Evaluation of web compactness limits for singly and doubly symmetric steel I-girders

This paper presents the results of research aimed at evaluating the web compactness limit for steel I-girders. Specifically, the paper tests the implications of a new web compactness limit equation provided in the 2003 AASHTO LRFD specifications [AASHTO LRFD bridge design specifications. 3rd ed. Washington (DC): AASHTO; 2003 [in press]] versus the web compactness limit in the 2001 AASHTO LRFD specifications [AASHTO LRFD bridge design specifications. 2nd ed. Washington (DC): AASHTO; 1998 [with 2001 interims]] and 1999 AISC LRFD specifications [AISC. Manual of steel construction, load and resistance factor design, Chicago (IL); 2001]. In both the AASHTO and AISC specifications, these limits are required for the nominal moment capacity to equal the plastic moment capacity of the girder, provided other requirements are also satisfied.The origins of the AASHTO [AASHTO LRFD bridge design specifications. 3rd ed. Washington (DC): AASHTO; 2003 [in press]; AASHTO LRFD bridge design specifications. 2nd ed. Washington (DC): AASHTO; 1998 [with 2001 interims]] web compactness limits are presented along with a performance evaluation of these equations. Specifically, resulting moment capacities from a comprehensive suite of finite element analyses are compared to the capacities that the respective limits are intended to provide. Results indicate the AASHTO (2003) web compactness provisions provide a more accurate representation of girder strength than those in the AASHTO (2001) and AISC (1999) Specifications.     

Impacts of Sewers on Groundwater Quality

This paper summarizes the findings of a recent research project on groundwater contamination from leaking sewers, which was completed for the Construction Industry Research and Information Association. Fifty-four incidents were identified in England and Wales from a combined questionnaire survey and literature review. In addition to recorded incidents, the poor quality of many urban groundwaters suggests some effects from leaking sewers. Age is considered to be the most significant characteristic governing leakage from sewers; ground conditions (predominantly aquifer vulnerability) and usage (private versus public ownership) are also important factors relating to the likelihood of groundwater pollution from leaking sewers. Recommended strategies for reducing groundwater contamination include (a) modification of existing criteria for the service performance grading of existing sewers, (b) improved construction of new sewers in appropriate areas, (c) increased groundwater monitoring, and (d) risk assessments for new groundwater sources.     

In-band noise suppression using novel monolithically integrated semiconductor optical amplifier-based ultra-compact interferometers

Novel all-optical noise suppressors based on the nonlinear transfer function properties of monolithically integrated active waveguide interferometers are proposed and demonstrated. Through a power map imbalance between the two arms of the interferometers, each of which contains multi-contact semiconductor optical amplifiers, a nonlinear transfer function is created, which can then be exploited to achieve in-band noise suppression. The authors demonstrate the use of such a mechanism in ultra-compact Mach-Zehnder and Michelson interferometers (MIs). Experimental work demonstrates a 5.0-dB optical signal-to-noise ratio improvement for the Mach-Zehnder and an 8.4-dB improvement for the MIs, respectively. It is shown that for input data the Mach-Zehnder is capable of providing a Q factor improvement of 4.1 dB. To the authors knowledge, these devices constitute the smallest integrated interferometer structures reported to date demonstrating in-band noise suppression.     

Overvaluation of shape and weight in binge eating disorder and overweight controls: Refinement of a diagnostic construct.

Debate continues regarding the nosological status of binge eating disorder (BED) as a diagnosis as opposed to simply reflecting a useful marker for psychopathology. Contention also exists regarding the specific criteria for the BED diagnosis, including whether, like anorexia nervosa and bulimia nervosa, it should be characterized by overvaluation of shape/weight. The authors compared features of eating disorders, psychological distress, and weight among overweight BED participants who overvalue their shape/weight (n = 92), BED participants with subclinical levels of overvaluation (n = 73), and participants in an overweight comparison group without BED (n = 45). BED participants categorized with clinical overvaluation reported greater eating-related psychopathology and depression levels than those with subclinical overvaluation. Both BED groups reported greater overall eating pathology and depression levels than the overweight comparison group. Group differences existed despite similar levels of overweight across the 3 groups, as well as when controlling for group differences in depression levels. These findings provide further support for the research diagnostic construct and make a case for the importance of shape/weight overvaluation as a diagnostic specifier. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Morbidity of DSM-IV Axis I disorders in patients with noncardiac chest pain: Psychiatric morbidity linked with increased pain and health care utilization.

The present study examined current and lifetime psychiatric morbidity, chest pain, and health care utilization in 229 patients with noncardiac chest pain (NCCP), angina-like pain in the absence of cardiac etiology. Diagnostic interview findings based on the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) revealed a psychiatrically heterogeneous sample of whom 44% had a current Axis I psychiatric disorder. A total of 41% were diagnosed with a current anxiety disorder, and 13% were diagnosed with a mood disorder. Overall, 75% of patients had an Axis I clinical or subclinical disorder. Lifetime diagnoses of anxiety (55%) and mood disorders (44%) were also prevalent, including major depressive disorder (41%), social phobia (25%), and panic disorder (22%). Patients with an Axis I disorder reported more frequent and more painful chest pain compared with those without an Axis I disorder. Presence of an Axis I disorder was associated with increased life interference and health care utilization. Findings reveal that varied DSM-IV Axis I psychiatric disorders are prevalent among patients with NCCP, and this psychiatric morbidity is associated with a less favorable NCCP presentation. Implications for early identification of psychiatric disorders are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An Experimental Study of Friction and Durability of a Thin PTFE Film on Rough Aluminum Substrates

Frictional and durability characteristics of 1-µm-thick polytetrafluoroethylene (PTFE) films deposited by hot filament chemical vapor deposition on aluminum substrates were investigated. A universal microtribotester was used to examine the frictional and durability properties using the ball-on-plate and ball-on-disk configurations, respectively. Effects of normal force (2.5, 5, 10, 15 N), sliding speed (0.1, 1, 5 mm/s), and surface roughness of the aluminum substrate (R_a = 0.01, 0.57, 1.28, 2.34 µm) on the coefficient of friction (COF) and the effects of normal force (2.5, 5 N), sliding speed (0.42, 4.19 mm/s), and surface roughness on the durability were investigated. It was shown that the COF of the PTFE-coated interface increases with increasing surface roughness or sliding speed. The COF depends on the normal force to a lesser extent than the other two parameters. The medium-level, O(0.5 µm), roughness of the substrate provides the longest durability, whereas the smoothest or very rough surface provides shorter durability. Analysis of variance (ANOVA) indicates that the surface roughness has the most significant effect on the COF and durability. In the case of a smooth interface, a relationship between COF, sliding speed, and normal force can be predicted. Results indicate an optimal surface roughness for improving durability.     

Agricultural landscape structure and invasive species: the cost-effective level of crop field clustering

Invasive pests in agricultural settings may have severe consequences for agricultural production, reducing yields and the value of crops. Once an invader population has established, controlling it tends to be very expensive. Therefore, when the potential impacts on production may be great, protection against initial establishment is often perceived to be the most cost-effective measure. Increasing attention in the ecological literature is being given to the possibility of curbing invasion processes by manipulating the field and cropping patterns in agricultural landscapes, so that they are less conducive to the spread of pests. However, the economic implications of such interventions have received far less attention. This paper uses a stochastic spatial model to identify the key processes that influence the vulnerability of a fragmented agricultural landscape to pests. We explore the interaction between the divergent forces of ecological invasion pressure and economic returns to scale, in relation to the level of clustering of crop fields. Results show that the most cost-effective distances between crop fields in terms of reducing food production impacts from an invasive pest are determined by a delicate balance of these two forces and depend on the values of the ecological and economic parameters involved. If agricultural productivity declines slowly with increasing distance between fields and the dispersal range of the potential invader is high, manipulation of cropping structure has the potential to protect against invasion outbreaks and the farmer can gain benefit overall from maintaining greater distances between fields of similar crops.     

NERD—middleware for IoT human machine interfaces

Industrial control systems (ICS), such as smart grid systems, are frequently composed of hundreds of devices distributed over a large geographic area. While mobile applications have been used with good success in managing ICSs, traditional methods of distributing applications (e.g., app stores) are not well suited to the task of discovering, distributing, and building human machine interfaces (HMIs) for ICS, as the highly individualized and often proprietary individual components of ICSs have vastly different interfaces leading to a need to download hundreds of applications. We propose the No Effort Rapid Development (NERD) middleware framework to address the challenges of in-field HMI discovery, provisioning, communication, and co-evolution with related ICSs. Middleware services offer the ability to simplify on-demand HMI distribution and operation of ICSs. NERD leverages existing ICS device-markers (e.g., QR-codes or RFID tags) or Bluetooth low-energy protocols for rapid cyber-physical discovery and provisioning of HMIs in the field. Device-markers and Bluetooth low-energy protocols have a very limited data capacity and transmission speed, and to achieve on-device storage of HMIs, we propose using a compact data-driven domain-specific language that emphasizes data sources and sinks between the HMI and IC.     

Two-dimensional localization with a single diffuse ultrasound field excitation

Traditional ultrasound imaging methods rely on the bandwidth and center frequency of transduction to achieve axial and radial image resolution, respectively. In this study, a new modality for spatially localizing scattering targets in a two-dimensional field is presented. In this method, the bandwidth of field excitation is high, and the center frequency is lowered such that the corresponding wavelengths are substantially larger than the target profiles. Furthermore, full two-dimensional field measurements are obtained with single send-receive sequences, demonstrating a substantial simplification of the traditional scanning techniques. Field reconstruction is based on temporal-spectral cross-correlations between measured backscatter data and a library of region of interest (ROI) backscatter data measured a priori. The transducer design is based upon a wedge-shaped geometry, which was shown to yield spatially frequency-separated bandwidths of up to 156% with center frequencies of 1.38 MHz. Initial results with these send-and-receive transducer parameters and cylindrical reflection targets in a 10-mm x 10-mm ROI demonstrate two-dimensional target localization to within 0.5 mm. Spatial localization of point scatterers is demonstrated for single and multiple scattering sites.     

The role of nitric oxide on matrix metalloproteinase 2 (MMP2) and MMP9 in placenta and fetus from diabetic rats

Matrix metalloproteinases (MMPs) play an important role in tissue remodeling that accompanies the rapid growth, differentiation, and structural changes of the placenta and several fetal organs. In the present study, we investigated whether the diabetic maternal environment may alter the regulatory homeostasis exerted by nitric oxide (NO) on MMPs activity in the feto-placental unit from rats at midgestation. We found that NADPH-diaphorase activity, which reflects the distribution and activity of NO synthases (NOS), was increased in both placenta and fetuses from diabetic rats when compared with controls. In addition, while a NO donor enhanced MMP2 and MMP9 activities, a NOS inhibitor reduced these activities in the maternal side of the placenta from control rats. This regulatory effect of NO was only observed on MMP9 in the diabetic group. On the other hand, the NO donor did not modify MMP2 and MMP9 activities, while the NOS inhibitor reduced MMP9 activity in the fetal side of both control and diabetic placentas. In the fetuses, MMP2 was enhanced by the NO donor and reduced by the NO inhibitor in both fetuses from control and diabetic rats. Overall, this study demonstrates that NO is able to modulate the activation of MMPs in the feto-placental unit, and provides supportive evidence that increased NOS activity leads to NO overproduction in the feto-placental unit from diabetic rats, an alteration closely related to the observed MMPs dysregulation that may have profound implications in the formation and function of the placenta and the fetal organs.