State of the art on Timber Concrete Composite floor

Interest in timber-concrete composite (TCC) floors has increased over the last 20-30 years. Since the 1990âs, TCC solution is seen as a viable and effective alternative to conventional reinforced concrete and/or traditional timber floors in multistorey buildings. In TCC technology, a timber beam, either solid wood, glued laminated or laminated veneer lumber (LVL), is connected to a concrete slab using a connection system that resists shear forces and impedes slip between the members of the composite section. The strength, stiffness, location and number of connectors play a crucial role for the composite action and determine the structural and serviceability performance of the floor system. This paper discusses the state of the art of TCC structures. It presents a comprehensive review of the literature about the development and structural behaviour of TCC structures. The review addresses construction aspects and shear connection concepts. It evaluates experimental tests, finite element and numerical models. It discusses the influence of concrete elements. As recommendations, the best types of shear connection for cast in-situ and prefabricated TCC floors are put forward and assessed for criteria such as strength, stiffness, ductility and ease of manufacturing. Furthermore the most relevant numerical models are introduced. These models can be used to further the experimental results in parameters such as connections, configurations, geometrical and material properties

The predictive model for strength of inclined screws as shear connection in timber-concrete composite floor

Interest in timber-concrete composite (TCC) floors has increased over the last 30 years. TCC technology relies on timber and concrete members acting compositely together. Both timber and concrete exhibit a quite brittle behaviour in bending/tension and compression respectively whilst the shear connection is identified as the only contributor of ductile behaviour. Therefore, the strength, stiffness and arrangement of the shear connection play a crucial role in the structural design of TCC. There are only few investigations on analytical closed-form equation to predict the stiffness and strength of TCC joints as input values to design a partially composite floor. For example, Johansen's yield theory was adopted as European yield model in Eurocode 5. However, the equations are limited to vertically inserted dowels or screws and Eurocode 5 recommends that the strength and stiffness of unconventional joints should be determined by push-out tests. Previous investigations reported that the inclined shear connector significantly increase the initial stiffness and ultimate strength of the TCC joints and consequently composite floor. This paper presents a model for the strength ofTCC joint using crossed (±45°) proprietary screws (SFS Intec). The Johansen yield theory is extended to derive the strenght model of TCC joint with crossed (±45°) screws which are loaded in tension and compression. The model is an upper bound plastic collapse model that assumes the behaviour of timber and screw perfectly plastic with undamaged concrete. The failure modes considers of yield of screw, in tension or shear, and some combined modes assuming screw withdrawal, lateral crushing of the timber and the development of plastic hinges in the screw. The experimental aspect of the research consists of push-out tests and aims to verify the strength model of TCC joints with inclined screws. The failure modes are also investigated. The model seems to be reasonably accurate in predicting both the characteristic strength and failure mode. This research suggests the model to facilitate the design of inclined screw shear connections for TCC construction. © 2013 Taylor & Francis Group

Traffic Stop Practices of the Iowa City Police Department: January 1 – December 31, 2002

This report summarizes the findings of a study conducted using data collected by the Iowa City Police Department between January 1 and December 31, 2002. These data resulted from 13,459 interactions between law enforcement officers and citizens during traffic-related contacts. Information was collected about the driver, the officer, and the stop event. Driver demographics included race, sex, age, residency, and vehicle registration. The only information collected about the officer was officer badge number. Finally, data collected about the stop event include the date, time of day, reason for stop, search, property seized, force, and outcome of the stop. Data analysis was conducted with the aid of SPSS-11.0 (Statistical Package for the Social Sciences). Analyses were conducted on two levels. First, descriptive analysis, using percentages, summarized stop patterns, stop characteristics, and driver demographics. Second, a program called “chisquare automatic interaction detector” or CHAID was used to evaluate the variables in terms of their relationships with one another (multivariate analysis). The greatest percentage of stops was made in the month of March (10.1%), with the fewest in June and December (6.9%). Interestingly, nearly 32% of stops occurred between midnight and 3am, with the third shift (11pm-7am) responsible for the greatest percentage (44.2%). Stopped drivers were mostly White (84%), male (63%), young (median age of 23), Iowa City residents (62%), with Iowa vehicle registrations (88%). Drivers were mainly stopped for moving violations (70%), were not searched (96%), and were released with a warning (58%). Descriptive statistics are included for a general view of the stop event and characteristics. Multivariate CHAID analyses were conducted to make inferences about the relationships among variables. CHAID segments the sample of traffic stops and reveals the interrelationship between the potential predictors and the events involved in the stop. The CHAID procedure generates a “decision tree” that identifies significant predictors of each decision in question. In effect, the procedure “crossreferences” each event with each potential predictor. Results from CHAID analyses resulted in four events (moving violation, equipment/registration violation, being warned, being arrested) with significant predictors. All four events were significantly related to the age of the driver, although different age groupings surfaced in different stop events. In addition, the sex of the driver (being male) appeared as a second order predictor in being arrested. Race of the driver never appeared as a predictor of any event. These data provide no empirical evidence that the ICPD is systematically engaging in discriminatory stop practices. Stops conducted by the Iowa City Police Department, as a whole, during the study period, do not involve the race of the driver as a significant factor related to events and outcomes. This does not mean, however, that no individual citizen ever experienced discrimination. It is always possible that individual officers may engage in racially biased practices, both in determining which drivers they will or will not stop and in determining what steps to take after the initial contact. To detect discriminatory practices at this level, however, requires constant vigilance by the community, by all the officers within the department, and by the departmental administration. Statistical analysis, while valuable, cannot substitute for community involvement and effective management. The full report notes some minor inconsistencies with the data, provides a discussion of the “baseline dilemma,” makes recommendations for the continued collection of data for future trend analysis, and suggests modifications of the data collection instrument to include more variables and to clarify some possible areas of confusion for officers who are collecting the data

Educational Intervention Improves Proton Pump Inhibitor Stewardship in Outpatient Gastroenterology Clinics

Background Improper chronic proton pump inhibitor (PPI) use has risen significantly in the last few decades. In our gastroenterology trainees’ clinics, we aimed to optimize PPI usage. Methods We collected baseline data on patients’ PPI use for 8 weeks. Based on gastroenterology society guidelines, we determined conditions for appropriate PPI use. If the indication could not be determined, it was categorized as “unknown”. Generated from the three most frequent causes for inappropriate PPI use, interventions were developed to correct each issue. Following a brief educational session, trainees implemented these interventions over a subsequent 8-week interval. Results During our pre-intervention period, trainees evaluated 263 patients who were prescribed a PPI. In 49% of the cases, the use of PPI was deemed inappropriate. The most common reasons were: gastroesophageal reflux disease (GERD) which was never titrated to the lowest effective dose, twice daily dosing for Barrett’s esophagus (BE) chemoprevention and unknown indication. During our intervention period, trainees evaluated 145 patients prescribed a PPI for GERD with well-controlled symptoms in 101 cases. PPI had not been titrated to lowest effective dose in 37 cases prompting intervention which was successful in 23 cases. PPI indication was unknown in 17 cases prompting a message to the prescribing provider to review appropriateness. Two cases of BE chemoprevention with twice daily dosing were appropriately reduced to daily dosing. Ultimately, after intervention, PPI use was deemed appropriate after intervention in 172 (77%) cases. Conclusions Improper chronic PPI use was significant. Focusing intervention efforts on PPI use for GERD, BE and unknown indications substantially increased appropriateness of PPI use

Traffic Stop Practices of the Louisville Police Department: January 15 - December 31, 2001

This report summarizes the findings of a study conducted using data collected by the Louisville Division of Police between January 15, 2001 and December 31, 2001. These data resulted from 48,586 interactions between law enforcement officers and citizens during traffic-related contacts. Information was collected about the driver, the officer, and the stop event. Driver demographics included race, sex, age, residency, license number, and vehicle registration. The only information collected about the officer was officer badge number. Finally, data collected about the stop event include the date, time of day, reason for stop, activities during the stop, number of passengers, and stop outcome. Data analysis was conducted with the aid of SPSS-11.0 (Statistical Package for the Social Sciences). Analyses were conducted on two levels. First, descriptive analysis, using percentages, summarized stop patterns, stop characteristics, and driver demographics. This information is useful only to describe the existing state of affairs (what is), but not to explain them (why) or to formulate predictions about future events (what if). To address the complex relationships that exist among different variables, a program called chi-square automatic interaction detector or CHAID was used to evaluate the variables in terms of their relationships with one another (multivariate analysis). Temporally, it was not feasible to determine which month was the most active given several problems with the data on this variable. The most active time of day for stops was between 5-6pm, with 7.4% of all stops, followed by the time period from 4-5pm with 6.7% of all stops. Overall, the 2nd shift (3-11pm) was the most active, with 46% of all stops, followed by the 3rd shift (30%), and the 1st shift (24%). Stopped drivers were mostly white (64%), male (70%), between 24 and 40 years old (46%), and Louisville residents (63%). Drivers were mainly stopped for penal code violations (67%), were checked for outstanding warrants (78%), were not searched (84%), and were issued citations (67%). Drivers who were searched (17%) were searched incident to arrest (52%), and by consent (40%). About 1 in 5 searches (19%) were because of the odor of drugs or alcohol. Contraband was discovered in 31% of searches. In cases where there was a search and contraband was discovered, 74% resulted in an arrest. The descriptive analysis indicated some slight percentage differences among the races in certain events (e.g., stopped for equipment/registration violations). These percentage differences, however, cannot be used to infer correlation or causation (racial profiling). To make these types of inferences, multivariate analyses using CHAID were conducted. CHAID segments the sample of traffic stops and reveals the interrelationship between the potential predictors and the events involved in the stop. The CHAID procedure generates a decision tree that identifies significant predictors of each decision in question. In effect, the procedure cross-references each event with each potential predictor. Results from CHAID analyses resulted in five events (violation of the penal code, being asked to exit, being searched, being subject to a warrant check, and being arrested) with significant predictors. Being stopped for a penal code violation was significantly related to the race of the driver; other persons of color (72%) and whites (69%) were most likely to be stopped for this reason. Age, however, had a strong interactive effect with race. Being asked to exit, being searched, being subject to a warrant check, and being arrested all were predicted by being stopped for a misdemeanor. Driver sex also surfaced as a predictor in some situations. These data provide no empirical evidence that the LPD is systematically engaging in discriminatory stop practices. In general, stops conducted by the department, as a whole, during the study period, do not involve the race of the driver as a significant factor related to events and outcomes. The only exception to this involves stops for penal code violations, where other persons of color and whites were most likely stopped for this reason. These types of stops involve fairly low levels of officer discretion given that penal code violations are more serious than other reasons for which a driver might be stopped. This does not mean, however, that no individual citizen ever experienced discrimination. It is always possible that individual officers may engage in racially biased practices, both in determining which drivers they will or will not stop and in determining what steps to take after the initial contact. To detect discriminatory practices at this level, however, requires constant vigilance by the community, by all the officers within the department, and by the departmental administration. Statistical analysis, while valuable, cannot substitute for community involvement and effective management. The full report provides a discussion of the baseline dilemmaand makes recommendations for continued study to obtain a full year of data

Adolescent Intermittent ethanol exposure enhances ethanol activation of the nucleus accumbens while blunting the prefrontal cortex responses in adult rat

The brain continues to develop through adolescence when excessive alcohol consumption is prevalent in humans. We hypothesized that binge drinking doses of ethanol during adolescence will cause changes in brain ethanol responses that persist into adulthood. To test this hypothesis Wistar rats were treated with an adolescent intermittent ethanol (AIE; 5 g/kg, i.g. 2 days on–2 days off; P25–P54) model of underage drinking followed by 25 days of abstinence during maturation to young adulthood (P80). Using markers of neuronal activation c-Fos, EGR1, and phophorylated extracellar signal regulated kinase (pERK1/2), adult responses to a moderate and binge drinking ethanol challenge, e.g., 2 or 4 g/kg, were determined. Adult rats showed dose dependent increases in neuronal activation markers in multiple brain regions during ethanol challenge. Brain regional responses correlated are consistent with anatomical connections. AIE led to marked decreases in adult ethanol PFC (prefrontal cortex) and blunted responses in the amygdala. Binge drinking doses led to the nucleus accumbens (NAc) activation that correlated with the ventral tegmental area (VTA) activation. In contrast to other brain regions, AIE enhanced the adult NAc response to binge drinking doses. These studies suggest that adolescent alcohol exposure causes long-lasting changes in brain responses to alcohol that persist into adulthood

Dealing with False Memories in Children and Adults: Recommendations for the Legal Arena

Children are often viewed as poor eyewitnesses. Fact-finders, lawyers, and researchers assume that children are exceptionally prone to accept external suggestive (leading) questions and to create false memories. Is this assumption justified? This review will show it is not. First, studies on spontaneous false memories— elicited without any suggestive pressure—reveal that children are less likely than adults to produce them. Second, under certain circumstances, children are even less prone to accept external suggestions than adults. This counterintuitive finding happens when false suggestions contain information that is associatively related but in actuality not experienced by children or adults. Using empirically-based interview protocols can maximize the retrieval of accurate memories in children and adults. Furthermore, expert witnesses should use alternative scenarios in order to better evaluate whether statements by children or adults are based on truth or fiction

Adolescent binge drinking increases expression of the danger signal receptor agonist HMGB1 and toll-like receptors in the adult prefrontal cortex

Adolescence is a critical developmental stage of life during which the prefrontal cortex (PFC) matures, and binge drinking and alcohol abuse are common. Recent studies have found that ethanol increases neuroinflammation via upregulated high-mobility group box 1 (HMGB1) signaling through Toll-like receptors (TLRs). HMGB1/TLR ‘danger signaling’ induces multiple brain innate immune genes that could alter brain function. To determine whether adolescent binge drinking persistently increases innate immune gene expression in the PFC, rats (P25–P55) were exposed to adolescent intermittent ethanol (AIE [5.0 g/kg, 2-day on/2-day off schedule]). On P56, HMGB1/TLR danger signaling was assessed using immunohistochemistry (i.e., +immunoreactivity [+IR]). In a separate group of subjects, spatial and reversal learning on the Barnes maze was assessed in early adulthood (P64–P75), and HMGB1/TLR danger signaling was measured using immunohistochemistry for +IR and RT-PCR for mRNA in adulthood (P80). Immunohistochemical assessment at P56 and 24 days later at P80 revealed increased frontal cortical HMGB1, TLR4, and TLR3 in the AIE-treated rats. Adolescent intermittent ethanol treatment did not alter adult spatial learning on the Barnes maze, but did cause reversal learning deficits and increased perseverative behavior. Barnes maze deficits correlated with the expression of danger signal receptors in the PFC. Taken together, these findings provide evidence that adolescent binge drinking leads to persistent upregulation of innate immune danger signaling in the adult PFC that correlates with adult neurocognitive dysfunction

Induction of innate immune genes in brain create the neurobiology of addiction

Addiction occurs through repeated abuse of drugs that progressively reduce behavioral control and cognitive flexibility while increasing limbic negative emotion. Recent discoveries indicate neuroimmune signaling underlies addiction and co-morbid depression. Low threshold microglia undergo progressive stages of innate immune activation involving astrocytes and neurons with repeated drug abuse, stress, and/or cell damage signals. Increased brain NF-κB transcription of proinflammatory chemokines, cytokines, oxidases, proteases, TLR and other genes create loops amplifying NF-κB transcription and innate immune target gene expression. Human post-mortem alcoholic brain has increased NF-κB and NF-κB target gene message, increased microglial markers and chemokine-MCP1. Polymorphisms of human NF-κB1 and other innate immune genes contribute to genetic risk for alcoholism. Animal transgenic and genetic studies link NF-κB innate immune gene expression to alcohol drinking. Human drug addicts show deficits in behavioral flexibility modeled pre-clinically using reversal learning. Binge alcohol, chronic cocaine, and lesions link addiction neurobiology to frontal cortex, neuroimmune signaling and loss of behavioral flexibility. Addiction also involves increasing limbic negative emotion and depression-like behavior that is reflected in hippocampal neurogenesis. Innate immune activation parallels loss of neurogenesis and increased depression-like behavior. Protection against loss of neurogenesis and negative affect by anti-oxidant, anti-inflammatory, anti-depressant, opiate antagonist and abstinence from ethanol dependence link limbic affect to changes in innate immune signaling. The hypothesis that innate immune gene induction underlies addiction and affective disorders creates new targets for therapy