A study of thin film vacuum deposited junctions Annual status report, 5 Dec. 1965 - 5 Dec. 1966

Mechanisms of charge carrier mobility in thin polycrystalline film junction

Early Learning and School Readiness: Can Early Intervention Make a Difference?

Children’s experiences prior to kindergarten entry are correlated with degree of cognitive development and school readiness as measured by standardized assessments of cognitive and linguistic performance. Children from economically poor and undereducated families are at elevated risk for lack of school readiness due to less knowledge and skill. This article reviews evidence from randomized controlled trials (RCTs) that were designed to test the hypothesis that preschool education, with an emphasis on seven particular classes of experiences, could be efficacious in improving readiness for school and subsequent academic achievement in reading and mathematics. Results indicate that the cumulative developmental toll that is measured reliably in high-risk samples of children beginning in the second year of life can be substantially reduced through a high-quality preschool program. This positive effect has been replicated in nine additional trials using RCT methodology. Additionally, long-term follow-up of the original study participants indicates not only improved performance in reading and mathematics in elementary and secondary school but also a reduction in special education placement and grade retention, among other practical benefits. Results are discussed with respect to public policy recommendations and suggestions for future research

The thin film microwave iris

Development of waveguide iris for microwave coupling applications using thin film techniques is discussed. Production process and installation of iris are described. Iris improves power transmission properties of waveguide window

The effects humidity & temperature has on DNA contamination during storage

Studies have been conducted on DNA cross-contamination throughout the criminal investigation process in order to evaluation the possibility that DNA from one sample could potentially influence the outcome of another. However, no published studies have examined the potential for contamination during the storage of genetic evidence after samples have been taken from crime scenes or suspects. This study is a continuation of a preliminary project, which examined storage drying time in relation to cross-contamination. The current study tested temperature and humidity for the potential of cross-contamination during storage prior to extraction. Prior to storage, 50 μl of male saliva was aliquoted to buccal swabs and then dried for 20 minutes in a Dry-Fast swab dryer. Each variable tested consisted of five buccal swabs that were introduced to DNA and five swabs that remained unopened, in order to see if the male DNA could then be detected on the unopened swabs. Cross-contamination was not detected below 8 °C or 35% relative humidity. Any DNA that was detected was unable to produce a STR profile either as result of nonspecific amplification or extremely low levels of DNA, suggesting that if it did move, it was not enough DNA to alter results. However, further research is needed to determine if higher levels of humidity impact the movement of DNA

DNA integrity in forensic samples

When packaged genetic evidence samples are stored in close proximity, there is a higher chance for cross-contamination, which can lead to potential false results. The goal of this study was to test DNA storage methods and environments to determine the best way to avoid potential cross-contamination. Established protocols for storing different types of genetic evidence samples were evaluated: biological swabs and DNA cards. A known concentration of pig DNA was introduced to the evidence samples. Three different evidence drying times of the DNA-free swabs and cards were implemented before packaging: immediate packaging, an hour drying, and 24 hours drying. The samples were then placed in the evidence envelopes in one of two ways. The first was with a DNA carrying swab/card in an envelope next to a non-DNA carrying swab/card in a separate envelope. The second was with two swabs/cards in the same envelope, one carrying DNA and the other not. The three drying methods and two packaging methods were completed in triplicate. A control sample of a non-DNA carrying sample was also included for both packaging techniques. The samples were placed into room temperature storage and aligned next to each other for different intervals: 72 hours, two weeks, and two months. Once the sample exposed to DNA was removed from storage, DNA analysis was completed to determine if cross-contamination occurred on the blank sample at the same time. DNA can be a vital piece of evidence in a court of law, therefore the integrity of the DNA is important. If cross-contamination occurs during storage, then the integrity of the evidence becomes jeopardized. Not only does cross-contamination render the genetic evidence problematic; but if left undetected, it has the potential to link an individual to a case they were not actually associated with, or render a genetic profile contaminated and unusable. Either scenario is not ideal and can be detrimental to individual’s lives and the judicial system. If storage methods can cause evidence contamination, then new ways to preserve the integrity of evidence must be analyzed. Cross-contamination is a rising problem throughout all aspects of a case. Prior studies have found cross-contamination occurring during collection and transportation due to materials or procedures (Fonneløp et al., 2016; Basset and Castella, 2018). Little prior research focused on contamination occurring during storage. This paper will impact the forensic science community by introducing the need for strict regulation and procedures for genetic evidence storage due to the potential of evidence cross-contamination

DNA integrity in forensic samples

DNA can be a vital piece of evidence in a court of law; therefore, the integrity of the DNA is essential. If cross-contamination occurs during storage, then the integrity of the evidence becomes jeopardized. Not only does cross-contamination render the genetic evidence problematic, but if left undetected, it has the potential to link an individual to a case they were not previously associated with or compromise DNA what is associated with a case so that it is unusable. Either scenario is not ideal, and every step should be taken to avoid such a situation. The goal of this project is to test DNA storage methods and environments to determine the best way to avoid potential cross-contamination. Known protocols for storing different types of genetic evidence samples are evaluated. When packaged genetic evidence samples are stored in close proximity to one another, there is a higher chance for cross-contamination. Studies have been conducted on cross-contamination throughout the investigation process. However, no published studies have examined the potential for contamination during the storage process. This study tested two DNA collection methods for the potential of cross-contamination during storage. Three different dry times of buccal swabs and Whatman cards were tested: none, one hour and 24 hours, in triplicate, and then placed into storage with an uncontaminated sample for one of the following times: 72 hours, 14 days, or 45 days. Cross-contamination was detected in the 72 hours and 45 days blank samples. There was no detection of cross-contamination in any of the blank 14 days samples. The statistics revealed there is a statistical significance for the storage time but not dry time. The fisher exact test yielded a 0.00 p-value (α = 0.05) for the Whatman card, while the buccal swabs yielded a 0.054 p-value (α = 0.05). Cross-contamination was detected upon removal from storage demonstrating that further research is needed to better understand cross-contamination during storage

A study of thin film vacuum deposited junctions Annual status report, Dec. 5, 1964 - Dec. 5, 1965

Thin film vacuum deposition semiconductors, electron tunneling devices, and field effect transistor

Application of thin films extremely high frequencies

The use of thin film irises to control the beam direction from an array of microwave horns is discussed. The phenomenon is based on the finite transmission of electromagnetic energy through thin films. Diagrams of characteristic waveguides and numerical analyses of the irises are presented

A Study of Thin Film Vacuum Deposited Junctions Semiannual Status Report, Dec. 5, 1965 - Jun. 5, 1966

Thin film vacuum deposited junction

A study of thin film vacuum deposited junctions semiannual status report, 5 dec. 1964 - 5 jun. 1965

Effects of surface states and grain boundaries on free carrier concentration, mobility, and free path of charge carriers in thin films - Design and fabrication of thin film electronic device