bluuebunny/crossref_metadata_2025 huggingface dataset:
A likely role for anoxygenic photosynthetic microbes in the formation of ancient stromatolites
Authors: BOSAK T. , GREENE S. E. , NEWMAN D. K.
Published: April 2007

Although cyanobacteria are the dominant primary producers in modern stromatolites and other microbialites, the oldest stromatolites pre‐date geochemical evidence for oxygenic photosynthesis and cyanobacteria in the rock record. As a step towards the development of laboratory models of stromatolite growth, we tested the potential of a metabolically ancient anoxygenic photosynthetic bacterium to build stromatolites. This organism, Rhodopseudomonas palustris, stimulates the precipitation of calcite in solutions already highly saturated with respect to calcium carbonate, and greatly facilitates the incorporation of carbonate grains into proto‐lamina (i.e. crusts). The appreciable stimulation of the growth of proto‐lamina by a nonfilamentous anoxygenic microbe suggests that similar microbes may have played a greater role in the formation of Archean stromatolites than previously assumed.
Niches of the pre‐photosynthetic biosphere and geologic preservation of Earth's earliest ecology
Authors: SLEEP NORMAN H. , BIRD DENNIS K.
Published: April 2007

The tree of terrestrial life probably roots in non‐photosynthetic microbes. Chemoautotrophs were the first primary producers, and the globally dominant niches in terms of primary productivity were determined by availability of carbon dioxide and hydrogen for methanogenesis and sulfite reduction. Methanogen niches were most abundant where CO2‐rich ocean water flowed through serpentinite. Black smoker vents from basalt supplied comparable amount of H2. Hydrogen from arc volcanoes supported a significant methanogenic niche at the Earth's surface. SO2from arc volcanoes reacted with organic matter and hydrogen, providing a significant surface niche. Methane ascended to the upper atmosphere where photolysis produced C‐rich haze and CO, and H escaped into space. The CO and C‐rich haze supported secondary surface niches. None of these ecologies were bountiful; less than 1% of the CO2vented by ridge axes, arcs, and metamorphism became organic matter before it was buried in carbonate. In contrast, a photosynthetic biosphere leaves copious amounts of organic carbon, locally concentrated in sediments. Black shales are a classic geologic biosignature for photosynthesis that can survive subduction and high‐grade metamorphism.
Transforming an Eighteenth‐Century Archive into a Twenty‐First‐Century Database: The Early California Population Project
Authors: Hackel Steven W. , Reid Anne Marie
Published: April 2007

The Early California Population Project is a database recently completed by research scholars at the Henry E. Huntington Library. The project is part of a wave of new databases that are opening up various regions of Early America for additional study; yet, unlike other databases, the Early California Population Project's records are overwhelmingly of Indians. The database offers new opportunities for historians and anthropologists interested in Indians, Catholic missions, Spanish soldiers and settlers, and family and community formation along the Spanish colonial frontier of North America between 1769 and 1850.
Construction of Skeletal Myoblast‐Based Polyurethane Scaffolds for Myocardial Repair
Authors: Siepe Matthias , Giraud Marie‐Noelle , Liljensten Elisabeth , Nydegger Urs , Menasche Philippe , Carrel Thierry , Tevaearai Hendrik T.
Published: April 2007

Abstract:  Intramyocardial transplantation of skeletal myoblasts augments postinfarction cardiac function. However, poor survival of injected cells limits this therapy. It is hypothesized that implantation of myoblast‐based scaffolds would result in greater cell survival. Rat skeletal myoblasts were seeded on highly porous polyurethane (PU) scaffolds (7.5 × 7.5 × 2.0 mm). The effect of several scaffold pretreatments, initial cell densities, and culture periods was tested by DNA‐based cell count and viability assessment. Seeded PU scaffolds were implanted on infarcted hearts and immunohistology was performed 4 weeks later. Precoating with laminin allowed the most favorable cell attachment. An initial inoculation with 5 × 106 cells followed by a 15‐day culture period resulted in optimal myoblast proliferation. Four weeks after their implantation in rats, numerous myoblasts were found throughout the seeded patches although no sign of differentiation could be observed. This myoblast seeding technique on PU allows transfer of a large number of living myoblasts to a damaged myocardium.
In Vitro Comparison of Peracetic Acid and Bleach Cleaning of Polysulfone Hemodialysis Membranes
Authors: Shao Jiahui , Wolff Susanne , Zydney Andrew L.
Published: April 2007

Abstract:  Dialyzer reuse has been employed throughout the history of hemodialysis, but the practice remains controversial. Many studies have found changes in the β2‐microglobulin clearance for reused dialyzers, but it is difficult to draw quantitative conclusions from the clinical data. The objective of this study was to quantitatively compare the effects of bleach and peracetic acid cleaning on the clearance and surface charge characteristics of Fresenius F80B polysulfone dialyzers (Fresenius Medical Care, Lexington, MA, USA). Clearance experiments were performed using urea, vitamin B12, and polydisperse dextrans, with data obtained before and after exposure to human plasma in an in vitro dialysis circuit. Dialyzers cleaned with peracetic acid had significantly lower clearance of the larger dextrans due to the presence of residual protein on or within the membrane. Bleach was able to remove this protein deposit, restoring the clearance characteristics, but there was a significant increase in the net negative charge of the membrane due to chemical reaction with the bleach. In addition, longer time exposure to bleach altered the membrane transport characteristics, increasing the solute clearance. These results provide important insights into the effects of bleach and peracetic acid on the properties of the F80B dialyzers.
Porous, Biphasic CaCO3‐Calcium Phosphate Biomedical Cement Scaffolds from Calcite (CaCO3) Powder
Authors: Tas A. Cuneyt
Published: April 2007

Calcite (CaCO3) is a geologically abundant material, which can be used as a starting material in producing biomedical scaffolds for clinical dental and orthopedic applications. Bone‐filling applications require porous, biocompatible, and resorbable materials. Commercially available CaCO3 powders were physically mixed, for 80–90 s, with an orthophosphoric acid (H3PO4) solution, which was partially neutralized to pH 3.2 by adding NaOH, to form biphasic, micro‐, and macroporous calcite‐apatitic calcium phosphate (Ap‐CaP) cement scaffolds of low strength. The resultant carbonated and Na‐doped Ap‐CaP phase in these scaffolds crystallographically and spectroscopically resembled calcium hydroxyapatite. Upon mixing CaCO3 powders and the setting solution, carbon dioxide gas was in situ generated and formed the pores. Thus formed scaffolds contained pores over the range of 20–750 μm. Scaffolds were also converted to single‐phase Ap‐CaP, without altering their porosity, by soaking them in 0.5 M phosphate buffer solutions at 80°C for 36 h in glass bottles. Soerensen's buffer solution was also shown to be able to convert the calcite powders into single‐phase Ap‐CaP powders upon soaking at 60–80°C. This robust procedure of synthesizing Ap‐CaP bioceramics is simple and economical.
Near‐Net‐Shape Fabrication of Ti3AlC2‐Based Composites
Authors: Yin Xiaowei , Travitzky Nahum , Greil Peter
Published: April 2007

A porous ceramic preform was fabricated by printing a powder blend of TiC, TiO2, and dextrin. The presintered preforms contained a bimodal pore size distribution with intra‐agglomerate pores (d50≈0.7 μm) and inter‐agglomerate pores (d50≈30 μm), which were subsequently infiltrated by aluminum melt spontaneously in argon above 1050°C. A redox reaction at 1400°C resulted in the formation of dense Ti–Al–O–C composites mainly composed of Ti3AlC2, TiAl3, Al, and Al2O3, which attained a bending strength of 320 MPa, a Young's modulus of 184 GPa, and a Vicker's hardness of 2.5 GPa.
The Strength and Hydrothermal Stability of Y‐TZP Ceramics for Dental Applications
Authors: Kosmač Tomaž , Dakskobler Aleš , Oblak Čedomir , Jevnikar Peter
Published: April 2007

Effects of dental grinding, sandblasting, fatigue, and aging on the biaxial flexural strength of yttria partially stabilized tetragonal zirconia ceramics were evaluated. Grinding lowers the mean strength and reliability under static and cyclic loading. In contrast, sandblasting provides a powerful tool for surface strengthening; it also hinders the propagation of the diffusion‐controlled transformation during exposure to aqueous environments. By introducing moderate porosity, a reasonable compromise between the mechanical strength and the elastic modulus has been achieved. Such biscuit‐sintered specimens also exhibited full hydrothermal stability. Novel experimental dental root posts were designed that exhibit certain advantages over the zirconia posts already in clinical use.
Brazing of Stainless Steel to Yttria‐Stabilized Zirconia Using Gold‐Based Brazes for Solid Oxide Fuel Cell Applications
Authors: Singh M. , Shpargel T. P. , Asthana R.
Published: April 2007

Two gold‐base active metal brazes (gold‐ABA and gold‐ABA‐V) were evaluated for oxidation resistance to 850°C, and used to join yttria‐stabilized zirconia (YSZ) to a corrosion‐resistant ferritic stainless steel for possible use in solid oxide fuel cells. Thermogravimetric analysis and optical microscopy and scanning electron microscopy coupled with energy‐dispersive spectroscopy were used to evaluate the braze oxidation behavior, and microstructure and composition of the YSZ/braze/steel joints. Both gold‐ABA and gold‐ABA‐V exhibited nearly linear oxidation kinetics at 850°C, with gold‐ABA‐V showing faster oxidation than gold‐ABA. Both brazes produced metallurgically sound YSZ/steel joints due to chemical interactions of Ti and V with the YSZ and steel substrates.
Fabrication and Characterization of Tubular Solid Oxide Fuel Cells
Authors: Sammes N. M. , Du Yanhai
Published: April 2007

Processes to fabricate tubular solid oxide fuel cells (SOFCs) using various electrolyte and electrode materials have been investigated. Single‐phase perovskite strontium‐ and magnesium‐doped lanthanum gallate (LSGM) was synthesized. Mechanical and thermal properties, and the cell performance of LSGM electrolyte fuel cells were studied and compared with yttria‐stabilized zirconia (YSZ) electrolyte systems. Paste extrusion was identified as a suitable method for high‐speed manufacture of the tubular support components. Procedures were developed to extrude dense, straight, round (OD: 2–4±0.1 mm), thin‐walled (0.2±0.02 mm) tubular LSGM and YSZ electrolytes, and porous anode or cathode support (5–20 mm OD, 0.5–2 mm wall thickness). The research systematically investigated developing a fabrication process, designing the extrusion die, the effects of formulation and process additives, and how to handle, dry, and sinter the extrudate. Dip coating, brush painting, vacuum infiltration, electrophoretic coating, and plasma spray were examined for applying thin films on the tubular support. The average three‐point bending strengths of extruded and sintered LSGM were determined to be 287, 195, 184, and 147 MPa at room temperature, 600°C, 800°C, and 1000°C, respectively. Room‐temperature burst strengths (average) of the tubular electrolytes made from YSZ and LSGM were 127 and 40 MPa, respectively. Room‐temperature bending strength and burst strength (average) of the as‐sintered NiO–YSZ anode were 300 and 100 MPa, respectively. The average thermal expansion coefficients of YSZ and LSGM were 10.18 × 10−6/°C and 11.01 × 10−6/°C, respectively, between room temperature and 800°C. The maximum power density at 800°C for a 220‐μm‐thick LSGM electrolyte was 460–482 mW/cm2, which is more than double the power density for YSZ cells (200–220 mW/cm2) at 850°C. Reducing LSGM thickness from 550 to 220 μm increased the maximum power densities by more than 30%. Repeatable cell power outputs per cell of 2.5 W at 800°C and 2.8 W at 850°C were obtained. The cell durability was evaluated during a 500‐h test. This comprehensive study intended to better understand the relationship between the materials, processing, manipulation of the microstructure, properties, and tubular SOFC performance.
Sealing Technology for Solid Oxide Fuel Cells (SOFC)
Authors: Singh Raj N.
Published: April 2007

A variety of seals such as metal–metal, metal–ceramic, and ceramic–ceramic are required for a functioning solid oxide fuel cells (SOFC). These seals must function at high temperatures between 600 and 900°C and in oxidizing and reducing environments of the fuels and air. Among the different type of seals, the metal–ceramic and ceramic–ceramic seals require significant attention, research, and development because the brittle nature of ceramics and glasses can lead to fracture and loss of seal integrity and functionality. This paper addresses the needs and possible approaches for high‐temperature ceramic–metal seals for SOFC and seals fabricated using some of these approaches. A new concept of self‐healing glass seals is proposed, developed, and used for making metal—glass–ceramic seals for potential application in SOFC in order to enhance the reliability and life of a cell. In this study, glasses displaying self‐healing behavior are investigated and used to fabricate seals. The performance of these seals under long‐term exposure at higher temperatures coupled with thermal cycling is characterized by leak tests. The self‐healing ability of these glass seals is also demonstrated by leak tests along with the long‐term performance.
Anode‐Supported Tubular Micro‐Solid Oxide Fuel Cell
Authors: Sarkar Partho , Yamarte Luis , Rho Hongsang , Johanson Lorne
Published: April 2007

A tubular anode‐supported “micro‐solid oxide fuel cell” (μSOFC) has been developed for producing high volumetric power density (VPD) SOFC systems featuring rapid turn on/off capability. An electrophoretic deposition (EPD)‐based, facile manufacturing process is being refined to produce the anode support, anode functional and electrolyte layers of a single cell. μSOFCs (diameter <5 mm) have two main potential advantages, a substantial increase in the electrolyte surface area per unit volume of a stack and also rapid start‐up. As fuel cell power is directly proportional to the active electrolyte surface area, a μSOFC stack can substantially increase the VPD of an SOFC device. A decrease in tube diameter allows for a reduction in wall thickness without any degradation of a cell's mechanical properties. Owing to its thin wall, a μSOFC has an extremely high thermal shock resistance and low thermal mass. These two characteristics are fundamental in reducing start‐up and turn‐off time for the SOFC stack. Traditionally, SOFC has not been considered for portable applications due to its high thermal mass and low thermal shock resistance (start‐up time in hours), but with μSOFCs' potential for rapid start‐up, new possibilities for portable and transportable applications open up.
Silver–Glass Composite for High Temperature Sealing
Authors: Deng Xiaohua , Duquette Jean , Petric Anthony
Published: April 2007

Silver–glass composites were investigated for high‐temperature sealing in fuel cells and sensors. The optimized composition exhibited good sealing integrity with a leak rate of less than 0.02 SCCM/cm of sealing length at 800°C, excellent thermal shock resistance, and self‐healing abilities between 800°C and room temperature.
Intermediate Temperature Reversible Fuel Cells
Authors: Elangovan Singaravelu , Hartvigsen Joseph J. , Frost Lyman J.
Published: April 2007

Electrolysis of water produces high‐purity hydrogen directly, with no need for additional clean‐up process. Efficiency and cost of electrolysis are favorable with high‐temperature steam electrolyzers where a portion of the required energy can be supplied as thermal energy. With the similarity in requirements, much of the materials and designs aspects for the high‐temperature electrolyzers have been derived from solid oxide fuel cell development. Lanthanum gallate electrolyte‐based cells were evaluated in fuel cell and electrolysis modes of operation. A modified nickel anode is shown to lower the reactivity with the gallate.
Implications of Evidence‐Centered Design for Educational Testing
Authors: Mislevy Robert J. , Haertel Geneva D.
Published: April 2007

Evidence‐centered assessment design (ECD) provides language, concepts, and knowledge representations for designing and delivering educational assessments, all organized around the evidentiary argument an assessment is meant to embody. This article describes ECD in terms of layers for analyzing domains, laying out arguments, creating schemas for operational elements such as tasks and measurement models, implementing the assessment, and carrying out the operational processes. We argue that this framework helps designers take advantage of developments from measurement, technology, cognitive psychology, and learning in the domains. Examples of ECD tools and applications are drawn from the Principled Assessment Design for Inquiry (PADI) project. Attention is given to implications for large‐scale tests such as state accountability measures, with a special eye for computer‐based simulation tasks.
Test Design with Cognition in Mind
Authors: Gorin Joanna S.
Published: April 2007

One of the primary themes of the National Research Council's 2001 book Knowing What Students Know was the importance of cognition as a component of assessment design and measurement theory (NRC, 2001). One reaction to the book has been an increased use of sophisticated statistical methods to model cognitive information available in test data. However, the application of these cognitive‐psychometric methods is fruitless if the tests to which they are applied lack a formal cognitive structure. If assessments are to provide meaningful information about student ability, then cognition must be incorporated into the test development process much earlier than in data analysis. This paper reviews recent advancements in cognitively‐based test development and validation, and suggests various ways practitioners can incorporate similar methods into their own work.
Commentary: Student Cognition, the Situated Learning Context, and Test Score Interpretation
Authors: La Marca Paul M.
Published: April 2007

Although it is assumed that student cognition contributes to student performance on achievement tests, it may be that current testing models lack the degree of specification necessary to warrant such inferences. With test score interpretations as the referent, the authors in this special issue address the role of student cognition in learning and educational measurement. The practicality of their recommendations is viewed through the filter of No Child Left Behind Act (NCLB) testing requirements. Commentary on the broader learning context is also shared. Although a focus on student cognition is an important one, the situational context within which learning occurs and tests are administered warrants consideration of a variety of social factors in order to fully specify the measurement construct and to interpret test scores meaningfully.
EVALUATION OF GLOBAL YIELD, COMPOSITION, ANTIOXIDANT ACTIVITY AND COST OF MANUFACTURING OF EXTRACTS FROM LEMON VERBENA (ALOYSIA TRIPHYLLA[L'HÉRIT.] BRITTON) AND MANGO (MANGIFERA INDICA L.) LEAVES
Authors: PEREIRA CAMILA G. , MEIRELES M. ANGELA A.
Published: April 2007

In this work, the global yields, composition and antioxidant activity (AA) of extracts from lemon verbena (Aloysia triphylla) and mango (Mangifera indica) leaves obtained by different separation processes were determined. Lemon verbena extracts were obtained by supercritical fluid extraction (SFE), while mango leaf extracts were obtained by SFE, low‐pressure solvent extraction (LPSE) and hydrodistillation. The extract's constituents were analyzed by thin‐layer chromatography, gas chromatography/mass spectrometry and gas chromatography/flame ionization detector. The AA of the extracts was evaluated by the coupled reaction of β‐carotene/linolenic acid. The cost of manufacturing (COM) was estimated for the SFE extracts. Higher global yields were obtained using SFE at 350 bar/45C (1.49%) for lemon verbena and LPSE (3.04%) for mango. The AAs of the extracts were larger than that of the β‐carotene for both plants. The minimum values of COM were U.S.$26.96 and 52.45/kg of extract for lemon verbena and mango, respectively.
SUPERCRITICAL FLUID EXTRACTION AND DETERMINATION OF LUTEIN IN HETEROTROPHICALLY CULTIVATED CHLORELLA PYRENOIDOSA
Authors: WU ZHENGYUN , WU SHIMIN , SHI XIANMING
Published: April 2007

Chlorella is a promising alternative resource of lutein, as it can be cultivated heterotrophically and efficiently in a fermentor. In this study, high density of Chlorella pyrenoidosa was achieved by fed‐batch cultivations. Lutein in Chlorella was extracted by supercritical fluid and was determined by high‐performance liquid chromatography and liquid chromatography‐mass spectrometry. The extraction degree of lutein reached 87.0% after 4‐h extraction under the optimized conditions of 50C, 25 MPa and modified CO2 with 50% ethanol. High purity of lutein could be obtained by supercritical fluid extraction with appropriate operation parameters. The whole process developed in this study may be useful for the commercial production of lutein.
INFLUENCE OF SAMPLE SIZE AND SHAPE ON TRANSPORT PARAMETERS DURING DRYING OF SHRINKING BODIES
Authors: RAHMAN NAJMUR , KUMAR SUBODH
Published: April 2007

An experimental investigation on the influence of sample size and shape on heat and mass transport parameters under natural convection air‐drying is presented. Potato cylinders with length of 0.05 m and thicknesses of 0.005, 0.008, 0.010 and 0.016 m, and circular slices with diameter of 0.05 m and thickness of 0.01 m were dried in a laboratory scale hot‐air cabinet dryer. Results indicate that each transport parameter exhibits a linear relationship with sample thickness. Convective heat and mass transfer coefficients (hcand hm) decreased whereas moisture diffusion coefficient (Deff) increased with increasing thickness. Considering no sample shrinkage effect in the parameter analysis, for the thickness range considered, the values of hcare found to be underestimated in the range of 29.0–30.6%, whereas those of hmand Deff are overestimated in the range of 33.7–38.0% and 75.9–128.1%, respectively. Using Levenberg–Marquardt algorithm for optimization, a correlation for Biot number for mass transfer (Bim) as a function of drying time and sample thickness is proposed. A close agreement was observed between dimensionless moisture contents predicted by this relation and those obtained from experiments for different sample thicknesses at drying air temperature of 60C. For the same thickness and drying conditions, circular slices caused an increase in each transport parameter significantly.
EFFECTS OF ADDED WEIGHTING AGENT AND XANTHAN GUM ON STABILITY AND RHEOLOGICAL PROPERTIES OF BEVERAGE CLOUD EMULSIONS FORMULATED USING MODIFIED STARCH
Authors: TAHERIAN ALI R. , FUSTIER PATRICK , RAMASWAMY HOSAHALLI S.
Published: April 2007

Stability of beverage emulsion is measured by the rate at which the emulsion creams, flocculates or coalesces, and is generally dependent on rheology of water phase, difference in specific gravities of the two phases and droplet size/distribution of the emulsion. The effects of weighting agents (sucrose acetate isobutyrate and brominated vegetable oil) and xanthan gum on modified starch‐based emulsions were evaluated in this study. Emulsion was formed by addition of 9% coconut oil, in the presence or absence of weighting agents, into the water phase containing modified starch at 10, 12 or 14% without or with the addition of 0.3% xanthan gum. Stabilities of emulsions were evaluated both in the concentrated form used for storage and dilute form used in beverages. The addition of xanthan gum into the water phase decreased the flow behavior index (n) from 0.88 down to 0.31 and increased elastic modulus (G′) over 20 times at elevated frequency (ω = 50 rad/s) and elevated the stability of the emulsion. The xanthan gum‐added emulsion had smaller particle size and demonstrated 14 and 5 times slower phase separation compared to the emulsions without or with the addition of weighting agents, respectively. When the elastic modulus was larger than the viscous modulus (G′ > G″), the emulsions demonstrated greater stability. In dilute beverage solutions, creaming was observed in the absence of xanthan gum.
EFFECT OF PROCESSING PARAMETERS ON THE TEMPERATURE AND MOISTURE CONTENT OF MICROWAVE‐BLANCHED PEANUTS
Authors: SCHIRACK A.V. , SANDERS T.H. , SANDEEP K.P.
Published: April 2007

Peanut blanching consists of heat application followed by abrasive removal of the seed coat. The use of a continuous microwave system for the blanching of peanuts has been proposed as a means of reducing processing time and energy costs compared to the traditional hot‐air, multizone oven. The purpose of this research was to characterize effective processing parameters for microwave blanching. The factors examined were the time of exposure in the microwave, use of increased airflow in the microwave applicator during processing and the initial moisture content (MC) of the peanuts. Processing treatments were differentiated by energy absorbed during processing, average and maximum internal temperature, loss in MC and blanchability. High blanchability resulted from higher process temperatures and greater loss in MC. Treatments exceeding 110C resulting in a final MC of 5.5% or below yielded blanchability percentages greater than the 85% industry standard. The time required to generate sufficient heat to dry peanuts for acceptable blanchability is greatly reduced by the use of microwave technology.
EXTRACTION OF VOLATILE OIL FROM CUMIN (CUMINUM CYMINUM L.) WITH SUPERHEATED WATER
Authors: EIKANI MOHAMMAD H. , GOLMOHAMMAD FERESHTEH , MIRZA MEHDI , ROWSHANZAMIR SOOSAN
Published: April 2007

A comparative study of superheated water extraction (SWE) with two conventional methods including hydrodistillation and Soxhlet extraction was performed on cumin (Cuminum cyminum L.). The effect of some superheated water parameters at 20 bar pressure on the essential oil extraction from 4 g cumin seeds such as temperatures from 100 to 175C, particle size at 0.25 and 0.50 mm, and flow rates at 2 and 4 mL/min were investigated. Separation and identification of the components were carried out by gas chromatography‐flame ionization detector and gas chromatography‐mass spectrometry. The best operating conditions for the SWE of C. cyminum L. were determined to be 150C temperature, 0.50 mm mean particle size and 4 mL/min flow rate for 3‐h extraction time. The SWE method resulted in a more valuable essential oil with respect to the oxygenated components.
Nurse practitioners in Canada: Beginnings, benefits, and barriers
Authors: Gould Odette N. , Johnstone Dusty , Wasylkiw Louise
Published: April 2007

Purpose: The goal of this qualitative study was to investigate the experiences of nurse practitioners (NPs) 1 year after they were first introduced to a mostly rural Canadian province.

Data sources: Qualitative analyses of individual 45‐min interviews with seven of the nine NPs in the province were carried out.

Conclusions: Three main themes of importance were identified. First, a nursing philosophy with a holistic approach was described as being clearly different from medical care. Second, difficulties and barriers encountered in the establishment of the profession in the province were described. Third, despite these barriers, a pioneering outlook characterized by a sense of excitement and pride in the work was expressed.

Implications for practice: For NPs to work effectively to reduce healthcare costs and increase access to health care, they need to be accepted by both the public and the other healthcare professionals. Moreover, it may be difficult for NPs to maintain their philosophy of care in the face of the expectations placed upon them.
The patient with Parkinson’s disease: Part I–Treating the motor symptoms; Part II–Treating the nonmotor symptoms
Authors: Snyder Charlene Hoffman , Adler Charles H.
Published: April 2007

Purpose: This two‐part article provides the nurse practitioner (NP) with information on the developments in the pathophysiology and expanded treatment options in the motor and nonmotor symptoms of Parkinson’s disease (PD). The discussion provides treatment strategies that may offer improved ability to manage the disabling symptoms of this neurodegenerative disorder.

Data sources: Review of scientific literature from PubMed search for English language articles on PD from 1998 to 2005 and books or chapters in textbooks published on the disease in the same time frame provided the data source for this article. The content reflects our clinical judgments and experience from clinical practice in the Movement Disorder Clinic at Mayo Clinic Arizona.

Conclusions: The high prevalence of the disease and important advances in its management means that the NP needs to have knowledge of the disorder and the combination of multiple treatment options available for both the motor and the nonmotor symptoms.

Implications for practice: PD is a progressive neurodegenerative disease affecting 1% of persons over the age of 60 in the United States. As prevalence increases with age, so does the need for early accurate diagnosis and proper treatment of the PD by the clinician. Advances in the treatment for the motor and nonmotor symptoms of PD provide the clinician with increased options to improve the patient’s quality of life.
X‐linked agammaglobulinemia in a 10‐year‐old child: A case study
Authors: Estrella Lissette , Foley Mary E. , Cunningham‐Rundles Charlotte
Published: April 2007

Purpose: To discuss the advanced practice nurse’s diagnosis and management of an unsuspected primary immunodeficiency (PI) disease, X‐linked agammaglobulinemia (XLA), in a child.

Data sources: Review of historical and current scientific literature, practice guidelines, and a case study.

Conclusions: While a diagnosis of XLA is most commonly made in the first 3 years of life, this case study presents a 10‐year‐old boy’s circuitous route to this diagnosis. A diagnosis of an immune defect should be considered for patients with chronic, recurrent, or unusual infections. For patients who lack immune globulins and antibodies, intravenous immune globulin, given monthly and continued throughout life, is the standard of care.

Implications for practice: Diagnosis of children and adults with primary immune deficiency diseases may be delayed if practitioners fail to find the root cause of recurrent infections. Nurses as patient advocates should recognize the need for a referral in clinical cases where immunodeficiency may not be suspected. Evaluation of the immune system is performed by a panel of blood tests. There is a need to increase awareness of PI, their manifestations, and treatment among nurses both at the bedside and in advanced practice settings.
Unipolar or bipolar depression? Improving diagnostic confidence with the adult patient
Authors: Ramsley Susan E.
Published: April 2007

Purpose: The purpose of this article is to inform advanced practice nurses in primary care about the differential diagnosis of bipolar disorder (BD), when depression is identified in the adult patient.

Data sources: Selected research and clinical articles.

Conclusions: Adult patients with BD are much more likely to seek treatment for depression than for mania or hypomania. Recognition of BD is improved when the primary care clinician is alerted to the factors indicating bipolarity and utilizes available screening tools.

Implications for practice: Misdiagnosis of a bipolar spectrum disorder delays proper treatment and precludes adequate management both pharmacologically and psychotherapeutically.
Cytoplasmic Extracts from Adipose Tissue Stromal Cells Alleviates Secondary Damage by Modulating Apoptosis and Promotes Functional Recovery Following Spinal Cord Injury
Authors: Kang Soo Kyung , Yeo Jee Eun , Kang Kyung Sun , Phinney Donald G.
Published: April 2007

Spinal cord injury (SCI) typically results from sustained trauma to the spinal cord, resulting in loss of neurologic function at the level of the injury. However, activation of various physiological mechanisms secondary to the initial trauma including edema, inflammation, excito‐toxicity, excessive cytokine release and apoptosis may exacerbate the injury and/or retard natural repair mechanisms. Herein, we demonstrate that cytoplasmic extracts prepared from adipose tissue stromal cells (ATSCs) inhibits H2O2‐mediated apoptosis of cultured spinal cord‐derived neural progenitor cells (NPCs) resulting in increased cell survival. The ATSC extracts mediated this effect by decreasing caspase‐3 and c‐Jun–NH2‐terminal kinase (SAPK/JNK) activity, inhibiting cytochrome c release from mitochondria and reducing Bax expression levels in cells. Direct injection of ATSC extracts mixed with Matrigel into the spinal cord immediately after SCI also resulted in reduced apoptotic cell death, astrogliosis and hypo‐myelination but did not reduce the extent of microglia infiltration. Moreover, animals injected with the ATSC extract showed significant functional improvement of hind limbs as measured by the BBB (Basso, Beattie and Bresnahan) scale. Collectively, these studies show a prominent therapeutic effect of ATSC cytoplasmic extracts on SCI principally caused by an inhibition of apoptosis‐mediated cell death, which spares white matter, oligodendrocytes and neurons at the site of injury. The ability of ATSC extracts to prevent secondary pathological events and improve neurologic function after SCI suggests that extracts prepared from autologous cells harvested from SCI patients may have clinical utility.
Congenital Glioblastoma: A Clinicopathologic and Genetic Analysis
Authors: Brat Daniel J. , Shehata Bahig M. , Castellano‐Sanchez Amilcar A. , Hawkins Cynthia , Yost Robert B. , Greco Claudia , Mazewski Claire , Janss Anna , Ohgaki Hiroko , Perry Arie
Published: April 2007

Congenital central nervous system (CNS) tumors are uncommon, accounting for 1% of all childhood brain tumors. They present clinically either at birth or within the first 3 months. Glioblastoma (GBM) only rarely occurs congenitally and has not been fully characterized. We examined clinicopathologic features and genetic alterations of six congenital GBMs. Tumors were seen by neuroimaging as large, complex cerebral hemispheric masses. All showed classic GBM histopathology, including diffuse infiltration, dense cellularity, GFAP‐positivity, high mitotic activity, endothelial proliferation and pseudopalisading necrosis. Neurosurgical procedures and adjuvant therapies varied. Survivals ranged from 4 days to 7.5 years; two of the three long‐term survivors received chemotherapy, whereas the three short‐term survivors did not. Paraffin‐embedded tissue sections were used for FISH analysis of EGFR, chromosomes 9p21 (p16/CDKN2A) and 10q ( PTEN/DMBT1); sequencing of PTEN and TP53; and immunohistochemistry for EGFR and p53. We uncovered 10q deletions in two cases. No EGFR amplifications, 9p21 deletions, or mutations of TP53 or PTEN were noted; however, nuclear p53 immunoreactivity was strong in 5/6 cases. Tumors were either minimally immunoreactive (n = 3) or negative (n = 3) for EGFR. We conclude that congenital GBMs show highly variable survivals. They are genetically distinct from their adult counterparts and show a low frequency of known genetic alterations. Nonetheless, the strong nuclear expression of p53 in these and other pediatric GBMs could indicate that p53 dysregulation is important to tumorigenesis.
THE ECONOMICS OF PLASTIC BAG LEGISLATION IN SOUTH AFRICA1
Authors: Hasson Reviva , Leiman Anthony , Visser Martine
Published: April 2007

In May 2003 South Africa introduced legislation intended to decrease plastic bag litter. It combined standards and price‐based economic tools in an attempt to reduce the public's demand for plastic bags. This paper analyses the short term effects of the legislation on bag demand. It also provides a background to these regulations and a theoretical overview. The assessment uses bag consumption data from four retailers, each representing a different consumer market. These are analysed, and respective price elasticities calculated. The results suggest that plastic bag demand is relatively price inelastic and imply that instruments utilising price alone, would have limited efficacy. However, the combination of standards and pricing successfully curbed plastic bag use in the short run. Further analysis suggests that the effectiveness of the legislation may be declining over time.
A MULTIVARIATE EVALUATION OF MAINSTREAM AND ACADEMIC DEVELOPMENT COURSES IN FIRST‐YEAR MICROECONOMICS
Authors: Smith Leonard , Edwards Lawrence
Published: April 2007

“There is no place for him [the Bantu] in the European community above the level of certain forms of labour. For that reason it is of no avail for him to receive a training, which has as its aim absorption in the European community, where he cannot be absorbed.” (Verwoerd, 1954, p. 24)

This paper analyses the impact of the University of Cape Town's first‐year microeconomics academic development course on performance in examinations. The paper makes two advances to existing empirical literature in this area. Firstly, we compare performance with a control group drawn from the mainstream economic course. Secondly, we evaluate performance in subsequent courses in first‐year macroeconomics and second‐year microeconomics. The results suggest that the academic development course has a major impact on students’ performance in the structured/essay questions, relative to the control group, in first‐ and second‐year microeconomics, and for the multiple‐choice questions in first‐year macroeconomics.

Matriculation results, mathematics, English first language, physical science and gender are also important determinants of performance.
ESTIMATING EXCHANGE RATE AND BILATERAL TRADE BALANCE RELATIONSHIPS: THE EXPERIENCE OF SUB‐SAHARAN AFRICAN COUNTRIES
Authors: Yol Marial Awou , Baharumshah Ahmad Zubaidi
Published: April 2007

This paper examines the effects of exchange rate changes on the bilateral trade balance of ten African countries vis‐à‐vis the US using annual data over period 1977‐2002. Both the Johansen and panel cointegration tests find cointegration among the series. The country FMOLS results show that real exchange rate depreciation improves the trade balance in six of ten countries in contrast to Tanzania in which it worsens the trade balance, with no effect found in Ghana, Morocco and Senegal. Foreign real income improves the trade balance in two countries but worsens it in another three. Finally, domestic real income negatively affects the trade balance in four countries but improves it in another three. The three‐panel coefficients are correctly signed and significant at the 1% level.
USING THE HIERARCHICAL LINEAR MODEL TO UNDERSTAND SCHOOL PRODUCTION IN SOUTH AFRICA
Authors: Gustafsson Martin
Published: April 2007

The emphasis placed in the existing South African school production function literature on better skilled teachers and better school management is discussed. Ordinary least squares and hierarchical linear production function models, using 2000 SACMEQ data, for the country and for a sub‐set of historically disadvantaged schools, are constructed. Ways of making the results more readable for policymakers are explored. The importance of physical infrastructure, textbook and nutrition budgets is highlighted by the models. Correct allocation of teaching and management time in schools, less learner repetition, and better teaching methodologies stand out as important school and classroom management imperatives.
CORRECTING FOR SAMPLING BIAS IN EDUCATION PRODUCTION FUNCTIONS
Authors: Parker Kudayja
Published: April 2007

Sample selectivity bias arises in the estimation of education production functions when the process of selecting the sample is not independent of the value of the dependent variable. In this study, the dependent variable was a student's retention of microeconomics knowledge after a period of 6 weeks following the final examination. Potential sampling bias arises from a student's decision to participate or not to participate in the research. Results obtained from the Heckman selection model indicated minor sampling bias. Student ability and the male dominance in economics performance were overestimated in the OLS model. Student effort was underestimated.
Proteinuria as a Therapeutic Target in Patients with Chronic Kidney Disease
Authors: Palmer Biff F.
Published: April 2007

Patients excreting large amounts of urinary protein, who are otherwise deemed to be optimally treated, should still be considered at high risk for renal disease progression. The observation that reductions in urinary protein excretion, in a graded fashion over a relatively short period of time, correlate with long-term preservation of renal function supports the idea of using urinary protein excretion as a guide to implementation of renoprotective therapies. The association between residual proteinuria and renal outcomes suggests that minimization of proteinuria is an important therapeutic goal in the management of proteinuric chronic kidney disease patients. This article reviews the evidence for using proteinuria as a target for the implementation of therapies shown to have renal protective effects.
Retrograde Neuron Tracing with Microspheres Reveals Projection of CGRP-Immunolabeled Vestibular Afferent Neurons to the Vestibular Efferent Nucleus in the Brainstem of Rats
Authors: Chi Fang-Lu , Jiao Yu , Liu Hong-Jian , Wang Jing , Shi Yu , Barr Jennifer J.
Published: April 2007

Objective: A new retrograde neuron-tracing technique with microspheres was used to explore the possible innervation of calcitonin gene-related peptide (CGRP)-immunolabeled vestibular afferent neurons in the vestibular efferent immunolabeled nucleus in the brainstem. Methods: 0.1 µl of 5% microfluorospheres was injected into the area of the vestibular efferent nucleus, which is located lateral to the genu of the facial nerve. CGRP immunohistochemistry was processed in serial sections of the brainstem at the facial nerve genu level. Double-labeled neurons with both CGRP immunoreactivity and microfluorospheres were examined with fluorescence and confocal laser microscopy. Results: Three types of labeled neurons were observed: (1) neurons only retrogradely microfluorosphere-labeled that were mainly located in the medial vestibular nucleus, lateral vestibular nucleus, superior vestibular nucleus and parvicellular reticular nucleus on the ipsilateral side of the injection; (2) neurons that were both immunolabeled with CGRP and also retrogradedly labeled with microfluorospheres, indicating that they are CGRP cells projecting to the area of vestibular efferent nucleus, these cells were mainly distributed in the superior vestibular nucleus and dorsal vestibular nucleus, and (3) cells only immunolabeled for CGRP that were scattered extensively in the brainstem. Conclusion: The presented methodical contribution demonstrates the suitability of fluorescein-labeled microspheres for retrograde neuronal tracing. The vestibular nuclei contain numerous afferent neurons that send projections to the vestibular efferent nucleus, some of which are CGRP cells. This afferent innervation provides morphological evidence that the vestibular efferent neurons receive input from the vestibular afferent neurons including CGRP cells. These vestibular primary CGRP afferent neurons may have an influence on vestibular efferent neurons. CGRP acts as an important co-transmitter or modulator in the afferent-mediated activity of vestibular efferent neurons, which in turn affect afferents in the vestibular end organs.
Interventional Electrophysiology and Cardiac Resynchronization Therapy
Authors: Burkhardt J. David , Wilkoff Bruce L.
Published: April 2007

Implantable devices have become a readily available option for patients with heart failure. Not only do these patients develop bradycardia and ventricular tachycardia, but their ventricular dysfunction can often improve with cardiac resynchronization therapy. However, this is a complex and rapidly developing clinical science for which the physician chooses techniques and selects patients on the basis of the results of clinical trials, clinical experience, and rapidly evolving tools. The results depend on the interplay of these complex variables. Placement of the left ventricular lead has forced the device physician to develop new skills and/or interdisciplinary relationships with physicians with vascular intervention, imaging, and surgical skills. Familiarity with the cardiac venous anatomy, occlusive venography, venoplasty, guide wire tools, guiding catheters, stenting, and new intracardiac visualization and magnetic intracardiac lead positioning tools are examples of just a few of the novel skills that are useful in the delivery of cardiac resynchronization therapy. Beyond implantation, these patients and devices require specialized follow-up with continued medical therapy and echo-guided adjustments of device programming. Finally, there are ongoing controversies and many as yet unanswered questions that are the subject of ongoing and planned clinical trials.
Changing Faces
Authors: Evans Andrea E.
Published: April 2007

As minority populations continue to grow, suburban school systems will bear a larger responsibility for educating students of color. Rapid demographic change may mean that students of color could walk into suburban schools ill prepared to address their academic and social needs. The focus of this study was to examine how and why several suburban high schools responded to demographic change in the ways they did. This multisite case study considered the policy and procedural changes that took place as growing numbers of African American students entered these schools. Interviews, documents, and archival data provided information on the programs, policies, and practices that schools modified and/or adopted in response to their growing African American population. This study suggests that racial meanings and interpretations affected issues of faculty efficacy and agency, school identity, and power and politics, which ultimately shaped school actions, beliefs, and decisions in response to demographic change.
Multicultural Concerns of Educators in the Western Cape Province of South Africa
Authors: Mentz Kobus , van der Walt Johannes L.
Published: April 2007

In the new democratic South Africa that emerged after 1994, educators are having to cope with the demands of multicultural situations that are developing in the former racially and ethnically segregated schools, and in the process striving for the equal treatment of the learners, the removal of discrimination and prejudice, the inculcation of respect, and an appreciation for diversity. In an empirical study to determine the extent to which educators harbor concerns about multiculturalism in their classrooms, a survey was done including 628 teachers in 13 multicultural, well-performing schools in the Western Cape Province of South Africa. It was found , inter alia, that educators have not been adequately prepared to meet the challenges confronting them in the increasingly multicultural schools in which they are teaching. They are, however, aware of the challenges posed by the new multicultural school environment and show real concern about dealing with them effectively.