bluuebunny/crossref_metadata_2025 huggingface dataset:
Conceptual design of a medium size flying wing
Authors: Martínez-Val R , Pérez E , Alfaro P , Pérez J
Published: February 2007

Flying wings are one of the most promising concepts regarding the ever-increasing air traffic demand. Furthermore, they help improving economic efficiency and are environmentally friendly, both in terms of emissions and noise. In the first place, the paper deals about the initial design of a medium size C-type flying wing, of the 300-seat class, showing that the aircraft is operationally efficient, and can beat conventional airplanes of similar capacity. It specifically exhibits some considerable gains in field and cruise performances. Second, the paper addresses the potential of some emerging technologies, such as laminar flow control, vectored thrust, and active stability, which provide additional improvements and allow the simplification of the original configuration to a U-type arrangement. A preliminary assessment of emergency evacuation is included.
Study of the effects of wing sweep on the aerodynamic performance of a blended wing body aircraft
Authors: Siouris S , Qin N
Published: February 2007

This article presents a study of the effects of wing sweep on the aerodynamic performance of a blended wing body (BWB) aircraft that is based on an aerodynamically optimized design with a fixed planform and pitching moment constraint. Sixteen BWB geometries with varying wing sweep angles ranging from −40° (forward sweep) to 55° sweep were evaluated, while keeping the aerofoil profiles and twist distribution unchanged from the original optimized geometry. This gives some insight into the effects of one of the key planform design parameters.

Numerical simulations were carried out using Euler solutions of the flow field with adaptive unstructured grids. Grid sensitivity studies were carried out, along with grid adaptation, on all geometries for solution accuracy. Results show that within 10° −55° sweep, there is significant variation in the lift-to-drag ratio ( LID), whereas for sweep values from −40° to 10°, the L/D ratio remained relatively constant. To maintain the design lift for varying wing sweep, the angle of attack of the aircraft needs to be changed. It was found that this variation followed an approximately parabolic curve, with a minimum incidence of 4.91° at 25° wing sweep. Furthermore, it was seen that the coefficient of moments versus the sweep angle varied almost linearly for all geometries under investigation.
Re-design of the Exeter V40 long-stem femoral component for ease of removal
Authors: Tevelen G A , Pearcy M J , Crawford R W
Published: February 2007

Clinical experience shows that removal of the Exeter long-stem femoral component (220 mm, 240 mm, 260 mm) of total hip arthroplasty is extremely difficult, often requiring splitting of the femur. To identify the reason for this, measurements of stem geometry and force required to pull the stems out of the cement mantle were conducted on three original Exeter long-stem and one standard femoral components. All implants required an initial force of approximately 4 kN for release from the cement. The long-stem components then required much larger forces and hence much higher expenditure of energy to pull them clear of the cement. This was attributed to the reverse taper seen on the nominally cylindrical distal section of the long-stem components. Following re-design of the manufacturing process to ensure the taper continued to the implant's distal tip, four further implants were tested. These demonstrated the requirement for initial cement release but then required no further energy expenditure similar to the standard stem. This study clearly demonstrated that the original difficulty in removing these long stems was owing to the manufacturing process resulting in a reverse taper on the distal stem. The adoption of recommended manufacturing changes to ensure the taper continues to the distal tip removed this difficulty.
A vortex pump-based optically-transparent microfluidic platform for biotech and medical applications
Authors: Lei Kin Fong , Law Wing Cheung , Suen Yick-Keung , Li Wen J , Yam Yeung , Ho Ho Pui , Kong Siu-Kai
Published: February 2007

This paper reports an automated polymer based microfluidic analysis system integrated with a surface plasmon resonance (SPR) biosensor that demonstrates the detection of specific binding of biomolecules and that qualitatively monitors cell adhesion on the sensor surface. Micropumps, microchannels, and an SPR biosensor were integrated into a single polymer (PMMA) based microfluidic system. The integrated system has been studied for its potential applications in bio-molecules detection and drugs discovery. Two experiments, (1) monitoring the reaction between the BSA-BSA antibody, and (2) monitoring the activities of living cells in the presence or absence of trypsin in a RPMI-1640 medium, were conducted to show the biomedical application capability. Because SPR based bio-detection requires optically transparent substrates, PMMA is a potential replacement for glass and silicon-glass in microfluidic systems, if bio-compatibility and low-cost are desired. Hence, our work has shown the feasibility of commercializing an SPR based bio-medical/chemical analysis system in the near future.
The development of a novel Bio-MEMS filtration chip for the separation of specific cells in fluid suspension
Authors: Prince M , Ma X , Docker P , Ward M , Prewett P
Published: February 2007

In the clinical/microbiological laboratory there are currently several ways of separating specific cells from a fluid suspension. Conventionally cells can be separated based on size, density, electrical charge, light-scattering properties, and antigenic surface properties. Separating cells using these parameters can require complex technologies and specialist equipment. This paper proposes new Bio-MEMS (microelectromechanical systems) filtration chips manufactured using deep reactive ion etching (DRIE) technology that, when used in conjunction with an optical microscope and a syringe, can filter and grade cells for size without the requirement for additional expensive equipment. These chips also offer great versatility in terms of design and their low cost allows them to be disposable, eliminating sample contamination. The pumping mechanism, unlike many other current filtration techniques, leaves samples mechanically and chemically undamaged.

In this paper the principles behind harnessing passive pumping are explored, modelled, and validated against empirical data, and their integration into a microfluidic device to separate cells from a mixed population suspension is described. The design, means of manufacture, and results from preliminary tests are also presented.
Exergy destruction minimization of an irreversible Carnot refrigeration cycle
Authors: Su Y-F , Chen C-K
Published: February 2007

In this paper, exergy destruction minimization has been carried out for an irreversible Carnot refrigeration cycle. The rates of destroyed exergy in various portion of this physical model are derived. The goal of exergy destruction minimization is to minimize the rate of total destroyed exergy of the system. By defining the recovery factor during power input process and introducing an irreversibility coefficient of the system, the optimum cycle temperatures in the isothermal cooling process and the isothermal heating process are obtained. The optimum values of cycle cooling rate, coefficient of performance of the system, and total destroyed exergy rate are derived simultaneously. The influences of various parameters on these optimum values are studied by numerical calculation. The results show that the exergy destruction minimization method is important and effective for the design of an irreversible Carnot refrigeration cycle.
Hypertonic Saline Treatment of Cystic Fibrosis
Authors: Taylor Lisa M , Kuhn Robert J
Published: February 2007

Objective:

To review the literature concerning the use of hypertonic saline (HS) in patients with cystic fibrosis and explain the rationale for its use.

Data Sources:

A MEDLINE search was conducted through February 2007. Search terms included hypertonic saline, mucociliary clearance, cystic fibrosis, and human DNASE 1 protein. Additional data were identified through subsequent bibliographic reviews.

Study Selection And Data Extraction:

All articles in English identified from the data sources were evaluated. Pertinent studies using HS in patients with cystic fibrosis were included in the analysis.

Data Synthesis:

Cystic fibrosis is caused by a deficiency in the cystic fibrosis transmembrane regulator gene, resulting in reduced chloride secretion and excessive sodium absorption. The most significant changes are seen in the airway lumen of the lungs. HS has been shown to improve mucociliary clearance versus placebo. A short-term efficacy trial showed a modest and variable increase in forced expiratory volume in 1 second (FEV1) over a 2 week period (15.0 ± 16.0% from baseline vs 2.8 ± 13.1% with HS 6% and NaCI 0.9%, respectively; p = 0.004). A long-term efficacy trial of either HS 7% or NaCI 0.9% twice daily for 48 weeks has shown a modest sustained improvement in FEV1 and a significantly increased exacerbation-free survival rato (76% vs 62% for HS 7% and NaCI 0.9%, respectively; p = 0.03).

Conclusions:

HS preceded by a bronchodilator is an inexpensive, safe, effective additional therapy in cystic fibrosis patients with stable lung function. Its use has been associated with a modest improvement in lung function and reduced frequency of pulmonary exacerbations.
Response Anticipation and Response Conflict: An Event-Related Potential and Functional Magnetic Resonance Imaging Study
Authors: Fan Jin , Kolster Rachel , Ghajar Jamshid , Suh Minah , Knight Robert T. , Sarkar Ranjeeta , McCandliss Bruce D.
Published: February 2007

Response anticipation and response conflict processes are supported by executive control. However, few neuroimaging studies have attempted to study the relationship between these two processes in the same experimental session. In this study, we isolated brain activity associated with response anticipation (after a cue to prepare vs relax) and with response conflict (responding to a target with incongruent vs congruent flankers) and examined the independence and interaction of brain networks supporting these processes using event-related potentials (ERPs) and functional magnetic resonance imaging. Response anticipation generated a contingent negative variation ERP that correlated with shorter reaction times, and was associated with activation of a thalamo-cortico-striatal network, as well as increased gamma band power in frontal and parietal regions, and decreased spectral power in theta, alpha, and beta bands in most regions. Response conflict was associated with increased activation in the anterior cingulate cortex (ACC) and prefrontal cortex of the executive control network, with an overlap in activation with response anticipation in regions including the middle frontal gyrus, ACC, and superior parietal lobule. Although the executive control network showed increased activation in response to unanticipated versus anticipated targets, the response conflict effect was not altered by response anticipation. These results suggest that common regions of a dorsal frontoparietal network and the ACC are engaged in the flexible control of a wide range of executive processes, and that response anticipation modulates overall activity in the executive control network but does not interact with response conflict processing.
Spatial Representations of Hippocampal CA1 Neurons Are Modulated by Behavioral Context in a Hippocampus-Dependent Memory Task
Authors: Griffin Amy L. , Eichenbaum Howard , Hasselmo Michael E.
Published: February 2007

Although it is well known that hippocampal neurons code spatial information, it is less clear how these spatial representations are influenced by memory demands, especially in hippocampus-dependent tasks. Recently, our laboratory has demonstrated that hippocampal spatial representations are influenced by mnemonic factors in a T-maze continuous alternation task. Another unique experimental approach that might reveal the ways in which task-related factors impact hippocampal spatial representations is to compare firing patterns between events that require distinct episodic memory processes. Therefore, we recorded from CA1 single neurons during a discrete trial delayed-nonmatch-to-place task that allowed within-trial comparison between an encoding (sample) phase and a retrieval (choice) phase. A large subset of neurons that fired on the central stem of the maze showed dramatic selectivity for either the sample or choice phase of the trial. However, surprisingly, there were fewer neurons that showed differential firing rates between left- and right-bound trajectories. Our results suggest that trial-phase-selective coding is common in tasks that require rapid alternation between encoding and retrieval processes.
Transgenic Mouse Lines Subdivide Medial Vestibular Nucleus Neurons into Discrete, Neurochemically Distinct Populations
Authors: Bagnall Martha W. , Stevens Renna J. , du Lac Sascha
Published: February 2007

The identification of neuron types within circuits is fundamental to understanding their relevance to behavior. In the vestibular nuclei, several classes of neurons have been definedin vivoon the basis of their activity during behavior, but it is unclear how those types correspond to neurons identified in slice preparations. By targeting recordings to neurons labeled in transgenic mouse lines, this study reveals that the continuous distribution of intrinsic parameters observed in medial vestibular nucleus (MVN) neurons can be neatly subdivided into two populations of neurons, one of which is GABAergic and the other of which is exclusively glycinergic or glutamatergic. In slice recordings, GABAergic neurons labeled in the EGFP (enhanced green fluorescent protein)-expressing inhibitory neuron (GIN) line displayed lower maximum firing rates (<250 Hz) than glycinergic and glutamatergic neurons labeled in the yellow fluorescent protein-16 (YFP-16) line (up to 500 Hz). In contrast to cortical and hippocampal interneurons, GABAergic MVN neurons exhibited wider action potentials than glutamatergic (and glycinergic) neurons. Responses to current injection differed between the neurons labeled in the two lines, with GIN neurons modulating their firing rates over a smaller input range, adapting less during steady depolarization, and exhibiting less rebound firing than YFP-16 neurons. These results provide a scheme for robust classification of unidentified MVN neurons by their physiological properties. Finally, dye labeling in slices shows that both GABAergic and glycinergic neurons project to the contralateral vestibular nuclei, indicating that commissural inhibition is accomplished through at least two processing streams with differential input and output properties.
Functional Integration across Brain Regions Improves Speech Perception under Adverse Listening Conditions
Authors: Obleser Jonas , Wise Richard J. S. , Alex Dresner M. , Scott Sophie K.
Published: February 2007

Speech perception is supported by both acoustic signal decomposition and semantic context. This study, using event-related functional magnetic resonance imaging, investigated the neural basis of this interaction with two speech manipulations, one acoustic (spectral degradation) and the other cognitive (semantic predictability). High compared with low predictability resulted in the greatest improvement in comprehension at an intermediate level of degradation, and this was associated with increased activity in the left angular gyrus, the medial and left lateral prefrontal cortices, and the posterior cingulate gyrus. Functional connectivity between these regions was also increased, particularly with respect to the left angular gyrus. In contrast, activity in both superior temporal sulci and the left inferior frontal gyrus correlated with the amount of spectral detail in the speech signal, regardless of predictability. These results demonstrate that increasing functional connectivity between high-order cortical areas, remote from the auditory cortex, facilitates speech comprehension when the clarity of speech is reduced.
Cannabinoid CB1and CB2Receptors and Fatty Acid Amide Hydrolase Are Specific Markers of Plaque Cell Subtypes in Human Multiple Sclerosis
Authors: Benito Cristina , Romero Juan Pablo , Tolón Rosa María , Clemente Diego , Docagne Fabián , Hillard Cecilia J. , Guaza Camen , Romero Julián
Published: February 2007

Increasing evidence supports the idea of a beneficial effect of cannabinoid compounds for the treatment of multiple sclerosis (MS). However, most experimental data come from animal models of MS. We investigated the status of cannabinoid CB1and CB2receptors and fatty acid amide hydrolase (FAAH) enzyme in brain tissue samples obtained from MS patients. Areas of demyelination were identified and classified as active, chronic, and inactive plaques. CB1and CB2receptors and FAAH densities and cellular sites of expression were examined using immunohistochemistry and immunofluorescence. In MS samples, cannabinoid CB1receptors were expressed by cortical neurons, oligodendrocytes, and also oligodendrocyte precursor cells, demonstrated using double immunofluorescence with antibodies against the CB1receptor with antibodies against type 2 microtubule-associated protein, myelin basic protein, and the platelet-derived growth factor receptor-α, respectively. CB1receptors were also present in macrophages and infiltrated T-lymphocytes. Conversely, CB2receptors were present in T-lymphocytes, astrocytes, and perivascular and reactive microglia (major histocompatibility complex class-II positive) in MS plaques. Specifically, CB2-positive microglial cells were evenly distributed within active plaques but were located in the periphery of chronic active plaques. FAAH expression was restricted to neurons and hypertrophic astrocytes. As seen for other neuroinflammatory conditions, selective glial expression of cannabinoid CB1and CB2receptors and FAAH enzyme is induced in MS, thus supporting a role for the endocannabinoid system in the pathogenesis and/or evolution of this disease.
NMDA Receptor Function and NMDA Receptor-Dependent Phosphorylation of Huntingtin Is Altered by the Endocytic Protein HIP1
Authors: Metzler Martina , Gan Lu , Pan Wong Tak , Liu Lidong , Helm Jeffrey , Liu Lili , Georgiou John , Wang Yushan , Bissada Nagat , Cheng Kevin , Roder John C. , Wang Yu Tian , Hayden Michael R.
Published: February 2007

Huntingtin-interacting protein 1 (HIP1) is an endocytic adaptor protein that plays a role in clathrin-mediated endocytosis and the ligand-induced internalization of AMPA receptors (AMPARs) (Metzler et al., 2003). In the present study, we investigated the role of HIP1 in NMDA receptor (NMDAR) function by analyzing NMDA-dependent transport and NMDA-induced excitotoxicity in neurons from HIP1−/−mice. HIP1 colocalizes with NMDARs in hippocampal and cortical neurons and affinity purifies with NMDARs by GST (glutathioneS-transferase) pull down and coimmunoprecipitation. A profound decrease in NMDA-induced AMPAR internalization of 75% occurs in neurons from HIP1−/−mice compared with wild type, using a quantitative single-cell-based internalization assay. This defect in NMDA-dependent removal of surface AMPARs is in agreement with the observed defect in long-term depression induction in hippocampal brain slices of HIP1−/−mice and supports a role of HIP1 in AMPAR internalizationin vivo. HIP1−/−neurons are partially protected from NMDA-induced excitotoxicity as assessed by LDH (lactate dehydrogenase) release, TUNEL (terminal deoxynucleotidyl transferase-mediated biotinylated dUTP nick end labeling) and caspase-3 activation assays, which points to a role of HIP1 in NMDA-induced cell death. Interestingly, phosphorylation of Akt and its substrate huntingtin (htt) decreases during NMDA-induced excitotoxicity by 48 and 31%, respectively. This decrease is significantly modulated by HIP1, resulting in 94 and 48% changes in P-Akt and P-htt levels in HIP1−/−neurons, respectively. In summary, we have shown that HIP1 influences important NMDAR functions and that both HIP1 and htt participate in NMDA-induced cell death. These findings may provide novel insights into the cellular mechanisms underlying enhanced NMDA-induced excitotoxicity in Huntington's disease.
Dual Role for LIM-Homeodomain GeneLhx2in the Formation of the Lateral Olfactory Tract
Authors: Saha Bhaskar , Hari Padmanabhan , Huilgol Dhananjay , Tole Shubha
Published: February 2007

The development of the olfactory system in vertebrates is a multistep process, in which several regulatory molecules are required at different stages. The development of the olfactory sensory epithelium and its projection to the olfactory bulb are both known to require the LIM-homeodomain transcription factor Lhx2. We examined whether Lhx2 plays a role in the development of the OB itself, as well as its projection to the olfactory cortex.

Although there is no morphological OB protuberance in theLhx2mutant, mitral cells are normally specified and cluster in a displaced olfactory bulb-like structure (OBLS). The OBLS is not able to pioneer the lateral olfactory tract (LOT) projectionin vivoor when provided control (host) telencephalic territory in anin vitroassay. Strikingly, the mutant OBLS is capable of projecting along the LOT if provided with an existing normal LOT in the host explant. This is the first report of a role for a transcription factor expressed in the OB that selectively affects the axon guidance but not the specification of mitral cells.

Furthermore, theLhx2mutant lateral telencephalon does not support growth of an LOT projection from control OB explants. The defect correlates with the disruption of a cellular mechanism that is thought to be critical for LOT pathfinding: a specialized cell population, the “lot cells,” is mislocalized in theLhx2mutant. In addition, the expression ofSema6Ais aberrantly upregulated. Together, these findings reveal a dual role for Lhx2, in the OB as well as in the lateral telencephalon, for establishing the LOT projection.
Researching Electronic Portfolios and Learner Engagement: The REFLECT Initiative
Authors: Barrett Helen C.
Published: February 2007

Theoretical background for researching student learning, engagement, and collaboration through the development of electronic portfolios is described in this article. After providing an overview of the limited research on portfolios in education, the author discusses the accepted definitions, multiple purposes, and conflicting theoretical paradigms of electronic portfolios. Principles of student motivation and engagement are covered, and the philosophical issues related to portfolio assessment and reflection are outlined—paying particular attention to the difference between assessment for learning and assessment of learning. Finally, the article describes how the REFLECT Initiative will begin to fill the current void in empirical data on electronic portfolio implementation at the secondary level.
Negotiating Teacher Identity: Exploring the Use of Electronic Teaching Portfolios With Preservice English Teachers
Authors: Hallman Heidi L.
Published: February 2007

Electronic portfolio use within the context of a teacher education program is explored in this article. Although the use of e‐portfolios has emerged as a topic that integrates new technologies and the education of preservice teachers, little work thus far has documented the complexities involved in the authoring process of e‐portfolios. To address this gap, this article focuses on two preservice teachers' processes of crafting e‐portfolios. Specifically, the article documents the realities of presenting oneself to multiple audiences through the vehicle of the electronic teaching portfolio.

The term teacher identity is introduced as a way to describe preservice teachers' need to present themselves through the e‐portfolio as both “competent beginning teachers” and “inquisitive college students.” The author analyzes interviews with preservice teachers, concluding that e‐portfolios can be viewed as potential spaces for important talk about teacher identity.
Dyslexia and the Brain: What Does Current Research Tell Us?
Authors: Hudson Roxanne F. , High Leslie , Al Otaiba Stephanie
Published: February 2007

Dyslexia is a disorder of the language‐processing systems in the brain. It is a specific learning disability in reading that often affects spelling as well. This article describes

Common characteristics experienced by people with dyslexia or reading disabilities

Common misconceptions about dyslexia

What brain research tell us about reading disabilities

What this information means for teachers and parents

The identification of a child with dyslexia is difficult for parents and teachers. Having information about the likely explanation for and potential cause of students' difficulties often relieves many fears and uncertainties about how to think about providing instruction that is relevant and effective.
Reinforcing Expository Reading and Writing Skills: A More Versatile Sentence Completion Task
Authors: Montelongo José A. , Hernández Anita C.
Published: February 2007

This article introduces a modification of the sentence completion task that acquaints students with various types of informational text structures (e.g., cause–effect, compare–contrast) and challenges their higher order reading and writing skills. When the individual sentences comprising an expository paragraph are intermingled with unrelated sentences and presented in a random order, students are challenged in several ways:

First, students must fill in the blanks with the appropriate vocabulary word.

Then they must separate the related sentences from the unrelated ones.

Next, they must locate the main idea or topic sentence.

Finally, students must arrange the related sentences to form a cohesive paragraph.

The results of an investigation conducted with fourth‐ and fifth‐grade students suggest that use of this strategy facilitates locating main ideas in addition to providing practice in forming logical paragraphs. Recommendations for introducing, creating, and modifying this activity are offered.
Characters as Guides to Meaning
Authors: Roser Nancy , Martinez Miriam , Fuhrken Charles , McDonnold Kathleen
Published: February 2007

Characters in children's books can help to guide readers through stories, contributing to deepened understandings of plot and themes. The authors discuss why characters become vivid and lasting in readers' minds, the ways in which students are often asked to think about characters in classroom literature study, and how students' understanding of characters develops as they develop as readers.

In addition, the authors contend that teachers can provide instructional support to nurture deeper insights on character—and ultimately on the entire text. To illustrate, the authors describe how one first‐grade teacher supported her students' literary meaning making as they followed dynamic characters through a complex text. The teacher's strategies included helping children to identify and collect character traits, introducing realia to increase understanding of the story world, allowing students to reenact critical story events, helping children thread meanings across chapters, and inviting personal responses through journal writing. Through these strategies, children were able to use the characters as guides to meaning. The authors include a list of character‐rich books for classroom discussion.
Character Trait Vocabulary: A Schoolwide Approach
Authors: Manyak Patrick
Published: February 2007

Research has documented the large differences in young children's vocabulary knowledge. In light of the strong relationship between vocabulary knowledge and reading comprehension, this gap is particularly worrisome and points to the critical need for well‐articulated vocabulary instruction across the grades.

The author describes character trait vocabulary, in which the teacher asks students to describe the traits of characters in their reading. The children share their thinking and the teacher lists the terms offered for each character and prompts the children to explain their responses. After the children have analyzed the characters, the teacher displays a grid with a set of new terms chosen specifically for the characters under discussion. In a schoolwide approach to the practice, the teacher consciously tries to incorporate terms from the provided grade‐level list. The teacher introduces a word at a time, providing a brief child‐friendly definition and example, and asks the students to consider whether the term would apply to each of the characters.
Incorporating Movement With Fluency Instruction: A Motivation for Struggling Readers
Authors: Peebles Jodi L.
Published: February 2007

This article discusses two activities—Readers Theatre and Rhythm Walks—that encourage students to “get moving” with fluency instruction. Movement can be a motivating factor for struggling students, as well as a kinesthetic tool for conceptualizing the rhythm and flow of fluent reading while triggering brain function for optimal learning. Also included is a discussion of the importance of motivating struggling students in order to engage them long enough to elicit changes in reading behavior and to learn to generalize skills to new experiences.
Effects of Multiple Applications of Simulated Quinclorac Drift Rates on Tomato
Authors: Lovelace Michael L. , Talbert Ronald E. , Scherder Eric F. , Hoagland Robert E.
Published: February 2007

Quinclorac drift has been speculated as the cause of injury to tomato crops throughout northeast Arkansas. In this study, we set out to determine whether tomato plant injury and yield reduction were correlated with simulated quinclorac drift. Experiments were carried out at Fayetteville, AR, in 1999 and 2000. Maximum plant injury (visual ratings) was about 20% when plants were treated with one, two, or three quinclorac applications (weekly intervals beginning at first flower) at 0.42 g ai ha−1(0.001 times the normal use rate to simulate drift). Maximum plant injury ranged from 48 to 68% with quinclorac simulated drift treatment of 42 g ha−1. Overall, increasing quinclorac rate and number of applications increased tomato injury. In both years, tomato plant fresh-weight accumulation was not influenced by one, two, or three applications of quinclorac at 0.42 g ha−1compared with the untreated control. In 1999, increasing the rate of quinclorac from 0.42 to 4.2 g ha−1reduced plant fresh-weight accumulation. In 2000, there was no significant difference in plant fresh weight when plants were treated with quinclorac at 2.1 to 4.2 g ha−1. Evaluation of the herbicide rate effect indicated that quinclorac at 0.42 g ha−1did not reduce tomato fruit yield (total weight of edible fruit) compared with the untreated control, but yield decreased as rate increased above 0.42 g ha−1. Increasing the number of applications generally decreased tomato yield, and overall as maximum visual plant injury increased, tomato yield reduction ALSo increased linearly. We conclude that quinclorac at simulated drift rates can adversely affect tomato plant growth and yield.
Role of Light Quality and Temperature on Pitted Morningglory (Ipomoea lacunosa) Germination with After-Ripening
Authors: Norsworthy Jason K. , Oliveira Marcos J.
Published: February 2007

Pitted morningglory seed were collected in the fall of 2003 from Blackville, SC, and 2004 from Pendleton, SC, to assess the effect of After-Ripening and burial on light and temperature requirements for germination. Pitted morningglory germination was evaluated over a 12-mo period after maturation. Germination was neither stimulated by red light or inhibited by far-red light, nor was it reversible by red or far-red light. Light was not essential for germination of buried seed. Direct exposure to sunlight prevented germination of recently mature seed, but not once seed had sufficiently after-ripened. Pitted morningglory was capable of germination in darkness over a wide range of constant and fluctuating temperatures immediately after maturation. Germination in response to temperature varied with time of year after maturation, with the population from Pendleton having increased germination in May. Thermal fluctuations increased germination of both populations at suboptimal temperatures. Thermal amplitude regulation of germination varied over time and appeared to play a more important role in germination of after-ripened seed than recently mature ones. The ecological significance of changes in germination requirements with After-Ripening is discussed.
Comparative Nitrogen Uptake and Distribution in Corn and Velvetleaf (Abutilon theophrasti)
Authors: Lindquist John L. , Barker Darren C. , Knezevic Stevan Z. , Martin Alexander R. , Walters Daniel T.
Published: February 2007

Weeds compete with crops for light, soil water, and nutrients. Nitrogen (N) is the primary limiting soil nutrient. Forecasting the effects of N on growth, development, and interplant competition requires accurate prediction of N uptake and distribution within plants. Field studies were conducted in 1999 and 2000 to determine the effects of variable N addition on monoculture corn and velvetleaf N uptake, the relationship between plant N concentration ([N]) and total biomass, the fraction of N partitioned to leaves, and predicted N uptake and leaf N content. Cumulative N uptake of both species was generally greater in 2000 than in 1999 and tended to increase with increasing N addition. Corn and velvetleaf [N] declined with increasing biomass in both years in a predictable manner. The fraction of N partitioned to corn and velvetleaf leaves varied with thermal time from emergence but was not influenced by year, N addition, or weed density. With the use of the [N]–biomass relationship to forecast N demand, cumulative corn N uptake was accurately predicted for three of four treatments in 1999 but was underpredicted in 2000. Velvetleaf N uptake was accurately predicted in all treatments in both years. Leaf N content (NL, g N m−2leaf) was predicted by the fraction of N partitioned to leaves, predicted N uptake, and observed leaf area index for each species. Average deviations between predicted and observed corn NLwere < 88 and 12% of the observed values in 1999 and 2000, respectively. Velvetleaf NLwas less well predicted, with average deviations ranging from 39 to 248% of the observed values. Results of this research indicate that N uptake in corn and velvetleaf was driven primarily by biomass accumulation. Overall, the approaches outlined in this paper provide reasonable predictions of corn and velvetleaf N uptake and distribution in aboveground tissues.
A Conceptual Framework for Preventing the Spatial Dispersal of Invasive Plants
Authors: Davies Kirk W. , Sheley Roger L.
Published: February 2007

Invasive plant species have adversely affected rangelands throughout the world and continue to invade previously uninfested lands at an alarming rate. Previous efforts have focused on eradication and control; however, recent efforts have recognized that preventing invasive plant species from infesting new areas is more cost-effective and efficient than trying to restore the system after it is infested. One of the major components of prevention is limiting the introduction of the invasive plant to uninfested areas. Guidelines to limit the introduction of invasive plants into new areas are usually general and not developed to address differences in dispersal vectors among invasive plants. To limit the dispersal of invasive plants, land managers need a framework that assists them in identifying major spatial dispersal vectors and management strategies based on those vectors. We propose an initial conceptual framework that integrates the ecology of invasive plant dispersal with prevention management. The framework identifies major potential vectors by incorporating invasive plant seed adaptations for dispersal through space and infestation locations relative to vector pathways. The framework then proposes management strategies designed to limit dispersal by those specific vectors. The framework ALSo identifies areas where research could improve the effectiveness of dispersal-prevention strategies by providing additional management tools.
Upscaling Schemes and Relationships for the Gardner and van Genuchten Hydraulic Functions for Heterogeneous Soils
Authors: Zhu Jianting , Young Michael H. , van Genuchten Martinus Th.
Published: February 2007

Upscaled soil hydraulic properties are needed for many large‐scale hydrologic applications such as regional and global climate studies and investigations of land–atmosphere interactions. Many larger scale subsurface flow and contaminant transport studies also require upscaled hydraulic property estimates. The objectives of this study were to develop a methodology for upscaling hydraulic property functions using a p‐norm approach, to examine how p‐norm values differ for two commonly used soil hydraulic property models (the Gardner and van Genuchten functions), and to investigate the relative sensitivities of p‐norms and the effective hydraulic parameters to the degree of soil heterogeneity (expressed in terms of variances and auto‐correlation lengths of the hydraulic parameters) and other environmental conditions. The p‐norm approach expresses upscaling schemes such that it reduces their sensitivity to uncertainties (heterogeneities) in site conditions. The upscaling schemes are obtained as the result of two new criteria proposed to upscale soil hydraulic properties in this study—one preserving the ensemble vertical moisture flux across the land–atmosphere boundary, and a second preserving the ensemble soil surface moisture content. The effective soil hydraulic parameters of a heterogeneous soil formation are then derived by conceptualizing the formation as an equivalent homogeneous medium that satisfies the upscaling criteria. Upscaling relationships between the Gardner and van Genuchten models can then also be established for steady‐state vertical flow using the statistical structures of the hydraulic parameters of these two models as estimated from field measurements. The upscaling scheme is demonstrated using hydraulic property data collected at 84 locations across a site in the Mojave Desert. Our results show that the p‐norms generally vary less in magnitude than the effective parameters when the variances of the hydraulic parameters increase. We also show that, in general, p‐norm values are better defined for the van Genuchten model than the Gardner model. Hydraulic parameter auto correlations, as defined by correlation lengths, were found to have little impact in relating the upscaling schemes (p‐norm values) for the two hydraulic property models, but correlation between the hydraulic parameters within the hydraulic property models can significantly affect p‐norm relationships.
New Polymer Tensiometers: Measuring Matric Pressures Down to the Wilting Point
Authors: Bakker Gerben , van der Ploeg Martine J. , de Rooij Gerrit H. , Hoogendam Cornelis W. , Gooren Hermanus P. A. , Huiskes Cindy , Koopal Luuk K. , Kruidhof Henk
Published: February 2007

Tensiometers are commonly used for measuring soil water matric pressures. Unfortunately, the water‐filled reservoir of conventional tensiometers limits their applicability to soil water matric pressures above approximately −0.085 MPa. Tensiometers filled with a polymer solution instead of water are able to measure a larger range of soil water matric pressures. We designed and constructed six prototype polymer tensiometers (previously called osmotic tensiometers) consisting of a wide‐range pressure transducer with a temperature sensor, a stainless steel casing, and a ceramic plate with a membrane preventing polymer leakage. A polymer chamber (0.1–2.2 cm3) was located between the pressure transducer and the plate. We tested the polymer tensiometers for long‐term operation, the effects of temperature, response times, and performance in a repacked sandy loam under laboratory conditions. Several months of continuous operation caused a gradual drop in the osmotic pressure, for which we developed a suitable correction. The osmotic potential of polymer solutions is temperature dependent, and requires calibration before installation. The response times to sudden and gradual changes in ambient temperature were found to be affected by polymer chamber height and polymer type. Practically useful response times (<0.2 d) are feasible, particularly for chambers shorter than 0.20 cm. We demonstrated the ability of the instrument to measure the range of soil water pressures in which plant roots are able to take up water (from 0 to −1.6 MPa), to regain pressure without user interference and to function properly for time periods of up to 1 yr.
Consumer evaluation of scab-resistant apple cultivars in Sweden
Authors: JÖNSSON Å. , NYBOM H.
Published: February 2007

The feasibility of using untrained consumers for sensory evaluation was investigated on Swedish-grown scab-resistant apple cultivars in 2002 (11 cultivars) and 2003 (15 cultivars). The consumers evaluated five cultivars each, including the control cultivar Aroma. Each cultivar was scored for appearance, texture, juiciness, taste and overall impression by a minimum of 100 consumers in 2002 and by 200 in 2003. All quality attributes were positively correlated when calculations were performed across all consumer scores, with overall impression and taste having the strongest association. Rubinola and K:1160 emerged as the best liked cultivars overall. Cultivar means were analysed for relationships with some previously scored or measured variables and with consumer profile data. Positive correlations with overall impression were obtained for amount of red colour in 2002, and for sugar levels in 2003. Among consumer profile variables, age had the largest influence on consumer scores, with some indications that older consumers preferred (or at least tolerated) soft-fleshed cultivars better than did younger consumers. Minimum number of consumers needed to obtain reliable results was determined by computer simulations indicating that the error rate became stabilized already with 50 consumers.;
Linking Professional Development to Teacher Learning and Practice: A Multi-Case Study Analysis of Urban Teachers
Authors: Mouza Chrystalla
Published: February 2007

This study describes and analyzes the pedagogical activities of two professional development models aimed at helping teachers effectively integrate technology in their classrooms. Most importantly, it investigates the impact of those activities on teacher learning and practice. Results of the study provide empirical evidence that links key components of professional development to changes in teacher knowledge, practices, and beliefs. Specifically, findings of the study indicate that both professional development models enabled participating teachers to: a) improve their technology proficiency, b) understand how to use technology as an instructional tool, c) incorporate technology into their professional and instructional practices, and d) reinforce and reconsider their beliefs toward teaching with technology. The study also offers much needed insights into the process by which teacher learning and change occur. The results of this study have significant implications for the design of in-service programs on the use of technology. They also include implications for policy and future research.
Improving Student Retention through Evidence Based Proactive Systems at the Open University (UK)
Authors: Gibbs Graham , Regan Peter , Simpson Ormond
Published: February 2007

The Open University has been undertaking an extended initiative to improve student retention through enhanced support for at-risk students. This initiative has evolved through a series of stages from ad hoc small scale local interventions relying largely on tutors and student self-referral, to an institution-wide pro-active system implemented by specialist staff, backed by cost-effectiveness data based on evaluations of controlled experiments, and driven by management information systems. This article will outline the similarities and differences between retention in distance learning in the United Kingdom (UK) and in United States (US) colleges, illustrate the way a program of planned interventions was evaluated at the Open University, explain how the cost-effectiveness of interventions was established, and describe the integrated proactive system now in operation.
Transition to Home Care: Quality of Mental Health, Pharmacy, and Medical History Information
Authors: Brown Ellen L. , Raue Patrick J. , Mlodzianowski Amy E. , Meyers Barnett S. , Greenberg Rebecca L. , Bruce Martha L.
Published: February 2007

Objective:

To assess the completeness and accuracy of clinical information provided by referral sources to visiting nurses for patients admitted to receive home health care.

Methods:

Clinical referral information for a representative sample of 243 older adults admitted to receive skilled home-health nursing was compared to medical record information from home-health charts and in-home research interviews to determine their concordance. Measures used included referral information, home-care chart documentation, in-home nurse review of medications, medication allergies, caregiver contact information, cognitive status, depression status, and follow-up plan.

Results:

There were medication discrepancies between in-home nurse review and admission information in 215 cases (88.4%). Clinical information on medication allergies was lacking from referrers in 85 cases (34.9%). No information was provided by the referrers about cognitive status in 38 (73%) cases classified as cognitively impaired and in only 2 of 35 cases with major depression identified with the Structured Clinical Interview for Axis I Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (SCID), was depression related information provided by referrers.

Conclusions:

The primary finding of this study is that during a transfer of an older adult to the home care service sector, essential clinical information is often missing, and there are significant discrepancies between medication regimens. These findings support the need for both educational initiatives and technology to address the complex care needs of older adults across settings to reduce the risk for medication errors and poor outcomes.
Technology-Rich Ethnography for Examining the Transition to Authentic Problem-Solving in a High School Computer Programming Class
Authors: Ge Xun , Thomas Michael K. , Greene Barbara A.
Published: February 2007

This study utilized elements of technology-rich ethnography to create a rich description of a multi-user virtual environment in a high school computer programming class. Of particular interest was the transition that took place in classroom culture from one characterized by a well-defined problem solving approach to one more indicative of open learning environment. Using technology, high school students created learning activities and resources for use by younger students in the virtual environment. Evidence supported that high school students initially benefitted from the new open environment; however, some immutable elements of the classroom environment presented barriers to peer collaboration and motivation for high-level, creative work. Our findings lend support to the argument that teachers in high school computer programming classes should incorporate the following features in their curricula: open-ended problem solving, real-world clients, group work, student autonomy and ample opportunities for student creative expression.