bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of antimetabolites in filtration surgery for neovascular glaucoma: intermediate‐term follow‐up
Authors: Sisto Dario , Vetrugno Michele , Trabucco Tiziana , Cantatore Francesco , Ruggeri Giuseppe , Sborgia Carlo
Published: December 2006

Purpose:  To compare the intermediate‐term efficacy of 5‐fluorouracil (5‐FU) and Mitomycin C (MMC) as adjunctive antimetabolites in neovascular glaucoma (NVG) filtration surgery.

Methods:  Forty consecutive eyes of 40 patients with NVG refractory to medical therapy were randomized to receive antimetabolite‐augmented trabeculectomy. Eighteen eyes received postoperative 5‐FU (5‐FU group) and 22 eyes received intraoperative, low‐dose (0.2 mg/ml) MMC for 2 mins (MMC group). The main outcome measure was intraocular pressure (IOP). Surgical success was defined as IOP < 21 mmHg with topical treatment (qualified success) or without topical treatment (complete success). Surgical failure was defined as IOP ≥ 21 mmHg, despite postoperative topical treatment, and by postoperative blindness.

Results:  The mean follow‐up period was 35.8 ± 22.6 months in the 5‐FU group and 18.6 ± 17.2 months in the MMC group. This difference was not significant. Mean IOP decreased from 40.4 ± 10.3 mmHg to 14.7 ± 3.4 mmHg (p < 0.0001) in the 5‐FU group and from 42 ± 11.3 mmHg to 22.9 ± 13.3 mmHg (p = 0.0006) in the MMC group; however, the difference between the 5‐FU and MMC groups was not significant at any point. The success rate in the 5‐FU group was 55.5% (44.4% complete, 11.1% qualified), compared with 54.5% (9.1% complete, 45.4% qualified) in the MMC group. This difference was not significant.

Conclusions:  The percentage of patients who achieved postoperative IOP < 21 mmHg was similar in both groups, although a larger proportion of patients treated with MMC‐augmented trabeculectomy required topical treatment in comparison with the 5‐FU group.
Sequels of Purtscher's retinopathy imaged by enhanced optical coherence tomography
Authors: Soliman Wael , Zibrandtsen Nathalie , Jørgensen Thomas , Sander Birgit , Alsbirk Poul‐Helge , Larsen Michael
Published: December 2006

Purpose:  To report the optical coherence tomography (OCT) findings in a case of Purtscher's retinopathy.

Methods:  Enhanced optical coherence tomography, fundus photography, multifocal electroretinography.

Results:  A 27‐years‐old female parachutist demonstrated outer retinal opacification with small intraretinal hemorrhages and corresponding binocular pericentric ring scotomata one day after suffering an unusually abrupt arrest of a free fall upon the unfolding of her parachute. When seen 20 years later, the scotomata were unchanged and optical coherence tomography showed bilateral disorganization at the transition between the retinal photoreceptor outer segments and the retinal pigment epithelium plus attenuation of the outer nuclear layer.

Conclusions:  Our observations document that the long term sequels of Purtscher's retinopathy are located in the outer segments of the photoreceptors.
Spontaneously healed horizontal root fracture in maxillary first premolar: report of a case
Authors: Çobankara Funda Kont , Üngör Mete
Published: December 2006

Abstract –  Root fractures of the posterior teeth are rare and occur as a result of severe trauma. This study describes the horizontal root fracture of a maxillary first premolar. The fractured roots were discovered during a routine radiographic examination. The tooth was asymptomatic and responded positively to electric pulp testing. The patient reported accidental trauma, which occurred 14 years before. Our case is an example of spontaneously healed fractured roots. The interesting findings were that the healing was observed even in the presence of two roots, including preservation of the vitality of the pulp.
A Generalized DIF Effect Variance Estimator for Measuring Unsigned Differential Test Functioning in Mixed Format Tests
Authors: Penfield Randall D. , Algina James
Published: December 2006

One approach to measuring unsigned differential test functioning is to estimate the variance of the differential item functioning (DIF) effect across the items of the test. This article proposes two estimators of the DIF effect variance for tests containing dichotomous and polytomous items. The proposed estimators are direct extensions of the noniterative estimators developed by Camilli and Penfield (1997) for tests composed of dichotomous items. A small simulation study is reported in which the statistical properties of the generalized variance estimators are assessed, and guidelines are proposed for interpreting values of DIF effect variance estimators.
Testing Features of Graphical DIF: Application of a Regression Correction to Three Nonparametric Statistical Tests
Authors: Bolt Daniel M. , Gierl Mark J.
Published: December 2006

Inspection of differential item functioning (DIF) in translated test items can be informed by graphical comparisons of item response functions (IRFs) across translated forms. Due to the many forms of DIF that can emerge in such analyses, it is important to develop statistical tests that can confirm various characteristics of DIF when present. Traditional nonparametric tests of DIF (Mantel‐Haenszel, SIBTEST) are not designed to test for the presence of nonuniform or local DIF, while common probability difference (P‐DIF) tests (e.g., SIBTEST) do not optimize power in testing for uniform DIF, and thus may be less useful in the context of graphical DIF analyses. In this article, modifications of three alternative nonparametric statistical tests for DIF, Fisher's χ

2

test, Cochran's Z test, and Goodman's U test (Marascuilo & Slaughter, 1981), are investigated for these purposes. A simulation study demonstrates the effectiveness of a regression correction procedure in improving the statistical performance of the tests when using an internal test score as the matching criterion. Simulation power and real data analyses demonstrate the unique information provided by these alternative methods compared to SIBTEST and Mantel‐Haenszel in confirming various forms of DIF in translated tests.
Modeling Randomness in Judging Rating Scales with a Random‐Effects Rating Scale Model
Authors: Wang Wen‐Chung , Wilson Mark , Shih Ching‐Lin
Published: December 2006

This study presents the random‐effects rating scale model (RE‐RSM) which takes into account randomness in the thresholds over persons by treating them as random‐effects and adding a random variable for each threshold in the rating scale model (RSM) (Andrich, 1978). The RE‐RSM turns out to be a special case of the multidimensional random coefficients multinomial logit model (MRCMLM) (Adams, Wilson, & Wang, 1997) so that the estimation procedures for the MRCMLM can be directly applied. The results of the simulation indicated that when the data were generated from the RSM, using the RSM and the RE‐RSM to fit the data made little difference: both resulting in accurate parameter recovery. When the data were generated from the RE‐RSM, using the RE‐RSM to fit the data resulted in unbiased estimates, whereas using the RSM resulted in biased estimates, large fit statistics for the thresholds, and inflated test reliability. An empirical example of 10 items with four‐point rating scales was illustrated in which four models were compared: the RSM, the RE‐RSM, the partial credit model (Masters, 1982), and the constrained random‐effects partial credit model. In this real data set, the need for a random‐effects formulation becomes clear.
A Comparative Study of IRT Fixed Parameter Calibration Methods
Authors: Kim Seonghoon
Published: December 2006

This article provides technical descriptions of five fixed parameter calibration (FPC) methods, which were based on marginal maximum likelihood estimation via the EM algorithm, and evaluates them through simulation. The five FPC methods described are distinguished from each other by how many times they update the prior ability distribution and by how many EM cycles they use. Specifically, the five FPC methods included no prior weights updating and one EM cycle (NWU‐OEM) or multiple EM cycles (NWU‐MEM), one prior weights updating and one EM cycle (OWU‐OEM) or multiple EM cycles (OWU‐MEM), and multiple weights updating and multiple EM cycles (MWU‐MEM) methods. All the five FPC methods were evaluated in terms of recovery of the underlying ability distribution and item parameters. An important factor in the simulation was three different ability (normal) distributions—N(0, 1), N(0.5, 1.22), and N(1, 1.42)—for FPC groups, with the fixed item parameters obtained with a reference N(0, 1) group. Only the MWU‐MEM method appeared to perform properly under all the three distributions. Under the N(0, 1) distribution, the NWU‐MEM and OWU‐MEM methods also appeared to perform properly. Under the N(0.5, 1.22), and N(1, 1.42) distributions, however, the four methods other than the MWU‐MEM method resulted in some or severe under‐estimation in the recovery.
THE CONTROL OF PEPSINOGEN SECRETION*
Authors: Hirschowitz Basil I.
Published: December 2006

Summary

The peptic cell makes and secretes a protein (pepsinogen) and the cellular mechanisms governing the rate of synthesis and its relation to secretion are described and schematically illustrated.

The peptic cell as a system secreting protein exists side by side with the parietal cell transporting H+, Cl, water and electrolytes. The functions of these two systems are usually closely integrated with each other and with the gastric musculature, but, under several well‐defined conditions, each system may be stimulated or inhibited separately from the other. The actions of cholinergic stimuli, histamine and gastrin and some of the characteristics of inhibition are described herein.
PHARMACOLOGICAL PROPERTIES OF PEPSIN INHIBITORS
Authors: Cook D. L. , Drill V. A.
Published: December 2006

Summary

A review of the literature along with certain experimental studies in our laboratories on the physical, chemical and biological properties of a variety of synthetic sulfated polysaccharides have shown that the pharmacological activities of these substances seem to depend upon a complex interaction of two or more physical or chemical parameters. For example, only fair correlations existed between high antipepsin, antiulcer and anticoagulant activity and high molecular weight or sulfate content. The roles of monosaccharide content, chain shape or the type of glucosidic linkage were difficult to evaluate with the data at hand.

Sulfated amylopectin (SN‐263) with high molecular weight and sulfate content along with a branched chain shape was found to be an active pepsin inhibitor with relatively low anticoagulant activity. Pepsin inhibition studies were carried out using both the hemoglobin and the RISA methods. Oral administration of SN‐263 to pyloric‐ligated rats has shown significant inhibition of gastric ulceration with reductions in proteolytic activity of the gastric juice. The volume of gastric juice or secretion of free and total acid were not significantly altered. SN‐263 also inhibited Δ1‐cortisol‐induced gastric ulceration in rats and histamine‐induced duodenal ulcers in guinea pigs. Reserpine‐induced ulceration in the rat was not significantly affected. SN‐263 possessed low anticoagulant activity both in vitro and when given i.v. to dogs. However, no effects on blood coagulation were found after large oral doses administered to normal dogs or to rats with previously induced ulcers. SN‐263 was nonanticholinergic and did not affect gastrointestinal propulsion, as measured by the charcoal meal test in mice.
REGULATION OF SECRETION OF MUCUS FROM THE GASTRIC ANTRUM*
Authors: Menguy René , Thompson A. E.
Published: December 2006

Summary

Gastric secretion of mucus was studied in dogs by collecting secretions from vagally‐denervated or ‐innervated gastric antral pouches. Mucous secretions were studied for volume and for concentration of nitrogen, hexsoses, hexsosamines, L‐fucose and sialic acid concentrations in dialyzed, lyophilized mucosubstance. Gastric mucosal content of mucus of rats was measured by analyzing the concentration of hexsosamine and sialic acid in freeze‐dried gastric mucosal scrapings. Vagal stimulation of the gastric antrum and administration of cholinomime‐tic agents had no detectable influence on either the volume or the biochemical composition of antral mucus. Insulin‐induced hypoglycemia appeared to depress the secretion of mucus. Adrenergic stimulation was without influence. Serotonin had a strong stimulatory effect on the volume of mucus secretion but did not alter its biochemical composition. Cortisone had a profound inhibitory influence on the secretion of mucus and altered its biochemical composition by decreasing the concentration of sialic acid. Parathyroid extract was found to increase gastric mucosal content of mucus in rats.
BLOOD VOLUME CHANGES AND SODIUM DISTRIBUTION IN PATIENTS WITH BURNS
Authors: Davies J. W. L.
Published: December 2006

In a recent study of the effects of various forms of therapy given during the first 48 hr to patients with burns, colloidal solutions were shown to be more effective in maintaining blood volume levels than only hypotonic saline solutions (Davies, 1964). Since these patients also received different amounts of sodium, the question whether the different inputs of sodium may have modified the changes in blood volume was left open.

This study attempts an assessment of the effects of differing inputs of sodium upon blood volume levels. A direct comparison has been made between the blood volume levels in patients given equal volumes of either hypotonic bicarbonate saline or isotonic lactate saline. A more complex comparison has been devised for patients with burns of more than 40% of the body surface since they were also given varying volumes of colloid–usually reconstituted freeze‐dried plasma.

Since all these forms of therapy result in substantial intakes of sodium, a study has also been made of some of the effects of these large intakes using two radioactive isotopes of sodium. Measurements have been made of the biological half‐life of sodium, its total exchangeable content, the dilution volume of sodium, and the amounts of sodium lost in urine and exudate.
VENTILATORY MANAGEMENT OF THE PULMONARY BURN*
Authors: Lee Arthur B. , Kinney John M.
Published: December 2006

Summary

Ventilatory management begins with a consideration of the requirements for gas exchange. The impaired ventilatory apparatus may adequately cope with resting demands for gas exchange, but may be unable to meet the requirements of increased metabolism.

Resting hypermetabolism may be particularly severe in the burn patient. This hypermetabolism with its increased rates of gas exchange places severe prolonged demands on ventilation.

Measurements of blood gas tensions and gas exchange describe the balance between cardiopulmonary supply and tissue need for gas exchange. This balance becomes more evident when gas tension and gas exchange are considered respectively as intensive and extensive properties of the same system. The hazard to the burn patient of elevation in gas exchange, cardiac output and heat loss may be unsuspected when only measuring intensive variables such as gas tensions.

The specificity of the failure of oxygenation as the ultimate functional lesion of the pulmonary burn has been described.

Asepsis, chest physiotherapy, airway humidification and quantitation of ventilator and oxygen therapy have been emphasized in the successful management of the severe pulmonary burn.
GRAPHICAL CONFLICT I: A NEW CLASS OF EXTREMAL PROBLEMS
Authors: Harary Frank , Kabell Jerald A.
Published: December 2006

Summary

Inspired by the analogy with the three traditional types of conflict in psychology (approach/approach, approach/avoid, and avoid/avoid), we consider corresponding types of extremal problems in graph theory. These are translated into the determination of extremal values of the product or quotient of two graphical parameters, subject to given constraints. For purposes of exemplification, we study and determine both the exact solution and the extremal graphs for several products and quotients which include confrontations of (a) point‐ and line‐independence and covering, (b) connectivity and coloring, (c) covering and connectivity. We conclude with an indication of several unsolved problems for future research.
PHARMACOLOGICAL MODIFICATION OF THE Ca2+‐PUMP ATPase ACTIVITY OF HUMAN ERYTHROCYTES*
Authors: Vincenzi Frank F.
Published: December 2006

Summary

The Ca2+‐pump ATPase of human RBC membranes appears to be exquisitely sensitive to a variety of amphipathic molecules. The acidic protein calmodulin (CaM) activates the enzyme some three‐ to fivefold with an apparent Kd of approximately 1–5 nM. A variety of other amphipathic anions, such as acidic phospholipids, free fatty acids, and anionic detergents, are less potent and in some cases less efficacious than CaM, but also activate the enzyme. Similar results have been observed for other CaM‐dependent enzymes, and it is suggested that these agents mimic CaM in a general, but rather nonspecific, fashion. Activation of the human RBC Ca2+‐pump ATPase by CaM or other amphipathic anions can be selectively antagonized by a wide variety (structurally and pharmacologically) of amphipathic cations. There is no simple relationship between antagonism of CaM in vitro and the general systemic pharmacology of these drugs. The only common feature of such drugs is that they are amphipathic cations. Neutral molecules such as saponin exerted neither CaM‐like activity nor CaM antagonism. Great caution is urged in the inferential use of presumed anti‐CaM drugs to study biological systems.
Embryo Transfer
Authors: JONES HOWARD W.
Published: December 2006

Success and failure of embryo transfer involves at least five major variables: (1) technique, (2) what is transferred, (3) when transfer occurs, (4) endometrial status at transfer, and (5) endometrial support subsequent to transfer. Because of these and other variables associated with programs of in vitro fertilization, it is quite impossible to develop impeccable data to support any of the various options available for each of the five major variables.
Strategic Defense Initiative Research A Gray Area for Ethics
Authors: ELZINGA AANT
Published: December 2006

The arguments concerning the militarization of research fifteen years ago in connection with the war in Vietnam had to do with more manifest indicators of a military link. Then it was a question often of applied research, and the physical or institutional control over such research. Today we are dealing with new technologies and their basic research underpinnings. Because of the character of these new military technologies, we are facing extensive gray areas. It is no longer possible to so clearly discern boundary lines. Thus it becomes more difficult also to clearly determine when one should hold off from a certain type of research for ethical reasons. Such boundaries also blur.

As research and development has become increasingly target or mission oriented, externalist assessments relating to social and political problem definitions have taken on greater prominence in defining what is important. An epistemic drift has been noted, a shift whereby assessments of quality or utility by outsiders and nonscientists have become more common. A corollary to this epistemic drift is the erosion of the meaning of basic research in the direction of practice‐relevance, a problem that concerns laser physicists as well as social scientists in newly emerging disciplines.37

At a very general level, we might speak of a change in the social paradigm of science, a change that has become more obvious in the last couple of decades as the role of the state has expanded.

Finally it is clear that the concept of epistemic drift has to be divested of ideological overtones, particularly those that would equate it with a purist assumption of autonomy and disembodied science. Science as a whole is founded as a social mandate, and autonomy is always relative. What is at issue here is rather the integrity and meaning of scientific enterprise.
Strategies for Malaria Control: Realities, Magic, and Science
Authors: MILLER LOUIS H.
Published: December 2006

I am commenting on methods for malaria eradication and control, while realizing my limitations in first‐hand experience with malaria‐control programs. I will not deal, therefore, with the potential impact of improvement of primary health care or the relative advantages and disadvantages of a vertical program organized centrally, as was the malaria eradication program of the 1950s and the 1960s. I will also not discuss economic considerations, although these are important. We are critical of economists for not considering the impact of health on development. Improvement of the standard of living of families in the developing world combined with health education is likely to have a marked effect on health. Who are more committed to the health of children than their parents? Because of my limited knowledge and experience in the above issues, I will draw strongly from the interaction of discoveries in the laboratory and their impact in the field and from my own experiences in the laboratory today.
Recent CLEO Results on B Decays
Authors: MISTRY NARI B.
Published: December 2006

Indirect evidence for a fourth generation can appear as inconsistencies in the three generation Cabbibo‐Kobayashi‐Maskawa description1 of weak decays. B decays offer a sensitive probe for such inconsistencies. As an example, the requirement that the three‐generation CKM matrix be unitary can be represented by a closed triangle of the type2 shown in Figure 1. (This particular triangle is obtained by setting the product of
Toward a Theory of Normality and Paracompactness in Box Products
Authors: LAWRENCE L. BRIAN
Published: December 2006

An introduction to the subject in the title where the factors are copies of a separable metric space is given.
Synaptic Pathology of Alzheimer's Diseasea
Authors: LASSMANN H. , FISCHER P. , JELLINGER K.
Published: December 2006

Prospective clinico‐pathological studies on dementia in Alzheimer's disease (AD), performed during the past decades, revealed a relatively poor correlation between the degree of clinical deficit and the severity of the typical neuropathological lesions of AD, the amyloid plaques and the neurofibrillary tangles. More recent data, obtained by electron microscopy, immunocytochemical as well as immunochemical techniques indicate that synaptic loss may be a better structural correlate of dementia than other brain lesions. Synaptic pathology is reflected by a loss of all major components of small synaptic vesicles and most peptides, stored in large dense cored vesicles. The significant increase of chromogranin A proprotein, a major component of large dense cored vesicles, may rather represent a defect of protein processing than preservation of a specific synaptic subpopulation. Within the brain of AD patients, the degree of synaptic loss is uneven. Most prominent reduction of synapses is found in the outer parts of the dentate gyrus molecular layer, possibly reflecting the destruction of neurons, located in the layer 2 of the entorhinal cortex. However, within the neocortex, no preferential loss of synapses in any of the cortical layers has been found. Cerebral amyloid deposition in diffuse plaques has little effect on synapse density and structure. However, within the dense amyloid core of a classical plaque, synapses are completely lost. In the surrounding neuritic portion of the plaques, synaptophysin reactivity is frequently increased, due to enlargement of synaptic boutons and to accumulation of synaptophysin in dystrophic axons. Although the reason for synapse loss in AD is yet unknown, most results suggest that it may reflect degeneration of neurons, projecting into the respective cortical areas.
Regulation of Amyloid Precursor Protein Release By Protein Kinase C in Swiss 3T3 Fibroblastsa
Authors: SLACK BARBARA E. , NITSCH ROGER M. , LIVNEH ETTA , KUNZ GEORGE M. , ELDAR HAGIT , WURTMAN RICHARD J.
Published: December 2006

Release of the amyloid precursor protein (APP) of Alzheimer's disease from Swiss 3T3 fibroblasts was stimulated in a concentration‐dependent manner by phorbol 12‐myristate 13‐acetate. In fibroblasts overexpressing protein kinase Co (PKCα), the EC50 for this response was 7 nM, while in control cells the EC50 was 63 nM. The effect of PMA was inhibited by the PKC antagonist H‐7 in control cells, but not in cells that overexpressed PKCα. Basal release of APP was higher in cells that overexpressed PKCα, and was not affected by the phosphatase inhibitor okadaic acid, although this compound doubled APP release from control cells. The results suggest that PKCα regulates APP processing in mammalian cells. Alterations in the activity of PKC have been reported to occur in Alzheimer's disease and might potentially contribute to abnormalities of APP metabolism characteristic of this disorder.
Transgenic Animal Models for Alzheimer's Diseasea
Authors: FUKUCHI KEN‐ICHIRO , OGBURN CHARLES E. , SMITH ANNETTE C. , KUNKEL DENNIS D. , FURLONG CLEMENT E. , DEEB SAMIR S. , NOCHLIN DAVID , SUMI S. MARK , MARTIN GEORGE M.
Published: December 2006

The neuropathology of Alzheimer's disease is characterized by the deposition of abnormal protein aggregates. The main constituent of the deposition is β‐amyloid protein. A seminal role of this protein is supported by the discovery of point mutations in the gene of its precursor protein in certain forms of familial Alzheimer's disease. In vitro (cultured neuronal cells), overexpression of the precursor protein or a part of the precursor leads to degeneration of neurons, suggesting neurotoxicity of its derivatives. At this tune, all of the reported transgenic mice bearing DNA construct for the precursor or a part of the precursor, however, have not developed convincing pathological changes similar to what is observed in patients with Alzheimer's disease. This interesting discrepancy between in vitro and in vivo suggests suppressors in vivo which ameliorate β‐amyloid precursor protein derivative‐mediated neurotoxicity.
Cholinergic Neurotransmission in the Hippocampus of Aged Rats: Influence of L‐α‐Glycerylphosphorylcholine Treatment
Authors: AMENTA F. , FRANCH F. , RICCI A. , VEGA J. A.
Published: December 2006

The influence of aging and of L‐α‐glycerylphosphorylcholine (GFC) treatment on the acetylcholine synthesizing and degradating enzymes choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) and on cholinergic muscarinic M‐1 and M‐2 receptors were assessed in the hippocampus using immunocytochemical, histochemical and radioligand binding techniques, respectively. The investigation was performed on male Wistar rats of 2 months (young), 12 months (adult), and 27 months (old). Oral GFC was given at the dose of 100 mg/Kg/day from the 21st to the 27th month of age. ChAT revealed the highest immunostaining in the hippocampus of adult rats followed by young and old animals. The highest expression of AChE reactivity was noticeable in the hippocampus of adult rats followed by old and young animals. Treatment with GFC restored in part ChAT immunoreactivity and AChE reactivity in the hippocampus of aged rats. Muscarinic M‐1 and M‐2 receptors were labeled with [3H]‐pirenzepine and [3H]‐AF‐DX‐116 respectively. The density of M‐1 muscarinic receptors decreased with age, whereas M‐2 muscarinic receptors did not change. GFC treatment countered in part the loss of M‐1 receptors in old rats and was without effect on M‐2 receptors.
Molecular and Functional Magnetic Resonance Neuroimaging for the Study of Dementiaa
Authors: GONZÁLEZ R. GILBERTO
Published: December 2006

The living brain's structure, function, and underlying chemistry are increasingly being revealed in sharpened detail by the extraordinary evolution of magnetic resonance (MR) technology. Recent years have ushered in a wealth of new information about neurophysiology and pathological states owing to such technologies as functional MR imaging (fMRI), MR spectroscopy (MRS), and MR spectroscopic imaging (MRSI). These advances are of substantial benefit in the study of the dementias, especially Alzheimer's disease (AD). One primary objective of our laboratory at the Massachusetts General Hospital NMR Center is to utilize these extant and emerging MR technologies to further understanding of the human brain as it undergoes assault by AD. Our approach is guided by the belief that the pathological states observed in the AD brain must be accompanied by structural, chemical and/or physiological changes that can be made visible in an in vivo MR study. Quantitative measurements by MRI medical temporal lobe structures have been shown to be abnormal by several groups including our own. This use of MRI will be reviewed by others. In this paper, I will review recent advances in the application of MR for the study of chemical and functional brain abnormalities in dementia, and in particular to the investigation of AD.
Apolipoprotein E, Plaques, Tangles and Cholinergic Dysfunction in Alzheimer's Diseasea
Authors: BEFFERT U. , POIRIER J.
Published: December 2006

Apolipoprotein E is a plasma cholesterol and phospholipid transporter which plays a central role in lipoprotein metabolism in the brain. Apolipoprotein E is a polymorphic protein with three common alleles in the general population, designated ε2, ε3 and ε4 coding for proteins ApoE2, ApoE3 and ApoE4, respectively. Recent findings have demonstrated a significant relationship between the ε4 allele and late onset familial and sporadic Alzheimer's disease. We examined several classical neuropathological hallmarks of Alzheimer's disease to determine whether they might be related to apolipoprotein E genotype: the presence of intracellular neurofibrillary tangles, extracellular senile plaques, and the attenuation of choline acetyltransferase activity. Significant correlations were found between ε4 allele copy number and senile plaque density in the frontal, parietal and fusiform cortical areas. Similarly, significant correlations were also found with increased neurofibrillary tangle number in the frontal and fusiform cortex. Interestingly, there was an inverse correlation between the ε4 allele with temporal cortical choline acetyltransferase activity. To further define the specific function of ApoE4, cultured rat hippocampal neurons were used to investigate interactions involving β‐amyloid protein. In this model, ApoE4 (but not ApoE2) was able to reverse the neuroprotective effects of β‐amyloid. ApoE3 was demonstrated to increase the internalization of β‐amyloid peptide into these neurons. Taken together, these results support the involvement of ApoE4 in the pathogenesis of Alzheimer's disease and also provide some explanations for the possible function of this protein.
A Novel Brain Cysteine Protease Forms an SDS Stable Complex with the β‐Amyloid Precursor Proteina
Authors: CHANG TIEN , ABRAHAM CARMELA R.
Published: December 2006

Alzheimer's disease (AD) brain accumulates β‐protein (Aβ) a peptide proteolytically derived from the β‐amyloid precursor protein (APP). The abnormal production and aggregation of Aβ have been implicated in the pathogenesis of the disease. The mechanism of production of Aβin vivo is not yet clear; but endoproteases capable of degrading APP are likely to be involved in the process. We have isolated a protease from AD brain by following its activity in digesting a synthetic peptide of 10 amino acids derived from the APP sequence flanking the N‐terminus of Aβ. The protease was purified by a fractionation scheme including ammonium sulfate precipitation and column chromatography using hydrophobic interaction, anion exchange, affinity, hydroxyapatite and size exclusion gels. The purity of the final product was assessed on a silver stained SDS gel by the presence of a single band. Microsequencing was performed following trypsin digestion of the sample. Internal peptide sequences were found to have sequence homology to cysteine proteases in the database. The enzyme requires DTT for activity and can be inhibited by specific inhibitors of cysteine but not serine proteases. The purified enzyme has a pi of 5.0 and a native tetrameric structure with subunits of 48 kD each. The enzyme is capable of digesting APP and generating a short peptide recognizable by antibodies specific to the C‐terminus of APP. Interestingly, the purified protease also forms heat‐ and SDS‐stable complexes with APP.
Defective Protein Kinase C α Leads to Impaired Secretion of Soluble β‐Amyloid Precursor Protein from Alzheimer's Disease Fibroblastsa
Authors: GOVONI S. , RACCHI M. , BERGAMASCHI S. , TRABUCCHI M. , BATTAINI F. , BIANCHETTI A. , BINETTI G.
Published: December 2006

The present study shows that cultured fibroblasts from sporadic AD patients present: a) reduced (‐30%) cytosolic protein kinase C (PKC) activity; b) increased KD of phorbol ester binding (+94%) in cytosolic fractions; c) reduced (‐30%) soluble protein kinase Cα immunoreactivity; d) lower (‐27.5%) basal soluble APP secretion and e) reduced soluble APP secretion in response to low phorbol ester concentrations (over threefold difference using 9 nM phorbol‐12,13‐dibutyrate‐PdBu). Since the PKC‐stimulated secretion of APP leads to the cleavage of the precursor within the amyloidogenic β‐A4 fragment, the reduced PKC activity in AD patients may lead to accumulation of potentially amyloidogenic or toxic APP fragments. A defect in the secretion of soluble amyloid β‐protein precursor is indeed suggested by literature data on familial AD fibroblasts as well as by the reported results.
Countably Compact Spaces which Cannot Be Cancellative Topological Semigroups
Authors: HOTA SANJU , PURISCH S. , RAJAGOPALAN M.
Published: December 2006

Forty years ago A.D. Wallace asked whether a countably compact, cancellative topological semigroup is a topological group.

We will prove that for various types of spaces Wallace's problem has an affirmative answer. This is done by showing that the most promising candidates for counterexamples do not admit cancellative topological semigroup structures.
On Free Topological Groups with the Inductive Limit Topologiesa
Authors: SIPACHEVA OLGA V.
Published: December 2006

Countable spaces with an only nonisolated point for which the free topological groups are the inductive limits of the sets of words having restricted length are characterized. It is proved for a collectionwise normal X that if its free topological group is the inductive limit of the sets of words having restricted length, then any closed discrete set of non‐P‐points in X is countable. All the results obtained are valid for both Abelian and non‐Abelian free groups.
HALO IN THE EXCITED STATES FOR N = 41 ISOTONES
Authors: YU MIAO , ZHANG PENG-FEI , RUAN TU-NAN , GUO JIAN-YOU
Published: December 2006

The properties of N = 41 isotones are investigated systemically by using the nonlinear relativistic mean field theory. It is found that all the calculating binding energies with four different interactions are comparable for the ground and low-lying excited states, and very close to the data available. The calculations show that there exists a neutron halo in the first excited state in 69 Ni , as well as in the second excited state in 69 Ni . It is also predicted that there exists a neutron halo in the first excited state in 65 Cr , 66 Mn , 67 Fe and 68 Co .
WAVE FUNCTION RENORMALIZATION PRESCRIPTION OF UNSTABLE PARTICLE
Authors: ZHOU YONG
Published: December 2006

We define four Wave function Renormalization Constants (WRCs) for unstable particles under the LSZ reduction formula. By CPT conservation law we obtain a new wave function renormalization condition and determine the four WRCs. By calculating the gauge dependence of the physical amplitudes we demonstrate the consistency of the current wave function renormalization prescription with the gauge theory in standard model. We also prove that the conventional wave function renormalization prescription leads to physical amplitudes of gauge dependent.
s-DEFORMED PARTICLE ALGEBRAS AND THE ADDITION OF s
Authors: ARIK METIN , ARIKAN ALI SERDAR
Published: December 2006

We begin by considering a system which gives the usual fermion algebra when the appropriate limiting case is considered. We study its Hopf algebra structure. Investigation of its representation forces us to impose additional constraints on the system such that by defining a central hermitian operator s in terms of the operators defining the system, we obtain s-deformed particle algebra. Finally, we find a formula for the addition of s values for the d = 2 case.
A VERTEX-STRUCTURE MODEL FOR NEW DIRECT CP-VIOLATING EFFECTS IN $\bar B^0(B^0)\to\phi K_{\rm S}$ AND IN B∓→π∓η′(η)
Authors: BARSHAY SAUL , KREYERHOFF GEORG
Published: December 2006

We consider effective Lagrangian models of CP-violating vertex structure in which a b→uW vertex, proportional to s13e-iδ13 with s13 very small (milliweak interaction) and δ13 large, is dynamically generated. A consequent, enhanced CP-violating vertex for b→sg results in an enhanced CP-violating phase in the ratio of amplitudes for [Formula: see text]. We estimate that this can significantly change the S-parameter from the value expected in the standard model.
EXPLOSIVE Z PINCH
Authors: GIACOSA FRANCESCO , HOFMANN RALF , SCHWARZ MARKUS
Published: December 2006

We propose an explanation for the recently observed powerful contained explosion in a Z pinch experiment performed at Sandia National Laboratories. Our arguments are based on the assumption that a pure SU(2) Yang–Mills theory of scale ~ 0.5 MeV is responsible for the emergence of the electron and its neutrino.
THEORETICAL SETTING OF INNER REVERSIBLE QUANTUM MEASUREMENTS
Authors: ZIZZI PAOLA A.
Published: December 2006

We show that any unitary transformation performed on the quantum state of a closed quantum system describes an inner, reversible, generalized quantum measurement.

We also show that under some specific conditions it is possible to perform a unitary transformation on the state of the closed quantum system by means of a collection of generalized measurement operators. In particular, given a complete set of orthogonal projectors, it is possible to implement a reversible quantum measurement that preserves the probabilities.

In this context, we introduce the concept of "Truth-Observable", which is the physical counterpart of an inner logical truth.
MORSE POTENTIAL AND ITS RELATIONSHIP WITH THE COULOMB IN A POSITION-DEPENDENT MASS BACKGROUND
Authors: BAGCHI B. , GORAIN P. S. , QUESNE C.
Published: December 2006

We provide some explicit examples wherein the Schrödinger equation for the Morse potential remains exactly solvable in a position-dependent mass background. Furthermore, we show how in such a context, the map from the full line (-∞, ∞) to the half-line (0, ∞) may convert an exactly solvable Morse potential into an exactly solvable Coulomb one. This generalizes a well-known property of constant-mass problems.
VIBRATION ANALYSIS OF A PRESTRESSED ROTATING CYLINDRICAL SHELL UNDER STATIONARY POINT LOAD
Authors: GUO DAN , ZHENG ZHAOCHANG
Published: December 2006

The vibration responses of a pre-stressed rotating cylindrical shell under stationary constant point load are analyzed by numerical method. The cylindrical shell is modeled by a nine-node super-parametric finite element which includes the effects of transverse shear deformation, axial deformation and rotary inertia. The geometric nonlinearity due to large deformation is also considered in the model. The numerical integer method is applied to attain the vibration responses. The effects of initial axial stress and rotating speed on the vibration of cylindrical shell are investigated in detail.
STEADY-STATE THERMOELASTIC ANALYSIS OF A FUNCTIONALLY GRADED ROTATING ANNULAR DISK
Authors: ZENKOUR ASHRAF M.
Published: December 2006

This paper is concerned with the thermoelastic analysis of a functionally graded rotating annular disk subjected to a nonuniform steady-state thermal load. Material properties are assumed to be temperature independent and continuously varying in the radial direction of the annular disk. The variations of Young's modulus, material density, thermal expansion and conductivity coefficients are represented by a novel exponential-law distribution through the radial direction of the disk, but Poission's ratio is kept constant. The governing differential equations are exactly satisfied at every point of the disk. Exact solutions for the temperature and stress fields are derived in terms of an exponential integral and Whittaker's functions. Presented are some results for stress, strain and displacement components due to thermal bending of the rotating disk. The effects of angular velocity, inner and outer temperature loads and material properties on the stress, strain and displacement components are discussed.
NONLINEAR DYNAMIC MODELING, INSTABILITY AND POST-BUCKLING ANALYSIS OF A ROTATING BEAM WITH A FLEXIBLE SUPPORT
Authors: XIAO S. F. , YANG M.
Published: December 2006

By employing the modeling method of flexible multi-body systems, the linear and nonlinear dynamic models of a rotating Euler-Bernoulli beam with a flexible support are established, in which the deformation is coupled with the overall motion resulting from the flexibility of the support. The flexural vibration equation in the linear coupling model can be linearly transformed into the classical model of a rotating beam with a flexible support. The nonlinear model is applicable to rotating beams with different flexible supports. Based on the nonlinear model, the global bifurcation behavior of the rotating beam with supports of different stiffnesses is investigated by applying assumed modes method, and the results including the critical rotary speeds, the diversely buckled-equilibria, and the bifurcation type are verified by the shooting method.
SOFTENING BRANCHES OF A TWO-DEGREE-OF-FREEDOM SYSTEM INDUCED BY SPATIAL BUCKLING
Authors: CHALLAMEL NOËL
Published: December 2006

The aim of this paper is to show how geometrical non-linearity may induce equivalent softening in a simple two-degree-of-freedom spatial elastic system. The generic structural model studied is a generalization of Augusti's spatial model, incorporating lateral loading. This model could be used as a teaching model to understand the softening effect induced by out-of-plane buckling. The lateral loading in the plane of maximal stiffness is considered as the varying load parameter, whereas the vertical load is perceived as a constant parameter. It is shown that a bifurcation occurs at the critical horizontal load. The fundamental path becomes unstable, beyond this critical value. However, two symmetrical bifurcate solutions appear, whose stability depend on the structural parameters value. No secondary bifurcation is observed for this system. The presented system possesses imperfection sensitivity, and imperfection insensitivity, depending on the values of the structural parameters. In any case, for sufficiently large rotations, collapse occurs with unstable softening branches induced by spatial buckling.
VIBRATION OF DOUBLE BELLOWS TYPE EXPANSION JOINT IN LATERAL AND ROCKING MODES
Authors: RADHAKRISHNA M. , RAO C. KAMESWARA
Published: December 2006

In this paper, the exact frequency and mode shape expressions are derived for universal bellows type of expansion joint in lateral and rocking modes of vibration. The effect of equivalent support stiffness and mass on the natural frequencies and mode shapes are studied in detail and the results for a range of non-dimensional parameters are presented in graphical forms which should be useful for piping and bellow designers.
PERFORMANCE OF DUAL-LAYER MULTIPLE TUNED MASS DAMPERS FOR STRUCTURES UNDER GROUND EXCITATIONS
Authors: LI CHUNXIANG
Published: December 2006

The dual-layer multiple tuned mass dampers (DL-MTMD) with a uniform distribution of natural frequencies are proposed, which consist of one large tuned mass damper (L-TMD) and an arbitrary number of small tuned mass dampers (S-TMD). The structure is represented by a generalized system corresponding to the specific vibration mode to be controlled. The criterion for assessing the optimum parameters and effectiveness of the DL-MTMD is based on the minimization of the minimum values of the maximum dynamic magnification factors (DMF) of the structure installed with the DL-MTMD. Also considered is the stroke of the DL-MTMD. The proposed DL-MTMD system is demonstrated to show higher effectiveness and robustness to the change in frequency tuning, in comparison to the multiple tuned mass dampers (MTMD) with equal total mass ratios. It is also demonstrated to be more effective than the dual tuned mass dampers (DTMD) with one large and one small tuned mass damper, but they maintain the same level of robustness to the change in frequency tuning. The DL-MTMD system can be easily manufactured as the optimum value for the linking dashpots between the structure and L-TMD is shown to be zero.
ELASTIC BUCKLING OF THIN-WALLED CIRCULAR TUBES CONTAINING AN ELASTIC INFILL
Authors: BRADFORD M. A. , ROUFEGARINEJAD A. , VRCELJ Z.
Published: December 2006

Circular thin-walled elastic tubes under concentric axial loading usually fail by shell buckling, and in practical design procedures the buckling load can be determined by modifying the local buckling stress to account empirically for the imperfection sensitive response that is typical in Donnell shell theory. While the local buckling stress of a hollow thin-walled tube under concentric axial compression has a solution in closed form, that of a thin-walled circular tube with an elastic infill, which restrains the local buckling mode, has received far less attention. This paper addresses the local buckling of a tubular member subjected to axial compression, and formulates an energy-based technique for determining the local buckling stress as a function of the stiffness of the elastic infill by recourse to a transcendental equation. This simple energy formulation, with one degree of buckling freedom, shows that the elastic local buckling stress increases from 1 to [Formula: see text] times that of a hollow tube as the stiffness of the elastic infill increases from zero to infinity; the latter case being typical of that of a concrete-filled steel tube. The energy formulation is then recast into a multi-degree of freedom matrix stiffness format, in which the function for the buckling mode is a Fourier representation satisfying, a priori, the necessary kinematic condition that the buckling deformation vanishes at the point where it enters the elastic medium. The solution is shown to converge rapidly, and demonstrates that the simple transcendental formulation provides a sufficiently accurate representation of the buckling problem.
OPTIMUM RELIABILITY BASED DESIGN CRITERIA FOR ELASTIC STRUCTURES SUBJECT TO RANDOM DYNAMIC LOADS
Authors: TRENTADUE F. , MARANO G. C.
Published: December 2006

In this work a new method for the optimal design of generic elastic structures, subject to random dynamic loads, is proposed. Elastic structures are described as deterministic multi-degree of freedom systems in which the structural failure probability, referred to as a first crossing passage problem, is minimized. The proposed method is here applied to optimize the shape of a vertical column with an extra-mass located at the free top end, subject to a base acceleration modeled as a Gaussian, stationary, filtered stochastic process. The elastic threshold crossing probabilities are determined in a finite number of column sections and the objective function is assumed to be a measure of these probabilities. Finally, this measure is minimized under a constant weight constraint (or even under more general conditions).