USB-C to 3.5mm adapter with PCB in audio jack

Traditional USB-C to 3.5mm adapters are provided for use with smartphones and other devices that do not include a 3.5mm audio jack. Such adapters have several problems that can impact user experience. Examples of the problems in current adapters include vulnerability to RF radiation interferences, desensitization of the cellular receiver in the phone, co-existence, antenna detune effect, etc. This disclosure describes an improved design of a USB-C to 3.5mm adapter. In the design, the USB-C PCB is moved away from the device end to make it less vulnerable to the radiations from the device. The techniques further include propose use of a braided cable between the main PCB and the USB-C plug to shield from noise coupling. Signals along the wires from USB-C plug to audio jack are either power or digital and are robust in the presence of noise sources. Further, only USB signals run from USB-C plug side to the audio jack, eliminating the need to twist the microphone signal with the ground signal

Understanding High School Assistant Principals’ Perspective of Standardized Testing Policy for English Language Learners in Maryland

Given federal and state mandates, school administrators in the United States are often held responsible for enacting standardized testing policies in their school settings. Standardized testing requirements apply for all students attending school including ELL (English Language Learner) students. However, a review of the literature finds that standardized testing for ELL students is problematic when schools interpret testing scores as some indication of content knowledge mastery. At the current time, content-area standardized testing policies and practices in public schools are not consistent with what we know about second language development. What is missing in the existing research is an examination of school administrator perspective on the standardized testing policies that they are responsible for when the students are English Language Learners. This study adopts a qualitative case study framework to examine the perspectives of high school assistant principals in a single Maryland school district. The following research question guided the data collection and data analysis: How do high school assistant principals in a large Maryland suburban county perceive standardized testing policy implemented for ELLs? Data collection involved semi-structured interviews with high school assistant principals in a single case study Maryland district. Subsequent data analysis involved coding interview data from transcription to identify overarching themes. The findings of the study were in two parts: experiential dimension and perspective dimension. For the experiential dimension, the analysis found that despite the variety of experiences as assistant principals in diverse locations, their understanding of standardized testing policies was uniform. Next for the perspective dimension, the analysis found that current standardized testing policies for English Language Learners did not achieve the intended goals. The findings of this study have important implications for the theoretical study of educational leadership and for the everyday lived experiences of school administrators in K-12 schools. The study yielded a recommendation for assistant principals to balance the need for additional standardized testing and the loss of instructional time. The study also provided recommendations for future research. This included broader research into the experiences of other standardized testing policy implementers and their perception of current testing policies for English Language Learners

Microencapsulation of imidazole curing agent by solvent evaporation method using W/O/W emulsion

The epoxy–imidazole resin system is used to form the anisotropic conducting film. The latent character of the system is very significant. In this study, imidazole (Im) or 2‐methylimidazole (2MI) was encapsulated for the latent curing system to use in the reaction of epoxy resin. Polycaprolactone was used as a wall material, and the solvent evaporation method was used to form the microcapsule using W/O/W emulsion. The shelf life of the microcapsules was studied for the epoxy resin, and the curing behavior of the microcapsules for epoxy resin was examined using a differential scanning calorimeter. The curing times at 150 and 180°C were estimated using an indentation method. The microcapsules of Im or 2MI exhibited a long shelf life for epoxy resin. When comparing the results of the previous methods with the results of this study using the W/O/W emulsion, finer microcapsules were formed and the microcapsule has longer shelf life. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98341/1/38767_ftp.pd

Exploring Factors That Influence Students’ Behaviors in Information Security

Due to the ever-increasing use of the Internet, information security has become a critical issue in society. This is especially the case for young adults who have different attitudes towards information security practices. In this research, we examine factors that motivate college students’ information security behaviors. Based on the concept of fear arousal in the presence of a threatened event, a well-founded theory known as Protection Motivation Theory (PMT) is adopted in the research model. Social norms and habit factors are integrated to the model as a means to assess students’ behaviors of information security. A survey of 202 responses is used to test the designed model using structural equation modeling to analyze relationships among variables. Results indicated that students are very motivated to practice information security if they perceive high levels of severity, response efficacy, response costs and self-efficacy. Their intentions, however, are not affected by perceived vulnerability or by social influence. Our findings suggest that PMT is a valuable model for predicting students’ attitudes towards information security and that their motivation is influenced by education in security awareness and understanding severity of such issues

Elucidating the mechanisms behind pre-breakdown phenomena in transformer oil systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 321-334).The widespread use of dielectric liquids for high voltage insulation and power apparatus cooling is due to their greater electrical breakdown strength and thermal conductivity than gaseous insulators. In addition, their ability to conform to complex geometries and self-heal means that they are often of more practical use than solid insulators. Unfortunately, as with all insulation, the failure of the liquid insulation can cause catastrophic damage. This has led researchers to study the insulating properties of dielectric liquids in an attempt to understand the underlying mechanisms that precede electrical breakdown in order to prevent them. This thesis develops a set of mathematical models which contain the physics to elucidate the pre-breakdown phenomena in transformer oil and other oil-based systems. The models are solved numerically using the finite element software package COMSOL Multiphysics. For transformer oil, the results show that transformer oil stressed by a positively charged needle electrode results in the ionization of oil molecules into positive ions and electrons. The highly mobile electrons are swept back towards the positive electrode leaving a net positive space charge region that propagates towards the negative electrode causing the maximum electric field to move further into the oil bulk. It is the moving electric field and space charge waves that allow ionization to occur further into the oil. This leads to thermal dissipation and creates a low density streamer channel. In comparing the numerical results to experimental data found in the literature, the results indicate that positive streamer propagation velocity regimes or modes are dictated by the onset of different ionization mechanisms (i.e., field ionization, impact ionization, photoionization) that are dependent on the liquid molecular structure and the applied voltage stress. In particular, the field ionization of different families of molecules plays a major role in development of slow and fast mode streamers, especially in liquids that are comprised of many different types of molecules such as transformer oil. The key characteristics of the molecules that affect streamer propagation are their molecular structure (i.e., packing, density, and separation distance) and ionization potential. A direct outcome of this work has been the ability to show that by adding low ionization potential additives to pure dielectric liquids, the voltage at which streamers transition from slow to fast mode can be significantly increased, a result counter-intuitive to conventional wisdom and common practice. For transformer oil with nanoparticle suspensions (nanofluids), the effects of nanoparticle charging on streamer development have been thoroughly investigated. The charging dynamics of a nanoparticle in transformer oil show that electron trapping by conductive nanoparticles is the cause of a decrease in positive streamer velocity. resulting in higher electrical breakdown strength for transformer oil-based nanofluids. Further generalized analysis of the charging of a perfectly conducting sphere from a single charge carrier or two charge carriers of opposite polarity, with different values of volume charge density and mobility and including an ohmic lossy dielectric region surrounding a perfectly conducting sphere or cylinder are also examined. Streamer development in liquid-solid insulation systems, such as oil-pressboard systems, is also investigated. Great effort has been undertaken to model the solid insulation region and a method has been developed to model the oil-solid interface to account for surface charge build up, which is important for streamer dynamics. Various ohmic and migration conduction laws are used for oil and solid insulation to solve for the time and space development of surface charge distributions in closed form for one-dimensional parallel plane and numerically for two-dimensional geometries. The work on streamers in oil-pressboard systems has shown that streamers are attracted to the oil-pressboard interface, due to the larger permittivity of the pressboard. Moreover, the models have shown that the determination of how streamers propagate in the presence of solid insulation is strongly dependent on the extent to which the solid insulation alters the streamer shape and the electric field created by the streamer's space charge. These results obtained from the modeling of streamers in oil-pressboard systems are supported by and help to explain the experimental data in the literature.by Jae-Won George Hwang.Ph.D

High-resolution crystal structure of the non-specific lipid-transfer protein from maize seedlings

AbstractBackground: The movement of lipids between membranes is aided by lipid-transfer proteins (LTPs). Some LTPs exhibit broad specificity, transferring many classes of lipids, and are termed non-specific LTPs (ns-LTPs). Despite their apparently similar mode of action, no sequence homology exists between mammalian and plant ns-LTPs and no three-dimensional structure has been reported for any plant ns-LTP.Results We have determined the crystal structure of ns-LTP from maize seedlings by multiple isomorphous replacement and refined the structure to 1.9 å resolution. The protein comprises a single compact domain with four α-helices and a long C-terminal region. The eight conserved cysteines form four disulfide bridges (assigned as Cys4–Cys52, Cys14–Cys29, Cys30–Cys75, and Cys50–Cys89) resolving the ambiguity that remained from the chemical determination of pairings in the homologous protein from castor bean. Two of the bonds, Cys4–Cys52 and Cys50–Cys89, differ from what would have been predicted from sequence alignment with soybean hydrophobic protein. The complex between maize ns-LTP and hexadecanoate (palmitate) has also been crystallized and its structure refined to 1.8 å resolution.Conclusion The fold of maize ns-LTP places it in a new category of all-α-type structure, first described for soybean hydrophobic protein. In the absence of a bound ligand, the protein has a tunnel-like hydrophobic cavity, which is large enough to accommodate a long fatty acyl chain. In the structure of the complex with palmitate, most of the acyl chain is buried inside this hydrophobic cavity