bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of reservoir influences on annual and seasonal streamflow changes for the Lena, Yenisei, and Ob' rivers
Authors: Adam Jennifer C. , Haddeland Ingjerd , Su Fengge , Lettenmaier Dennis P.
Published: December 2007

Since the 1930s, combined streamflow from the largest Eurasian rivers discharging to the Arctic Ocean has been increasing. For many of these rivers, an increase in annual streamflow volume has been accompanied by a shift in seasonality (e.g., earlier snowmelt runoff in the spring). These changes in annual and seasonal streamflow may be due to direct effects of climate change (e.g., increased precipitation, or changes in snow accumulation and ablation patterns), indirect effects of climate change (e.g., changes in permafrost), or human effects (e.g., storage and release of river runoff in reservoirs). We develop and describe a method to estimate the potential contributions of artificial reservoirs to long‐term changes in annual and seasonal streamflow between 1937 and 1998. Reservoir effects on downstream flow are simulated using a reservoir routing model coupled off‐line to the Variable Infiltration Capacity (VIC) land surface hydrology model for the Lena, Yenisei and Ob' river basins. The effects of reservoirs on basin average evaporation are also represented. We perform trend analysis on long‐term (≥30 years) time series of seasonal and annual streamflow and isolate the effects of reservoirs. Although reservoirs have had little effect on trends in annual discharge from the Lena, Yenisei, and Ob' river basins, we conclude that they are responsible for many of the seasonal changes that have been observed. For the Lena, reservoirs account for up to 80% and 30% of the observed winter and spring trends, respectively. For the Yenisei, reservoirs account for up to 100%, 40%, and 60% to 100% of the observed winter, spring, and late summer to early fall trends, respectively. For the Ob', reservoirs may account for more than 70% of the observed trends during the months of January to March. A result of this study is a set of reconstructed streamflow at the outlets of the Lena, Yenisei, and Ob' river basins which can be used in subsequent studies to improve the understanding of climate change effects on runoff generation in the Eurasian Arctic.
Comparing irradiance fields derived from Moderate Resolution Imaging Spectroradiometer airborne simulator cirrus cloud retrievals with solar spectral flux radiometer measurements
Authors: Schmidt K. Sebastian , Pilewskie Peter , Platnick Steven , Wind Gala , Yang Ping , Wendisch Manfred
Published: December 2007

During the Cirrus Regional Study of Tropical Anvils and Cirrus Layers–Florida Area Cirrus Experiment, the Moderate Resolution Imaging Spectroradiometer (MODIS) airborne simulator (MAS) and the solar spectral flux radiometer (SSFR) operated on the same aircraft, the NASA ER‐2. While MAS provided two‐dimensional horizontal fields of cloud optical thickness and effective ice particle radius, the SSFR measured spectral irradiance in the visible to near‐infrared wavelength range (0.3–1.7 μm). The MAS retrievals, along with vertical profiles from a combined radar/lidar system on board the same aircraft were used to construct three‐dimensional cloud fields, which were input into Monte Carlo radiative transfer models. The simulated field of spectral albedo (ratio of reflected upwelling to incident downwelling irradiance) was compared with the SSFR measurements. For two cases, the relative importance of spatial cloud heterogeneities, various approximations of the single scattering parameters, vertical structure, cirrus optical thickness, and ice crystal effective radius was studied.
Single‐particle laser‐induced‐fluorescence spectra of biological and other organic‐carbon aerosols in the atmosphere: Measurements at New Haven, Connecticut, and Las Cruces, New Mexico
Authors: Pan Yong‐Le , Pinnick Ronald G. , Hill Steven C. , Rosen James M. , Chang Richard K.
Published: December 2007

This study focuses on organic carbon (OC) aerosols, including natural biological aerosols, in the Earth's troposphere, and on laser‐induced fluorescence (LIF) spectral methods for studying these aerosols. LIF spectra of atmospheric OC and biological aerosols (having diameters greater than approximately 3 μm) measured at New Haven, Connecticut, and Las Cruces, New Mexico, are reported. A hierarchical clustering method was used to cluster approximately 90% of the single‐particle LIF spectra into 8–10 groups. Some of these groups have spectra that are similar to spectra of some important classes of atmospheric aerosol, such as humic/fulvic acids and humic‐like substances, bacteria, cellulose, marine aerosol, and polycyclic aromatic hydrocarbons (PAH). A comparison with previous measurements made at Adelphi, Maryland, reveals that the most highly populated clusters found at Adelphi, and some of the less populated ones, also appear in the LIF spectra at New Haven and Las Cruces, even though the regional climates at these locations is different (New England/Atlantic Coastal, for New Haven and Adelphi, and Chihuahuan Desert for Las Cruces), and the measurements were made in different seasons. The results are consistent with some (perhaps most) of the fluorors in OC and biological atmospheric aerosols being common to these three sites. On average, spectra characteristic of humic/fulvic acids and humic‐like substances (HULIS) comprise 28–43% of fluorescent particles at all three sites; whereas cellulose‐like spectra contribute only 1–3%.
Aura Microwave Limb Sounder upper tropospheric and lower stratospheric H2O and relative humidity with respect to ice validation
Authors: Read W. G. , Lambert A. , Bacmeister J. , Cofield R. E. , Christensen L. E. , Cuddy D. T. , Daffer W. H. , Drouin B. J. , Fetzer E. , Froidevaux L. , Fuller R. , Herman R. , Jarnot R. F. , Jiang J. H. , Jiang Y. B. , Kelly K. , Knosp B. W. , Kovalenko L. J. , Livesey N. J. , Liu H.‐C. , Manney G. L. , Pickett H. M. , Pumphrey H. C. , Rosenlof K. H. , Sabounchi X. , Santee M. L. , Schwartz M. J. , Snyder W. V. , Stek P. C. , Su H. , Takacs L. L. , Thurstans R. P. , Vömel H. , Wagner P. A. , Waters J. W. , Webster C. R. , Weinstock E. M. , Wu D. L.
Published: December 2007

The validation of version 2.2 (v2.2) H2O measurements from the Earth Observing System (EOS) Microwave Limb Sounder (Aura MLS) on the Aura satellite are presented. Results from comparisons made with Aqua Atmospheric Infrared Sounder (AIRS), Vaisala radiosondes, frost point hygrometer, and WB57 aircraft hygrometers are presented. Comparisons with the Aura MLS v1.5 H2O, Goddard global modeling and assimilation office Earth Observing System analyses (GEOS‐5) are also discussed. For H2O mixing ratios less than 500 ppmv, the MLS v2.2 has an accuracy better than 25% between 316 and 147 hPa. The precision is 65% at 316 hPa that reduces to 25% at 147 hPa. This performance is better than expected from MLS measurement systematic error analyses. MLS overestimates H2O for mixing ratios greater than 500 ppmv which is consistent with a scaling error in either the calibrated or calculated MLS radiances. The validation of the accuracy of MLS v2.2 H2O from 121 to 83 hPa which is expected to be better than 15% cannot be confirmed at this time because of large disagreements among the hygrometers used in the AVE campaigns. The precision of the v2.2 H2O from 121 to 83 hPa is 10–20%. The vertical resolution is 1.5–3.5 km depending on height. The horizontal resolution is 210 × 7 km2 along and perpendicular to the Aura orbit track, respectively. Relative humidity is calculated from H2O and temperature. The precision, accuracy, and spatial resolution are worse than for H2O.
Environmental stability control of the intensity of squall lines under low‐level shear conditions
Authors: Takemi Tetsuya
Published: December 2007

The environment for the development and evolution of linearly organized convective systems, i.e., squall lines is diverse for their existence in various climate regions. Understanding the behavior of squall lines under various environmental conditions is required for diagnosing and forecasting the development and intensity of the convective systems. The present study investigates the effects of environmental static stability on the squall‐line intensity by conducting a systematic series of idealized cloud‐resolving simulations of squall lines that develop in line‐perpendicular, low‐level westerly shear. Changing the temperature lapse rate with convective available potential energy (CAPE) being unchanged, we showed that the environmental stability in a convectively unstable layer well describes the intensity of the simulated squall lines. A less stable stability is favorable for generating stronger convective systems. The amount of CAPE does not account for the difference in the squall‐line intensity in different temperature environments. An environment with a less static stability leads to the development of stronger cold pool, which will strongly controls the scale and strength of convective updrafts, the intensity of tropospheric overturning, and thus the organization and intensity of squall lines. The CAPE value can only be a good measure for diagnosing the development and intensity of the convective systems so long as the environmental static stability is identical. The static stability is a controlling parameter in determining the intensity of squall lines.
Diffuse UV erythemal radiation experimental values
Authors: Utrillas M. P. , Marín M. J. , Esteve A. R. , Tena F. , Cañada J. , Estellés V. , Martínez‐Lozano J. A.
Published: December 2007

Measurements of diffuse UV erythemal radiation (UVER) using a shadowband have been corrected using the models proposed by Drummond (1956), LeBaron et al. (1990), and Batlles et al. (1995). Two different methods were used to validate these models: intercomparison with an Optronic OL754 spectroradiometer and comparison with the values simulated by two radiative transfer codes, SMARTS and SBDART. For this comparison only clear days have been used. The corrected experimental values were analyzed in order to study the average values of the diffuse UVER fraction in relation to the clearness index kt. These varied between 62%, for kt close to 0.8, and 93% for kt of 0.2–0.3. Finally, a study of the monthly average and extreme values of the UV Index for diffuse radiation is presented, showing a maximum value of 6 in June.
Examining feedbacks of aerosols to urban climate with a model that treats 3‐D clouds with aerosol inclusions
Authors: Jacobson Mark Z. , Kaufman Yoram J. , Rudich Yinon
Published: December 2007

Anthropogenic aerosol particles alter clouds, radiation, and precipitation, thereby affecting weather, climate, and air pollution. To examine and understand such feedbacks, a module that simulates the evolution, movement, and microphysics of three‐dimensional size‐resolved mixed‐phase clouds and precipitation and their multicomponent aerosol inclusions was developed and implemented into the GATOR‐GCMOM global‐through‐urban air pollution‐weather‐climate model. A unique feature of the module is that aerosol particles and their chemical components are tracked in time and space within size‐resolved liquid, ice, and graupel and interstitially within clouds. Modeled parameters were evaluated against in situ data, compared with MODIS climatologies, and nested with emission data down to 5 km resolution to study aerosol‐cloud feedbacks in Los Angeles. Although updrafts are not resolved during deep convection at this resolution, most convection is shallow in Los Angeles. This resolution is also near the lower limit for which a hydrostatic solution to vertical momentum (used here) is similar to a nonhydrostatic solution. Aerosols in Los Angeles were found to increase cloud optical depth, cloud liquid water, cloud fraction, net downward thermal‐infrared radiation, soil moisture, the relative humidity, and (slightly) middle‐boundary layer air temperatures. Aerosols also decreased precipitation, surface solar, and near‐surface temperatures. Both boundary layer warming due to black carbon and surface cooling due to all aerosol components increased stability, inhibiting cloud top growth under some conditions. Aerosols may feed back to themselves by increasing cloud liquid, gas dissolution, and aerosol volume upon evaporation. They may also decrease visibility by increasing the relative humidity and decrease photolysis below them by enhancing cloud thickness.
Timing and spatial distribution of mid‐Holocene drying over northern China: Response to a southeastward retreat of the East Asian Monsoon
Authors: Jiang W. Y. , Liu T. S.
Published: December 2007

To determine the timing and spatial distribution of mid‐Holocene drying over northern China, the mineralogical and oxygen isotopic composition of authigenic carbonate from a closed lake at Bayanchagan, southern Inner Mongolia, were measured. Further analysis and synthesis of the spatial geological data were performed. Results from Lake Bayanchagan show a significant drying at 6000 calendar years (cal years) B.P., indicated by dolomite precipitation and a striking rise in δ18O values. The synthesis of spatial data reveals a zonal distribution for timing of drying over northern China in the mid‐Holocene, which began at 9000–7000 cal years B.P. in deserts of north‐central China. At 7000–5500 cal years B.P., drying extended into the desert‐steppe transitional zone and at ∼4500 cal years B.P. into northeastern and south‐central China. This pattern indicates that the east Asian summer monsoon has significantly retreated southeastward since the mid‐Holocene, which may be related to orbitally induced Northern Hemisphere insolation changes. A retreat of ∼400–550 km is inferred for the front of the summer monsoon from 6500 to 4500 cal years B.P.
Modeling the refreezing of meltwater as superimposed ice on a high Arctic glacier: A comparison of approaches
Authors: Wright A. P. , Wadham J. L. , Siegert M. J. , Luckman A. , Kohler J. , Nuttall A. M.
Published: December 2007

The refreezing of meltwater is known to be a critical factor when assessing the mass balance state of glaciers in the high Arctic. Several different models of this process are widely used in numerical glacier simulations but, as yet, no attempt has been made to compare these approaches or to assess their relative performance against field measurements. Such models are likely to include implicit calibrations which may prove to be invalid under conditions different from those for which they were constructed. We test a selection of six refreezing algorithms taken from the literature against field measurements of net mass balance and superimposed ice formation made at a high Arctic glacier. Running these models for 1971–2002 using daily meteorological data and forward until 2050 using a range of future scenarios for the climate of Svalbard we are able to make the following conclusions concerning mass balance modeling: (1) The choice of meltwater refreezing model has a significant impact on the calculated net mass balance of a glacier. (2) Three of the models tested could, with suitable tuning, simultaneously reproduce both superimposed ice quantities and net mass balance measurements within their respective bounds of uncertainty, while the other three could not. (3) In situations where the model can be tuned to field measurements indicative of mass balance, future predictions of mass balance are largely independent of the specific meltwater refreezing model used.
A glacier respires: Quantifying the distribution and respiration CO2 flux of cryoconite across an entire Arctic supraglacial ecosystem
Authors: Hodson Andy , Anesio Alexandre M. , Ng Felix , Watson Rory , Quirk Joe , Irvine‐Fynn Tristram , Dye Adrian , Clark Chris , McCloy Patrick , Kohler Jack , Sattler Birgit
Published: December 2007

This paper quantifies the mass distribution of cryoconite at the glacier scale using photographic surveys conducted either at ground level, or at 20 m elevation using a novel uninhabited aerial vehicle (UAV). Image acquisition allowed three key deposits to be quantified: cryoconite holes, cryoconite in streams (“stream cryoconite”), and dispersed cryoconite granules (detectable only in the ground‐based images). Cryoconite was found all over the snow‐free parts of the glacier in one or more of these forms, covering about 0.42% (4600 kg km−2 dry weight) as holes and stream cryoconite deposits (>0.25 cm2 and thus visible in the UAV images), or 1% (10600 kg km−2) when smaller dispersed granules were included (using the ground images). No spatial patterns in the distribution of cryoconite cover were apparent, although cryoconite holes were far more common than stream cryoconite at high altitude due to lower melt rates. Measurements of respiration and bacterial carbon production estimated from in situ incubations of cryoconite–water mixtures indicated rates of 1.174 ± 0.182 (1 standard deviation) and 0.040 ± 0.019 μg C g−1 h−1, respectively. The respiration measurements then yielded glacier‐wide CO2 fluxes for 1998 and 2000 of 6.3 and 5.1 kg C km−2 a−1 when the loci and duration of activity were defined using the UAV images and a degree day model, respectively. These fluxes increased to 14 and 12 kg C km−2 a−1 when the dispersed cryoconite detected in the ground‐based images were also considered. The measurements therefore show that cryoconite ecosystems clearly have the capacity to impact upon carbon cycling in glacial environments.
Quantification of uncertainty in geochemical reactions
Authors: Srinivasan Gowri , Tartakovsky Daniel M. , Robinson Bruce A. , Aceves Alejandro B.
Published: December 2007

Predictions of reactive transport in the subsurface are routinely compromised by both model (structural) and parametric uncertainties. We present a set of computational tools for quantifying these two types of uncertainties. The model uncertainty is resolved at the molecular scale where epistemic uncertainty incorporates aleatory uncertainty. The parametric uncertainty is resolved at both molecular and continuum (Darcy) scales. We use the proposed approach to quantify uncertainty in modeling the sorption of neptunium through a competitive ion exchange. This radionuclide is of major concern for various high‐level waste storage projects because of its relatively long half‐life and its high‐solubility and low‐sorption properties. We demonstrate how parametric and model uncertainties affect one's ability to estimate the distribution coefficient. The uncertainty quantification tools yield complete probabilistic descriptions of key parameters affecting the fate and migration of neptunium in the subsurface rather than the lower statistical moments. This is important, since these distributions are highly skewed.
Nitrate reduction in streambed sediments: Effects of flow and biogeochemical kinetics
Authors: Gu Chuanhui , Hornberger George M. , Mills Aaron L. , Herman Janet S. , Flewelling Samuel A.
Published: December 2007

The effect of retention time on redox sequences along the hydrological flow path of groundwater discharging through low‐relief coastal stream sediments and the subsequent impact on the fate of NO3− carried in the groundwater was examined in two intact cores. Rates of denitrification were determined for the organic‐rich streambed sediments, and a macroscopic, multispecies, reactive transport model based on multiple Monod kinetics was developed to interpret and extend the experimental results. Regionalized sensitivity analysis and parameter estimation were used to determine a set of parameters that best describe the experimental data for one column. The calibrated model successfully replicated the spatial profiles of nitrate under both steady and transient conditions in the second column operated under different conditions. A dimensionless form of the model was used to examine how coupled biogeochemical reactions and hydrological transport processes operate within the stream sediments could be understood in terms of Peclet (ratio of advection to dispersion) and Damkohler numbers (the ratio of the characteristic time of transport to the characteristic time for reaction). At the study site, the Peclet number and the Damkohler numbers for both oxygen and nitrate are high (Pe = 25, DaN = 47.5, and DaO = 40). When Pe > 5, Damkohler numbers explain observed variations in nitrate removal rates; as the flow rate increases, the solute residence time in the reactive zone is shortened resulting in a lesser extent of reaction, such that more NO3− is delivered to the stream water.
Extracting Functional Modules from Biological Pathways
Authors: Zhao Sihai , Li Yong
Published: December 2007

It has been proposed that functional modules are the fundamental units of cellular function. Methods to identify these modules have thus far relied on gene expression data or protein-protein interaction (PPI) data, but have a few limitations. We propose a new method, using biological pathway data to identify functional modules, that can potentially overcome these limitations. We also construct a network of these modules using functionally relevant PPI data. This network displays the flow and integration of information between modules and can be used to map cellular function.
Siblings of Children With Speech Impairment: Cavalry on the Hill
Authors: Barr Jacqueline , McLeod Sharynne , Daniel Graham
Published: December 2007

Purpose

The purpose of this article was to examine the experiences of siblings of children with speech impairment, an underresearched area of family-centered practice.

Method

Using naturalistic inquiry, we interviewed 6 siblings and 15 significant others. Interview transcripts were analyzed for meaning statements, and meaning statements were coded and organized thematically.

Results

Four major themes emerged as significant in these children’s experiences. The first theme described the typically positive relationship when siblings were together. The second theme related to the siblings' relationship in the context of outsiders, when the sibling of the child with speech impairment frequently undertook the roles of protector and interpreter. Exemplifying this, 1 mother described her daughter as thecavalry on the hill.In the third theme, the impact on self, siblings expressed jealousy and resentment as well as worry and concern toward the child with speech impairment. In the fourth theme, the impact on parent–child relationships, siblings expressed an awareness that they experienced less parental attention, had concerns regarding the impact of the circumstances on their parents, and took on a parent-like role toward the child with impairment, and for some, toward their parents.

Conclusion

As part of family-centered practice, speech-language pathologists need to be aware of the important roles that siblings play and should routinely include siblings in assessment and intervention.
Empirically Derived Combinations of Tools and Clinical Cutoffs: An Illustrative Case With a Sample of Culturally/Linguistically Diverse Children
Authors: Oetting Janna B. , Cleveland Lesli H. , Cope Robert F.
Published: December 2007

Purpose

Using a sample of culturally/linguistically diverse children, we present data to illustrate the value of empirically derived combinations of tools and cutoffs for determining eligibility in child language impairment.

Method

Data were from 95 4- and 6-year-olds (40 African American, 55 White; 18 with language impairment, 77 without) who lived in the rural South; they involved primarily scores from the Comprehension subtest of the Stanford-Binet Intelligence Scale—Fourth Edition (CSSB; R. Thorndike, E. Hagen, & J. Sattler, 1986), but scores from an experimental nonword repetition task (NRT; C. Dollaghan & T. Campbell, 1998) were also included as supplements to these scores.

Results

Although the CSSB led to low fail rates in children without impairment and a statistically reliable group difference as a function of the children’s clinical status but not their race, only 56% of children with impairment were accurately classified when −1
SD
was employed as the cutoff. Diagnostic accuracy improved to 81% when an empirically derived cutoff of −.5
SD
was used. When scores from the NRT were added to those from the CSSB, diagnostic accuracy increased to 90%.

Implications

This illustrative case adds to the growing number of studies that call for empirically derived combinations of tools and cutoffs as one option within an evidence-based practice framework.
Identifying Language Comprehension Impairment in Preschool Children
Authors: Skarakis-Doyle Elizabeth , Dempsey Lynn , Lee Christopher
Published: December 2007

Purpose

This study examined the validity of 3 discourse comprehension measures for preschool children and the ability of a combination of them to classify children with and without language impairment.

Method

Thirty-seven children with typical language and 12 children with language impairment completed 3 measures of oral story comprehension: the Joint Story Retell task, the Expectancy Violation Detection task, and comprehension questions.

Results

Discriminant analyses revealed that each measure successfully classified pre-identified groups. The clinical combination of all 3 measures resulted in 96% accurate identification of the language status of this cohort.

Conclusion

Results support these procedures as valid measures of discourse comprehension and monitoring and provide preliminary evidence that their combination can be validly employed for identifying young children with language comprehension impairment.
Training and Knowledge in Autism Among Speech-Language Pathologists: A Survey
Authors: Schwartz Heatherann , Drager Kathryn D. R.
Published: December 2007

Purpose

The current study was designed to answer the following questions: (a) What knowledge do school-based speech-language pathologists (SLPs) have concerning autism? (b) What educational and clinical training do SLPs receive in autism? (c) Do SLPs have confidence in their ability to provide services to children with autism and their families?

Method

An original 52-item survey was designed to answer the research questions. Participants were recruited through e-mail and were asked to respond to a Web-based survey.

Results

Sixty-seven school-based SLPs practicing in 33 states across the United States responded to the survey. Most participants had accurate knowledge about the characteristics of children with autism; however, they had mixed perceptions of diagnostic criteria for autism. Although most participants did address autism at some level of their educational training, little time was spent discussing the topic. Additionally, some SLPs lack confidence in their abilities to provide services to children with autism.

Conclusion

The return rate for participants was small, and it is difficult to generalize the results. However, the majority of respondents reported that they could have benefited from additional training in the area of autism. As a result, it may be necessary to consider strategies for providing this training.
A Qualitative Examination of Current Guidelines for Evidence-Based Practice in Child Language Intervention
Authors: Brackenbury Tim , Burroughs Elizabeth , Hewitt Lynne E.
Published: December 2007

Purpose

The present investigation examines the time, effort, and resources that evidence-based practice (EBP) requires, and looks at what types of results are obtained.

Method

Principles of EBP as outlined by the American Speech-Language-Hearing Association were applied to 3 treatment case studies.

Results

The cases took between 3 and 7 hr to complete and yielded different amounts and types of results. Individual article searches yielded better results than did searches of systematic reviews. Most evidence found was from small-group and individual case studies.

Conclusion

EBP is a necessary part of effective and ethical treatment. The resources needed, time involved, and availability of relevant information make current guidelines for EBP challenging for most full-time practitioners. Specific recommendations to address these concerns are offered.
The Impact of Early Intervention on Speech and Lexical Development for Toddlers With Cleft Palate: A Retrospective Look at Outcome
Authors: Hardin-Jones Mary , Chapman Kathy L.
Published: December 2007

Purpose

The purpose of the present investigation was to examine the impact of early intervention on speech and lexical measures for toddlers with cleft palate.

Method

Speech measures of ten 27-month-old toddlers with cleft palate who had been referred for therapy at 17 months of age were compared to those of 10 toddlers with cleft palate who had been referred but did not receive therapy. Both groups were compared to 2 other groups of children who had never been referred for therapy.

Results

Multivariate analysis of variance revealed only 1 significant difference between the children who received therapy and those who did not receive therapy. Children who received therapy produced a significantly greater percentage of glides (
p
< .001) than did children who did not receive therapy.

Conclusion

The findings of this study indicated that early intervention as conducted by the speech-language pathologists in this study was not as effective as expected for this group of toddlers with cleft palate.
Preventing Multiple-Choice Tests From Impeding Educational Advancement After Acquired Brain Injury
Authors: Schutz Larry E. , Rivers Kenyatta O. , Schutz Judith A. , Proctor Adele
Published: December 2007

Purpose

The purpose of this article is to present management strategies that can be used to breach barriers created for students with acquired brain injuries by testing the students in the multiple-choice format.

Method

This article presents a case study of a high school student with severe hydrocephalus and difficulties with state-mandated reading comprehension tests who was denied exceptional student education services because her grades were “so good.”

Result

Although an honor student who received academic awards, she was never taught how to pass the state reading test and was denied her diploma at graduation.

Implications

The cognitive obstacles posed by the multiple-choice format can be specified and treated. In-service training can help school staff and officials to recognize and serve these children promptly so that academic disability can be prevented.
The thyroid hormone mimetic compound KB2115 lowers plasma LDL cholesterol and stimulates bile acid synthesis without cardiac effects in humans
Authors: Berkenstam Anders , Kristensen Jens , Mellström Karin , Carlsson Bo , Malm Johan , Rehnmark Stefan , Garg Neeraj , Andersson Carl Magnus , Rudling Mats , Sjöberg Folke , Angelin Bo , Baxter John D.
Published: December 2007

Atherosclerotic cardiovascular disease is a major problem despite the availability of drugs that influence major risk factors. New treatments are needed, and there is growing interest in therapies that may have multiple actions. Thyroid hormone modulates several cardiovascular risk factors and delays atherosclerosis progression in humans. However, use of thyroid hormone is limited by side effects, especially in the heart. To overcome this limitation, pharmacologically selective thyromimetics that mimic metabolic effects of thyroid hormone and bypass side effects are under development. In animal models, such thyromimetics have been shown to stimulate cholesterol elimination through LDL and HDL pathways and decrease body weight without eliciting side effects. We report here studies on a selective thyromimetic [KB2115; (3-[[3,5-dibromo-4-[4-hydroxy-3-(1-methylethyl)-phenoxy]-phenyl]-amino]-3-oxopropanoic acid)] in humans. In moderately overweight and hypercholesterolemic subjects KB2115 was found to be safe and well tolerated and elicited up to a 40% lowering of total and LDL cholesterol after 14 days of treatment. Bile acid synthesis was stimulated without evidence of increased cholesterol production, indicating that KB2115 induced net cholesterol excretion. KB2115 did not provoke detectable effects on the heart, suggesting that the pharmacological selectivity observed in animal models translates to humans. Thus, selective thyromimetics deserve further study as agents to treat dyslipidemia and other risk factors for atherosclerosis.
p53 and TFIIEα share a common binding site on the Tfb1/p62 subunit of TFIIH
Authors: Di Lello Paola , Miller Jenkins Lisa M. , Mas Caroline , Langlois Chantal , Malitskaya Elena , Fradet-Turcotte Amélie , Archambault Jacques , Legault Pascale , Omichinski James G.
Published: December 2007

The general transcription factor IIH is recruited to the transcription preinitiation complex through an interaction between its p62/Tfb1 subunit and the α-subunit of the general transcription factor IIE (TFIIEα). We have determined that the acidic carboxyl terminus of TFIIEα (TFIIEα
336–439
) directly binds the amino-terminal PH domain of p62/Tfb1 with nanomolar affinity. NMR mapping and mutagenesis studies demonstrate that the TFIIEα binding site on p62/Tfb1 is identical to the binding site for the second transactivation domain of p53 (p53 TAD2). In addition, we demonstrate that TFIIEα
336–439
is capable of competing with p53 for a common binding site on p62/Tfb1 and that TFIIEα
336–439
and the diphosphorylated form (pS46/pT55) of p53 TAD2 have similar binding constants. NMR structural studies reveal that TFIIEα
336–439
contains a small domain (residues 395–433) folded in a novel ββααα topology. NMR mapping studies demonstrate that two unstructured regions (residues 377–393 and residues 433–439) located on either side of the folded domain appear to be required for TFIIEα
336–439
binding to p62/Tfb1 and that these two unstructured regions are held close to each other in three-dimensional space by the novel structured domain. We also demonstrate that, like p53, TFIIEα
336–439
can activate transcription
in vivo
. These results point to an important interplay between the general transcription factor TFIIEα and the tumor suppressor protein p53 in regulating transcriptional activation that may be modulated by the phosphorylation status of p53.
Evolutionarily conserved gene family important for fat storage
Authors: Kadereit Bert , Kumar Pradeep , Wang Wen-Jun , Miranda Diego , Snapp Erik L. , Severina Nadia , Torregroza Ingrid , Evans Todd , Silver David L.
Published: December 2007

The ability to store fat in the form of cytoplasmic triglyceride droplets is conserved from
Saccharomyces cerevisiae
to humans. Although much is known regarding the composition and catabolism of lipid droplets, the molecular components necessary for the biogenesis of lipid droplets have remained obscure. Here we report the characterization of a conserved gene family important for lipid droplet formation named fat-inducing transcript (FIT). FIT1 and FIT2 are endoplasmic reticulum resident membrane proteins that induce lipid droplet accumulation in cell culture and when expressed in mouse liver. shRNA silencing of FIT2 in 3T3-LI adipocytes prevents accumulation of lipid droplets, and depletion of FIT2 in zebrafish blocks diet-induced accumulation of lipid droplets in the intestine and liver, highlighting an important role for FIT2 in lipid droplet formation
in vivo
. Together these studies identify and characterize a conserved gene family that is important in the fundamental process of storing fat.
Three-dimensional cellular microarray for high-throughput toxicology assays
Authors: Lee Moo-Yeal , Kumar R. Anand , Sukumaran Sumitra M. , Hogg Michael G. , Clark Douglas S. , Dordick Jonathan S.
Published: December 2007

We have developed a miniaturized 3D cell-culture array (the Data Analysis Toxicology Assay Chip or DataChip) for high-throughput toxicity screening of drug candidates and their cytochrome P450-generated metabolites. The DataChip consists of human cells encapsulated in collagen or alginate gels (as small as 20 nl) arrayed on a functionalized glass slide for spatially addressable screening against multiple compounds. A single DataChip containing 1,080 individual cell cultures, used in conjunction with the complementary human P450-containing microarray (the Metabolizing Enzyme Toxicology Assay Chip or MetaChip), simultaneously provided IC50values for nine compounds and their metabolites from CYP1A2, CYP2D6, and CYP3A4 and a mixture of the three P450s designed to emulate the human liver. Similar responses were obtained with the DataChip and conventional 96-well plate assays, demonstrating that the near 2,000-fold miniaturization does not influence the cytotoxicity response. The DataChip may therefore enable toxicity analyses of drug candidates and their metabolites at throughputs compatible with the availability of compounds at early-stage drug discovery.
Multiroute memories in desert ants
Authors: Sommer Stefan , von Beeren Christoph , Wehner Rüdiger
Published: December 2007

When offered a permanent food source, central Australian desert ants,
Melophorus bagoti
, develop individually distinct, view-based foraging routes, which they retrace with amazing accuracy during each foraging trip. Using a particular channel setup connected to an artificial feeder, we trained
M. bagoti
ants to either two or three inward routes that led through different parts of their maze-like foraging grounds. Here, we show that ants are able to adopt multiple habitual paths in succession and that they preserve initially acquired route memories even after they have been trained to new routes. Individual ants differ in the consistency with which they run along habitual pathways. However, those ants that follow constant paths retain their route-specific memories for at least 5 days of suspended foraging, which suggests that even multiple route memories, once acquired, are preserved over the entire lifetime of a forager.
Computing Mechanisms
Authors: Piccinini Gualtiero
Published: December 2007

This paper offers an account of what it is for a physical system to be a computing mechanism—a system that performs computations. A computing mechanism is a mechanism whose function is to generate output strings from input strings and (possibly) internal states, in accordance with a general rule that applies to all relevant strings and depends on the input strings and (possibly) internal states for its application. This account is motivated by reasons endogenous to the philosophy of computing, namely, doing justice to the practices of computer scientists and computability theorists. It is also an application of recent literature on mechanisms, because it assimilates computational explanation to mechanistic explanation. The account can be used to individuate computing mechanisms and the functions they compute and to taxonomize computing mechanisms based on their computing power.
Why Unification Is Neither Necessary Nor Sufficient for Explanation
Authors: Gijsbers Victor
Published: December 2007

In this paper, I argue that unification is neither necessary nor sufficient for explanation. Focusing on the versions of the unificationist theory of explanation of Kitcher and of Schurz and Lambert, I establish three theses. First, Kitcher's criterion of unification is vitiated by the fact that it entails that every proposition can be explained by itself, a flaw that it is unable to overcome. Second, because neither Kitcher's theory nor that of Schurz and Lambert can solve the problems of asymmetry and accidental generalizations, it follows that unification is not sufficient to ground explanation. Third, some good explanations are disunifying, which entails that unification is not necessary for explanation either.
Mirroring as an A Priori Symmetry
Authors: Saunders Simon
Published: December 2007

A relationist will account for the use of ‘left’ and ‘right’ in terms of relative orientations, and other properties and relations invariant under mirroring. This analysis will apply whenever mirroring is a symmetry, so it certainly applies to classical mechanics; we argue it applies to any physical theory formulated on a manifold: it is in this sense an a priori symmetry. It should apply in particular to parity violating theories in quantum mechanics; mirror symmetry is only broken in such theories as a special symmetry.
Extension theorems, orbits, and automorphisms of the computably enumerable sets
Authors: Cholak Peter , Harrington Leo
Published: December 2007

We prove an algebraic extension theorem for the computably enumerable sets,

E

\mathcal {E}

. Using this extension theorem and other work we then show if

A
A

and

A
^

\widehat {A}

are automorphic via

Ψ
\Psi

, then they are automorphic via

Λ
\Lambda

where

Λ
↾

L

∗

(
A
)
=
Ψ

\Lambda \restriction \mathcal {L}^*(A) = \Psi

and

Λ
↾

E

∗

(
A
)

\Lambda \restriction \mathcal {E}^*(A)

is

Δ
3
0

\Delta ^0_3

. We give an algebraic description of when an arbitrary set

A
^

\widehat {A}

is in the orbit of a computably enumerable set

A
A

. We construct the first example of a definable orbit which is not a

Δ
3
0

\Delta ^0_3

orbit. We conclude with some results which restrict the ways one can increase the complexity of orbits. For example, we show that if

A
A

is simple and

A
^

\widehat {A}

is in the same orbit as

A
A

, then they are in the same

Δ
6
0

\Delta ^0_6

-orbit and, furthermore, we provide a classification of when two simple sets are in the same orbit.
Support varieties for modules over Chevalley groups and classical Lie algebras
Authors: Carlson Jon , Lin Zongzhu , Nakano Daniel
Published: December 2007

Let

G
G

be a connected reductive algebraic group over an algebraically closed field of characteristic

p
>
0

p>0

,

G

1

G_{1}

be the first Frobenius kernel, and

G
(

F

p

)

G({\mathbb F}_{p})

be the corresponding finite Chevalley group. Let

M
M

be a rational

G
G

-module. In this paper we relate the support variety of

M
M

over the first Frobenius kernel with the support variety of

M
M

over the group algebra

k
G
(

F

p

)

kG({\mathbb F}_{p})

. This provides an answer to a question of Parshall. Applications of our new techniques are presented, which allow us to extend results of Alperin-Mason and Janiszczak-Jantzen, and to calculate the dimensions of support varieties for finite Chevalley groups.
Central invariants and higher indicators for semisimple quasi-Hopf algebras
Authors: Ng Siu-Hung , Schauenburg Peter
Published: December 2007

In this paper, we define the higher Frobenius-Schur (FS-)indicators for finite-dimensional modules of a semisimple quasi-Hopf algebra

H
H

via the categorical counterpart developed in a 2005 preprint. When

H
H

is an ordinary Hopf algebra, we show that our definition coincides with that introduced by Kashina, Sommerhäuser, and Zhu. We find a sequence of gauge invariant central elements of

H
H

such that the higher FS-indicators of a module

V
V

are obtained by applying its character to these elements. As an application, we show that FS-indicators are sufficient to distinguish the four gauge equivalence classes of semisimple quasi-Hopf algebras of dimension eight corresponding to the four fusion categories with certain fusion rules classified by Tambara and Yamagami. Three of these categories correspond to well-known Hopf algebras, and we explicitly construct a quasi-Hopf algebra corresponding to the fourth one using the Kac algebra. We also derive explicit formulae for FS-indicators for some quasi-Hopf algebras associated to group cocycles.
Symmetric Markov chains on ℤ^{𝕕} with unbounded range
Authors: Bass Richard , Kumagai Takashi
Published: December 2007

We consider symmetric Markov chains on

Z

d

\mathbb {Z}^d

where we do not assume that the conductance between two points must be zero if the points are far apart. Under a uniform second moment condition on the conductances, we obtain upper bounds on the transition probabilities, estimates for exit time probabilities, and certain lower bounds on the transition probabilities. We show that a uniform Harnack inequality holds if an additional assumption is made, but that without this assumption such an inequality need not hold. We establish a central limit theorem giving conditions for a sequence of normalized symmetric Markov chains to converge to a diffusion on

R

d

\mathbb {R}^d

corresponding to an elliptic operator in divergence form.
Non-crossing partition lattices in finite real reflection groups
Authors: Brady Thomas , Watt Colum
Published: December 2007

For a finite real reflection group

W
W

with Coxeter element

γ
\gamma

we give a case-free proof that the closed interval,

[
I
,
γ
]

[I, \gamma ]

, forms a lattice in the partial order on

W
W

induced by reflection length. Key to this is the construction of an isomorphic lattice of spherical simplicial complexes. We also prove that the greatest element in this latter lattice embeds in the type

W
W

simplicial generalised associahedron, and we use this fact to give a new proof that the geometric realisation of this associahedron is a sphere.
Quantum cohomology and the 𝑘-Schur basis
Authors: Lapointe Luc , Morse Jennifer
Published: December 2007

We prove that structure constants related to Hecke algebras at roots of unity are special cases ofkk-Littlewood-Richardson coefficients associated to a product ofkk-Schur functions. As a consequence, both the 3-point Gromov-Witten invariants appearing in the quantum cohomology of the Grassmannian, and the fusion coefficients for the WZW conformal field theories associated tosu^(ℓ)\widehat {su}(\ell )are shown to bekk-Littlewood-Richardson coefficients. From this, Mark Shimozono conjectured that thekk-Schur functions form the Schubert basis for the homology of the loop Grassmannian, whereaskk-Schur coproducts correspond to the integral cohomology of the loop Grassmannian. We introduce dualkk-Schur functions defined on weights ofkk-tableaux that, given Shimozono’s conjecture, form the Schubert basis for the cohomology of the loop Grassmannian. We derive several properties of these functions that extend those of skew Schur functions.
Branch structure of 𝐽–holomorphic curves near periodic orbits of a contact manifold
Authors: Harris Adam , Wysocki Krzysztof
Published: December 2007

Let

M
M

be a three–dimensional contact manifold, and

ψ
~

:
D
∖
{
0
}
→
M
×

R

\tilde {\psi }:D\setminus \{0\}\to M\times {\mathbb R}

a finite–energy pseudoholomorphic map from the punctured disc in

C

{\mathbb C}

that is asymptotic to a periodic orbit of the contact form. This article examines conditions under which smooth coordinates may be defined in a tubular neighbourhood of the orbit such that

ψ
~

\tilde {\psi }

resembles a holomorphic curve, invoking comparison with the theory of topological linking of plane complex algebroid curves near a singular point. Examples of this behaviour, which are studied in some detail, include pseudoholomorphic maps into

E

p
,
q

×

R

{\mathbb E}_{p,q}\times {\mathbb R}

, where

E

p
,
q

{\mathbb E}_{p,q}

denotes a rational ellipsoid (contact structure induced by the standard complex structure on

C

2

{\mathbb C}^{2}

), as well as contact structures arising from non-standard circle–fibrations of the three–sphere.
Conformal energy, conformal Laplacian, and energy measures on the Sierpinski gasket
Authors: Azzam Jonas , Hall Michael , Strichartz Robert
Published: December 2007

On the Sierpinski Gasket (SG) and related fractals, we define a notion of conformal energy

E

φ

\mathcal {E}_\varphi

and conformal Laplacian

Δ

φ

\Delta _{\varphi }

for a given conformal factor

φ
\varphi

, based on the corresponding notions in Riemannian geometry in dimension

n
≠
2

n\neq 2

. We derive a differential equation that describes the dependence of the effective resistances of

E

φ

\mathcal {E}_\varphi

on

φ
\varphi

. We show that the spectrum of

Δ

φ

\Delta _{\varphi }

(Dirichlet or Neumann) has similar asymptotics compared to the spectrum of the standard Laplacian, and also has similar spectral gaps (provided the function

φ
\varphi

does not vary too much). We illustrate these results with numerical approximations. We give a linear extension algorithm to compute the energy measures of harmonic functions (with respect to the standard energy), and as an application we show how to compute the

L

p

L^{p}

dimensions of these measures for integer values of

p
≥
2

p\geq 2

. We derive analogous linear extension algorithms for energy measures on related fractals.