bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and ring openings of cinnamate-derived N-unfunctionalised aziridines
Authors: Armstrong Alan , Ferguson Alexandra
Published: October 2012

tert-Butyl cinnamates are aziridinated with high trans-selectivity by an N–N ylide generated in situ from N-methylmorpholine and O-diphenylphosphinyl hydroxylamine. The resulting N-unfunctionalised aziridines are shown to be versatile synthetic building blocks that undergo highly selective ring-opening reactions with a wide range of nucleophiles.
OUT-OF-PLANE VIBRATIONS OF CURVED NONPRISMATIC BEAM UNDER A MOVING LOAD
Authors: Meissner Małgorzata , Ruta Piotr
Published: October 2012

The forced vibrations of a curved-in-plane nonprismatic beam with a variable cross section and any curvature, generated by a load moving at a variable velocity are analyzed. Approximation with Chebyshev series and a generalized eigentransformation were used to solve the system of the partial differential equations describing the considered problem. The derived equations in their final form enable one to determine displacement and rotation functions for any beam. In order to verify the derived formulas the eigenproblem solution (used in the eigentransformation method) was compared with the one obtained by the finite element method.
Managing Challenging Situations in Practice: A New Program Developed to Meet the Specific Needs of Nursing Students
Authors: Lyng Colette , Cocoman Angela , Ward Emer , McGrath Mary
Published: October 2012

Health care workers, nurses, and nursing students face a high risk of workplace aggression and violence. Potential adverse consequences oblige health care providers and educators to protect the safety of everyone in the health care setting. It is broadly agreed that health care personnel should receive education and training in the management of work-related aggression and violence. However, there are no training programs designed to meet the specific needs of nursing students. In the absence of Irish or international policies or guidelines, an evidence-based training program for first-year undergraduate nursing students was developed. Its focus was to enable nursing students to recognize potential problems and develop the skills necessary to appropriately handle situations that may arise during their clinical nursing practice. This article outlines the development and delivery of a training program for first-year nursing students, entitled Managing Challenging Situations in Practice.
Clinical Liaison Nurse Model in a Community Hospital: A Unique Academic–Practice Partnership That Strengthens Clinical Nursing Education
Authors: Lovecchio Catherine P. , DiMattio Mary Jane K. , Hudacek Sharon
Published: October 2012

The necessity to help baccalaureate nursing students transition to clinical practice in a health care environment governed by change has compelled nurse educators to investigate alternative clinical instruction models that nurture academic–practice partnerships and facilitate student clinical learning. This article describes an academic–practice partnership in a community hospital using the Clinical Liaison Nurse (CLN) model as a link between students and clinical faculty and reports results of a quasi-experimental study that compared perceptions of the clinical learning environment between students participating in the CLN model (experimental group) and those in a traditional, instructor-led clinical model (control group). Students assigned to the CLN model had statistically significantly higher individualization, satisfaction, and task orientation scores on the Clinical Learning Environment Inventory. The findings provide evidence that academic–practice partnerships can be successful in community hospital settings and enhance students’ perceptions in the clinical learning environment.
Dose and Sequence of Simulation and Direct Care Experiences Among Beginning Nursing Students: A Pilot Study
Authors: Schlairet Maura C. , Fenster Mark J.
Published: October 2012

Accumulating suggests human patient simulation is an effective instructional technique. Simulated clinical experiences may be a reasonable substitute for direct care experiences. Educators and regulators need to know what mix of simulation and direct care promotes learning and how these experiences can be designed to help nursing students achieve essential outcomes. The goal of this pilot study was to identify a model to promote development of clinical judgment among beginning nursing students. Principles related to types of learning and practice (blocked by type or interleaved) were used in exploring simulation and direct care design schema. Using a 50% interleaved simulation design schema, robust clinical judgment scores and positive perceptions of learning were identified among beginning students participating in a basic nursing concepts and skills course. Further study is warranted to determine whether this schema is effective in other nursing courses or with novice-level students from diverse health care disciplines.
Surgical Outcomes Following Repair of Traumatic Retinal Detachments in Cognitively Impaired Adolescents With Self-Injurious Behavior
Authors: Sisk Robert A. , Motley W. Walker , Yang Michael B. , West Constance E.
Published: October 2012

Purpose:

To assess anatomic outcomes following repair of traumatic retinal detachment (RD) among a cohort of cognitively impaired adolescents with self-injurious behaviors.

Methods:

Main outcome measures in this retrospective, consecutive, interventional case series were retinal attachment and postoperative complications.

Results:

Complete retinal reattachment was initially achieved in all 9 eyes of 9 patients. Six (67%) eyes had chronic RD at initial presentation, and 7 (78%) patients had limited vision from inoperable RD in the fellow eye. Proliferative vitreoretinopathy led to recurrent RD in 4 (44%) eyes at a mean of 2.7 months. Final total or partial retinal attachment was achieved in 6 (67%) and 3 (33%) eyes, respectively, with a mean of 1.7 procedures over a mean follow-up of 22.4 months. Silicone oil emulsification led to progressive glaucoma in 4 (50%) of 8 eyes in which it was used, requiring silicone oil exchange (2 eyes) or removal (2 eyes). Recurrent RD developed in both eyes from which silicone oil was removed despite prior retinal anatomic stability for more than 6 months.

Conclusion:

Cognitively impaired adolescents with self-injurious behaviors typically presented with severe visual impairment from chronic traumatic RD in one or both eyes. Despite initial anatomic success, formation of proliferative vitreoretinopathy and further ocular trauma from continued self-injurious behaviors led to a high rate of recurrent RD. Long-term silicone oil tamponade may prevent recurrent RD in this challenging scenario but is associated with vision loss from progressive glaucoma and corneal decompensation.
Spontaneous Subluxation of Iris-Claw Aphakic Intraocular Lens Causing Complications in Two Children
Authors: Ong Hon Shing , Subash Malavika , Adams G. G. W.
Published: October 2012

Many surgeons consider implantation of iris-claw intraocular lenses a favorable option for pediatric aphakic eyes with poor capsular support. The authors present two children who had spontaneous subluxation of such lenses resulting in complications that required explantation. These cases highlight the potential sight-threatening complications of such intraocular lenses.
Corneal Higher Order Aberrations After LASIK for High Myopia With a Fast Repetition Rate Excimer Laser, Optimized Ablation Profile, and Femtosecond Laser–assisted Flap
Authors: Vega-Estrada Alfredo , Alió Jorge L. , Mosquera Samuel Arba , Moreno Luis J.
Published: October 2012

PURPOSE:

To evaluate corneal higher order aberrations (HOAs) after LASIK for the correction of high myopia using a new generation of excimer laser (500-Hz repetition rate) and optimized ablation profiles.

METHODS:

Retrospective consecutive study including 29 eyes from 17 patients (age range: 24 to 61 years) with high levels of myopia (spherical equivalent refraction ⩾8.50 diopters). All cases underwent LASIK using the sixth-generation Amaris (SCHWIND eye-tech-solutions) excimer laser and flap creation with the IntraLase (Abbott Medical Optics) femtosecond laser. Postoperative changes in corneal HOAs and corneal asphericity were analyzed during 6-month follow-up.

RESULTS:

Significant improvement in uncorrected distance visual acuity and spherical equivalent was observed (
P
<.01). Corrected distance visual acuity did not change after surgery (
P
=.37). Significant increases in corneal root-mean-square (RMS) HOA, RMS spherical aberration (SA), and RMS coma were observed 6 months after surgery (
P
<.01). Corneal asphericity for the 4.5-mm (Q45) and 8-mm (Q8) corneal diameter also increased significantly during the postoperative period (
P
<.01). Significant correlations were found between postoperative RMS HOA and RMS SA and RMS coma (r
2
=0.375,
P
=0.000 and r
2
=0.596,
P
=.000, respectively). Linear regression analysis showed a significant relationship between postoperative Q45 and preoperative pachymetry and treatment optical zone (R
2
=0.24,
P
<.05). A correlation was also found between postoperative Q8 and preoperative sphere and treatment ablation zone (R
2
=0.459,
P
<.006).

CONCLUSIONS:

A significant induction of corneal HOAs still exists with the latest generation S
chwind
excimer laser. Linear regression analysis will help predict postoperative asphericity obtained when using LASIK for the correction of high myopia.
Photoactivated Riboflavin Treatment of Infectious Keratitis Using Collagen Cross-linking Technology
Authors: Price Marianne O. , Tenkman Lawrence R. , Schrier Amilia , Fairchild Kelly M. , Trokel Stephen L. , Price Francis W.
Published: October 2012

PURPOSE:

To evaluate riboflavin/ultraviolet-A (UVA) as an adjunct treatment for infectious keratitis.

METHODS:

This prospective, dual-center, interventional case series included cases of infectious keratitis that were treated by instilling riboflavin 0.1% solution for 30 minutes to saturate the cornea, followed by exposure to 365-nm UVA light (3 mW/cm
2
) for 15 to 45 minutes, with continued instillation of riboflavin. Eyes continued on standard antibiotic treatment. The primary outcome measures were the times to resolution of the infiltrate and the epithelial defect.

RESULTS:

Forty patients aged 14 to 86 years were enrolled. Seven (18%) eyes had a previous keratoplasty. Bacterial species were identified in 24 eyes, fungal in 7, protozoan in 2, viral in 1, and no organism in 6. The maximum infiltrate diameter ranged from 1 to 12 mm and the epithelial defect diameter was 0 to 8 mm before treatment. In 6 cases (2 bacterial, 3 fungal, and 1 without growth), the keratitis did not resolve successfully and the eye received a penetrating keratoplasty (PK). In 1 eye with prior PK, the infection resolved following treatment, but a regraft was required to address perforation of the PK incision.

CONCLUSIONS:

Riboflavin/UVA should be avoided in eyes with prior herpes simplex but otherwise posed no obvious safety risk in this series and appeared to be most effective when the infection depth was limited. The success rate was higher for bacterial infections than fungal infections. Randomized studies against antibiotics alone are needed to further evaluate efficacy.
Regional Biomechanical Properties of Human Sclera After Cross-linking by Riboflavin/Ultraviolet A
Authors: Wang Mengmeng , Zhang Fengju , Qian Xiuqing , Zhao Xu
Published: October 2012

PURPOSE:

To evaluate the biomechanical difference of human scleral collagen cross-linking (CXL) by comparing different riboflavin-instilling methods and different cross-linked regions (equatorial and posterior sclera).

METHODS:

Fifteen donor human eyes were randomly divided into five groups. One group, in which CXL was not applied, was designated as the control group. In the remaining four groups, 0.1% riboflavin solution was instilled on the scleral surface for 5, 10, 20, or 30 minutes, respectively, followed by 30 minutes of ultraviolet A irradiation. The equatorial and posterior scleral strips in each eye were dissected. Stress–strain measurements of all scleral strips were performed by a biomaterial tester. Young modulus was calculated at 8% strain. Data of the stress and Young modulus in different regions and groups were compared using one-way analysis of variance.

RESULTS:

Under a 1 mm/minute stretching, the sclera exhibited an exponential stress–strain behavior. The stress and modulus of equatorial and posterior sclera after CXL gradually increased with riboflavin instillation before surgery. No statistical difference was noted in the modulus between 20 and 30 minutes riboflavin infiltration after CXL (
P
>.05). At the same strain levels, equatorial sclera with and without CXL exhibited higher stress and Young modulus than that of posterior sclera.

CONCLUSIONS:

Equatorial and posterior human sclera may be enhanced by CXL with riboflavin/ultraviolet A irradiation. Equatorial scleral CXL may be a good choice for the treatment of progressive myopia. Because of its safety and efficacy, 20 minutes of riboflavin infiltration before CXL is recommended.
Occupational Therapists and Observation: What are You Looking At?
Authors: MacKenzie Diane E. , Westwood David A.
Published: October 2012

Visual observation is a fundamental skill underlying all occupational performance assessments in occupational therapy. The purpose of this study was to determine whether eye movement patterns differ between occupational therapists and non-healthcare professionals during observation of static images portraying a client post-stroke (domain-specific content) or naturalistic scenes (domain-irrelevant content). Ten licensed occupational therapists (OT group) and 10 participants matched for age, gender, and education level (NonOT group) completed the study. Participants viewed two counterbalanced blocks of 10 images (scene and stroke) under the pretext of preparing for a memory test. The OT group differed in the viewing strategies during observation and in how they directed their eyes (higher frequency of fixations, shorter fixation durations, and increased saccade count) for domain-specific and domain-irrelevant images alike. Observation patterns used by occupational therapists are presumably related to top-down influences that are not necessarily related to domain-specific knowledge but perhaps to general experience with performing assessments using observational methods.
Partial Differential Hamiltonian Systems
Authors: Vitagliano Luca
Published: October 2012

We define partial differential (PD in the following), i.e., field theoretic analogues ofHamiltonian systems on abstract symplectic manifolds and study their main properties, namely, PD Hamilton equations, PD Noether theorem, PD Poisson bracket, etc. Unlike the standard multisymplectic approach to Hamiltonian field theory, in our formalism, the geometric structure (kinematics) and the dynamical information on the “phase space” appear as just different components of one single geometric object.
Optimization of parameters on material removal rate in micro-WEDG process
Authors: Periyanan PR , Natarajan U , Elango A
Published: October 2012

The micro-electrical discharge machining (micro-EDM) process has proved to be an appropriate nonconventional machining method for manufacturing accurate and complex three dimensional structural micro-parts and micro-tools which are difficult to be produced by conventional machining processes. The accuracy and the repeatability of the μEDM process are still highly dependent on the μWEDG process. In this work, an orthogonal array, signal to noise (S/N) ratio and Pareto analysis of variance (ANOVA) are employed to analyze the effect of the micro-WEDG parameters such as feed rate, capacitance and voltage on MRR. This paper focuses on the Taguchi technique for the optimization in micro-WEDG process to achieve maximum metal removal rate (MRR) considering the feed rate, capacitance and voltage as the cutting parameters. Based on the experimental result and analysis it is concluded that medium feed rate, high value of capacitance and voltage such combination of optimized parameters gives high value of MRR (0.39mg/min). The experimental result shows that the most influential parameter on the MRR is feed rate, capacitance and voltage. Also from the verification experiment it is concluded that Taguchi technique is suitable to solve the above said problem.
Prediction of the weld pool geometry of TIG arc welding by using fuzzy logic controller
Authors: Narang HK , Singh UP , Mahapatra MM , Jha PK
Published: October 2012

The present paper describes fuzzy logic simulation of tungsten inert gas welding (TIG) process to predict the weldment macrostructure zones' shape profile characteristics. The prediction of the weld pool geometry together with the shape of the heat affected zone (HAZ) was accomplished taking into account of TIG welding process parameters such as arc traverse speed, welding current and arc length. Structural steel plates of 8 mm thickness were used for the experiments. Full factorial design of experiment methodology was followed while selecting the input process parameters (control factors). These control factors were having three levels. The TIG weld pool geometry profiles' (boundaries of thermal cycle zones) like the weld bead reinforcement, penetration and heat affected zones were the responses from the experiment. A series of 27 experiments were carried out for collecting the data. The experimental data were then used for building a fuzzy logic model to predict the effects of control factors on the responses. A graphical mapping scheme was employed for the graphical representation of the macrostructure zones' shape profiles including that of HAZ. The model was also tested for a number of test cases to establish it's adequacy. The fuzzy logic modeling technique employed in the present investigation can be used for online prediction of the TIG weldment shape profiles. The methodology adopted in the present investigation indicated adequacy of fuzzy logic model for predicting the TIG weld-pool geometry and HAZ.
The effect of powder metallurgy process parameters on mechanical properties of micro and nano-iron powder
Authors: Delavari M , Salarvand A , Rahi A , Shahri F
Published: October 2012

The ever-increasing development of applying the iron pieces made by powder metallurgy in car industries and other usages depends on making pieces with high density and consequently acceptable physical and mechanical properties. Regarding the effect of decrease in the powder bits’ size on improvement of the mechanical characteristics and on decrease in the temperature of sinter, the experiments on the pure iron powder with the bits’ size of 5, 45, 63 micron in which 20% of iron nanopowder was added to the powder with the bits’ size of 45 micron, have been studied. Mere iron nanopowder also was applied for experiments. Pieces are compacted under 300-850 MPa and lubricants by0.4 and 0.6 percent of the total weight was mixed with the powders. Various amounts of sintering time and sintering temperature were considered for the sintering of the samples. The survey suggested that applying micro powders resulted in an increase in the linear density and the strength at the relatively high temperatures and high keeping times. Sintering temperature and shrinkage has declined considerably with the decrease in the powder size and as a result the strength increases. High strength for products made by smaller powders under high pressures and low sintering temperatures using lubricated frame wall are obtained. SEM pictures from the fracture junctions of the samples show the decrease in porosity due to the close impact of the smaller powder size.
Evaluation of a new middle-lower tropospheric CO2 product using data assimilation
Authors: Tangborn A. , Strow L. L. , Imbiriba B. , Ott L. , Pawson S.
Published: October 2012

Abstract. Atmospheric CO2 retrievals with peak sensitivity in the mid- to lower troposphere from the Atmospheric Infrared Sounder (AIRS) have been assimilated into the Global Modeling and Assimilation Office (GMAO) constituent assimilation system for the period 1 January 2005 to 31 December 2006. A corresponding model simulation, using identical initial conditions, circulation, and CO2 boundary fluxes was also completed. The analyzed and simulated CO2 fields are compared with surface measurements globally and aircraft measurements over North America. Surface level monthly mean CO2 values show a marked improvement due to the assimilation in the Southern Hemisphere, while less consistent improvements are seen in the Northern Hemisphere. Mean differences with aircraft observations are reduced at all levels, with the largest decrease occurring in the mid-troposphere. The difference standard deviations are reduced slightly at all levels over the ocean, and all levels except the surface layer over land. These initial experiments indicate that the retrieved channel contains useful information on CO2 in the middle to lower troposphere. However, the benefits of assimilating these data are reduced over the land surface, where concentrations are dominated by uncertain local fluxes and where the observation density is quite low. Away from these regions, the study demonstrates the power of the data assimilation technique for evaluating data that are not co-located, in that the improvements in mid-tropospheric CO2 by the sparsely distributed partial-column retrievals are transported by the model to the fixed in-situ surface observation locations in more remote areas.
High temporal and spatial variability of dissolved oxygen and pH in a nearshore California kelp forest
Authors: Frieder C. A. , Nam S. H. , Martz T. R. , Levin L. A.
Published: October 2012

Abstract. Predicting consequences of ocean deoxygenation and ocean acidification for nearshore marine ecosystems requires baseline dissolved oxygen (DO) and carbonate chemistry data that are both high-frequency and high-quality. Such data allow accurate assessment of environmental variability and present-day organism exposure regimes. In this study, scales of DO and pH variability were characterized over one year in a nearshore kelp forest ecosystem in the Southern California Bight. DO and pH were strongly, positively correlated, revealing that organisms on this upwelling shelf are not only exposed to low pH but also to low DO. The dominant scale of temporal DO and pH variability occurred on semidiurnal, diurnal and event (days–weeks) time scales. Daily ranges in DO and pH at 7 m water depth (13 mab) could be as large as 220 μmol kg−1 and 0.36 units, respectively. Sources of pH and DO variation include photosynthesis within the kelp forest ecosystem, which can elevate DO and pH by up to 60 μmol kg−1 and 0.1 units over one week following the intrusion of high-density, nutrient-rich water. Accordingly, highly productive macrophyte-based ecosystems could serve as deoxygenation and acidification refugia by acting to elevate DO and pH relative to surrounding waters. DO and pH exhibited greater spatial variation over a 10 m increase in water depth (from 7 to 17 m) than along a 5 km stretch of shelf in a cross-shore or alongshore direction. Over a three-month time period, mean DO and pH at 17 m water depth were 168 μmol kg−1 and 7.87, respectively. These values represent a 35% decrease in mean DO and 37% increase in [H+] relative to near-surface waters. High-frequency variation was also reduced at depth. The mean daily range in DO and pH was 39% and 37% less, respectively, at 17 m water depth relative to 7 m. As a consequence, the exposure history of an organism is largely a function of its depth of occurrence within the kelp forest. With knowledge of local alkalinity conditions and high-frequency temperature, salinity, and pH data, we estimated pCO2 and calcium carbonate saturation states with respect to calcite and aragonite (Ωcalc and Ωarag) for the La Jolla kelp forest at 7 m and 17 m water depth. pCO2 ranged from 246 to 1016 μatm, Ωcalc was always supersaturated, and Ωarag was undersaturated at the beginning of March for five days when pH was less than 7.75 and DO was less than 115 μmol kg−1. These findings raise the possibility that the benthic communities along eastern boundary current systems are currently acclimatized and adapted to natural, variable, and low DO and pH. Still, future exposure of coastal California populations to even lower DO and pH may increase as upwelling intensifies and hypoxic boundaries shoal, compressing habitats and challenging the physiological capacity of intolerant species.
Comment on: "Possible source of ancient carbon in phytolith concentrates from harvested grasses" by G. M. Santos et al. (2012)
Authors: Sullivan L. A. , Parr J. F.
Published: October 2012

Abstract. Santos et al. (2012) address the important issue that 14C dating of the carbon occluded in silica phytoliths (PhytOC) isolated from contemporary plant materials can produce ages that are incompatible, being often several kyr older, with both their known recent origin and the 14C age of the bulk plant material. In their article, Santos et al. (2012) propose that the anomalously old 14C carbon dates of PhytOC from harvested plant materials are based on plants taking up "old" dissolved soil carbon to the plant by roots during nutrient uptake. They then propose that this old soil-derived carbon is subsequently partitioned from the general plant biomass into either the silica phytoliths they produce, or as recalcitrant organic matter elsewhere in the plant. We suggest that the full data available for PhytOC 14C dating does not support this hypothesis. Santos et al. (2012) also address the important issue of contamination of PhytOC by general plant biomass material that can occur with procedures that incompletely extract phytoliths. Whilst we agree that such contamination needs to be avoided when examining the nature of PhytOC, we also point out that the converse problem, i.e. removal of PhytOC by over-vigorous extraction procedures, can also have important adverse consequences.
Carbon sources in the Beaufort Sea revealed by molecular lipid biomarkers and compound specific isotope analysis
Authors: Tolosa I. , Fiorini S. , Gasser B. , Martín J. , Miquel J. C.
Published: October 2012

Abstract. Molecular lipid biomarkers (hydrocarbons, alcohols, sterols and fatty acids) and compound specific isotope analysis of suspended particulate organic matter (SPM) and surface sediments of the Mackenzie Shelf and slope (Southeast Beaufort Sea, Arctic Ocean), were studied in summer 2009. The concentrations of the molecular lipid markers, characteristic of known organic matter sources, were grouped and used as proxies to evaluate the relative importance of fresh algal, detrital algal, fossil, C3 terrestrial plants, bacterial and zooplankton material in the sedimentary organic matter (OM). Fossil and detrital algal contributions were the major fractions of the freshwater SPM from the Mackenzie River with ~34% each of the total molecular biomarkers. Fresh algal, C3 terrestrial, bacterial and zooplanktonic components represented much lower percentages, 17, 10, 4 and < 1%, respectively. In marine SPM from the Mackenzie slope, the major contributions were fresh and detrital algal components (> 80%) with a minor contribution of fossil and C3 terrestrial biomarkers. Characterization of the sediments revealed a major sink of refractory algal material mixed with some fresh algal material, fossil hydrocarbons and a small input of C3 terrestrial sources. In particular, the sediments from the shelf and at the mouth of the Amundsen Gulf presented the highest contribution of detrital algal material (60–75%) whereas those from the slope contained the highest proportion of fossil (40%) and C3 terrestrial plant material (10%). Overall, considering that the detrital algal material is marine derived, autochthonous sources contributed more than allochthonous sources to the OM lipid pool. Using the ratio of an allochthonous biomarker (normalized to total organic carbon, TOC) found in the sediments to those measured at the river mouth water, we estimated that the fraction of terrestrial material preserved in the sediments accounted for 30–40% of the total carbon in the inner shelf sediments, 17% in the outer shelf and Amundsen Gulf and up to 25% in the slope sediments.
Marine denitrification rates determined from a global 3-dimensional inverse model
Authors: DeVries T. , Deutsch C. , Rafter P. A. , Primeau F.
Published: October 2012

Abstract. A major impediment to understanding long-term changes in the marine nitrogen (N) cycle is the persistent uncertainty about the rates, distribution, and sensitivity of its largest fluxes in the modern ocean. We use a global 3-dimensional ocean circulation model to obtain the first estimate of marine denitrification rates that is maximally consistent with available observations of nitrate deficits and the nitrogen isotopic ratio of ocean nitrate. We find a global rate of marine denitrification in suboxic waters and sediments of 120–240 Tg N yr−1, which is lower than most other recent estimates. The difference stems from the ability to represent the 3-D spatial structure of suboxic zones, where denitrification rates of 50–77 Tg N yr−1 result in up to 50% depletion of nitrate. This depletion reduces the effect of local isotopic enrichment on the rest of the ocean, allowing the N isotope ratio of oceanic nitrate to be achieved with a sedimentary denitrification rate about 1.3–2.3 times that of suboxic zones. This balance of N losses between sediments and suboxic zones is shown to obey a simple relationship between isotope fractionation and the degree of nitrate consumption in the core of the suboxic zones. The global denitrification rates derived here suggest that the marine nitrogen budget is likely close to balanced.
Air quality modelling using the Met Office Unified Model: model description and initial evaluation
Authors: Savage N. H. , Agnew P. , Davis L. S. , Ordóñez C. , Thorpe R. , Johnson C. E. , O'Connor F. M. , Dalvi M.
Published: October 2012

Abstract. The on-line air quality model AQUM (Air Quality in the Unified Model) is a limited-area forecast configuration of the Met Office Unified Model which uses the UKCA (UK Chemistry and Aerosols) sub-model. AQUM has been developed with two aims: as an operational system to deliver regional air quality forecasts and as a modelling system to enable air quality studies to be conducted to inform policy decisions relating to emissions controls. This paper presents a description of the model and the methods used to evaluate the performance of the forecast system. Results are presented of evaluation studies conducted for a year-long period of operational forecast trials and several past cases of poor air quality episodes. To place the model performance in context we compare AQUM ozone forecasts with those of another forecasting system, the MACC ensemble, for a 5-month period. The results demonstrate that AQUM has a large dynamic range of modelled ozone levels and has a good level of responsiveness to elevated ozone episode conditions – a characteristic which is essential for forecasting poor air quality episodes. An analysis of the variation of model skill with forecast lead-time is presented and the insights this provides to the relative sources of error in air quality modelling are discussed.
Multi-satellite rainfall sampling error estimates – a comparative study
Authors: Itkin M. , Loew A.
Published: October 2012

Abstract. This study focus is set on quantifying sampling related uncertainty in the satellite rainfall estimates. We conduct observing system simulation experiment to estimate sampling error for various constellations of Low-Earth orbiting and geostationary satellites. There are two types of microwave instruments currently available: cross track sounders and conical scanners. We evaluate the differences in sampling uncertainty for various satellite constellations that carry instruments of the common type as well as in combination with geostationary observations. A precise orbital model is used to simulate realistic satellite overpasses with orbital shifts taken into account. With this model we resampled rain gauge timeseries to simulate satellites rainfall estimates free of retrieval and calibration errors. We concentrate on two regions, Germany and Benin, areas with different precipitation regimes. Our results show that sampling uncertainty for all satellite constellations does not differ greatly depending on the area despite the differences in local precipitation patterns. Addition of 3 hourly geostationary observations provides equal performance improvement in Germany and Benin, reducing rainfall undersampling by 20–25% of the total rainfall amount. Authors do not find a significant difference in rainfall sampling between conical imager and cross-track sounders.
Evaluation of Release-05 GRACE time-variable gravity coefficients over the ocean
Authors: Chambers D. P. , Bonin J. A.
Published: October 2012

Abstract. The latest release of GRACE (Gravity Recovery and Climate Experiment) gravity field coefficients (Release-05, or RL05) are evaluated for ocean applications. Data have been processed using the current methodology for Release-04 (RL04) coefficients, and have been compared to output from two different ocean models. Results indicate that RL05 data from the three Science Data Centers – the Center for Space Research (CSR), GeoForschungsZentrum (GFZ), and Jet Propulsion Laboratory (JPL) – are more consistent among themselves than the previous RL04 data. Moreover, the variance of residuals with the output of an ocean model is 50–60% lower for RL05 data than for RL04 data. A more optimized destriping algorithm is also tested, which improves the results slightly. By comparing the GRACE maps with two different ocean models, we can better estimate the uncertainty in the RL05 maps. We find the standard error to be about 1 cm (equivalent water thickness) in the low- and mid-latitudes, and between 1.5 and 2 cm in the polar and subpolar oceans, which is comparable to estimated uncertainty for the output from the ocean models.
Chaotic variability of the meridional overturning circulation on subannual to interannual timescales
Authors: Hirschi J. J.-M. , Blaker A. T. , Sinha B. , Coward A. , de Cuevas B. , Alderson S. , Madec G.
Published: October 2012

Abstract. Observations and numerical simulations have shown that the meridional overturning circulation (MOC) exhibits substantial variability on sub- to interannual timescales. This variability is not fully understood. In particular it is not known what fraction of the MOC variability is caused by processes such as mesoscale ocean eddies and internal waves which are ubiquitous in the ocean. Here we analyse twin experiments performed with a global ocean model at eddying (1/4°) and non-eddying (1°) resolutions. The twin experiments are forced with the same surface fluxes for the 1958 to 2001 period but start from different initial conditions. Our results show that on subannual to interannual timescales a large fraction of MOC variability directly reflects variability in the surface forcing. Nevertheless, in the eddy-permitting case there is an initial condition dependent MOC variability (hereinafter referred to as "chaotic" variability) of several Sv (1 Sv = 106 m3 s−1) in the Atlantic and the Indo-Pacific. In the Atlantic the chaotic MOC variability represents up to 30% of the total variability at the depths where the maximum MOC occurs. In comparison the chaotic MOC variability is only 5–10% in the non-eddying case. The surface forcing being identical in the twin experiments suggests that mesoscale ocean eddies are the most likely cause for the increased chaotic MOC variability in the eddying case. The exact formation time of eddies is determined by the initial conditions which are different in the two accordance with and as a consequence the mesoscale eddy field is decorrelated in the twin experiments. In regions where eddy activity is high in the eddy-permitting model, the correlation of sea surface height variability in the twin runs is close to zero. In the non-eddying case in contrast, we find high correlations (0.9 or higher) over most regions. Looking at the sub- and interannual MOC components separately reveals that despite the amplitude of the chaotic variability being larger on subannual than on interannual timescales, the ratio of chaotic to total MOC variability is larger on interannual than on subannual timescales.
Accelerated contributions of Canada's Baffin and Bylot Island glaciers to sea level rise over the past half century
Authors: Gardner A. , Moholdt G. , Arendt A. , Wouters B.
Published: October 2012

Abstract. Canadian Arctic glaciers have recently contributed large volumes of meltwater to the world's oceans. To place recently observed glacier wastage into a historical perspective and to determine the region's longer-term (~50 years) contribution to sea level, we estimate mass and volume changes for the glaciers of Baffin and Bylot Islands using digital elevation models generated from airborne and satellite stereoscopic imagery and elevation postings from repeat airborne and satellite laser altimetry. In addition, we update existing glacier mass change records from GRACE satellite gravimetry to cover the period from 2003 to 2011. Using this integrated approach, we find that the rate of mass loss from the region's glaciers increased from 11.1 ± 3.4 Gt a−1 (271 ± 84 kg m−2 a−1) for the period 1963–2006 to 23.8 ± 6.1 Gt a−1 (581 ± 149 kg m−2 a−1) for the period 2003–2011. The doubling of the rate of mass loss is attributed to higher temperatures in summer with little change in annual precipitation. Through both direct and indirect effects, changes in summer temperatures accounted for 70–98% of the variance in the rate of mass loss, to which the Barnes Ice Cap was found to be 1.7 times more sensitive than either the Penny Ice Cap or the region's glaciers as a whole. This heightened sensitivity is the result of a glacier hypsometry that is skewed to lower elevations, which are shown to have a higher mass change sensitive to temperature compared to glacier surfaces at higher elevations. Between 2003 and 2011 the glaciers of Baffin and Bylot Islands contributed 0.07 ± 0.02 mm a−1 to sea level rise accounting for 16% of the total contribution from glaciers outside of Greenland and Antarctica, a rate much higher than the longer-term average of 0.03 ± 0.01 mm a−1 (1963 to 2006).
Variability of light transmission through Arctic land-fast sea ice during spring
Authors: Nicolaus M. , Petrich C. , Hudson S. R. , Granskog M. A.
Published: October 2012

Abstract. The amount of solar radiation transmitted through Arctic sea ice is determined by the thickness and physical properties of snow and sea ice. Light transmittance is highly variable in space and time since thickness and physical properties of snow and sea ice are highly heterogeneous on variable time and length scales. We present field measurements of under-ice irradiance along repeated (March, May, June 2010) transects under un-deformed land-fast sea ice at Barrow, Alaska. The objective was to quantify seasonal evolution and spatial variability of light transmittance through snow and sea ice. Along with optical measurements, snow depth, sea ice thickness, and freeboard were recorded, and ice cores were analyzed for Chlorophyll a and particulate matter. Our results show that snow cover variability prior to onset of snow melt may cause as much spatial variability of relative light transmittance as the contrast of ponded and white ice during summer. In both instances, a spatial variability of up to three times above and below the mean was measured. In addition, we found a thirtyfold increase of light transmittance as a result of partial snowmelt. Hence, the seasonal evolution of transmittance through sea ice exceeded the spatial variability. Nevertheless, more comprehensive under-ice radiation measurements are needed for a more generalized and large-scale understanding of the under-ice energy budget for physical, biological, and geochemical applications.
An Overview of the Methodological Approach to the in Vitro Study of Anti-Infective Biomaterials
Authors: Campoccia Davide , Cangini Ilaria , Selan Laura , Vercellino Marco , Montanaro Lucio , Visai Livia , Arciola Carla Renata
Published: October 2012

Biomaterial-associated infections have an enormous impact in terms of morbidity of the patients and costs to national health systems. Perioperative antibiotics and aseptic procedures have not proved sufficient to eradicate the occurrence of this type of infections which often lead to devastating effects. Adjunctive strategies for preventing the establishment of infections are increasingly being centered on the development of new biomaterials with anti-infective properties. The creation of new anti-infective biomaterials can be obtained by alternative approaches oriented to achieve either bacteria-repellent surfaces or bioactive surfaces expressing self-sterilizing properties when not even able to treat preexisting infections in the surrounding tissues. Here, we offer a short overview of the currently available in vitro methods that can be used to investigate and assess the performance of anti-infective biomaterials, with special emphasis on those whose mechanism of action is based on bacteria-repellent surfaces.
Immune Defense against S. Epidermidis Biofilms: Components of the Extracellular Polymeric Substance Activate Distinct Bactericidal Mechanisms of Phagocytic Cells
Authors: Meyle Eva , Brenner-Weiss Gerald , Obst Ursula , Prior Birgit , Hänsch G. Maria
Published: October 2012

Bacteria, organized in biofilms, are a common cause of relapsing or persistent infections and the ultimate cause of implant-associated osteomyelitis. Bacterial biofilms initiate a prominent local inflammatory response with infiltration of polymorphonuclear neutrophils (PMN), the main protagonists of the local innate host defense against bacteria. In our previous work we found that PMN recognize and adhere to biofilms, and that phagocytosis and degranulation of bactericidal substances, such as lactoferrin, were initiated. In contrast to the situation with planktonic bacteria, opsonization of biofilms with immunoglobulin and complement was not required for PMN activation, suggesting that biofilms contain signaling components for PMN. In the present study we identified in the bacteria-free extracellular substance of Staphylococcus epidermidis biofilms protein fractions that activated PMN in vitro.
Facebook and the Liberal Arts
Authors: Moore Andrew
Published: October 2012

This essay argues that the liberal arts must play a role in explaining the origins and consequences of social communications technologies. Once we recognize their function and comprehend their impact on communities, we may consider how best to incorporate social networking and related technologies into a twenty-first-century liberal arts curriculum.
Selling Students on the Character of Liberal Arts: A Benefit of Worldview Awareness in Education?
Authors: Newell Ted
Published: October 2012

Durkheim, the sociologist and education professor, said that the personality developed by a form of literary study was contrary to genuinely Christian character. Provoked by this insight, I explore whether a Christian university's reliance on classical liberal arts education might be working against its desires for the character of graduates.
Differences in Fruit Size, Postharvest Pathology and Phytochemicals between Irvingia gabonensis and Irvingia wombolu
Authors: Etebu Ebimieowei
Published: October 2012

Irvingia (bush mango) species are economically important trees, but studies aimed at their prospect for domestication did not take into account the potential differences between members of the Genus. Hence fruit size, postharvest pathology and phytochemicals of I. gabonensis and I. wombolu were studied. Results showed that whilst the mean weight, length, width and thickness of fruits of I. gabonensis were 125.08g, 60.85mm, 62.66mm and 56.78mm, respectively, those obtained from I. wombolu were 86.08g, 54.23mm, 54.09mm and 50.97mm, respectively. Difference in brownish-black rot fruit disease between the two Irvingia species was not significant (P=0.05), but disease severity increased correspondingly with increase in storage days. Four genera of fungi (Aspergillus, Penicillium, Rhizopus and Mucor) were isolated from fruits of both Irvingia species, and I. wombolu was found to sustain a significantly lower fungal population (7.76E+07 cfu) than I. gabonensis (1.05E+08 cfu). High fungal population led to a correspondingly high severity of brownish-black rot disease. Fruits of both Irvingia species possessed all five phytochemicals (alkaloids, flavonoids, saponins, tannins and glucosides). However, whilst both species had the same amounts of flavonoids and glycosides, I. wombolu possessed relatively higher amounts of alkaloids, saponins and tannins than I. gabonensis. I. wombolu may be the preferred choice if domestication would be based on phytochemicals. In like manner, I. gabonensis may be the preferred choice for domestication if taste, weight and size of fruits were the parameters of interest.
Cell Encapsulating Biomaterial Regulates Mesenchymal Stromal/Stem Cell Differentiation and Macrophage Immunophenotype
Authors: Cantu David Antonio , Hematti Peiman , Kao Weiyuan John
Published: October 2012

Bone marrow mesenchymal stromal/stem cell (MSC) encapsulation within a biomatrix could improve cellular delivery and extend survival and residence time over conventional intravenous administration. Although MSCs modulate monocyte/macrophage (Mø) immunophenotypic properties, little is known about how such interactions are influenced when MSCs are entrapped within a biomaterial. Furthermore, the impact of the cell-encapsulating matrix on MSC multipotency and on Møs, which infiltrate biomaterials, remains poorly understood. Here we elucidate this three-way interaction. The Mø immunophenotype and MSC differentiation were examined with regard to established and experimental collagen-based biomaterials for MSC entrapment. Tumor necrosis factor-α secretion was acutely inhibited at 4 days. MSCs cocultured with Møs demonstrated attenuated chondrocyte differentiation, whereas osteoblast differentiation was enhanced. Adipocyte differentiation was considerably enhanced for MSCs entrapped within the gelatin/polyethylene glycol-based matrix. A better understanding of the effect of cell encapsulation on differentiation potency and immunomodulation of MSCs is essential for MSC-based, biomaterial-enabled therapies.
Concise Review: The Potential of Stromal Cell-Derived Factor 1 and Its Receptors to Promote Stem Cell Functions in Spinal Cord Repair
Authors: Jaerve Anne , Schira Jessica , Müller Hans Werner
Published: October 2012

Transplanted stem cells provide beneficial effects on regeneration/recovery after spinal cord injury (SCI) by the release of growth-promoting factors, increased tissue preservation, and provision of a permissive environment for axon regeneration. A rise in chemokine stromal cell-derived factor 1 (SDF-1/CXCL12) expression levels in central nervous system (CNS) injury sites has been shown to play a central role in recruiting transplanted stem cells. Although technically more challenging, it has been shown that after SCI few endogenous stem cells are recruited via SDF-1/CXCR4 signaling. Evidence is accumulating that increasing SDF-1 levels at the injury site (e.g., by exogenous application or transfection methods) further enhances stem cell recruitment. Moreover, SDF-1 might, in addition to migration, also influence survival, proliferation, differentiation, and cytokine secretion of stem cells. Here, we discuss the experimental data available on the role of SDF-1 in stem and progenitor cell biology following CNS injury and suggest strategies for how manipulation of the SDF-1 system could facilitate stem cell-based therapeutic approaches in SCI. In addition, we discuss challenges such as how to circumvent off-target effects in order to facilitate the transfer of SDF-1 to the clinic.