cssi/SciSciGPT-SciSciNet huggingface dataset:
Conducting case study research in operations management

Abstract Recently, there have been numerous calls for more empirical field-based research to be conducted in operations management (OM). Knowledge of how operations systems work can be enhanced significantly through contact with the “real-world” conditions that OM models seek to describe. Case study research is a primary means of exploring field conditions but is an unfamiliar methodology for many in OM. Moreover, the case study method is viewed with scepticism by those who consider it to be a weak form of research, one that lacks rigor and objectivity. Here, we offer an introduction to the case study method for OM researchers who may have little background in field based research. We provide an outline of the procedure and cite some excellent sources that cover case study design, data analysis and the philosophical rationale for the methodology. We also identify some recent examples of OM case studies that illustrate our points. We then contrast the various uses for case study research and their different design and theory requirements. An appendix provides a listing of case studies that have appeared in some OM journals in recent years, classifying the studies by their research purpose. However, regardless of their purposes, case study research need to be conducted in a manner that assures maximum measurement reliability and theory validity. We describe some of the steps that must be taken to ensure that a study is as rigorous as possible. We also argue that, properly conducted, a case study is a truly scientific research approach. We conclude by pointing out some areas of OM research where case studies might be particularly valuable.
Specificity and catalysis of uracil DNA glycosylase. A molecular dynamics study of reactant and product complexes with DNA.

The structure of uracil DNA glycosylase (UDG) in complex with a nonamer duplex DNA containing a uracil has been determined only in the product state. The reactant state was constructed by reattaching uracil to the deoxyribose, and both complexes were studied by molecular dynamics simulations. Significant changes in the positions of secondary structural elements in the enzyme are induced by the hydrolysis of the glycosidic bond. The simulations show that the specificity of the uracil pocket in the enzyme is largely retained in both complexes with the exception of Asn-204, which has been identified as a residue that contributes to discrimination between uracil and cytosine. The hydrogen bond between the amide group of Asn-204 and O4 of uracil is disrupted by fluctuations of the side chain in the reactant state and is replaced by a hydrogen bond to water molecules trapped in the interior of the protein behind the uracil binding pocket. The role of two residues implicated by mutation experiments to be importa...
Effects of olfactory bulb removal on brain norepinephrine in golden hamsters

Abstract Changes in brain norepinephrine levels after olfactory bulb removal have been found in rats. Several investigators have suggested that the dramatic behavioral effects of bilateral olfactory bulb removal in hamsters might be due to a possible similar change rather than anosmia per se. The results of this study do not support this hypothesis since no significant differences in brain norepinephrine were found between sham operated and bilaterally bulbectomized male hamsters treated identically to those used in earlier behavioral studies on olfactory bulb removal. Also, since there were no changes in the norepinephrine levels in female hamsters which were treated identically to female rats used in earlier neurochemical studies, it is probable that there is a species difference in the effects of olfactory bulb removal on brain norepinephrine.
Uniquely Covered Groups

In this paper, we investigate finite groups which have exactly one irredundant covering by proper subgroups.
Detection of Resistance to the Russian Wheat Aphid in Hexaploid Wheat

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), poses a serious threat to wheat (Triticum aestivum L.) production in many parts of the world. This research was initiated to evaluate wheat accessions for detection of resistance to the RWA. Over 12,000 wheat cultivars and plant introductions (PIs) from the USDA-ARS National Small Grains Collection were evaluated for reaction to RWA feeding damage. Twenty-nine PIs from Iran, Afghanistan, and the former Soviet Union, of various agronomic backgrounds were identified as having moderate to high levels of RWA resistance. This information is useful to wheat breeders searching for sources of resistance to the RWA to incorporate into their breeding programmes.
Safety Issues Concerning Robotic Welding of Large Elements

Robotic welding of large elements poses significant difficulties regarding the technological process, robot functions and the safety of the operator and other people. The health risks involved arise out of the weight of elements, high heat capacity, harmful gases and fumes. Under the Eureka project, the PIAP team is developing a model of a robotized cell designed mainly for welding large elements. Occupational safety is of paramount importance and hence is a constructive discussion on occupational health risk factors. The replacement of human workers with robots on assembly nests, especially in SMEs, eliminates the exposure of workers to hazard, but is focused on a reduction in employment rather than in significant improvements to the workplace. The paper analyzes and discusses European safety regulations contained in the European directives and applicable EN standards. Appropriate safety programs of diverse welding processes and materials to be implemented by designers and suppliers of robotic welding stations and lines, as well as by the users thereof, will be indicated.
Structure benefits all

Accessibility for the Dynamic Web is now possible due to new standards being developed at the W3C and being implemented in Firefox. The technology allows today's web pages to contain additional markup describing semantics. An often-cited benefit of this technology is the ability to describe scripted widgets with dynamic behaviour. However, another major benefit is to differentiate the sections of a web page, via human-readable labels or predefined semantics such as "main", "contentinfo", "navigation" and "search". Marking the sections of a web page offers significant improvement for users who need access to today's web with a small device or an assistive technology.
Arsenic removal from groundwater using iron electrocoagulation: Effect of charge dosage rate

We demonstrate that electrocoagulation (EC) using iron electrodes can reduce arsenic below 10 μg/L in synthetic Bangladesh groundwater and in real groundwater from Bangladesh and Cambodia, while investigating the effect of operating parameters that are often overlooked, such as charge dosage rate. We measure arsenic removal performance over a larger range of current density than in any other single previous EC study (5000-fold: 0.02 - 100 mA/cm(2)) and over a wide range of charge dosage rates (0.060 - 18 Coulombs/L/min). We find that charge dosage rate has significant effects on both removal capacity (μg-As removed/Coulomb) and treatment time and is the appropriate parameter to maintain performance when scaling to different active areas and volumes. We estimate the operating costs of EC treatment in Bangladesh groundwater to be $0.22/m(3). Waste sludge (~80 - 120 mg/L), when tested with the Toxic Characteristic Leachate Protocol (TCLP), is characterized as non-hazardous. Although our focus is on developing a practical device, our results suggest that As[III] is mostly oxidized via a chemical pathway and does not rely on processes occurring at the anode. Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Environmental Science and Health, Part A, to view the free supplemental file.
In situ observations of oxygen adsorption on a Cu(100) substrate using atomic force microscopy

Abstract In situ atomic force microscopy (AFM) images of Cu(100) single crystals in dilute acid solutions reveal that a ( 2 × 2 ) R 45° adlattice is formed on this material at negative potentials. This adlattice can be removed by sweeping the potential of the Cu(100) surface approximately 0.5 V negative of the open circuit potential. Based on the insensitivity of the ( 2 × 2 ) R 45° structure to electrolyte and electrode surface preparation, and our data showing that Cu(111) surfaces in the same acidic solution exhibit only the hexagonal Cu lattice, we associate the overlayer with adsorbed O or OH−, in which the oxygen is chemisorbed in alternate 4-fold hollow sites. AFM images of monatomic steps in an electrochemical environment are reported.
Expansion of a dipolar condensate

We discuss the expansion of an initially trapped dipolar condensate. When the nominal isotropic s-wave interaction strength becomes tunable through a Feshbach resonance, anisotropic dipolar effects are shown to be detectable under current experimental conditions [E. A. Donley et al., Nature London 412, 295 (2001)].
Accumulation of heavy metals and PCB's in an urban lake

Abstract A contaminated, urban lake was surveyed for the areal and depth distribution of toxic metals and PCBs. Additionally, 137Cs dating of sediment cores were conducted to get an estimate of sedimentation rates, PCB loading rates, and the period of peak loading of metals. Lead and Zn concentrations were greatly elevated in the surface sediments. The depositional history of lead in the sediment profile reflected the lake's position adjacent to a interstate highway and .the phasing out of leaded gasoline in recent years.
Rat-anterior pituitary nucleic acid levels as function of age.

SummaryA study was made of RNA, water, and collagen contents of adenohypophyses of rats of various age groups from 35 days to one year old, sacrificed by decapitation or an overdose of ether. There were no significant differences in level of RNA in tissue from one age group to another. Concentration of anterior pituitary nucleic acid was not influenced by manner of sacrifice for most age groups studied. Contents of water and collagen in the tissue were similar in young and old rats.
Do Neuropsychological Measures Contribute to the Prediction of Academic Achievement? The Predictive Validity of the LNNB-CR Pathognomonic Scale:

It is well known that measures of intelligence are good predictors of academic achievement. Because many children with behavioral or learning problems also do poorly on neuropsychological measures,...
The social shaping of Videotex: how information services for the public have evolved

“Videotex” was an early incarnation of what have been more recently called “end-user information services.” This article considers the origins and historical development of videotex over three decades, comparing various nationally sponsored and private systems in Europe and North America, and discussing reasons given for the “failure” of videotex. The influence of nontechnical factors on videotex and perceptions of critical problems and acceptable solutions are described. According to this interpretation, the development of videotex faced four “bottlenecks” at once: the determination of transmission channels; the choice of a display device; agreement on coding standards; and the marketing of the resulting services. In how it accommodated these problems, videotex provides an example of how social, political, and economic elements are inseparable from technical constraints in the development of new information technologies. © 1994 John Wiley & Sons, Inc.
Hydrology: An Introduction : (Wilfried Brutsaert)

Brutsaert's Hydrology: An Introduction (Brutsaert, 2005) is an excellent textbook based on university courses the author has taught during an illustrious career. After completing the review, I congratulate anyone who had the good fortune to take Professor Brutsaert's class. In comparison to other introductory hydrology texts, this book leans more toward the theoretical side and is therefore better suited to graduate courses or for use as a reference book for practicing hydrologists who want to continue to improve their understanding of hydrology. An appropriate alternate title for this book might be Theoretical Hydrology: An Introduction Based on Fluid Mechanics. Before describing the book, I want to point out two features of this text that are unique and very useful. The first is the treatment of fluid mechanics specifically relevant to hydrology. Separate treatment is provided for atmospheric water, surface hydrology, and subsurface hydrology at the beginning of the text. Fluid mechanics is an area in which all hydrologists should be well versed, but this topic is not typically …
Implantation of inflatable penile prosthesis in patients with severe corporeal fibrosis: introduction of a new penile cavernotome.

Purpose: Implantation of penile prosthetic cylinders into scarred corpora remains a challenge in the field of prosthetic urology. We describe a new penile cavernotome, which allows for easier dilation of fibrotic corpora cavernosa and facilitates inflatable penile prosthesis cylinder insertion. Materials and Methods: A set of 5 cavernotomes between 6 and 13 mm. in diameter are used to drill a space in fibrotic corpora with controlled 1 mm. cuts. The cavernotomes are advanced in an oscillating fashion and also allow shaving of severely stenotic areas for easier cavity development. They were used in 16 patients with fibrotic corpora secondary to different etiologies. A high transverse scrotal incision was used in all cases. Of the 16 patients 14 received downsized cylinders. Results: Implantation of both cylinders of an inflatable 3-piece device was successful in all cases. Proximal crural perforation occurred intraoperatively in 5 patients and was corrected by attaching the rear tip extender to the tunica with nonabsorbable suture. Postoperatively, distal tunical perforation of the corpora in 4 patients was repaired with natural tissue. Operative time was reduced compared to our previous experience with implantation in cases of corporeal fibrosis using extensive corporotomies or the Carrion-Rossello cavernotomes. In no case was the procedure terminated for urethral laceration or inadequate dilation for cylinder insertion. No grafting materials were necessary to close the corporotomy. Conclusions: The new cavernotomes along with the high transverse scrotal incision and downsized prostheses resulted in successful implantation in all of our cases. Dilation of fibrotic corpora was easier and quicker with the new cavernotomes because extensive corporeal resection was not necessary. Complications were acceptable for these difficult cases and prosthesis survival is 100% to date.
Sealable femtoliter chamber arrays for cell-free biology

Cell-free systems provide a flexible platform for probing specific networks of biological reactions isolated from the complex resource sharing (e.g., global gene expression, cell division) encountered within living cells. However, such systems, used in conventional macro-scale bulk reactors, often fail to exhibit the dynamic behaviors and efficiencies characteristic of their living micro-scale counterparts. Understanding the impact of internal cell structure and scale on reaction dynamics is crucial to understanding complex gene networks. Here we report a microfabricated device that confines cell-free reactions in cellular scale volumes while allowing flexible characterization of the enclosed molecular system. This multilayered poly(dimethylsiloxane) (PDMS) device contains femtoliter-scale reaction chambers on an elastomeric membrane which can be actuated (open and closed). When actuated, the chambers confine Cell-Free Protein Synthesis (CFPS) reactions expressing a fluorescent protein, allowing for the visualization of the reaction kinetics over time using time-lapse fluorescent microscopy. Here we demonstrate how this device may be used to measure the noise structure of CFPS reactions in a manner that is directly analogous to those used to characterize cellular systems, thereby enabling the use of noise biology techniques used in cellular systems to characterize CFPS gene circuits and their interactions with the cell-free environment.
A cryogenic solid target for the production of [18F]fluoride from enriched [18O]carbon dioxide

Abstract A new target design is described for the production of fluorine-18 in the chemical form of fluoride. The target is conical in shape with a cooling block extending radially. The target material is oxygen-18 enriched carbon dioxide gas which is frozen onto the cooled surface. The rear of the cone and cooling block are surrounded by a bath of liquid nitrogen. The use of C 18 O 2 in place of H 2 18 O as a target material increases the recovery efficiency and thus reduces the amount lost in each irradiation. After irradiation, 99% of the enriched gas was recovered by warming the target and cryogenically transferring the gas into a storage bubl. After transfer, the fluoride was rinsed from the target surface with water. The production from this target was 90–140 mCi/μA at saturation. The chemical form of fluoride has been verified by ion chromatography and the reactivity has been verified by use in the synthesis of FDG. This target is superior to the oxygen-18 enriched water target in the efficiency of recovery of the enriched target material which in turn reduces the cost of each irradiation.
Effect of pH on organic acid production by Clostridium propionicum in test tube and fermentor cultures

Clostridum propionicum is a chemical autotroph that metabolizes alanine to propionic acid (reduction product) and acetic acid (oxidation product). The ratio of propionate/acetate predicted by the electron balance is 2:1. This study reports the effect of pH on growth and organic acid production by this organism when grown in both test tube cultures initially buffered from pH 7.0 to 5.0, and in fermentors maintained at pH 7.0 and 6.5. Highest growth and organic acid production was found at pH 7.0 in both cases. HPLC analysis showed that at pH 7.0, the ratios of propionate to acetate were 0.45:1 (stationary tube, 24 h). The highest ratio observed was 1.8:1 (stationary tube, pH 6.0, 24h). This tube produced 8.5% of the acids produced in the pH 7.0 culture tube. The identify of the major portion of the reduction products of the organism remains unknown.
Effects of extra-epithelial factors on the incorporation of thymidine by embryonic epidermis.

Abstract Cells in explants of eleven-day chick shank epidermis rapidly lose most of their ability to incorporate tritiated thymidine. Concomitantly, epidermal basal cells lose their columnar shape. Both properties reappear if dermis is combined with such epidermis. A number of experiments suggest that thymidine incorporation frequencies in epidermis can be influenced by the kind or age of dermis present, or by muscle as opposed to dermis. The addition of horse serum to the protein-free nutrients has no effect on such incorporation, although subsequent differentiative behavior is altered. Preliminary data further suggest that pre-culture in unlabeled thymidine is followed by slightly increased incorporation frequencies of tritiated thymidine. These and other results are discussed in relation to the hypothesis that cellular incorporation of thymidine is dependent upon conditions in the epidermis tissue as a whole. These tissue conditions seem dependent upon specific mesenchymal association with the epidermis.
Production and processing of Cu-Cr-Nb alloys

A new Cu-based alloy possessing high strength, high conductivity, and good stability at elevated temperatures was recently produced. This paper details the melting of the master alloys, production of rapidly solidified ribbon, and processing of the ribbon to sheet by hot pressing and hot rolling.
IEADVISE — an undergraduate course‐advising expert system in Industrial Engineering

: IEADVISE is an undergraduate course-advising expert system developed and used by the Department of Industrial Engineering at the University of Missouri-Columbia, USA. The motivation for this development was the need for an online system that would make undergraduate course-advising accessible at all times to the Industrial Engineering students. Expert System Environment (ESE), an expert system shell on the IBM mainframe, was chosen as the development tool. This paper describes the knowledge base, the expert system and its operation, and the verification and validation procedures. Results of the verification and validation performed to ensure accuracy and reliability will be discussed.
Prenatal nicotine exposure impairs the cardiorespiratory response to acute hypoxemia in sleeping lambs. • 1798

Maternal smoking is a major risk factor for SIDS. The mechanism of action may be a nicotine mediated attenuation of the hypoxic defense as evidenced by impaired arousal and blunted ventilatory response to acute hypoxemia in young lambs exposed to an acute nicotine infusion (Hafstrom et al, Pediatr Res 39:386A, 1996). The aim of this study was to determine whether prenatal nicotine exposure alters the cardiorespiratory response to hypoxia after birth.
The Labor Market Impacts of Post‐school Occupational Training for Young Men

The period 1966 to 1976 was a decade of change, contrast and challenge. In this article a model is developed and estimated contrasting the labor market experiences of young men who participated in post-school occupational training during this period with those young men who did not participate. Participation in post-school forms of occupational training is identified as a significant contributor to individual labor market success during the period and racial differences in returns to training participation are highlighted. The results prompt questions concerning the direction of current federal training policy.
Psychophysiological responses of adults who do not stutter while listening to stuttering

The present study examined the psychophysiological responses of fluent listeners to stuttered speech. Specifically, skin conductance and heart rate changes were measured from adults who do not stutter while watching one-minute video speech samples of persons stutter read aloud. Fifteen adult participants observed three stuttered and three fluent speech samples, presented in random order with a two-minute interstimulus intervals. Results revealed that observing stuttered speech evoked a significant increase in skin conductance and a significant deceleration in heart rate relative to watching fluent speech samples. These findings suggest that listeners are physiologically aroused by stuttering and appear to maintain feelings of unpleasantness to stuttered speech. Further, deceleration in heart rate during stuttered samples also suggest that listeners may be paying more attention to the stuttered speech samples as compared to the fluent speech samples. We speculate that aberrant and anomalous stuttering behaviors probably simulate the mirror neuronal mechanism eliciting the emotional arousal associated within them. Such physiological arousal may provide the emotional genesis to the listener's negative stereotypical perceptions towards people who stutter.
Referral to outpatient cardiac rehabilitation: intervention research at the patient, provider, and health system levels

This article sets out the clinical context of the research presented by Grace et al. in an accompanying article in this journal. Secondary preventive measures against cardiovascular disease, such as outpatient cardiac rehabilitation (OCR), can greatly reduce associated burden on health systems. Here, I discuss the study carried out by Grace and colleagues--a multilevel study of the contribution of patient and physician factors to cardiac rehabilitation referral. Grace et al. demonstrate that both physician and patient factors have key roles in OCR referral. In this commentary I explore the limitations of studying the factors that contribute to referral alone as a final end point given the lower-than-desired rates of enrollment among referred patients.
Periaqueductal gray and cerebral cortex modulate responses of medial thalamic neurons to noxious stimulation

The response of medial thalamic neurons to noxious peripheral stimulation were studied with intracellular recording methods in the cat. Electrical stimulation of the contralateral forepaw produced an EPSP-IPSP sequence followed by rebound excitation in these medial thalamic neurons. Action potentials appeared with the initial EPSP or with the rebound excitation. The mean latency to onset was 15 ms for the EPSP and 33 ms for IPSP. In contrast, electrical stimulation of the PAG or of the pericruciate cerebral cortex produced large IPSPs in the medial thalamic neurons. When PAG or cortex stimulation were paired with noxious stimulation, both the PAG and cortex responses predominated over the noxious response. This shows that the PAG and the cerebral cortex have the capabilities of influencing the responses of the medial thalamus to noxious stimulation. The medial thalamus is part of the relay system which sends information about noxious stimulation to the cerebral cortex where the noxious information reaches conscious awareness, so influencing the message at the level of the medial thalamus would probably alter the conscious perception of pain. The data suggest the existence of an ascending pain modulation system from the midbrain to the thalamus and also suggests a mechanism of cortical control over pain perception.
Born DMO Revisited

Born DMO (BDMO) is a method of transformation of finite offset data to zero offset data The method cascades an inversion of offset data to produce a subsurface model with a generation of zero offset data from the resulting model. Both the inversion and the modeling steps are based on a Born approximation for modeling wave prop% g&ion, hence the name, Born DMO. A method for processing spatial-temoporal domain common offset data to produce zero offset data was proposed by Liner (1989). That method required a fractional derivative on the given offset data, thus making it difficult to compare the final operator with Hale’s wavenumber-temporal domain DMO operator. Here, we derive a BDMO operator for common offset data that does not require thii fractional derivative and allows for a direct comparison. We find that the operator differs from Hale’s in only one additional simple amplitude factor. We test the operator by applying it to Kirchhoff approximate data for a tilted plane. The operator produces an output with finite offset traveltime and geometrical spreading transformed to zero offset traveltime and geometrical spreading. Furthermore, the operator preserves the angularly dependent reflection coefficient of the original data and also includes the cosine of the specular angle as a multiplicative factor. This is the fully nonlinear (in earth parameters) geometrical optics reflection coefficient, thus, indicating a more robust result than its basii in the Born approximation might lead one to expect. A second BDMO operator, including an addional scale factor in the operator, producea the same output as the first, multiplied by an additional factor of cosine-squared of the specular angle. The ratio of the outputs provides an estimate of the cosine-square. The output from Hale’s DMO produces the same result as our first BDMO operator with an addition scale factor that depends on offset, dip and zero offset diitance to the rdector. We have also compared thii result to Zhang (1988). We find that Zhaug’e result agrees with ours, except that the zero offset geometrical spreading is replaced by normal incidence geometrical spreading from the midpoint of the source/receiver pair having the same specular reflection point as the zero o&et response.
Time Management and Instructional Supervision.

role as instructional leaders. If principals are to improve instruction, they not only must be able to devote time to supervision but also must use that time effectively. Thus, the purpose of this article is to review existing data concerning time management and instructional supervision and to suggest more effective means for managing the time devoted to instructional supervision. Both school superintendents and building principals view principals as instructional leaders. Teachers, on the other hand, view principals not as instructional leaders but rather as school man-
Response latencies of neurons in visual areas MT and MST of monkeys with striate cortex lesions.

Cortical area, MT (middle temporal area) is specialized for the visual analysis of stimulus motion in the brain. It has been suggested [Brain 118 (1995) 1375] that motion signals reach area MT via two dissociable routes, namely a ‘direct’ route which bypasses primary visual cortex (area, striate cortex (V1)) and is specialized for processing ‘fast’ motion (defined as faster than 6 ◦ /s) with a relatively short latency, and an ‘indirect’ route via area V1 for processing ‘slow’ motion (slower than 6 ◦ /s) with a relatively long latency. We tested this proposal by measuring the effects of unilateral V1 lesions on the magnitudes and latencies of responses to fast- and slow-motion (depicted by random dot kinematograms (RDK) ) of single neurons in areas MT and medial superior temporal area (MST) of anaesthetized macaque monkeys. In the unlesioned hemisphere contralateral to a V1 lesion, response magnitudes and latencies of MT neurons were similar to those previously reported from MT neurons in normal monkeys, and there was no significant association between slow movement and long response latency (>100 ms), or between fast movement and short latency (≤100 ms). V1 lesions led to diminished response magnitudes and increased latencies in area MT of the lesioned hemisphere, but did not selectively abolish MT responses to slow moving stimuli, or abolish long-latency responses to either slow- or fast-moving stimuli. Response magnitudes and latencies in area MST, which receives visual inputs directly from area MT and is also specialized for visual analysis of motion, were unaffected by V1 lesions (though we have shown elsewhere that directionally-selective responses in both areas were impaired by V1 lesions). Overall, the results are incompatible with the hypothesis that there are dissociable routes to MT specialized for processing separately fast and slow motion. © 2003 Published by Elsevier Ltd.
Effects of vehicles and elicitation concentration in contact dermatitis testing. I. Experimental contact sensitization in humans.

A study was made to evaluate the effects of vehicle and challenge concentration on response of human subjects to potential allergens. In the vehicle studies the modified Draize test was used to test the response of subjects to cinnamic aldehyde and to costus oil, administered at two skin sites, in petrolatum and in 95 % ethyl alcohol. In two tests of costus oil, alcohol proved to be more effective in eliciting a response than petrolatum; on the other hand, in one les< with cinnamic aldehyde, no difference in results was obtained with these two vehicles. In the concentration studies, subjects known to he sensitive lo the test substance were tested by the Al® test with costus oil (three concentrations), chloracetamide (four concentrations), or thimerosal (three concentrations): petrolatum was used as the vehicle in each case. Results of the vehicle test showed no compelling reason for the selection of one vehicle rather than another. Results of the concentration tests indicated that concentration does have an effect on the intensity and frequency of reactions to potential allergens.
Role of cerebrospinal fluid and plasma biomarkers in the diagnosis of neurodegenerative disorders and mild cognitive impairment

Biomarkers are one type of laboratory testing being developed in response to the therapeutic imperative for diseases that cause cognitive impairment and dementia. The role of biomarkers is already transforming the organization and conduct of clinical trials, and if successful will likely contribute in the future to the medical management of patients with these diseases. Despite the obvious utility of practicality of blood- or urine-based biomarkers, so far results from these fluid compartments have not been reproducible. In contrast, substantial progress has been made in cerebrospinal fluid biomarkers. Here we review the stages of cerebrospinal fluid biomarker development for several common and unusual diseases that cause cognitive impairment and dementia, stressing the distinction between diagnostic and mechanistic biomarkers. Future applications will likely focus on diagnosis of latent or early-stage disease, assessment of disease progression, mechanism of injury, and response to experimental therapeutics.
Regional and grain size influences on the geochemistry of soil at Gusev crater, Mars

[1] Congruous with earlier work, Martian soil along the Spirit Rover's traverse at Gusev crater can be divided into three broad groups by size: fines (<150 μm), sand, and a mix of various grain sizes. The key chemical observation is greater homogeneity in fines relative to the other two, consistent with regional- and global-scale sampling of chemical compositions by finer particle sizes. The mix class is generally more heterogeneous as are samples from the Columbia Hills within each class. Variation in the trace element Ni is consistent with a CI contribution not exceeding 3%, while that of Ti is compatible with Fe-Ti oxide enrichment not exceeding 3%. Physical mixing models are poorly supported. Among many potential binary and three-component mixing models, only two show some consistency with the soil data: typical fines with the opaline Si end-member identified at Home Plate and typical fines with sulfates (bearing a variable mix of Ca, Fe, and Mg cations). We also infer that binary mixing transcends classes, contrasting strongly with terrestrial sediments, and that mixing trends are consistent with significant nonmixing contributions, perhaps including localized chemical alteration. The decoupling between chemistry and grain size classes also suggests that processes linking composition with grain size, such as heavy mineral sorting, may have been minimal or absent entirely. The primary exception to this is the correlation between Cl and Si, Cl-S, and Al-Si, which is strongest in the fines class.
Detection of cerebral ischemia in neurovascular surgery using quantitative frequency-domain near-infrared spectroscopy

Object There is great value in monitoring for signs of ischemia during neurovascular procedures. Current intraoperative monitoring techniques provide real-time feedback with limited accuracy. Quantitative frequency-domain near-infrared spectroscopy (Q-NIRS) allows measurement of tissue oxyhemoglobin (HbO2), deoxyhemoglobin (HHb), and total hemoglobin (tHb) concentrations and brain tissue oxygen saturation (SO2), which could be useful when monitoring for evidence of intraoperative ischemia. Methods Using Q-NIRS, the authors monitored 25 neurovascular procedures including aneurysm clip placement, arteriovenous malformation resection, carotid endarterectomy, superficial temporal artery–middle cerebral artery (MCA) bypass surgery, external carotid artery–MCA bypass surgery, encephaloduromyosynangiosis, and balloon occlusion testing. The Q-NIRS technology provides measurable cerebral oxygenation values independent from those of the scalp tissue. Thus, alterations in the variables measured with Q-NIRS quantitat...
Mechanism of Neutralization of Herpes Simplex Virus by Antibodies Directed at the Fusion Domain of Glycoprotein B

Glycoprotein B (gB), the fusogen of herpes simplex virus (HSV), is a class III fusion protein with a trimeric ectodomain of known structure for the postfusion state. Seen by negative-staining electron microscopy, it presents as a rod with three lobes (base, middle, and crown). gB has four functional regions (FR), defined by the physical location of epitopes recognized by anti-gB neutralizing monoclonal antibodies (MAbs). Located in the base, FR1 contains two internal fusion loops (FLs) and is the site of gB-lipid interaction (the fusion domain). Many of the MAbs to FR1 are neutralizing, block cell-cell fusion, and prevent the association of gB with lipid, suggesting that these MAbs affect FL function. Here we characterize FR1 epitopes by using electron microscopy to visualize purified Fab-gB ectodomain complexes, thus confirming the locations of several epitopes and localizing those of MAbs DL16 and SS63. We also generated MAb-resistant viruses in order to localize the SS55 epitope precisely. Because none of the epitopes of our anti-FR1 MAbs mapped to the FLs, we hyperimmunized rabbits with FL1 or FL2 peptides to generate polyclonal antibodies (PAbs). While the anti-FL1 PAb failed to bind gB, the anti-FL2 PAb had neutralizing activity, implying that the FLs become exposed during virus entry. Unexpectedly, the anti-FL2 PAb (and the anti-FR1 MAbs) bound to liposome-associated gB, suggesting that their epitopes are accessible even when the FLs engage lipid. These studies provide possible mechanisms of action for HSV neutralization and insight into how gB FR1 contributes to viral fusion. IMPORTANCE For herpesviruses, such as HSV, entry into a target cell involves transfer of the capsid-encased genome of the virus to the target cell after fusion of the lipid envelope of the virus with a lipid membrane of the host. Virus-encoded glycoproteins in the envelope are responsible for fusion. Antibodies to these glycoproteins are important biological tools, providing a way of examining how fusion works. Here we used electron microscopy and other techniques to study a panel of anti-gB antibodies. Some, with virus-neutralizing activity, impair gB-lipid association. We also generated a peptide antibody against one of the gB fusion loops; its properties provide insight into the way the fusion loops function as gB transits from its prefusion form to an active fusogen.
Effect of magnetic-field-induced frustration on the superconducting transition of proximity-coupled arrays

The magnetic field dependence of the superconducting transition has been studied in triangular arrays of Pb-Sn proximity-coupled junctions. The transition temperature T/sub c/ and the array resistance R(T) are found to vary periodically in a perpendicular magnetic field with a period corresponding to one flux quantum per unit cell of the array. In addition, both quantities show substructure at rational fractions of a flux quantum f = Phi/Phi/sub 0/ = (1/4),(1/3),1 /2,(2/3),(3/4). The current-voltage characteristics of the arrays are nonlinear at temperatures near the transition temperature T/sub c/, with voltage increasing as a power of the current Vapprox.I/sup a/(T,f). As a function of reduced temperature t = (T/sub c/(f)-T)/T/sub c/(f), the power-law exponent a(t,f) is insensitive to f.
Anatomical and psychological limits in microscopically controlled excision of basal cell carcinomas of the medial canthus

Radical cure of patients with basal cell carcinomas is a realistic goal in oculoplastic surgery. An important tool is careful microscopic control of the margins of the excised tissues. In the medial canthal area, however, anatomical and psychological limits can make control of the excision hazardous. The surgeon must be aware of the problem and decide what he can expect from his patient.
Topological effects on the electrophoretic mobility of rigid rodlike DNA in polyacrylamide gels.

The electrophoretic migration of rigid rodlike DNA structures with well defined topologies has been investigated in polyacrylamide (PA) hydrogels prepared by copolymerization of acrylamide and N, N′-methylenebisacrylamide. Previous studies have reported structural and dynamic characteristics of linear and branched DNA during electrophoresis in PA gels using a variety of experimental parameters. However, a thorough investigation aimed at establishing specific relationships between topological features of rigid rodlike DNA structures and their electrophoretic behavior is still needed. In order to study these topological effects on mobility, an intensive examination of the electrophoretic mobility of small linear and starlike DNA was performed. A series of model DNA structures with well-defined branched topologies were synthesized with varying molecular parameters, such as number of arms surrounding the branch point and arm length. The electrophoretic mobility of these structures was then contrasted with a series of data obtained using linear DNA of comparable molecular size. When large DNA stars (M ≥ 60 bp) were compared with linear DNA of identical molecular weight, the Ferguson plots were quite different. However, small DNA stars (24–32 bp) and linear analogues had identical Ferguson plots. This indicates that a different motional mode or greater interaction with the gel exists for the larger DNA stars. When the total molecular weight of the DNA stars was held constant and the number of arms varied, the Ferguson plots for all the stars were identical. Additionally, a critical pore size was reached when the ratio of linear DNA mobility to star DNA mobility increased dramatically. Thus, while the incorporation of a single branch point can produce a large reduction in mobility, above a critical molecular size, the incorporation of additional branch points does not appear to provide further reduction in mobility. This finding is consistent with the transport properties of large synthetic star polymers, where a large reduction in their diffusion coefficient is observed when a single branch is added. When additional arms are incorporated, large synthetic stars do not display an appreciable further reduction in diffusion coefficient. The effect of arm length on mobility for rigid rod DNA stars was also studied. For four-arm DNA stars, the mobility was found to scale as an exponential function of the arm length. Finally, a recently proposed phenomenological model was used to successfully fit the mobility data for linear rigid rod DNA at various concentrations of PA. © 2003 Wiley Periodicals, Inc. Biopolymers 70: 471–481, 2003
Effect of ethanol on energy status and intracellular calcium of Sertoli cells: a study using immobilized perfused cells.

The effects of ethanol on ATP, O2 consumption, and cytosolic ionized Ca2+ (Ca2+i) were studied in Sertoli cells isolated from the testes of 18- to 21-day-old rats. The cells were immobilized in agarose gel threads and perfused with Dulbecco's Modified Eagle's Medium. Intracellular ATP was determined by 31P nuclear magnetic resonance spectroscopy and enzymatic assay, Cai2+ was measured with the photoprotein aequorin, cell viability was assessed by trypan blue exclusion, and O2 consumption was monitored with a Clark electrode. Ethanol was used with or without pretreatment with the alcohol dehydrogenase inhibitor 4-methylpyrazole (MP). Perfusing the cells for 90 min with 500 mM ethanol produced a 50% reduction in the 31P nuclear magnetic resonance beta ATP signal, and pretreatment with 15 mM MP enhanced this decline of the beta ATP peak to 75%. Enzymatic measurements of ATP revealed that exposure to 500 mM ethanol reduced the ATP levels from 52 +/- 5 to 38 +/- 3 nmol/10(6) cells with MP pretreatment and to 2...
Batch Uptake of Lysozyme: Effect of Solution Viscosity and Mass Transfer on Adsorption

In this study, solid-phase adsorption by macroporous and hyper-diffusive resins was investigated in a batch uptake adsorption system to quantify solid-phase diffusion rates as a function of bulk phase viscosity. The performance of chromatographic resins used for adsorption of proteins is dependent on several factors including solid and liquid-phase diffusivity, boundary layer mass transfer, and intraparticle mass transfer effects. Understanding these effects is critical to process development and optimization of both packed and fluidized bed adsorption systems. The macroporous resin used here was Streamline SP, and the hyper-diffusive resin was S-HyperD LS. Both have been frequently used in fluidized bed adsorption of proteins; however, factors that affect uptake rates of these media are not well quantified. Adsorption isotherms were well represented by an empirical fit of a Langmuir isotherm. Solid-phase diffusion coefficients obtained from simulations were in agreement with other models for macroporous and hyper-diffusive particles. S-HyperD LS in the buffer system had the highest uptake rate, but increased bulk phase viscosity decreased the rate by approximately 50%. Increases in bulk phase viscosity increased film mass transfer effects, and uptake was observed to be a strong function of the film mass transfer coefficient. Uptake by Streamline SP particles was slower than S-HyperD in buffer, due to a greater degree of intraparticle mass transfer resistance. The effect of increased film mass transfer resistance coupled with intraparticle mass transfer resistances at an increased bulk phase viscosity resulted in a decrease of 80% in the uptake rate by Streamline SP relative to S-HyperD.
Calibration of multiple LDR brachytherapy sources

A trend is underway toward the use of prepackaged low dose rate brachytherapy sources, which come in the form of strands, coiled line sources, preloaded needles, and sterile cartridge packs. Since the medical physicist is responsible for verification of source strength prior to patient treatment, development of prepackaged source strength verification methods is needed. Existing guidelines are reviewed to establish the situation that medical physicists find with respect to prepackaged sources. This investigation presents an experimental evaluation of the effect of some of these multiseed geometries on source strength measurements. Multiseed strands and coils, whether 125I, 103Pd, or 192Ir can be measured in a chamber with a long, sensitive axial length with a uniform response. Sterile seed cartridge packs can also be measured but require a correction factor to be applied. Sources in needles, however, cannot be measured in the needle since there is too great a variation in needle composition and needle tolerance thickness. Removing these seeds from the needle into a sterile measurement insert, which maintains sterility is a practical source strength verification method, similar to those done for multiple seed configurations in a well chamber with adequate axial uniformity. Values are compared with individual air kerma strength calibrations, and correction factors, are presented' where needed. In each case, care must be taken to maintain sterility as multiple seeds are measured in well chamber inserts.