caspase 3 and Bax protein expression.

Conclusions

Histopathological studies and myocardial creatine phosphokinase content further confirmed the cardioprotective effects of B. monniera (75 mg/kg) in the experimental model of ischaemia–reperfusion injury. The study provides scientific basis for the putative therapeutic effect of B. monniera in ischaemic heart disease.
BRANE-WORLD COSMOLOGY AND VARYING G
Authors: AMARILLA LEONARDO , VUCETICH HÉCTOR
Published: August 2010

We consider a brane-world cosmological model coupled to a bulk scalar field. Since the brane tension turns out to be proportional to Newton's coupling G, in such a model a time variation of G naturally occurs. By resorting to available bounds on the variation of G, the parameters of the model are constrained. The constraints coming from nucleosynthesis and CMB result to be the severest ones.
PATH INTEGRAL QUANTIZATION FOR MASSIVE VECTOR BOSONS
Authors: DJUKANOVIC D. , GEGELIA J. , SCHERER S.
Published: August 2010

A parity-conserving and Lorentz-invariant effective field theory of self-interacting massive vector fields is considered. For the interaction terms with dimensionless coupling constants the canonical quantization is performed. It is shown that the self-consistency condition of this system with the second-class constraints in combination with the perturbative renormalizability leads to an SU(2) Yang–Mills theory with an additional mass term.
Privacy-aware role-based access control
Authors: Ni Qun , Bertino Elisa , Lobo Jorge , Brodie Carolyn , Karat Clare-Marie , Karat John , Trombeta Alberto
Published: August 2010

In this article, we introduce a comprehensive framework supporting a privacy-aware access control mechanism, that is, a mechanism tailored to enforce access control to data containing personally identifiable information and, as such, privacy sensitive. The key component of the framework is a family of models (P-RBAC) that extend the well-known RBAC model in order to provide full support for expressing highly complex privacy-related policies, taking into account features like purposes and obligations. We formally define the notion of privacy-aware permissions and the notion of conflicting permission assignments in P-RBAC, together with efficient conflict-checking algorithms. The framework also includes a flexible authoring tool, based on the use of the SPARCLE system, supporting the high-level specification of P-RBAC permissions. SPARCLE supports the use of natural language for authoring policies and is able to automatically generate P-RBAC permissions from these natural language specifications. In the article, we also report performance evaluation results and contrast our approach with other relevant access control and privacy policy frameworks such as P3P, EPAL, and XACML.
On the consistency of distributed proofs with hidden subtrees
Authors: Lee Adam J. , Minami Kazuhiro , Winslett Marianne
Published: August 2010

Previous work has shown that distributed authorization systems that fail to sample a consistent snapshot of the underlying system during policy evaluation are vulnerable to a number of attacks. Unfortuantely, the consistency enforcement solutions presented in previous work were designed for systems in which only CA-certified evidence is used during the decision-making process, all of which is available to the decision-making node at runtime. In this article, we generalize previous results and present light-weight mechanisms through which consistency constraints can be enforced in proof systems in which the full details of a proof may be unavailable to the querier due to information release policies, and the existence of certificate authorities for certifying evidence is unlikely; these types of distributed proof systems are likely candidates for use in pervasive computing and sensor network environments. We present modifications to one such distributed proof system that enable three types of consistency constraints to be enforced while still respecting the same confidentiality and integrity policies as the original proof system. We then discuss how these techniques can be adapted and applied to other, less restrictive, distributed proof systems. Further, we detail a performance analysis that illustrates the modest overheads of our consistency enforcement schemes.
A logical specification and analysis for SELinux MLS policy
Authors: Hicks Boniface , Rueda Sandra , St.Clair Luke , Jaeger Trent , McDaniel Patrick
Published: August 2010

The SELinux mandatory access control (MAC) policy has recently added a multilevel security (MLS) model which is able to express a fine granularity of control over a subject's access rights. The problem is that the richness of the SELinux MLS model makes it impractical to manually evaluate that a given policy meets certain specific properties. To address this issue, we have modeled the SELinux MLS model, using a logical specification and implemented that specification in the Prolog language. Furthermore, we have developed some analyses for testing information flow properties of a given policy as well as an algorithm to determine whether one policy is compliant with another. We have implemented these analyses in Prolog and compiled our implementation into a tool for SELinux MLS policy analysis, called PALMS. Using PALMS, we verified some important properties of the SELinux MLS reference policy, namely that it satisfies the simple security condition and ⋆-property defined by Bell and LaPadula. We also evaluated whether the policy associated to a given application is compliant with the policy of the SELinux system in which it would be deployed.
A survey of B-tree locking techniques
Authors: Graefe Goetz
Published: August 2010

B-trees have been ubiquitous in database management systems for several decades, and they are used in other storage systems as well. Their basic structure and basic operations are well and widely understood including search, insertion, and deletion. Concurrency control of operations in B-trees, however, is perceived as a difficult subject with many subtleties and special cases. The purpose of this survey is to clarify, simplify, and structure the topic of concurrency control in B-trees by dividing it into two subtopics and exploring each of them in depth.
Privacy-aware location data publishing
Authors: Hu Haibo , Xu Jianliang , On Sai Tung , Du Jing , Ng Joseph Kee-Yin
Published: August 2010

This article examines a new problem of
k
-anonymity with respect to a reference dataset in privacy-aware location data publishing: given a user dataset and a sensitive event dataset, we want to generalize the user dataset such that by joining it with the event dataset through location, each event is covered by at least
k
users. Existing
k
-anonymity algorithms generalize every
k
user locations to the same vague value, regardless of the events. Therefore, they tend to overprotect against the privacy compromise and make the published data less useful. In this article, we propose a new generalization paradigm called
local enlargement
, as opposed to conventional hierarchy- or partition-based generalization. Local enlargement guarantees that user locations are enlarged just enough to cover all events
k
times, and thus maximize the usefulness of the published data. We develop an
O
(
H

n

)-approximate algorithm under the local enlargement paradigm, where
n
is the maximum number of events a user could possibly cover and
H

n

is the Harmonic number of
n
. With strong pruning techniques and mathematical analysis, we show that it runs efficiently and that the generalized user locations are up to several orders of magnitude smaller than those by the existing algorithms. In addition, it is robust enough to protect against various privacy attacks.
Improving XML search by generating and utilizing informative result snippets
Authors: Liu Ziyang , Huang Yu , Chen Yi
Published: August 2010

Snippets are used by almost every text search engine to complement the ranking scheme in order to effectively handle user searches, which are inherently ambiguous and whose relevance semantics are difficult to assess. Despite the fact that XML is a standard representation format of Web data, research on generating result snippets for XML search remains limited.

To tackle this important yet open problem, in this article, we present a system eXtract which generates snippets for XML search results. We identify that a good XML result snippet should be a meaningful information unit of a small size that effectively summarizes this query result and differentiates it from others, according to which users can quickly assess the relevance of the query result. We have designed and implemented a novel algorithm to satisfy these requirements. Furthermore, we propose to cluster the query results based on their snippets. Since XML result clustering can only be done at query time, snippet-based clustering significantly improves the efficiency while compromising little clustering accuracy. We verified the efficiency and effectiveness of our approach through experiments.
Semantic imitation in social tagging
Authors: Fu Wai-Tat , Kannampallil Thomas , Kang Ruogu , He Jibo
Published: August 2010

We present a semantic imitation model of social tagging and exploratory search based on theories of cognitive science. The model assumes that social tags evoke a spontaneous
tag-based topic inference
process that primes the semantic interpretation of resource contents during exploratory search, and the semantic priming of existing tags in turn influences future tag choices. The model predicts that (1) users who can see tags created by others tend to create tags that are semantically similar to these existing tags, demonstrating the social influence of tag choices; and (2) users who have similar information goals tend to create tags that are semantically similar, but this effect is mediated by the semantic representation and interpretation of social tags. Results from the experiment comparing tagging behavior between a social group (where participants can see tags created by others) and a nominal group (where participants cannot see tags created by others) confirmed these predictions. The current results highlight the critical role of human semantic representations and interpretation processes in the analysis of large-scale social information systems. The model implies that analysis at both the individual and social levels are important for understanding the active, dynamic processes between human knowledge structures and external folksonomies. Implications on how social tagging systems can facilitate exploratory search, interactive information retrievals, knowledge exchange, and other higher-level cognitive and learning activities are discussed.
Results of 244 Consecutive Patients with Hemorrhoids Treated with Doppler-Guided Hemorrhoidal Artery Ligation
Authors: Pol Robert A. , van der Zwet Wil C. , Hoornenborg Daniel , Makkinga Babbeth , Kaijser Miriam , Eeftinck Schattenkerk M. , Eddes Eric-Hans
Published: August 2010

Aim: This study was designed to determine the effect of treating hemorrhoids with the Doppler-guided hemorrhoidal artery ligation (DG-HAL) procedure. Methods: From June 2005 to March 2008, 244 consecutive hemorrhoidal patients underwent hemorroidal artery ligation performed with the DG-HAL system from AMI®. All patients were evaluated postoperatively with a proctologic examination and interview. Further follow-up was performed by telephone with a standardized questionnaire. When indicated, patients revisited the clinic for further examination and treatment. Results: 244 patients were treated with DG-HAL. The mean follow-up time was 18.4 months (range 1.4–37.2). Sixty-seven percent of the patients had an improvement of symptoms after one treatment. Fifty-three patients (22%) underwent a second procedure because of persisting symptoms. Thirteen patients (25%) underwent a second DG-HAL and 40 (75%) underwent rubber band ligation. In total, 69% of the patients had a good response using the DG-HAL technique. Multivariate logistic regression analysis revealed prolapse to be an independent risk factor for persistent symptoms (OR = 2.38, 95% CI 1.10–5.15). Patients with grades 3 and 4 hemorrhoids had a higher risk of developing recurrent disease (OR = 4.94, 95% CI 0.67–36.42). Conclusion: DG-HAL seems to be an effective procedure for treating low-grade hemorrhoids. A resection procedure should be the treatment for patients with recurrent disease.
Significance of Measuring S100A12 and sRAGE in the Serum of Sepsis Patients with Postoperative Acute Lung Injury
Authors: Kikkawa Tomohiro , Sato Nobuhiro , Kojika Masahiro , Takahashi Gaku , Aoki Kiichi , Hoshikawa Koichi , Akitomi Shinji , Shozushima Tatsuyori , Suzuki Kenji , Wakabayashi Go , Endo Shigeatsu
Published: August 2010

Background: There is a report that S100A12 is useful as an early marker of acute lung injury (ALI). The purpose of this study was to determine whether S100A12 or sRAGE is useful as a marker during the development of ALI in postoperative sepsis patients. Methods: The subjects were patients who underwent emergency surgery because of sepsis secondary to perforation of the lower gastrointestinal tract. We conducted a retrospective study comparing 2 groups of patients: a group of 9 patients who developed postoperative ALI, the ALI(+) group, and a group of 8 patients who did not develop postoperative ALI, the ALI(–) group. Their blood S100A12, sRAGE, IFN-γ, WBC count, and CRP values were measured immediately after surgery and on postoperative day 1 (D1). Results: The changes in S100A12 showed significantly higher values immediately postoperatively in the ALI(+) group (p < 0.05). The sRAGE values immediately postoperatively were similar, but on D1, they were significantly higher in the ALI(–) group (p < 0.05). Conclusions: S100A12 increases in the early stage of development of ALI. sRAGE production increases in patients who do not develop ALI.
A Spectral Parameterization of Drag, Eddy Diffusion, and Wave Heating for a Three-Dimensional Flow Induced by Breaking Gravity Waves
Authors: Zhu Xun , Yee Jeng-Hwa , Swartz William H. , Talaat Elsayed R. , Coy Lawrence
Published: August 2010

There are three distinct processes by which upward-propagating gravity waves influence the large-scale dynamics and energetics of the middle atmosphere: (i) nonlocalized transport of momentum through wave propagation in three dimensions that remotely redistributes atmospheric momentum in both zonal and meridional directions from wave generation to wave dissipation regions; (ii) localized diffusive transport of momentum, heat, and tracers due to mixing induced by wave breaking; and (iii) localized transport of heat by perturbing wave structures due to dissipation that redistributes the thermal energy within a finite domain. These effects become most significant for breaking waves when momentum drag, eddy diffusion, and wave heating— the “breaking trinity”—are all imposed on the background state. This paper develops a 3D parameterization scheme that self-consistently includes the breaking trinity in large-scale numerical models. The 3D parameterization scheme is developed based on the general relationship between the wave action flux and the subgrid-scale momentum and heat fluxes developed by Zhu in 1987 and a mapping approximation between the wave source spectrum and momentum deposition distribution developed by Alexander and Dunkerton in 1999. For a set of given input wind and temperature profiles at each model grid, the parameterization scheme outputs the vertical profiles of the subgrid-scale force terms together with the eddy diffusion coefficients in the momentum and energy equations for a 3D background flow.
Saturn’s Northern Hemisphere Ribbon: Simulations and Comparison with the Meandering Gulf Stream
Authors: Sayanagi Kunio M. , Morales-Juberías Raúl , Ingersoll Andrew P.
Published: August 2010

Voyager observations of Saturn in 1980–81 discovered a wavy feature engirdling the planet at 47°N planetographic latitude. Its latitude coincides with that of an eastward jet stream, which is the second fastest on Saturn after the equatorial jet. The 47°N jet’s wavy morphology is unique among the known atmospheric jets on the gas giant planets. Since the Voyagers, it has been seen in every high-resolution image of this latitude for over 25 years and has been termed the Ribbon. The Ribbon has been interpreted as a dynamic instability in the jet stream. This study tests this interpretation and uses forward modeling to explore the observed zonal wind profile’s stability properties. Unforced, initial-value numerical experiments are performed to examine the nonlinear evolution of the jet stream. Parameter variations show that an instability occurs when the 47°N jet causes reversals in the potential vorticity (PV) gradient, which constitutes a violation of the Charney–Stern stability criterion. After the initial instability development, the simulations demonstrate that the instability’s amplitude nonlinearly saturates to a constant when the eddy generation by the instability is balanced by the destruction of the eddies. When the instability saturates, the zonal wind profile approaches neutral stability according to Arnol’d’s second criterion, and the jet’s path meanders in a Ribbon-like manner. It is demonstrated that the meandering of the 47°N jet occurs over a range of tropospheric static stability and background wind speed. The results here show that a nonlinearly saturated shear instability in the 47°N jet is a viable mechanism to produce the Ribbon morphology. Observations do not yet have the temporal coverage to confirm the creation and destruction of eddies, but these simulations predict that this is actively occurring in the Ribbon region. Similarities exist between the behaviors found in this model and the dynamics of PV fronts studied in the context of meandering western boundary currents in Earth’s oceans. In addition, the simulations capture the nonlinear aspects of a new feature discovered by the Cassini Visual and Infrared Mapping Spectrometer (VIMS), the String of Pearls, which resides in the equatorward tip of the 47°N jet. The Explicit Planetary Isentropic Coordinate (EPIC) model is used herein.
Baroclinic Waves with Parameterized Effects of Moisture Interpreted Using Rossby Wave Components
Authors: de Vries Hylke , Methven John , Frame Thomas H. A. , Hoskins Brian J.
Published: August 2010

A theoretical framework is developed for the evolution of baroclinic waves with latent heat release parameterized in terms of vertical velocity. Both wave–conditional instability of the second kind (CISK) and large-scale rain approaches are included. The new quasigeostrophic framework covers evolution from general initial conditions on zonal flows with vertical shear, planetary vorticity gradient, a lower boundary, and a tropopause. The formulation is given completely in terms of potential vorticity, enabling the partition of perturbations into Rossby wave components, just as for the dry problem. Both modal and nonmodal development can be understood to a good approximation in terms of propagation and interaction between these components alone. The key change with moisture is that growing normal modes are described in terms of four counterpropagating Rossby wave (CRW) components rather than two. Moist CRWs exist above and below the maximum in latent heating, in addition to the upper- and lower-level CRWs of dry theory. Four classifications of baroclinic development are defined by quantifying the strength of interaction between the four components and identifying the dominant pairs, which range from essentially dry instability to instability in the limit of strong heating far from boundaries, with type-C cyclogenesis and diabatic Rossby waves being intermediate types. General initial conditions must also include passively advected residual PV, as in the dry problem.
Finite-Amplitude Wave Activity and Diffusive Flux of Potential Vorticity in Eddy–Mean Flow Interaction
Authors: Nakamura Noboru , Zhu Da
Published: August 2010

An exact diagnostic formalism for finite-amplitude eddy–mean flow interaction is developed for barotropic and quasigeostrophic baroclinic flows on the beta plane. Based on the advection–diffusion–reaction equation for potential vorticity (PV), the formalism quantifies both advective and diffusive contributions to the mean flow modification by eddies, of which the latter is the focus of the present article. The present theory adopts a hybrid Eulerian–Lagrangian-mean description of the flow and defines finite-amplitude wave activity in terms of the areal displacement of PV contours from zonal symmetry. Unlike previous formalisms, wave activity is readily calculable from data and the local Eliassen–Palm relation does not involve cubic or higher-order terms in eddy amplitude. This leads to a natural finite-amplitude extension to the local nonacceleration theorem, as well as the global stability theorems, in the inviscid and unforced limit. The formalism incorporates mixing with effective diffusivity of PV, and the diffusive flux of PV is shown to be a sink of wave activity. The relationship between the advective and diffusive fluxes of PV and its implications for parameterization are discussed in the context of wave activity budget. If all momentum associated with wave activity were returned to the zonal-mean flow, a balanced eddy-free flow would ensue. It is shown that this hypothetical flow uREF is unaffected by the advective PV flux and is driven solely by the diffusive PV flux and forcing. For this reason, uREF, rather than the zonal-mean flow, is proposed as a diagnostic for the diffusive mean-flow modification. The formalism is applied to a freely decaying beta-plane turbulence to evaluate the contribution of the diffusive PV flux to the jet formation.
The Skill of ECMWF Medium-Range Forecasts during the Year of Tropical Convection 2008
Authors: Chakraborty Arindam
Published: August 2010

This study uses the European Centre for Medium-Range Weather Forecasts (ECMWF) model-generated high-resolution 10-day-long predictions for the Year of Tropical Convection (YOTC) 2008. Precipitation forecast skills of the model over the tropics are evaluated against the Tropical Rainfall Measuring Mission (TRMM) estimates. It has been shown that the model was able to capture the monthly to seasonal mean features of tropical convection reasonably. Northward propagation of convective bands over the Bay of Bengal was also forecasted realistically up to 5 days in advance, including the onset phase of the monsoon during the first half of June 2008. However, large errors exist in the daily datasets especially for longer lead times over smaller domains.

For shorter lead times (less than 4–5 days), forecast errors are much smaller over the oceans than over land. Moreover, the rate of increase of errors with lead time is rapid over the oceans and is confined to the regions where observed precipitation shows large day-to-day variability. It has been shown that this rapid growth of errors over the oceans is related to the spatial pattern of near-surface air temperature. This is probably due to the one-way air–sea interaction in the atmosphere-only model used for forecasting. While the prescribed surface temperature over the oceans remain realistic at shorter lead times, the pattern and hence the gradient of the surface temperature is not altered with change in atmospheric parameters at longer lead times. It has also been shown that the ECMWF model had considerable difficulties in forecasting very low and very heavy intensity of precipitation over South Asia. The model has too few grids with “zero” precipitation and heavy (>40 mm day−1) precipitation. On the other hand, drizzle-like precipitation is too frequent in the model compared to that in the TRMM datasets.

Further analysis shows that a major source of error in the ECMWF precipitation forecasts is the diurnal cycle over the South Asian monsoon region. The peak intensity of precipitation in the model forecasts over land (ocean) appear about 6 (9) h earlier than that in the observations. Moreover, the amplitude of the diurnal cycle is much higher in the model forecasts compared to that in the TRMM estimates. It has been seen that the phase error of the diurnal cycle increases with forecast lead time. The error in monthly mean 3-hourly precipitation forecasts is about 2–4 times of the error in the daily mean datasets. Thus, effort should be given to improve the phase and amplitude forecast of the diurnal cycle of precipitation from the model.
Roll Circulations in the Convective Region of a Simulated Squall Line
Authors: Bryan George H. , Rotunno Richard , Fritsch J. Michael
Published: August 2010

In high-resolution numerical simulations (using horizontal grid spacing less than ∼1 km), the convective region of squall lines will sometimes overturn as quasi-horizontal convective rolls. The authors study one case in detail using output from a simulation with 125-m grid spacing. The rolls have an average spacing of 3 km and are aligned parallel to the vertical wind shear. Individual convective cells often have long-lived, undiluted cores that entrain primarily on the sides of the rolls (i.e., between the roll updraft and downdraft). The following set of conditions is proposed for obtaining roll overturning: the formation of a moist absolutely unstable layer (MAUL); vertical shear of the horizontal wind within the MAUL; an environment without large-amplitude perturbations; and quasi-horizontal flow over the squall line’s surface-based cold pool.

Further insight is gained through a series of more idealized simulations wherein a specified MAUL is perturbed by analytic potential temperature perturbations. These simulations confirm classical studies based on linear analysis because the smallest perturbations grow fastest (with the exception of the very smallest scales that are affected by diffusion). The results also confirm that, with shear, updrafts oriented across the shear vector are inhibited by the shear. An explanation for the ∼3-km roll spacing also emerges from these simulations. The argument focuses on the perturbations that exist in the cold pool underneath the MAUL; they induce pressure fields that extend upward into the overlying MAUL. The perturbations with large horizontal scale have pressure fields that extend farther vertically and with a greater amplitude, and thus are more effective at initiating motions in the overlying MAUL. The convective scale that ultimately emerges within the MAUL is somewhere between two scales, whereby comparatively large scales are perturbed more strongly by perturbations in the cold pool, but the comparatively small scales grow faster.
Competence and Performance in Language Teaching
Authors: Richards Jack C.
Published: August 2010

In order to plan for the professional development of English language teachers, we need to have a comprehensive understanding of what competence and expertise in language teaching consists of. What essential skills, knowledge, values, attitudes and goals do language teachers need, and how can these be acquired? This paper seeks to explore these questions by examining ten core dimensions of skill and expertise in language teaching. These are: language proficiency, content knowledge, teaching skills, contextual knowledge, language teacher identity, learner-focussed teaching, specialized cognitive skills, theorizing from practice, joining a community of practice, and professionalism. Each construct will be examined, its contribution to teacher competence and performance illustrated, and implications discussed for the development of English language teachers and teacher education programmes.
The Nexus Between Direct Reading Instruction, Reading Theoretical Perspectives, and Pedagogical Practices of University of Swaziland Bachelor of Education Students
Authors: Sibanda Jabulani
Published: August 2010

The present study investigated the influence direct reading instruction had on university student teachers’ reading cognition and the influence their theoretical perspectives had on their pedagogical practices. The study was conducted on all the seven year 2 (2008) Bachelor of Education (primary) students at the University of Swaziland. Questionnaire items were used to determine the student teachers’ reading cognition before and after their study of a course ‘ Teaching Reading’ which the researcher taught. Document analysis in the form of detailed lesson plan analyses and lesson observations during the students’ teaching practice were the basis for the determination of the student teachers’ pedagogical practices. Follow-up interviews were conducted with the student teachers to establish the explanations for the consistencies and inconsistencies between the students’ theoretical perspectives and pedagogical practices. The study’s findings point to a causal relationship between direct instruction and reading theoretical orientation (on account of the shifts in reading orientation in the post-reading course questionnaire responses), which does not always hold for reading theoretical perspectives and pedagogical practices (where prevailing environmental factors often compel teachers to implement reading perspectives different from those they theoretically subscribe to most). The study recommends a paradigm shift from predominantly text-based reading conceptions to an infusion of other conceptions in classroom teaching, textbook writing and examination setting.
Beliefs about Language Learning: A Study of Malaysian Pre-Service Teachers
Authors: Wong Mary Siew-Lian
Published: August 2010

This paper presents the findings of a study to explore pre-service teachers’ beliefs about learning English and the stability of these beliefs over time. Participants were 25 pre-service teachers (11 males, 14 females) enrolled in a Bachelor of Education (TESL) programme. The Horwitz (1987) Beliefs about Language Learning Inventory (BALLI), a 34-item survey instrument, was used to collect data at the beginning of the second semester of Year One of their degree programme and also fourteen months later. Data analysis using frequency statistics showed that generally, pre-service teachers recognized the existence of foreign language aptitude and placed strong emphasis on excellent pronunciation, vocabulary acquisition, the benefits of practice, and an immersion approach to language learning. Most of them reported of being highly motivated to learn English and were positive about their ability to master the language. The findings also revealed that with the exception of slight change (ranging from 4% to 20%) to two items on language learning difficulty and six items on nature of language learning, most of their beliefs were stable over time.
Bases of Support for the EU’s Common Foreign and Security Policy: Gender, Attitudes toward Economic Integration, and Attachment to Europe
Authors: Kentmen Cigdem
Published: August 2010

The present study examines the determinants of individual support for the European Union’s (EU) Common Foreign and Security Policy (CFSP). Using data from the 2005 Eurobarometer survey, I specified models that test whether gender, subjective economic evaluations of the European integration, and attachment to Europe affect how EU citizens view the CFSP and a possible rapid European military force. My findings show that there is no gender gap in EU foreign policy attitudes: women are not less pacific than men. Individuals base their evaluations of the EU on their experience of the economic integration and their feelings for Europe.
Determinants of Coup d’État Events 1970—90: The Role of Property Rights Protection
Authors: Tusalem Rollin F.
Published: August 2010

Existing research on the political-economic determinants of coup d’état events has not explored the role of property rights protection in decreasing the likelihood of their global and regional incidence. Case studies confirm that the military institutions of the developing world began to represent elite class values that reacted adversely to state attempts at the redistribution of wealth and the expropriation of property after the 1970s. Thus far, no empirical analysis has tested the assertions made by these cases. Using Binary Times Series Cross-Section models from the period 1970—90, this article investigates the impact of the Contract Intensive Money ratio and International Country Risk Guide measures, which are tapped as property rights proxy variables, on decreasing the likelihood of a coup. The findings show that developing states that secure their property rights (as a function of these measures) are more likely to experience a decreased likelihood of a coup. The effect of property rights protection on the decreased likelihood of a coup shows statistical significance in Africa, Asia, and Latin America. The results hold true even when the global model is subjected to a sensitivity analysis where lagged coup events over a six-year period are included as a control variable.
The Heuristic Value of the Left—Right Schema in East Asia
Authors: Jou Willy
Published: August 2010

The semantics of left and right provide an efficient heuristic to understand and organize political information. Most studies on the left—right schema have focused on established democracies, but the anchoring function that it serves for party systems may be particularly relevant in new democracies where partisanship has not taken root. This article investigates the heuristic value of left and right in East Asian democracies by examining survey data from Japan, South Korea, Taiwan, and the Philippines. Data from Australia and New Zealand are also included for comparative purposes. These countries offer useful contrasts for hypotheses testing because they cover a wide range of democratic experiences and party-system stabilization. The following questions will be addressed: (1) Are publics in East Asian democracies familiar with the left—right dimension? (2) Can the publics locate the positions of political parties and consistently rank them on the left—right spectrum? (3) To what extent do the publics’ left—right self-placements affect their party preference? Left— right cognition, consistency of party rankings, and correlations between self-placements and attitudes toward parties for each of the six cases are presented and discussed in detail. Similarities and differences between older and newer democracies in patterns of cognition and party ranking are also discussed.