bluuebunny/crossref_metadata_2025 huggingface dataset:
Forced vibration of a tall steel‐frame building
Authors: Jennings P. C. , Matthiesen R. B. , Brent Hoerner J.
Published: March 2007

The dynamic properties of the twenty‐two‐story, steel‐frame San Diego Gas and Electric Company Building in San Diego, California, have been determined experimentally in a series of co‐operative tests between the California Institute of Technology and the University of California at Los Angeles. The building was vibrated by two eccentric mass exciters capable of frequencies up to 10 c/sec and forces as much as 5000 Ib each. The natural frequencies, associated mode shapes and the amounts of damping were determined for the first six modes of vibration in each of the two translational directions, and also in torsion. The mode shapes and frequencies showed, in general, the regularity and uniformity that appears typical of many tall buildings, but the three fundamental modes (nominally NS, EW and torsion) of the structure showed a coupling of translational and rotational components to a degree that was unexpected in a building whose structural frame is essentially symmetric. It is believed that this may be a consequence of the exceptionally small differences among the three fundamental frequencies. The damping in the first eighteen modes of the structure varied from 1.6 to 4.4 per cent, with a slight tendency for the larger values to be associated with the higher modes. Of the simpler damping models that might be used for analysis of the building, constant modal damping appears most appropriate and stiffness or mass proportional damping would not be realistic.
Comparisons between ambient and forced vibration experiments
Authors: Trifunac Mihailo D.
Published: March 2007

The ambient and forced vibration techniques for testing full‐scale structures are critically compared. Both methods, based on small level excitation, may be used to determine many mode shapes and frequencies of vibration and the corresponding damping values, with adequate accuracy for most purposes. The two techniques give mutually consistent results.

The mode amplitudes determined by ambient and forced vibration tests show systematic departure for high modes and near the top levels of buildings tested. This phenomenon is attributed to the participation of all mode shapes and is a consequence of excitation by a concentrated force near the top of a building and at a frequency differing by only a few per cent from a natural frequency of vibrations.

A new way of showing the effect of unwanted modes on the response near resonance of the mode being sought is developed. It is particularly useful for the analysis of steady, forced vibration tests of structures using eccentric mass vibration generators.
The earthquake experience at koyna dam and stresses in concrete gravity dams
Authors: Chopra Anil K. , Chakrabarti P.
Published: March 2007

A number of questions concerning the response of concrete gravity dams to earthquakes, motivated by the structural damage caused to Koyna Dam, which has an unconventional cross section, by the December 1967 Koyna earthquake, are considered in this work. The study is not restricted to the earthquake experience at Koyna Dam, but includes consideration of a dam with a typical section and another earthquake motion having similar intensity but different peak acceleration and frequency characteristics compared to the Koyna ground motion. The earthquake response in a number of cases is analysed by the finite element method and results are presented. These results lead to a number of conclusions. Significant tensile stresses must have developed in Koyna Dam during the Koyna earthquake and similar stresses would have developed even in typical gravity dam sections. The Koyna ground motion is relatively more severe, compared to California earthquakes of similar intensity, on concrete gravity dams. The extra concrete mass near the crest of a gravity dam to support the roadway, etc. is responsible for causing a significant part of the critical tensile stresses; attention should therefore be given to developing lightweight supporting systems.
Curved beam finite elements for coupled bending and torsional vibration
Authors: Davis R. , Henshell R. D. , Warburton G. B.
Published: March 2007

Curved beam finite elements are presented for out of plane coupled bending and torsional vibration. The element formulation is based upon the exact differential equations of an infinitesimal element in static equilibrium. The effects of shear deformation and rotary inertia are allowed for in the analysis. The element stiffness and mass matrices can be easily restricted to those of a ‘thin’ beam without the secondary effects. Frequencies obtained using either formulation are shown to converge onto exact values using ‘thick’ or ‘thin’ beam theories.
An experimental assessment of the added mass of some plates vibrating in water
Authors: Selby A. , Severn R. T.
Published: March 2007

A reservoir of water is contained by a concrete valley block, a ferrocement wall and a steel plate. Both wall and plate contain an array of pressure transducer sockets (Figures 1 and 2).

Using the M.A.M.A.1 equipment pure modes of vibration are excited. Frequency and mode shape are measured with the reservoir empty. When the reservoir is full hydrodynamic pressure is also measured. These hydrodynamic pressures are compared with Chopra's2 two‐dimensional, series solution, which includes compressibility of water, and with two‐ and three‐dimensional finite element solutions of Laplace's equation, which do not include compressibility. Chopra's solution is unsatisfactory for modes which contain a vertical node line.

The best agreement between experimental and theoretical hydrodynamic pressure is obtained when the latter is obtained from three‐dimensional solutions of Laplace's equations, indicating that compressibility does not play a significant rǒle. This conclusion is supported by agreement between experimental frequencies (reservoir full) and those calculated using added mass obtained from the Laplace solution.

Similar conclusions were reached from tests on a floating steel plate, suspended in the surface of the reservoir by a soft spring. Here, dynamic pressure measurements were not made, reliance being placed on agreement between calculated and measured frequencies and mode shapes.
Long distance effects of the 28 march 1970 gediz turkey earthquake
Authors: Tezcan Semih S. , Ipek Muzaffer
Published: March 2007

In this paper, soil‐structure interaction studies are presented for buildings which collapsed at the Tofas automobile factory, Bursa, Turkey, during the 28 March 1970 Gediz earthquake. Acceleration response spectrum curves of the ground were determined using the vibrations of an after shock recorded by a Willmore velocity seismometer. These spectrum curves provide an essential source of information for establishing the reasons of collapse, as well as for explaining the relative response to the earthquake of various buildings in the factory area.

The factory not only is 135 km away from the epicentre, but also is far outside the fifth degree damage intensity zone. The prime reason why a low value of ground acceleration caused such surprisingly heavy damage to modern reinforced concrete structures is concluded to be the resonance phenomenon arising from the natural period of the structures coinciding with the predominant period of the soil.
A comparison of single‐run pushover analysis techniques for seismic assessment of bridges
Authors: Pinho R. , Casarotti C. , Antoniou S.
Published: March 2007

Traditional pushover analysis is performed subjecting the structure to monotonically increasing lateral forces with invariant distribution until a target displacement is reached; both the force distribution and target displacement are hence based on the assumption that the response is controlled by a fundamental mode, that remains unchanged throughout.

However, such invariant force distributions cannot account for the redistribution of inertia forces caused by structural yielding and the associated changes in the vibration properties, including the increase of higher‐mode participation. In order to overcome such drawbacks, but still keep the simplicity of using single‐run pushover analysis, as opposed to multiple‐analyses schemes, adaptive pushover techniques have recently been proposed.

In order to investigate the effectiveness of such new pushover schemes in assessing bridges subjected to seismic action, so far object of only limited scrutiny, an analytical parametric study, conducted on a suite of continuous multi‐span bridges, is carried out. The study seems to show that, with respect to conventional pushover methods, these novel single‐run approaches can lead to the attainment of improved predictions. Copyright © 2007 John Wiley & Sons, Ltd.
Use of terrain variables for mapping gully erosion susceptibility in Lebanon
Authors: Kheir Rania Bou , Wilson John , Deng Yongxin
Published: March 2007

This paper predicts the geographic distribution and size of gullies across central Lebanon using a geographic information system (GIS) and terrain analysis. Eleven primary (elevation; upslope contributing area; aspect; slope; plan, profile and tangential curvature; flow direction; flow width; flow path length; rate of change of specific catchment area along the direction of flow) and three secondary (steady‐state; quasi‐dynamic topographic wetness; sediment transport capacity) topographic variables were generated and used along with digital data collected from other sources (soil, geology) to statistically explain gully erosion field measurements. Three tree‐based regression models were developed using (1) all variables, (2) primary topographic variables only and (3) different pairs of variables. The best regression tree model combined the steady‐state topographic wetness and sediment transport capacity indices and explained 80% of the variability in field gully measurements. This model proved to be simple, quick, realistic and practical, and it can be applied to other areas of the Mediterranean region with similar environmental conditions, thereby providing a tool to help with the implementation of plans for soil conservation and sustainable management. Copyright © 2007 John Wiley & Sons, Ltd.
Optimal hedging with a regime‐switching time‐varying correlation GARCH model
Authors: Lee Hsiang‐Tai , Yoder Jonathan
Published: March 2007

The authors develop a Markov regime‐switching time‐varying correlation generalized autoregressive conditional heteroscedasticity (RS‐TVC GARCH) model for estimating optimal hedge ratios. The RS‐TVC nests within it both the time‐varying correlation GARCH (TVC) and the constant correlation GARCH (CC). Point estimates based on the Nikkei 225 and the Hang Seng index futures data show that the RS‐TVC outperforms the CC and the TVC both in‐ and out‐of‐sample in terms of variance reduction. Based on H. White's (2000) reality check, the null hypothesis of no improvement of the RS‐TVC over the TVC is rejected for the Nikkei 225 index contract but is not rejected for the Hang Seng index contract. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:495–516, 2007
Realized bond—stock correlation: Macroeconomic announcement effects
Authors: Christiansen Charlotte , Ranaldo Angelo
Published: March 2007

The authors investigate the effects of macroeconomic announcements on the realized correlation between bond and stock returns. It was found that it is not so much the surprise component of the announcement, but the mere fact that an announcement occurs that influences the realized bond—stock correlation. The impact of macroeconomic announcements varies across the business cycle. Announcement effects are highly dependent on the sign of the realized bond—stock correlation, which has recently gone from positive to negative. Macroeconomic announcement effects on realized bond and stock volatilities are also investigated. Our results are robust across 8:30 A.M. and 10:00 A.M. announcements. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:439—469, 2007
Alpha‐T‐catenin (CTNNA3) displays tumour specific monoallelic expression in urothelial carcinoma of the bladder
Authors: Meehan Maria , Melvin Audrey , Gallagher Emma , Smith James , Goldrick Alo Mc , Moss Catherine , Goossens Steven , Harrison Michèle , Kay Elaine , Fitzpatrick John , Dervan Peter , Mc Cann Amanda
Published: March 2007

CTNNA3 (alpha‐T‐catenin) is imprinted with preferential monoallelic expression of the maternal allele in placental tissue. The allelic expression pattern of CTNNA3 in adult human cancer is unknown and warrants investigation as CTNNA3 stabilizes cellular adherence, a feature which if compromised could enable cells to acquire an increased capability to detach and invade. We document the frequency of monoallelic versus biallelic expression of CTNNA3 in urothelial carcinoma of the bladder (UCB) samples and compare the observed patterns with that found in the paired normal sample. DNA PCR reactions encompassing a transcribable SNP polymorphism within exon 12 of CTNNA3 were sequence analyzed to identify heterozygous cases. A total of 96 samples were analyzed and included 22 paired normal and tumor UCB cases, 38 formalin fixed paraffin embedded (FFPE) UCB samples consisting of 18 noninvasive pTa tumors and 20 lamina propria invasive pT1 tumors and 14 cell lines of various lineages. RT‐PCR analysis of 35 heterozygous samples followed by sequence analysis allowed monoallelic versus biallelic patterns to be assigned. We have provided the first demonstration that CTNNA3 displays differing allelic expression patterns in UCB. Specifically, 35% (7/20) of informative UCB, showed monoallelic expression, a feature confined to the tumor, with normal urothelial samples displaying biallelic expression. Real time RT‐PCR analyses, demonstrated a significantly lower (P = 0.00039) level of CTNNA3 in the tumor samples compared with the paired normals, all of which displayed biallelic expression. In conclusion, monoallelic and biallelic CTNNA3 expression patterns are demonstrable in tumor bladder tissue, whereas normal cases show only biallelic expression. © 2007 Wiley‐Liss, Inc.
A normal radial glial scaffold is necessary for migration of interneurons during neocortical development
Authors: Poluch Sylvie , Juliano Sharon L.
Published: March 2007

The relationship between radial glia and neurons migrating tangentially from the ganglionic eminence (GE) has been suggested but not firmly established. To study this relationship we used a ferret model of cortical dysplasia where radial glia are highly disorganized. To produce this, an antimitotic, methylazoxy methanol (MAM) is injected on the 24th day of gestation (E24 MAM). Neurons migrating away from the GE in MAM‐treated animals tend to remain in the intermediate zone (IZ) and do not reach the cortical plate (CP) as they do in normal ferret slices. We recently observed that the disrupted radial glia after MAM treatment could be restored toward their normal morphology by exogenous application of neuregulin1 (NRG1). We demonstrate here that when E24 MAM slices are treated with NRG1, the distribution of cells arising from the GE was similar to normal slices. In a second paradigm, we disrupted radial glia by adding ciliary neurotrophic factor (CNTF) to the culture media of normal ferret slices; CNTF induces acute differentiation of radial glia into astrocytes. After CNTF exposure, few tangentially migrating cells reach the CP compared to untreated slices. These results show that interneurons fail to reach the CP by disrupted normal radial glia and restoring the normal radial glial scaffold is sufficient to allow migrating cells to invade the CP. Our results suggest an important role for radial glia by controlling directly or indirectly the migration of interneurons to the CP, their main target. © 2007 Wiley‐Liss, Inc.
Higher education assessment: Linking accreditation standards and the Malcolm Baldrige criteria
Authors: Ruben Brent D.
Published: March 2007

The Baldrige quality criteria generate a number of questions that can make accreditation self‐studies more productive.
Dual thyroid ectopia with a normally located pretracheal thyroid gland: Case report and literature review
Authors: Huang Ting‐Shuo , Chen Huang‐Yang
Published: March 2007

Background.

Only 1 case with dual thyroid ectopy and a normally located thyroid gland has been reported.

Methods.

We present the case of a 71‐year‐old woman who had 1‐sided lateral neck swelling in the right submandibular space, which grew and doubled in size within 1 year. A CT scan demonstrated 2 right submandibular, lobulated, heterogeneously enhanced masses, an ectopic lingual thyroid, and bilateral thyroid goiter. A Tc‐99m sodium pertechnetate thyroid scan revealed a cold area in the right lateral neck region below the submandibular gland, an ectopic lingual thyroid, and bilateral pretracheal thyroids. She underwent total thyroidectomy and en bloc excision of right neck masses. Thyroxin was prescribed following the surgery.

Results.

Pathological diagnoses were ectopic thyroid tissue with goitrous change and bilateral thyroid goiter.

Conclusion.

This report demonstrates that dual ectopic thyroid tissue accompanying a normally located thyroid gland can exist and should be differentiated from head and neck malignancies. © 2007 Wiley Periodicals, Inc. Head Neck 2007
Overview of economic concepts, models, and methods for institutional research
Authors: Paulsen Michael B. , Toutkoushian Robert K.
Published: March 2007

This chapter introduces the key economic concepts, models, and methods that can help inform institutional research in higher education.
Applying economics to institutional research on higher education revenues
Authors: Cheslock John J.
Published: March 2007

To properly evaluate the financial contributions of each revenue source, institutional researchers must use key economic concepts in their work.
Using economic concepts in institutional research on higher education costs
Authors: Brinkman Paul T.
Published: March 2007

Economics provides fertile ground, both theoretical and empirical, for institutional researchers interested in higher education costs.
Economic contributions to institutional research on faculty
Authors: Toutkoushian Robert K.
Published: March 2007

Economic models of the way in which faculty allocate their time, and the behavior of labor markets, can help inform institutional research on faculty in a variety of ways.
Economics and institutional research: Expanding the connections and applications
Authors: Paulsen Michael B. , Toutkoushian Robert K.
Published: March 2007

This chapter provides some examples and recommendations for expanding the connections between economics and institutional research.
Nonlinear autoregressive leading indicator models of output in G‐7 countries
Authors: Anderson Heather M. , Athanasopoulos George , Vahid Farshid
Published: March 2007

This paper studies linear and nonlinear autoregressive leading indicator models of business cycles in G‐7 countries. Our models use the spread between short‐term and long‐term interest rates as leading indicators for GDP. We examine data admissibility by determining whether these models have the ability to produce time series with classical cycles that resemble the observed classical cycles in the data, and then we ask whether this data admissibility lends itself to better predictions of the probability of recession. Copyright © 2007 John Wiley & Sons, Ltd.
Ontogeny of hepatic CYP1A2 and CYP2E1 expression in rat
Authors: Elbarbry Fawzy A. , McNamara Patrick J. , Alcorn Jane
Published: March 2007

We report a comprehensive examination of rat hepatic CYP1A2 and CYP2E1 ontogeny. We compare the data to human data to determine the rat's capacity as a model to identify CYP‐mediated mechanisms underlying age‐dependent differences in susceptibility to toxicity. We evaluated CYP expression using real‐time RT‐PCR, immunoblot and immunohistochemistry, and specific probe activity in male rat livers (n= 4) at critical developmental life stages. CYP2E1 mRNA expression was low at birth, then increased rapidly to peak prior to weaning. CYP1A2 transcript levels remained very low postnatally and then increased dramatically to reach peak expression during weaning. Immunoreactive CYP1A2 and CYP2E1 was first detected at postnatal day 3 (PD3), and reached 50% of adult levels after weaning, and adult levels by puberty. CYP1A2 and CYP2E1 probe activity (pmol/(min mg)) was detected at PD3 and peaked during weaning and late neonatal period, respectively. CYP activity fell to adult values by puberty, a pattern that closely mirrored the temporal changes in mRNA but not protein. An increasing preferential localization of CYP1A2 and CYP2E1 immunoreactivity in perivenous hepatocytes was observed with maturation to adulthood. Although differences in CYP1A2 and CYP2E1 ontogeny between rats and humans exist, knowledge of these differences will aid interspecies extrapolation of developmental toxicokinetic data. © 2007 Wiley Periodicals, Inc. J Biochem Mol Toxicol 21:41–50, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20156
Substrate activation of butyrylcholinesterase and substrate inhibition of acetylcholinesterase by 3,3‐dimethylbutyl‐N‐n‐butylcarbamate and 2‐trimethylsilyl‐ethyl‐N‐n‐butylcarbamate
Authors: Chiou Shyh‐Ying , Wu Yon‐Gi , Lin Yan‐Fu , Lin Long‐Yau , Lin Gialih
Published: March 2007

Carbamates are used to treat Alzheimer's disease. These compounds inhibit acetylcholinesterase and butyrylcholinesterase. The goal of this work is to use the substrate analogs of butyrylcholinesterase, 3,3‐dimethylbutyl‐N‐n‐butylcarbamate (1) and 2‐trimethylsilyl‐ethyl‐N‐n‐butylcarbamate (2) to probe the substrate activation mechanism of butyrylcholinesterase. Compounds 1 and 2 are characterized as the pseudo substrate inhibitors of acetylcholinesterase; however, compounds 1 and 2 are characterized as the essential activators of butyrylcholinesterase. Therefore, compounds 1 and 2 mimic the substrate in the acetylcholinesterase‐catalyzed reactions, but the behavior of compounds 1 and 2 mimics the substrate activation in the butyrylcholinesterase‐catalyzed reactions. © 2007 Wiley Periodicals, Inc. J Biochem Mol Toxicol 21:24–31, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20158
Sonographic diagnosis of cesarean scar pregnancy at 16 weeks
Authors: Smith Alison , Ash Alok , Maxwell Darryl
Published: March 2007

Cesarean scar pregnancy is rare. However, there has been a rapid increase in the reporting of such cases in recent years. Most of the cases reported in the literature were diagnosed early in the first trimester. Possible management options proposed are pertinent to an early diagnosis. We present a case of a cesarean scar pregnancy diagnosed at 16 weeks that posed a dilemma with regard to management. The patient subsequently suffered a ruptured uterus, which was preserved at surgery. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007
Cutaneous metastasis of esophageal adenocarcinoma with an unusual presentation
Authors: Riley Sara , Wah Tze
Published: March 2007

We describe an unusual presentation of a cutaneous metastasis of esophageal adenocarcinoma in the left tempero‐parietal skull and the sonographic features that helped establish the diagnosis. The patient had a primary tumor surgically resected 4 years earlier and was in clinical remission at the time of presentation. The patient presented to our radiology department with a lump on the head after a fall, and sonographic examination was recommended to assess the presumed posttraumatic hematoma. The examination revealed typical features of malignancy: a superficial solid mass invading the skull surrounded by an irregular network of blood vessels. This was confirmed on CT, and a definitive diagnosis was obtained on histologic analysis following sonographically guided biopsy. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007
Intraductal sonography of biliary varices associated with extrahepatic portal vein obstruction
Authors: Rai Tsuyoshi , Irisawa Atsushi , Takagi Tadayuki , Shibukawa Goro , Wakatsuki Takeru , Imamura Hidemichi , Takahashi Yuta , Sato Ai , Sato Masaki , Hikichi Takuto , Obara Katsutoshi , Ohira Hiromasa
Published: March 2007

We report a case of biliary varices associated with extrahepatic portal vein obstruction (EHPVO) that were identified via intraductal sonography during endoscopic retrograde cholangiography. A 35‐year‐old man was admitted to our hospital because of jaundice that had developed during an episode of EHPVO. Laboratory data showed obstructive jaundice. Endoscopic retrograde cholangiography showed some bile duct stenosis with smooth stricture along the extrahepatic biliary duct. Intraductal sonographic examination revealed numerous vessels around the lower and upper parts of the bile duct. Compression by these vessels was susprcted as the cause of the biliary stricture. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007
Chromatophore distribution and inferior performance of albino Japanese flounder Paralichthys olivaceus with special reference to different chromatophore expression between albinism and pseudo‐albinism
Authors: Shikano Takahito , Shimada Yukinori , Nakamura Aiko
Published: March 2007

Albinism with a large variation in body color was found in a hatchery population of Japanese flounder. In addition to albinism, ambicoloration and pseudo‐albinism were simultaneously observed in some individuals. Albinos had a remarkably lower number of melanophores on the scales of ocular side than wild‐type individuals did, although no significant difference was observed in the numbers of xanthophores and iridophores. The intensity of body color significantly correlated with the number of melanophores among the albinos. No significant differences were observed in the intensity of body color and the number of melanophores between the ocular side and the ambicoloration area. Pseudo‐albinism was accompanied by the reductions of melanophores and xanthophores, indicating the different expression patterns of chromatophores between albinism and pseudo‐albinism. The combined effects of albinism and pseudo‐albinism caused the disappearances of melanophores and xanthophores in the pseudo‐albinism area of albinos. In addition to chromatophores, the different characteristics of several phenotypic traits were observed between albinos and wild‐type individuals. Growth‐related traits of the albinos were inferior to those of the wild‐type individuals. Furthermore, the albinos had a larger pseudo‐albinism area and a higher vertebral deformed rate than the wild‐type individuals did. Individual multilocus heterozygosity and inbreeding coefficient measured by microsatellite loci did not show any indication that the albinos had higher inbreeding coefficient than the wild‐type individuals did. This study demonstrated the expression patterns of chromatophores in the body color abnormalities of a flatfish species and the potential pleiotropic effects of an albinism gene on some phenotypic traits. J. Exp. Zool. 307A:263–273, 2007. © 2007 Wiley‐Liss, Inc.
Egg jelly of the newt, Cynops pyrrhogaster contains a factor essential for sperm binding to the vitelline envelope
Authors: Hiyoshi Wataru , Sasaki Takayuki , Takayama‐Watanabe Eriko , Takai Hiroyuki , Watanabe Akihiko , Onitake Kazuo
Published: March 2007

The acrosome reaction of newt sperm is induced at the surface of egg jelly and the acrosome‐reacted sperm acquire the ability to bind to the vitelline envelope. However, because the substance that induces the acrosome reaction has not been identified, the mechanism by which the acrosome‐reacted sperm bind to the vitelline envelope remains unclear. We found here that a Dolichos biforus agglutinin (DBA) specifically mimicked the acrosome reaction immediately upon its addition in the presence of milimolar level Ca2+. Fluorescein isothiocyanate‐labeled DBA bound specifically to the acrosomal cap of the intact sperm in the presence of a Ca2+‐chelating agent, EDTA, suggesting that binding of DBA to the native receptor for the egg jelly substance on the acrosomal region took the place of the egg jelly substance‐induced acrosome reaction. In contrast, the sperm that had been acrosome reacted by DBA treatment did not bind to the vitelline envelope of the egg whose jelly layers were removed. Subsequent addition of jelly extract caused the sperm binding to vitelline envelope, indicating that the egg jelly of the newt contains substances that are involved in not only inducing the acrosome reaction but also binding to the vitelline envelope. This is the first demonstration of the involvement of egg jelly substance in the binding of acrosome‐reacted sperm to the vitelline envelope. J. Exp. Zool. 307A:301–311, 2007. © 2007 Wiley‐Liss, Inc.
Black blood dual phase turbo FLASH MR imaging of the heart
Authors: Sinha Shantanu , Sinha Usha
Published: March 2007

An MR imaging scheme for dark blood cardiac images acquired simultaneously in e∼d diastolic and end systolic phases, in breath‐hold times, is presented. The sequence consists of a magnetization preparation period followed by two segmented k‐space acquisitions. Image quality was investigated with respect to different sequence parameters (optimal values are indicated in brackets): (a) echo time (TE)/repetition time (TR)/flip angle (FA) (3/6.2 msec/20°); (b) number of lines/segments in the acquisition window (11 lines/segment); (c) location of acquisition windows and inversion time; and (d) thickness of slice „reinverted”︁ during preparation (1.53 times the acquisition slice thickness). The image quality of the basal slices at end systole was critically dependent on the last parameter. High quality short axis views of the heart, with good blood signal suppression, were acquired with the optimized sequence on four volunteers from apex to base at two phases in 10 breath‐holds.
Dynamic range extension of cine velocity measurements using motion registered spatiotemporal phase unwrapping
Authors: Yang Guang Z. , Burger Peter , Kilner Philip J. , Karwatowski Stefan P. , Firmin David N.
Published: March 2007

A motion‐registered spatiotemporal phase‐unwrapping method for extending the dynamic range of cine magnetic resonance phase velocity measurements is presented. The interframe cardiac movement is estimated from the magnitude image derived from the velocity encoded raw data, which ensures that the phase signal is unwrapped in the temporal direction with reference to pixels belonging to the same anatomic flow region. An extra step of spatial phase correction is then used to further eliminate any residual errors. The combination of spatial and temporal information for phase unwrapping provides a robust way of extending the dynamic range of cine velocity data in the presence of large phase aliasing errors.
The effects of time varying intravascular signal intensity and k‐space acquisition order on three‐dimensional MR angiography image quality
Authors: Maki Jeffrey H. , Prince Martin R. , Londy Frank J. , Chenevert Thomas L.
Published: March 2007

The optimum infusion timing and k‐space ordering for obtaining gadolinium‐enhanced three‐dimensional MR angiograms was determined through computer modeling using temporal contrast characteristics obtained from patient gadolinium infusion data. The effects of bolus timing were evaluated by varying the relationship between peak intravascular gadolinium concentration and the time at which the center of k space was acquired (tck) for sequential and centric acquisition techniques. Flow phantom experiments were performed to validate the theoretical computations.

Gadolinium concentration at the time of central k‐space acquisition determines intravascular signal intensity. Artifacts, including vessel broadening and edge ringing, depend on the order in which k space is collected and on how rapidly the gadolinium concentration changes. Artifacts are greatest when the center of k space is acquired before the intravascular gadolinium peak. Application of the optimal infusion timing results in preferential arterial enhancement with a minimum of artifacts in patients undergoing MR angiography.
Viscoelastic property detection by elastic displacement NMR measurements
Authors: Lewa Czeslaw J. , De Certaines Jacques D.
Published: March 2007

An attempt was undertaken to analyze the phase changes in the transverse magnetization component, M[perp], determined in NMR response by an elastic wave in the presence of two pulses with opposite magnetic field gradient directions. The obtained theoretical results indicate that such changes are significant in biologic tissues. Their measurement by NMR opens up new possibilities for detecting the displacement and some viscoelastic properties such as the adiabatic compressibility coefficient, amplitude wave damping coefficient, frequency and dispersion strength of elastic relaxation processes, etc. The method may be useful in basic applied research and in medical diagnosis of some diseases resulting in the variation of elastic properties of biological tissues, eg, atherosclerosis.
High speed diffusion imaging in the presence of eddy currents
Authors: Sinha Usha , Sinha Shantanu
Published: March 2007

This paper describes two schemes for fast diffusion imaging on a 1.5‐T MRI unit with unshielded gradients and 10‐mT/m gradient system. The prepared longitudinal magnetization is sampled by a turbo fast low‐angle shot (FLASH) sequence. The first scheme involves modifications to a diffusion‐weighted driven‐equilibrium preparation sequence that yields quantitative diffusion imaging. The second scheme consists of four 90° pulses that form the preparatory period with diffusion gradients applied between the first and last two 90° pulses. Sufficient time is allowed between the diffusion gradients and the beginning of the echo readout to allow eddy currents to decay to an acceptable level. Phantom studies show agreement between diffusion coefficients in the literature with those determined using the above schemes. The potential application of these sequences in monitoring temperature is demonstrated in phantoms. Artifact‐free quantitative diffusion‐weighted images of the brain using the second scheme are presented.
MR prediction of benign and malignant vertebral compression fractures
Authors: Moulopoulos Lia A. , Yoshimitsu Kengo , Johnston Dennis A. , Leeds Norman E. , Libshitz Herman I.
Published: March 2007

We reviewed spinal MR images of 58 patients with 98 compressed vertebrae. Benign (47 vertebrae) or malignant (51 vertebrae) etiology was established by biopsy or radiologic follow‐up. Compressed vertebrae were analyzed for presence and characteristics of signal abnormality, altered vertebral contour, Schmorl's nodes, pedicular involvement, and contrast uptake. Statistical analysis was performed. Diffuse and homogeneous decrease in signal intensity on T1‐weighted images, convex vertebral contour, involvement of the pedicles, and a lumbar location were more frequently observed in malignant fractures (P < .01). A thoracic location, lack of signal change, or a band‐like abnormality and absence of pedicular involvement or contour abnormality characterized benign fractures (P < .01). Schmorl's nodes and enhancement did not help establish a diagnosis. When a constellation of MR criteria are applied, the accuracy of the diagnosis of malignant and benign vertebral compression fractures may reach 94%.
Differentiating between T1 and T2* changes caused by gadopentetate dimeglumine in the kidney by using a double‐echo dynamic MR imaging sequence
Authors: Kuperman Vadim Y U. , Karczmar Gregory S. , Blomley Martin J. K. , Lewis Marta Z. , Lubich Leslie M. , Lipton Martin J.
Published: March 2007

Dynamic MR images of the passage of gadopentetate dimeglumine through the kidneys of normal rats are obtained using a dual gradient‐echo sequence. The amplitudes of gradient echoes are defined by local T1 and T2* values in the tissue. The ratio of these amplitudes, primarily defined by local T2*, can be used to differentiate between T1 and T2* effects. This is particularly important with regard to renal studies because, due to a highly inhomogeneous distribution of gadopentetate dimeglumine in the kidney, T2* shortening can impede MR data analysis. To study changes in the observed signal caused by gadopentetate dimeglumine, curves of MR renal intensity versus time were obtained in the cortex and medulla after administration of the contrast agent. Using T2* compensation, distinct temporal peaks were observed in the cortex and outer medulla, indicating a high concentration of gadopentetate dimeglumine in the vascular phase. The authors conclude that this technique can be a useful tool for studying renal function noninvasively.
Anterior disc displacement without reduction in the temporomandibular joint: MRI and associated clinical findings
Authors: Müller‐Leisse Christoph , Augthun Michael , Bauer Waltraud , Roth Auke , Günther Rolf
Published: March 2007

To determine the value of MRI in temporomandibular joint (TMJ) disorders, the data of MRI‐proven anterior disc dislocation without reduction (ADWOR) were correlated with clinical history and clinical data. MRI demonstrated degenerative bony changes and a reduced sagittal diameter of the condyle, a variable degree of disc deformation, and a thinned bilaminar zone in each of the joints with ADWOR, which clearly differed from patients with anterior disc dislocation with reduction (ADWR) (P = .01) and normal disc position (NDP) (P < .001). Of 59 patients and 83 TMJs that had been investigated in a 2‐year period, as shown by MRI, 22 patients (27 TMJs) had ADWOR (32 %), 16 joints had NDP (19 %), and 40 patients had ADWR (49 %). In patients with ADWOR, the clinical history revealed pain in either of the joints and/or cervical or masticatory muscles in 25 (93%) joints. Clinical investigation revealed various abnormalities in 22 joints; five of those presented without any pathologic clinical finding. Mouth opening was unlimited in nine patients (47%), palpation of the muscles of mastication was painless in 13 patients (52%), and joint noises during mouth opening or closing were noted in 14 patients (56%). According to clinical histories, four patients were suspected to have become symptomatic only after dental treatment. ADWOR is difficult to diagnose with clinical methods alone. The indication for MRI evaluation of the TMJ should be extended for asymptomatic patients with a history of limitation in mouth opening and pathologic x‐ray morphology of the condyle. Because symptoms may arise after dental treatment in these patients, aggravation of internal derangement may be avoided by careful handling.
MR lesion detection in a breast cancer population
Authors: Obdeijn Inge‐Marie A. , Kuijpers Theodore J. A. , van Dijk Pieter , Wiggers Theodore , Oudkerk Matthijs
Published: March 2007

Implementation of MR imaging of the breast as an extension of the existing imaging modalities in the diagnosis of breast cancer was evaluated in a university cancer center. MR imaging of the breast was performed in 54 patients, in whom the MR results were compared with the triple test (the combination of clinical examination, mammographic evaluation, and cytology) and the final histological diagnosis. MR imaging of the breast depicted 30 of the 33 malignancies (sensitivity, 91%). In two of the malignancies, the carcinoma was clinically and mammographically occult. For the three patients with a false‐negative MRI diagnosis, the conventional mammography showed suspicious clustered microcalcifications as a sign of in situ carcinoma. For seven patients, MR imaging of the breast incorrectly suggested the presence of a malignant lesion (specificity, 67%). To improve MR specificity, we perform MR‐guided ultrasonographic fine‐needle aspiration biopsy (FNAB). Although MR imaging of the breast is a highly sensitive examination, conventional x‐ray mammography remains the most efficient imaging modality in the diagnosis of breast cancer. In our patient population, MR imaging of the breast had additional value for women with mammographically dense breast tissue and especially for patients with clinical evidence of breast carcinoma that could not be detected with conventional diagnostic methods.
Multislice T1‐weighted hybrid rare in CNS imaging: Assessment of magnetization transfer effects and artifacts
Authors: Melhem Elias R. , Jara Hernan , Yucel E. Kent
Published: March 2007

Using a T1‐weighted hybrid rapid acquisition with relaxation enhancement (RARE) MR sequence that implements an echo‐to‐view mapping scheme termed “low‐high profile order,” we evaluated signal intensity changes in different brain tissues as a function of number of slices, interslice gap, and echo train length (ETL). We also measured phase‐encode and frequency‐encode noise as well as blurring artifacts along the phase‐encode direction as a function of ETL. Off‐resonance magnetization transfer effects were demonstrated to be responsible for signal intensities changes in white matter and gray matter when using multislice techniques. These effects are amplified by increasing the number of slices and ETL. Due to the nature of the implemented echo‐to‐view mapping scheme, no on‐resonance magnetization transfer effects were observed from the intraslice echo train. Selective background (white matter and gray matter) suppression in multislice T1‐weighted hybrid RARE, secondary to off‐resonance magnetization transfer effects, may provide better contrast resolution of enhancing central nervous system (CNS) lesions at much shorter scan time as compared to conventional spin‐echo T1‐weighted sequences. This improvement in contrast resolution as a function of ETL may be limited by worsening phase‐encode noise and blurring artifacts.
Separation of water and fat MR images in a single scan at .35 T using „sandwich”︁ echoes
Authors: Zhang Weiguo , Goldhaber David M. , Kramer David M.
Published: March 2007

A method was developed for separation of water and fat MR images in a single scan with correction of static field inhomogeneity. The imaging sequence uses a single radiofrequency (RF) echo that is „sandwiched”︁ between two gradient echoes. The gradient echoes are used to determine the Bo distribution and to produce out‐of‐phase images after phase correction using the field map. An algorithm was developed to unwrap the phase images for quantitating the Bo inhomogeneity. To account for differences in geometric distortion between the RF echo image and the gradient echo images due to the reversal of the read gradients, methods were developed to correct the images before the calculation of the final water and fat images. The proposed technique was implemented at .35 T. Both phantom and human images were acquired using the method. It is shown that water‐ and fat‐separated images can be obtained in a single scan using the „sandwich”︁ echoes in the presence of a relatively large Bo inhomogeneity.
Analysis and comparison of motion‐correction techniques in diffusion‐weighted imaging
Authors: Trouard Theodore P. , Sabharwal Yashvinder , Altbach Maria I. , Gmitro Arthur F.
Published: March 2007

Motion continues to be a significant problem in MRI, producing image artifacts that can severely degrade image quality. In diffusion‐weighted imaging (DWI), the problem is amplified by the presence of large gradient fields used to produce the diffusion weighting. Three correction methods applicable for correction of specific classes of motion are described and compared. The first is based on a generalized projection onto convex sets (GPOCS) postprocessing algorithm. The second technique uses the collection of navigator echoes to track phase errors. The third technique is based on a radial‐scan data acquisition combined with a modified projection‐reconstruction algorithm. Although each technique corrects well for translations, the radial‐scan method proves to be more robust when more complex motions are present. A detailed description of the causes of MR data errors caused by rigid body motion is included as an appendix.
Single‐shot GRASE imaging with short effective TEs
Authors: Johnson Glyn , Feinberg David A. , Venkataraman Viswanathan
Published: March 2007

A new phase‐encoding scheme for gradient‐ and spin‐echo (GRASE) imaging giving a short effective TE is described. Unlike previous orders, phase encoding is centric rather than sequential. The sequence is a development of k‐banded GRASE that uses different time segments of the echo train to encode different bands of k space. This phase‐encoding order has been implemented in single‐shot sequences on an imager with high performance gradients. Approximately 144 phase‐encoding lines can be acquired in an echo train time of 390 ms. With centric phase encoding, the effective TE is 8 ms, compared with 75 ms for sequential encoding, and signal‐to‐noise ratios (SNRs) in brain tissue are 50 to 70% higher. The sequence can be employed in, for example, diffusion and velocity imaging.
Development of an MRI‐compatible catheter for pacing the heart: Initial in vitro and in vivo results
Authors: Jerzewski Anastazia , Pattynama Peter M. T. , Steendijk Paul , Doornbos Joost , de Roos Albert , Baan Jan
Published: March 2007

An MRI‐compatible catheter was developed for pacing the heart during MRI imaging. The device was tested in vitro and in vivo in 10 animal experiments, using spin‐echo, gradient‐echo, and echo‐planar MRI sequences. Images were of good quality in all sequences. Pacing was effective without induced arrhythmias. Therefore, pacing the heart during MRI is feasible and seems to be safe when using dedicated hardware.
Ceramic surgical instruments: Ex vivo evaluation of compatibility with MR imaging at 1.5 T
Authors: Shellock Frank G. , Shellock Vincent J.
Published: March 2007

The purpose of this study was to evaluate the MR compatibility of ceramic instruments. Nine different ceramic instruments were tested with respect to ferromagnetism, heating, and artifacts using previously described techniques. There was no magnetic field attraction, temperature increases were ≤.1°C, and artifacts involved a signal void similar to the size and shape of each instrument. The ceramic instruments were demonstrated to be compatible with MR imaging and acceptable for use during intraprocedural MR imaging.
A simulation study to assess SVD encoding for interventional MRI: Effect of object rotation and needle insertion
Authors: Duerk Jeffrey L. , Wu Dee H. , Chung Y. C. , Liang Zhi‐Pei , Lewin Jonathan S.
Published: March 2007

Singular value decomposition (SVD) encoding offers great promise to provide high spatial and temporal resolution required for interventional MRI (I‐MRI) (1). This study investigates its efficacy when (a) objects are rotated and (b) a small device (ie, a needle) is moved within anatomic structures. It was found that SVD‐encoded MRI is biased toward the reference from which encoding vectors are derived, thus providing a potential limitation under conditions in which the object has undergone significant global change. Reference images with partial device insertion may be needed to accurately resolve the device or track the object motion. Theoretically, the differences between the reference and the object being imaged suggest that SVD encoding is suboptimal (in a minimum mean squared error sense). Other encoding/reconstruction algorithms may come closer to achieving the desired advantages in spatial and temporal fidelity.