bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization of two new X‐linked quantitative trait loci controlling corpus callosum size in the mouse
Authors: Kusek G. K. , Wahlsten D. , Herron B. J. , Bolivar V. J. , Flaherty L.
Published: August 2006

Corpus callosum (CC) size is a complex trait, characterized by a gradation of values within a normal range, as well as abnormalities that include a small or totally absent CC. Among inbred mouse strains with defects of the CC, BTBR T+tf/J (BTBR) mice have the most extreme phenotype; all animals show total absence of the CC and severe reduction of the hippocampal commissure (HC). In contrast, the BALB/cByJ (BALB) strain has a low frequency of small CC and consistently normal HC. Reciprocal F1 crosses between BTBR and BALB suggest the presence of X‐linked quantitative trait loci (QTLs) affecting CC size. Through linkage analysis of backcross male progeny, we have localized two regions on the X chromosome, having peaks at 68.5 Mb (∼29.5 cM) and at 134.5 Mb (∼60.5 cM) that are largely responsible for the reciprocal differences, with the BTBR allele showing X‐linked dominant inheritance associated with CC defects.
Bone Graft and Implants in a Patient with Systemic Mastocytosis
Authors: Thor Andreas , Stenport Victoria F. , Larsson Åke , Boström Åsa
Published: August 2006

Background:

Systemic mastocytosis (mast‐cell proliferation in various organs, including the skeleton) is a rare disease. Reports on mastocytosis that affects facial bones are few. The bone lesions may be osteolytic or sclerotic.

Purpose:

To describe (for the first time) bone grafting followed by dental implant treatment yielding a good result in a patient with systemic mastocytosis.

Materials and Methods:

A bone graft was performed on a 60‐year‐old woman with systemic mastocytosis. Dental implant treatment was performed 13 weeks after sclerotic bone of the iliac crest was grafted to the maxillary sinus bilaterally. A microimplant was installed simultaneously with the dental implants and was removed 6 months later for histo‐morphometric evaluation. Bone biopsy specimens from the donor site of the sclerotic iliac crest and later from the remodeled maxillary bone graft were histologically analyzed. A clinical examination of the patient with regard to her mastocytosis was performed by a dermatologist. The patient was followed up after 3 years.

Results:

Bone grafting and dental implant treatment were successful, and the patient's clinical and radiologic situation was stable after 3 years. Histologic examination of the bone grafted from the iliac crest showed sclerotic lesions in the bone and a dense infiltration of mast cells. The bone graft seemed to remodel initially in a normal way in the maxillary sinus. However, computed tomography 3 years later showed regions of sclerosis in the remodeled maxillary bone. These lesions now had a pattern similar to the adjacent facial bone. Both the microimplant and the dental implants integrated well. Bone‐implant contact measured on the microimplants was 20% higher in this actual case, compared to that of patients previously treated and grafted with the same technique.

Conclusions:

There are many clinical implications to be considered when treating this group of patients. Bone grafting, remodeling of the bone, and dental implant installation were successful in this patient with systemic mastocytosis and signs of osteosclerosis. Installation of microimplants in patients with pathologic bone conditions may allow successful dental implant treatment.
Bone Tissue Responses to Surface‐Modified Zirconia Implants: A Histomorphometric and Removal Torque Study in the Rabbit
Authors: Sennerby Lars , Dasmah Amir , Larsson Birgitta , Iverhed Mattias
Published: August 2006

Background:

Zirconia ceramics are biocompatible and have mechanical properties that make them suitable as materials for dental implants. Little is known about how surface modification influences the stability and bone tissue response to zirconia implants.

Purpose:

The objective of the investigation was to histologically and biomechanically evaluate the bone tissue response to zirconia implants with two different surface modifications in comparison with machined, nonmodified zirconia implants and oxidized titanium implants.

Materials and Methods:

Threaded zirconia implants with a diameter of 3.75 mm with either a machined surface (Zr‐Ctr) or one of two surface modifications (Zr‐A and Zr‐B) were manufactured. Oxidized titanium (Ti‐Ox) implants 3.75 mm in diameter were also used. The implants were characterized with regard to surface topography using an interferometer. Twelve rabbits received 96 implants using a rotational scheme, two in each tibia and two in each femur. The implants in six rabbits were subjected to removal torque (RTQ) tests after a healing period of 6 weeks. The implants in the remaining six animals were removed en bloc for light microscopic analysis. Back‐scatter scanning electron microscopic (BS‐SEM) analyses were used to evaluate the state of the bone‐implant interface at the modified zirconia implants after RTQ testing.

Results:

The Ti‐Ox and Zr‐A implants showed the highest surface roughness, followed by the Zr‐B implants and, finally, the Zr‐Ctr implants. The nonmodified ZrO2 implants showed statistically significant lower RTQs than all other implants. No significant differences in bone‐implant contact or bone area filling the threads were observed. BS‐SEM showed intact surface layers of the surface‐modified implants after RTQ testing and revealed fracture of the interface bone rather than a separation.

Conclusion:

The present study showed a strong bone tissue response to surface‐modified zirconia implants after 6 weeks of healing in rabbit bone. The modified zirconia implants showed a resistance to torque forces similar to that of oxidized implants and a four‐ to fivefold increase compared with machined zirconia implants. The findings suggest that surface‐modified zirconia implants can reach firm stability in bone.
Direct Implant Loading in the Edentulous Maxilla Using a Bone Density–Adapted Surgical Protocol and Primary Implant Stability Criteria for Inclusion
Authors: Östman Pär‐Olov , Hellman Mats , Sennerby Lars
Published: August 2006

Background:

Long healing periods and submerged implant placement are commonly used in the maxilla. This extends the time of oral handicap and makes the use of immediate loading protocols an attractive option. The current clinical literature on direct loading of dental implants in the maxilla is limited.

Purpose:

The purpose of this prospective clinical study was to evaluate the clinical outcome and stability of directly loaded Brånemark System® or Replace Select® Tapered implants (Nobel Biocare AB, Göteborg, Sweden) after using a modified surgical protocol and inclusion by primary implant stability. In addition, a reference group treated according to a two‐stage protocol was used for comparison.

Materials and Methods:

Twenty patients planned for prosthetic rehabilitation with implant‐supported bridges in the edentulous maxilla participated in the study group. The final decision on immediate loading was made after implant placement using insertion torque and resonance frequency analysis (RFA) as acceptance criteria. All patients were included, and 123 oxidized implants (TiUnite™, Nobel Biocare AB) were placed using a surgical protocol for enhanced primary stability. A screw‐retained temporary bridge was delivered within 12 hours and a final bridge within 3 months of implant placement. The patients were monitored through clinical and radiographic follow‐up examinations from implant placement to at least 12 months. Marginal bone level was measured at bridge delivery and after 12 months of loading. Additional RFA measurements were made after 6 months of loading. A reference group comprising 20 patients with 120 implants treated according to a two‐stage protocol was used for comparison.

Results:

One (0.8%) of the 123 implants in the study group failed, and no implant was lost in the reference group. The cumulative survival rates after 12 months of loading were thus 99.2% and 100% for immediate and delayed loading protocols, respectively. The marginal bone resorption was 0.78 (SD 0.9) in the study group and 0.91 (SD 1.04) in the reference group. RFA showed a mean value of 62.9 (SD 4.9) implant stability quotient (ISQ) at placement and 64.5 (SD 4.8) ISQ after 6 months for immediately loaded implants (not significant). The corresponding figures for the reference groups were 61.3 (SD 8.8) ISQ and 62.6 (SD 7.0) ISQ (not significant). There were no statistically significant differences between the groups at any time point.

Conclusion:

The use of six to seven implants for immediate loading of a fixed provisional bridge is a viable option for implant treatment of the edentulous maxilla, at least when good primary implant stability can be ensured.
Retrospective Clinical Evaluation of 86 Procera AllCeram™ Anterior Single Crowns on Natural and Implant‐Supported Abutments
Authors: Zarone Fernando , Sorrentino Roberto , Vaccaro Francesco , Russo Simona , De Simone Giorgio
Published: August 2006

Background:

The Procera AllCeram™ (Nobel Biocare AB, Göteborg, Sweden, and Procera Sandvik AB, Stockholm, Sweden) technique is one alternative to metal‐ceramic restorations. However, few long‐term evaluations of its use for single crowns on natural and implant‐supported abutments are available.

Purpose:

The aim of the present study was to assess the clinical performance of Procera AllCeram single crowns when placed in aesthetic sites supported by either natural teeth or implants over a period of 48 months.

Materials and Methods:

Eighty‐six single crowns were fabricated and used in 51 patients. The restorations were examined according to the California Dental Association's quality assessment system.

Results:

One crown was lost after 20 months of follow‐up. Of the 85 restorations that completed the 48‐month follow‐up, only one crown (1.2%) showed a veneering porcelain chip. All crowns were ranked as either excellent or acceptable. The success rates of single crowns supported by natural tooth and implant‐supported abutments were 100% and 98.3%, respectively; the total crown success rate was 98.8%.

Conclusion:

Within the limitations of the present study, Procera AllCeram crowns proved to be a reliable therapeutic choice for the restoration of anterior teeth on both natural and implant‐supported abutments. The hybrid glass‐ionomer cement used in the present study appeared to be a reliable luting agent.
Characterization of DNA transport in the thermophilic bacterium Thermus thermophilus HB27
Authors: Schwarzenlander Cornelia , Averhoff Beate
Published: August 2006

Horizontal gene transfer has been a major force for genome plasticity over evolutionary history, and is largely responsible for fitness‐enhancing traits, including antibiotic resistance and virulence factors. In particular, for adaptation of prokaryotes to extreme environments, lateral gene transfer seems to have played a crucial role. Recently, by performing a genome‐wide mutagenesis approach with Thermus thermophilus HB27, we identified the first genes in a thermophilic bacterium for the uptake of free DNA, a process called natural transformation. Here, we present the first data on the biochemistry and bioenergetics of the DNA transport process in this thermophile. We report that linear and circular plasmid DNA are equally well taken up with a high maximal velocity of 1.5 µg DNA·(mg protein)−1·min−1, demonstrating an extremely efficient binding and uptake rate of 40 kb·s−1·cell−1. Uncouplers and ATPase inhibitors immediately inhibited DNA uptake, providing clear evidence that DNA translocation in HB27 is an energy‐dependent process. DNA uptake studies with genomic DNA of Bacteria, Archaea and Eukarya revealed that Thermus thermophilus HB27 takes up DNA from members of all three domains of life. We propose that the extraordinary broad substrate specificity of the highly efficient Thermus thermophilus HB27 DNA uptake system may contribute significantly to thermoadaptation of Thermus thermophilus HB27 and to interdomain DNA transfer in hot environments.
Oligomerization of the Mg2+‐transport proteins Alr1p and Alr2p in yeast plasma membrane
Authors: Wachek Marcin , Aichinger Michael C. , Stadler Jochen A. , Schweyen Rudolf J. , Graschopf Anton
Published: August 2006

Alr1p is an integral plasma membrane protein essential for uptake of Mg2+ into yeast cells. Homologs of Alr1p are restricted to fungi and some protozoa. Alr1‐type proteins are distant relatives of the mitochondrial and bacterial Mg2+‐transport proteins, Mrs2p and CorA, respectively, with which they have two adjacent TM domains and a short Mg2+ signature motif in common. The yeast genome encodes a close homolog of Alr1p, named Alr2p. Both proteins are shown here to be present in the plasma membrane. Alr2p contributes poorly to Mg2+ uptake. Substitution of a single arginine with a glutamic acid residue in the loop connecting the two TM domains at the cell surface greatly improves its function. Both proteins are shown to form homo‐oligomers as well as hetero‐oligomers. Wild‐type Alr2p and mutant Alr1 proteins can have dominant‐negative effects on wild‐type Alr1p activity, presumably through oligomerization of low‐function with full‐function proteins. Chemical cross‐linking indicates the presence of Alr1 oligomers, and split‐ubiquitin assays reveal Alr1p–Alr1p, Alr2p–Alr2p, and Alr1p–Alr2p interactions. These assays also show that both the N‐terminus and C‐terminus of Alr1p and Alr2p are exposed to the inner side of the plasma membrane.
Angiotensin II induced contraction of rat and human small intestinal wall musculaturein vitro
Authors: Ewert S. , Spak E. , Olbers T. , Johnsson E. , Edebo A. , Fändriks L.
Published: August 2006

Background: Angiotensin II (Ang II) is a well‐known activator of smooth muscle in the vasculature but has been little explored with regard to intestinal wall muscular activity. This study investigates pharmacological properties of Ang II and expression of its receptors in small‐intestinal smooth muscle from rats and humans.

Methods: Isometric recordings were performedin vitroon small intestinal longitudinal muscle strips. Protein expressions of Ang II typ 1 (AT1R) and typ 2 (AT2R) receptors were assessed by Western blot.

Results: Ang II elicited concentration‐dependent contractions of rat jejunal and ileal muscle preparations. The concentration–response curve (rat ileum, EC50: 1.5 ± 0.9 × 10−8 m) was shifted to the right by the AT1R receptor antagonist losartan (10−7 m) but was unaffected by the AT2R antagonist PD123319 (10−7 m) as well as by the adrenolytic guanethidine (3 × 10−6 m) and the anticholinergic atropine (10−6 m). Human duodenal, jejunal and ileal longitudinal muscle preparations all contracted concentration‐dependently in response to Ang II. The concentration–response curve (human jejunum, EC50: 1.5 ± 0.8 × 10−8 m) was shifted to the right by losartan (10−7 m) but was unaffected by PD123319 (10−7 m). Both AT1R and AT2R were detected in all segments of the rat small intestinal wall musculature, whereas only AT1R was readily detectable in the human samples.

Conclusion: Ang II elicits contractions of small‐intestinal longitudinal muscle preparations from the small intestine of rats and man. The pharmacological pattern and protein expression analyses indicate mediation via the AT1R.
Risk and ageing populations: practice development research through an international research network
Authors: Clarke Charlotte L. ,   and members of the International Collaborative Research Network on Risk and Ageing Populations
Published: August 2006

Background.  Risk theories derive from a range of disciplines, with nursing traditionally concentrating on scientific medical perspectives. However, for older people, risk perception and management is filled with complexity and paradox, and the threat of focusing on physical safety only to the detriment of the well‐being of the older person.

Method.  An international collaborative research network on risk in ageing populations has been developed, with 22 members in six countries (Britain, USA, India, South Africa, Australia and Northern Ireland). The network supports several independent projects, many of which have developed as a result of the network. An annual workshop for members has provided the opportunity to share and synthesize methodological experiences and to identify a developing model of risk for older people.

Findings.  The developing model highlights the importance for older people of engaging with risk in a positive way, and describes patterns of risk‐philic and risk‐phobic activity. The inter‐relationship of the individual older person with their community, with practitioners and with society is specific to the context of different countries.

Conclusion.  Socio‐critical practice development research can be a vehicle for advancing an understanding of risk theory for older people. Risk underpins concepts of choice and capacity to execute decisions. It is influenced by society, policy, health and social care services, and has a profound impact on the experiences of older people.
NECESSARY CONDITIONS FOR VECTOR-VALUED OPERATOR INEQUALITIES IN HARMONIC ANALYSIS
Authors: CHRIST MICHAEL , SEEGER ANDREAS
Published: August 2006

Via a random construction we establish necessary conditions for $L^p (\ell^q)$ inequalities for certain families of operators arising in harmonic analysis. In particular, we consider dilates of a convolution kernel with compactly supported Fourier transform, vector maximal functions acting on classes of entire functions of exponential type, and a characterization of Sobolev spaces by square functions and pointwise moduli of smoothness.
THE SHARP BOUND FOR THE DEFORMATION OF A DISC UNDER A HYPERBOLICALLY CONVEX MAP
Authors: BARNARD ROGER W. , COLE LEAH , PEARCE KENT , WILLIAMS G. BROCK
Published: August 2006

We complete the determination of how far convex maps can deform discs in each of the three classical geometries. The euclidean case was settled by Nehari in 1976, and the spherical case by Mejía and Pommerenke in 2000. We find the sharp bound on the Schwarzian derivative of a hyperbolically convex function and thus complete the hyperbolic case. This problem was first posed by Ma and Minda in a series of papers published in the 1980s. Mejía and Pommerenke then produced partial results and a conjecture as to the extremal function in 2000. Their function maps onto a domain bounded by two proper geodesic sides, a ‘hyperbolic strip’. Applying a generalization of the Julia variation and a critical Step Down Lemma, we show that there is an extremal function mapping onto a domain with at most two geodesic sides. We then verify using special function theory that, among the remaining candidates, the two-sided domain of Mejía and Pommerenke is in fact extremal. This correlates nicely with the euclidean and spherically convex cases in which the extremal is known to be a map onto a two-sided ‘strip’.
Float Over Installation Method—Comprehensive Comparison Between Numerical and Model Test Results
Authors: Tahar Arcandra , Halkyard John , Steen Atle , Finn Lyle
Published: August 2006

Installing a large deck onto a platform, such as a spar, using the floatover method is gaining popularity. This is because the operational cost is much lower than other methods of installation, such as modular lifts or a single piece installation by a heavy lift barge. Deck integration can be performed on land, at quay side and will not depend on a heavy lift barge. A new concept for a floatover vessel has been developed for operations in the Gulf of Mexico and West Africa. In this application sea state conditions are essential factors that must be considered in the Gulf of Mexico, especially for transportation. In West Africa, swell conditions will govern floatover deck (FOD) installation. Based on these two different environmental conditions, Technip Offshore, Inc. developed the FOD installation concept using semi-submersible barge type vessels. A significant amount of development work and model testing has been done on this method in recent years on spar floatover. These tests have validated our numerical methods. Another test was conducted to investigate the feasibility of a deck float-over operation onto a compliant tower for a West Africa project. The project consists of a compliant tower supporting a 25,401metricton(28,000s.ton) integrated deck. This paper will describe comparisons between model test data and numerical predictions of the compliant tower floatover operation.
System Identification of a Coupled Two DOF Moored Floating Body in Random Ocean Waves
Authors: Selvam R. Panneer , Bhattacharyya S. K.
Published: August 2006

Dynamics of a large moored floating body in ocean waves involves frequency dependent added mass and radiation damping as well as the linear and nonlinear mooring line characteristics. Usually, the added mass and radiation damping matrices can be estimated either by potential theory-based calculations or by experiments. The nonlinear mooring line properties are usually quantified by experimental methods. In this paper, we attempt to use a nonlinear system identification approach, specifically the reverse multiple input-single output (R-MISO) method, to coupled surge-pitch response (two-degrees-of-freedom) of a large floating system in random ocean waves with linear and cubic nonlinear mooring line stiffnesses. The system mass matrix has both frequency independent and frequency dependent components whereas its damping matrix has only frequency dependent components. The excitation force and moment due to linear monochromatic waves which act on the system are assumed to be known that can either be calculated or obtained from experiments. For numerical illustration, a floating half-spheroid is adopted. The motion as well as the loading are simulated assuming Pierson-Moskowitz (PM) spectrum and these results have been analyzed by the R-MISO method yielding frequency dependent coupled added mass and radiation damping coefficients, as well as linear and nonlinear stiffness coefficients of mooring lines satisfactorily.
Adaptive Control Strategy for the Dynamic Positioning of a Shuttle Tanker During Offloading Operations
Authors: Tannuri Eduardo A. , Kubota Leonardo K. , Pesce Celso P.
Published: August 2006

In deep water oil production, Dynamic positioning systems (DPS) strategy has shown to be an effective alternative to tugboats, in order to control the position of the shuttle tanker during offloading operations from a FPSO (floating production, storage, and offloading system). DPS reduces time, cost, and risks. Commercial DPS systems are usually based on control algorithms which associate Kalman filtering techniques with proportional-derivative (PD) or optimal linear quadratic (LQ) controllers. Since those algorithms are, in general, based on constant gain controllers, performance degradation may be encountered in some situations, as those related to mass variation during the loading operation of the shuttle tanker. The positioning performance of the shuttle changes significantly, as the displacement of the vessel increases by a factor of three. The control parameters are adjusted for one specific draught, making the controller performance to vary. In order to avoid such variability, a human-based periodic adjustment procedure might be cogitated. Instead and much safer, the present work addresses the problem of designing an invariant-performance control algorithm through the use of a robust model-reference adaptive scheme, cascaded with a Kalman filter. Such a strategy has the advantage of preserving the simple structure of the usual PD and LQ controllers, the adaptive algorithm itself being responsible for the on-line correction of the controller gains, thus insuring a steady performance during the whole operation. As the standard formulation of adaptive controllers does not guarantee robustness regarding modeling errors, an extra term was included in the controller to cope with strong environmental disturbances that could affect the overall performance. The controller was developed and tested in a complete mathematical simulator, considering a shuttle tanker operating in Brazilian waters subjected to waves, wind and current. The proposed strategy is shown to be rather practical and effective, compared with the performance of constant gain controllers.
Dynamic Compression of Rigid and Flexible Risers: Experimental and Numerical Results
Authors: Simos Alexandre N. , Fujarra André L. C.
Published: August 2006

Dynamic compression and buckling are critical issues in the viability analysis of rigid and flexible risers developed for offshore applications, especially concerning deep-water operations. Those subjects have been addressed both numerically and analytically. However, few experimental data for validation purposes is found in literature. This paper presents a set of experimental results on the dynamic compression of rigid and flexible risers in catenary configurations, obtained by means of towing-tank tests. Two small-scale models have been built, the first one emulating the dynamic behavior of a steel catenary riser (SCR) and the other representing a much more flexible line. Uniform circular motion has been applied to the top of the models, emulating the floating system first-order oscillations. Different amplitudes of top motion have been considered, each one of them imposed with different frequencies of oscillation. Tension has been measured at the top of the models. The influence of current velocity has also been evaluated. Dynamic tension estimations obtained through finite element analysis are compared to the experimental results. Tension amplitude and critical compression load values are evaluated and compared for both, the steel catenary (SCR) and the flexible models. Comparisons show, in general, a fair agreement between simulations and experiments, reassuring the reliability of numerical models. Results also demonstrate that finite element code provides good predictions of maximum tension loads even when the risers are subjected to high levels of dynamic compression and buckle. Nevertheless, it is clearly noted that difficulties arise in the treatment of flexible structures under severe buckling and torsion. The accuracy of analytical methods proposed for the estimation of critical compression loads is also discussed, based on the experimental results.
Critical Buckling Strain Equations for Energy Pipelines—A Parametric Study
Authors: Dorey Alfred B. , Murray David W. , Cheng J. J. Roger
Published: August 2006

A recent review of available predictive critical buckling strain equations for segments of line pipe has shown that the equations give poor test-to-predicted ratios when validated using the more than 50 full-scale experimental pipeline test results available in the University of Alberta (U of A) database (Dorey, A. B., Murray, D. W., and Cheng, J. J. R., 2000, “An Experimental Comparison of Critical Buckling Strain Criteria,” Proceeding of the International Pipeline Conference, Calgary, Alberta, Oct. 1–5, ASME, New York, pp. 71–77, Paper No. IPC00-0157.). The pipeline specimens in the experimental database were subjected to a combination of axial load, internal pressure, and monotonically increasing curvature with magnitudes representative of those that might be experienced under field operating conditions. Research has been undertaken at the U of A to develop more reliable equations and a database of over 200 experimental and numerical results now exists. The numerical results were generated using a nonlinear finite element analysis (FEA) model that was validated using the experimental database. The FEA model provided a mean test-to-predicted ratio for the peak moment capacity of 1.025 with a coefficient of variation of 0.040 and a mean test-to-predicted ratio for the local critical buckling strain of 0.997 with a coefficient of variation of 0.067 (Dorey, A. B., Murray, D. W., and Cheng, J. J. R., 2005b, “A Comparison of Experimental and FEA Results for Segments of Line Pipe Under Combined Loads,” ASME J. Offshore Mech. Arct. Eng., in press.) for the 162 load cases analyzed. This paper presents the new predictive critical buckling strain equations developed from the U of A database.
An Approach for Testing Methods for Modeling Uncertainty
Authors: Haftka Raphael T. , Rosca Raluca I. , Nikolaidis Efstratios
Published: August 2006

To address the need for efficient and unbiased experimental testing of methods for modeling uncertainty that are used for decision making, we devise an approach for probing weaknesses of these methods by running numerical experiments on arbitrary data. We recommend using readily available data recorded in real-life activities, such as competitions, student design projects, medical procedures, or business decisions. Because the generating mechanism and the probability distribution of this data is often unknown, the approach adds dimensions, such as fitting errors and time dependencies of data that may be missing from tests conducted using computer simulations. For an illustration, we tested probabilistic and possibilistic methods using a database of results of a domino tower competition. The experiments yielded several surprising results. First, even though a probabilistic metric of success was used, there was no significant difference between the rates of success of the probabilistic and possibilistic models. Second, the common practice of inflating uncertainty when there is little data about the uncertain variables shifted the decision differently for the probabilistic and possibilistic models, with the latter being counter-intuitive. Finally, inflation of uncertainty proved detrimental even when very little data was available.
Optimum Gear Tooth Geometry for Minimum Fillet Stress Using BEM and Experimental Verification With Photoelasticity
Authors: Spitas Vasilios A. , Costopoulos Theodore N. , Spitas Christos A.
Published: August 2006

This paper introduces the concept of nondimensional gear teeth to be used in gear stress minimization problems. The proposed method of modeling reduces the computational time significantly when compared to other existing methods by essentially reducing the total number of design variables. Instead of modeling the loaded gear tooth and running BEA to calculate the maximum root stress at every iterative step of the optimization procedure, the stress is calculated by interpolation of tabulated values, which were calculated previously by applying the BEM on nondimensional models corresponding to different combinations of the design parameters. The complex algorithm is used for the optimization and the root stresses of the optimum gears are compared with the stresses of the standard gears for the same transmitted torque. Reduction in stress up to 36.5% can be achieved in this way. This reduction in stress has been confirmed experimentally with two-dimensional photoelasticity.
Design Space of Single-Loop Planar Folded Micro Mechanisms With Out-of-Plane Motion
Authors: Lusk Craig P. , Howell Larry L.
Published: August 2006

Microelectromechanical systems (MEMS) are usually fabricated using planar processing methods such as surface micromachining, bulk micromachining, or LIGA-type fabrication. If a micro mechanism is desired that has motion out of the plane of fabrication, it can be a folded mechanism in its fabricated position. The desire to design MEMS for a wide range of out-of-plane motions has led to the need for a better theoretical understanding of the design space for folded mechanisms. Thus, this paper derives the design space of arbitrary planar folded mechanisms. This results in the definition of the orientation set measures equality condition (OSMEC) which can be used in constructing adjacency set patches and joining them to construct the design space. The results can be used to explore different properties of the mechanisms in the design space. One such property, the mechanisms’ folded length, is given as an example. Although MEMS provide the primary motivation for the work, the results are general and apply to other areas of application.
Dynamics and Control of a Helicopter Carrying a Payload Using a Cable-Suspended Robot
Authors: Oh So-Ryeok , Ryu Ji-Chul , Agrawal Sunil K.
Published: August 2006

In this paper we present a study of the dynamics and control of a helicopter carrying a payload through a cable-suspended robot. The helicopter can perform gross motion, while the cable suspended robot underneath the helicopter can modulate a platform in position and orientation. Due to the underactuated nature of the helicopter, the operation of this dual system consisting of the helicopter and the cable robot is challenging. We propose here a two time scale control method, which makes it possible to control the helicopter and the cable robot independently. In addition, this method provides an effective estimation on the bound of the motion of the helicopter. Therefore, even in the case where the helicopter motion is unknown, the cable robot can be stabilized by implementing a robust controller. Simulation results of the dual system show that the proposed control approach is effective for such a helicopter-robot system.
Film Cooling Measurements for Novel Hole Configurations
Authors: Lu Yiping , Nasir Hasan , Faucheaux David , Ekkad Srinath V.
Published: August 2006

Experimental Procedure: •Blower is set appropriately for required mainstream velocity •Heater is turned on and allowed to heat the air to a desired mainstream temperature •The coolant air is provided from separate compressed air supply and is metered for flow measurement •The mainstream and coolant are triggered at the same instant when the IR system starts taking images and saving to hard drive at set intervals •Images are saved then processed to calculate the heat transfer coefficients and film effectiveness using the theory
Jet Impingement Heat Transfer Visualization Using a Steady State Liquid Crystal Method
Authors: Esposito Eric , Ekkad Srinath V.
Published: August 2006

Experimental Procedure: •Blower is set appropriately for required jet Reynolds number •Heater is turned on and allowed to reach steady state •A picture is taken of the liquid crystal coated test plate and heater amperage and voltage measured •Heater power is incrementally increased and additional pictures taken to capture temperature and heater flux data at every point in the array •Pictures are converted to Hue and liquid crystal calibration curve used to determine temperature at corresponding point
Experimental Estimate of the Continuous One-Dimensional Kernel Function in a Rectangular Duct With Forced Convection
Authors: Rhee Jinny , Moffat Robert J.
Published: August 2006

The continuous, one-dimensional kernel function in a rectangular duct subject to forced convection with air was experimentally estimated using liquid crystal thermography techniques. Analytical relationships between the kernel function for internal flow and the temperature distribution resulting from a known heat flux distribution were manipulated to accomplish this objective. The kernel function in the hydrodynamically fully developed region was found to be proportional to the streamwise temperature gradient resulting from a constant heat flux surface. In the hydrodynamic entry region of the rectangular duct, a model for the kernel function was proposed and used in its experimental determination. The kernel functions obtained by the present work were shown to be capable of predicting the highly nonuniform surface temperature rise above the inlet temperature resulting from an arbitrary heat flux distribution to within the experimental uncertainty. This is better than the prediction obtained using the analytically derived kernel function for turbulent flow between parallel plates, and the prediction obtained using the conventional heat transfer coefficient for constant heat flux boundary conditions. The latter prediction fails to capture both the quantitative and qualitative nature of the problem. The results of this work are relevant to applications involving the thermal management of nonuniform temperature surfaces subject to internal convection with air, such as board-level electronics cooling. Reynolds numbers in the turbulent and transition range were examined.
Dryout Heat Flux During Penetration of Water Into Solidifying Rock
Authors: Epstein Michael
Published: August 2006

A model for the dryout heat flux during penetration of water into solidifying rock is developed by combining steady-state one-dimensional phase change theory with available semiempirical equations for (i) the dryout heat flux in a porous medium and (ii) the permeability of hot rock cooled by water. The model is in good agreement with measurements made during the pouring of water onto molten magma. The implication of the model with respect to stabilizing molten-nuclear-reactor-core material by flooding from above is discussed.
Fin Efficiency of an Annular Fin Composed of a Substrate Metallic Fin and a Coating Layer
Authors: Tu Ping , Inaba Hideo , Horibe Akihiko , Li Zhongmin , Haruki Naoto
Published: August 2006

An analytical solution to a composite annular fin made of a substrate metallic fin and a coating layer has been carried out. Useful expressions for calculating temperature distribution and fin efficiency have been derived. Comparing the analytical results to those of numerical calculation, the premise for the expressions is also explored. Theoretical analyzing results show that fin efficiency of a coated fin decreases with an increase of the coating layer thickness if the thermal conductivity of coating layer is much less than that of the substrate metallic fin. Whereas, the reverse influence of the coating layer thickness on the fin efficiency appears if the thermal conductivity of the coating layer is beyond the above range.
Divergent Induced Responses to an Invasive Predator in Marine Mussel Populations
Authors: Freeman Aaren S. , Byers James E.
Published: August 2006

Invasive species may precipitate evolutionary change in invaded communities. In southern New England (USA) the invasive Asian shore crab,
Hemigrapsus sanguineus
, preys on mussels (
Mytlius edulis
), but the crab has not yet invaded northern New England. We show that southern New England mussels express inducible shell thickening when exposed to waterborne cues from
Hemigrapsus
, whereas naïve northern mussel populations do not respond. Yet, both populations thicken their shells in response to a long-established crab,
Carcinus maenas
. Our findings are consistent with the rapid evolution of an inducible morphological response to
Hemigrapsus
within 15 years of its introduction.
Comment on "Gene Regulatory Networks and the Evolution of Animal Body Plans"
Authors: Coyne Jerry A.
Published: August 2006

Davidson and Erwin (Reviews, 10 February 2006, p. 796) argued that known microevolutionary processes cannot explain the evolution of large differences in development that characterize phyla. Instead, they proposed that phyla arise from novel evolutionary processes involving large mutations acting on conserved core pathways of development. I question some of their assumptions and show that natural selection adequately explains the origin of new phyla.
An Experimental Study of the Coloring Problem on Human Subject Networks
Authors: Kearns Michael , Suri Siddharth , Montfort Nick
Published: August 2006

Theoretical work suggests that structural properties of naturally occurring networks are important in shaping behavior and dynamics. However, the relationships between structure and behavior are difficult to establish through empirical studies, because the networks in such studies are typically fixed. We studied networks of human subjects attempting to solve the graph or network coloring problem, which models settings in which it is desirable to distinguish one's behavior from that of one's network neighbors. Networks generated by preferential attachment made solving the coloring problem more difficult than did networks based on cyclical structures, and “small worlds” networks were easier still. We also showed that providing more information can have opposite effects on performance, depending on network structure.
Tequila, a Neurotrypsin Ortholog, Regulates Long-Term Memory Formation in
Drosophila
Authors: Didelot Gérard , Molinari Florence , Tchénio Paul , Comas Daniel , Milhiet Elodie , Munnich Arnold , Colleaux Laurence , Preat Thomas
Published: August 2006

Mutations in the human neurotrypsin gene are associated with autosomal recessive mental retardation. To further understand the pathophysiological consequences of the lack of this serine protease, we studied Tequila (Teq), the
Drosophila
neurotrypsin ortholog, using associative memory as a behavioral readout. We found that
teq
inactivation resulted in a long-term memory (LTM)–specific defect. After LTM conditioning of wild-type flies,
teq
expression transiently increased in the mushroom bodies. Moreover, specific inhibition of
teq
expression in adult mushroom bodies resulted in a reversible LTM defect. Hence, the Teq pathway is essential for information processing in
Drosophila
.
Time-Resolved Seismic Tomography Detects Magma Intrusions at Mount Etna
Authors: Patanè D. , Barberi G. , Cocina O. , De Gori P. , Chiarabba C.
Published: August 2006

The continuous volcanic and seismic activity at Mount Etna makes this volcano an important laboratory for seismological and geophysical studies. We used repeated three-dimensional tomography to detect variations in elastic parameters during different volcanic cycles, before and during the October 2002–January 2003 flank eruption. Well-defined anomalous low
P
- to
S
-wave velocity ratio volumes were revealed. Absent during the pre-eruptive period, the anomalies trace the intrusion of volatile-rich (≥4 weight percent) basaltic magma, most of which rose up only a few months before the onset of eruption. The observed time changes of velocity anomalies suggest that four-dimensional tomography provides a basis for more efficient volcano monitoring and short- and midterm eruption forecasting of explosive activity.
From Individual Dispersal to Species Ranges: Perspectives for a Changing World
Authors: Kokko Hanna , López-Sepulcre Andrés
Published: August 2006

Dispersal is often risky to the individual, yet the long-term survival of populations depends on having a sufficient number of individuals that move, find each other, and locate suitable breeding habitats. This tension has consequences that rarely meet our conservation or management goals. This is particularly true in changing environments, which makes the study of dispersal urgently topical in a world plagued with habitat loss, climate change, and species introductions. Despite the difficulty of tracking mobile individuals over potentially vast ranges, recent research has revealed a multitude of ways in which dispersal evolution can either constrain, or accelerate, species' responses to environmental changes.
Conflicting Evidence About Long-Distance Animal Navigation
Authors: Alerstam Thomas
Published: August 2006

Because of conflicting evidence about several fundamental issues, long-distance animal navigation has yet to be satisfactorily explained. Among the unsolved problems are the nature of genetic spatial control of migration and the relationships between celestial and magnetic compass mechanisms and between different map-related cues in orientation and homing, respectively. In addition, navigation is expected to differ between animal groups depending on sensory capabilities and ecological conditions. Evaluations based on modern long-term tracking techniques of the geometry of migration routes and individual migration history, combined with behavioral experiments and exploration of the sensory and genetic mechanisms, will be crucial for understanding the spatial principles that guide animals on their global journeys.
Polarized Light Cues Underlie Compass Calibration in Migratory Songbirds
Authors: Muheim Rachel , Phillips John B. , Åkesson Susanne
Published: August 2006

Migratory songbirds use the geomagnetic field, stars, the Sun, and polarized light patterns to determine their migratory direction. To prevent navigational errors, it is necessary to calibrate all of these compass systems to a common reference. We show that migratory Savannah sparrows use polarized light cues from the region of sky near the horizon to recalibrate the magnetic compass at both sunrise and sunset. We suggest that skylight polarization patterns are used to derive an absolute (i.e., geographic) directional system that provides the primary calibration reference for all of the compasses of migratory songbirds.
A Cellular and Molecular Foundation for Understanding Cancer
Authors: Klein George
Published: August 2006

The Biology of Cancer
.
By Robert A. Weinberg
. Garland Science, New York, 2006. 864 pp + CD-ROM. $140, £89.99. ISBN 0-8153-4078-8. Paper, $99, £41.99. ISBN 0-8153-4076-1.

This textbook offers students and researchers a comprehensive introduction to the molecular and cellular bases of cancer.
The Gamma Interferon (IFN-γ) Mimetic Peptide IFN-γ(95-133) Prevents Encephalomyocarditis Virus Infection both in Tissue Culture and in Mice
Authors: Mujtaba Mustafa G. , Patel Chintak B. , Patel Ravi A. , Flowers Lawrence O. , Burkhart Marjorie A. , Waiboci Lilian W. , Martin James , Haider Mohammad I. , Ahmed Chulbul M. , Johnson Howard M.
Published: August 2006

We have demonstrated previously that the C-terminal gamma interferon (IFN-γ) mimetic peptide consisting of residues 95 to 133 [IFN-γ(95-133)], which contains the crucial IFN-γ nuclear localization sequence (NLS), has antiviral activity in tissue culture. Here we evaluate the efficacy of this peptide and its derivatives first in vitro and then in an animal model of lethal viral infection with the encephalomyocarditis (EMC) virus. Deletion of the NLS region from the IFN-γ mimetic peptide IFN-γ(95-133) resulted in loss of antiviral activity. However, the NLS region does not have antiviral activity in itself. Replacing the NLS region of IFN-γ(95-133) with the NLS region of the simian virus 40 large T antigen retains the antiviral activity in tissue culture. IFN-γ(95-133) prevented EMC virus-induced lethality in mice in a dose-dependent manner compared to controls. Mice treated with IFN-γ(95-133) had no or low EMC virus titers in their internal organs, whereas control mice had consistently high viral titers, especially in the heart tissues. Injection of B8R protein, which is encoded by poxviruses as a defense mechanism to neutralize host IFN-γ, did not inhibit IFN-γ(95-133) protection against a lethal dose of EMC virus, whereas mice treated with rat IFN-γ were not protected. The data presented here show that the IFN-γ mimetic peptide IFN-γ(95-133) prevents EMC virus infection in vivo and in vitro and may have potential against other lethal viruses, such as the smallpox virus, which encodes the B8R protein.