Evaluation of the characteristics of a field emission cathode for use in a Mercury ion trap frequency standard

The performance is reported of a field emission array characterized for the purpose of replacing the filament in a trapped ion frequency standard. This dark electron emitter eliminates the need for the interference filter currently used in the trapped ion standard. While reducing the filament's unwanted light, this filter causes a significant reduction in the signal. The magnetic field associated with the filament is also eliminated, thus potentially improving the present stability of the trapped ion standard. The operation of the filament in the present system is described, as well as the associated concerns. The cathode considered for the filament's replacement is then described along with the experimental system. Experimental results, observations, and conclusions are presented

Evaluation of frictional forces between brackets of different types at various angulations and an arch wire: With and without pulsating vibration

Objective: The objective of this study was to determine the effect of pulsating vibration on the sliding resistance between orthodontic brackets and stainless steel wires. Brackets were placed at two different angulations (0° and 5°) to simulate leveling of a tipped tooth during tooth movement. Pulsating vibration was delivered via the AcceleDent device. Background: Friction is defined as a force that retards or resists the relative motion of two objects in contact, and its direction is tangential to the common boundary of the two surfaces in contact. This has been of interest to the orthodontist since the mid-20th century. Since the time of Stoner’s paper in 1960, the orthodontic literature has been full of studies done on friction in orthodontics including: friction with different ligation methods, friction among different arch wire materials, friction and different bracket materials, and friction with various slot designs. Understanding friction has led to the emergence of new technologies in orthodontics. One of the most popular is the self-ligating bracket. This popularity arose from claims that they reduce friction during treatment. Other innovations have been introduced in the field of orthodontics to help accelerate tooth movement. Among these innovations is the application of a pulsating vibration during active orthodontic treatment. Such pulsating vibration can be delivered during orthodontic treatment by AcceleDent, which is a hands- free device designed by OrthoAccel Technologies, Inc., Bellaire, TX. The company claims the output force helps accelerate bone turnover. The following study investigated whether it could decrease treatment time via a different mechanism: decreasing frictional resistance to tooth movement along the arch wire. Methods: A paper template was made of a typodont tooth with a bracket window cut out. The bracket cut out was made with the bracket window angulated 0° and 5°. 0.022” x 0.028” standard prescription edgewise brackets (American Orthodontics, Sheboygan, WI) of ceramic, twin and self-ligating design were bonded to 3 maxillary 1st premolar typodont teeth using the template. The teeth were leveled with a 0.019” x 0.025” SS arch wire and placed in a metal scaffold. They were held in place with Aquasil Ultra XLV wash material PVS (DENTSPLY Caulk, Milford, DE.). Only the middle bracket was adjusted for angulation and accuracy was checked with the iPhone 6 level. The AcceleDent Aura device (OrthoAccel Technologies, Inc., Bellaire, TX). was attached to the occlusal surface of the teeth via cable ties. The AcceleDent Aura device provided 30 Hz of pulsating vibration. All tests were performed with a 0.019” x 0.025” SS arch wire pulled through the brackets via a Universal Testing Machine (Instron, Grove City, PA) at a crosshead speed of 2.5mm/min for 30 seconds. Frictional resistance was measured by averaging 6 recordings every 5 seconds. Results: The pulsating vibration provided by the AcceleDent device significantly reduced the resistance to sliding for each bracket type at both 0° and 5° (p\u3c0.05). Ceramic brackets had the highest resistance to sliding of all bracket types. Conclusions: Pulsating vibration via the AcceleDent Aura device reduces the resistance to sliding between a bracket and arch wire in vitro. This may potentially decrease overall treatment time but more in vivo studies need to be done to evaluate this

The Role of SERCA in Neural Development and Brain Tumors

Ion channels are essential for neural function, playing a variety of necessary cellular roles including excitability, maintaining ion gradients, and volume control. While the role of ion channels in neurons is well-defined, much less is known about excitability in neural progenitor cells. Recently it has emerged that these neural precursors may be affected by channelopathies, indicating a critical role of ion channels in neural development. Using the model system Drosophila melanogaster (fruit fly), I investigated the role of the ion channel SERCA (sarco/endoplasmic reticulum Ca2+ATPase). SERCA is a vital calcium ion pump located on the wall of the endoplasmic reticulum, and it is integral in maintenance of cellular homeostasis and signal transduction in larval brain development. The use of RNAi knockdown technology to reduce the expression of SERCA resulted in a significant decrease in larval brain volume. Further experiments found that the SERCA RNAi knockdown not only decreased cell numbers in neural stem cell lineages but changed the identity of the lineage, implicating an important role for SERCA in both neural stem cell asymmetric division and cell fate. These results indicated that SERCA channels hold a prominent role in cellular proliferation in normal development. The knockdown of SERCA in a brain tumor model additionally showed significantly decreased brain tumor volume, implicating SERCA in tumor development and the proliferation of “neural stem cell-like” cancer cells. Together, these data pinpoint SERCA as a promising potential treatment target for both neural developmental disorders and cancer

Processing of submicron grain 304 stainless steel

A novel thermomechanical processing technique for the synthesis of bulk submicron grain (grain size approximate to 200 nm) 304 stainless steel is reported. This ingot-metallurgical technique requires a total deformation of only 95%, and the key steps to this processing technique involve (i) formation of ultrafine dislocation cell structure, and (ii) the conversion of dislocation cells into grains with medium to high misorientation by grain boundary sliding

Previously Unidentified Changes in Renal Cell Carcinoma Gene Expression Identified by Parametric Analysis of Microarray Data

BACKGROUND. Renal cell carcinoma is a common malignancy that often presents as a metastatic-disease for which there are no effective treatments. To gain insights into the mechanism of renal cell carcinogenesis, a number of genome-wide expression profiling studies have been performed. Surprisingly, there is very poor agreement among these studies as to which genes are differentially regulated. To better understand this lack of agreement we profiled renal cell tumor gene expression using genome-wide microarrays (45,000 probe sets) and compare our analysis to previous microarray studies. METHODS. We hybridized total RNA isolated from renal cell tumors and adjacent normal tissue to Affymetrix U133A and U133B arrays. We removed samples with technical defects and removed probesets that failed to exhibit sequence-specific hybridization in any of the samples. We detected differential gene expression in the resulting dataset with parametric methods and identified keywords that are overrepresented in the differentially expressed genes with the Fisher-exact test. RESULTS. We identify 1,234 genes that are more than three-fold changed in renal tumors by t-test, 800 of which have not been previously reported to be altered in renal cell tumors. Of the only 37 genes that have been identified as being differentially expressed in three or more of five previous microarray studies of renal tumor gene expression, our analysis finds 33 of these genes (89%). A key to the sensitivity and power of our analysis is filtering out defective samples and genes that are not reliably detected. CONCLUSIONS. The widespread use of sample-wise voting schemes for detecting differential expression that do not control for false positives likely account for the poor overlap among previous studies. Among the many genes we identified using parametric methods that were not previously reported as being differentially expressed in renal cell tumors are several oncogenes and tumor suppressor genes that likely play important roles in renal cell carcinogenesis. This highlights the need for rigorous statistical approaches in microarray studies.National Institutes of Healt

Assessment Of An Engineering Technology Outreach Program For 4th-7th Grade Girls

This paper describes a workshop led by female Engineering Technology students, with support from female faculty, to provide an introduction to Engineering Technology to 4th – 7th grade girls through a series of interactive laboratory experiments. This outreach program was developed to improve attitudes towards science and engineering in middle school-aged girls by making science tangible and fun. The workshop takes place on a college campus and makes use of four different Engineering Technology laboratories. Each lab activity includes a hands-on experiment, beginning with an overview of the engineering technology discipline and a brief description of the theories related to the experiment. The day culminates with a panel session between the participants and the college students. An ancillary outcome of the program is that it serves as a community building event for female Engineering Technology college students. Connections are developed between the students and between students and faculty in the college. The college students gain the satisfaction of influencing the attitudes of participants and develop critical communication skills. An attitude survey given to participants before and after the workshop shows that participation in these workshops results in a more positive attitude towards science and technology. College student volunteers were also surveyed after the workshop to determine the impact of their participation. A full workshop description is given in this paper as well as analysis of the assessment results for the participants and the college students.

Holocaust narratives : exploration of the emotional impact of disclosure status among first, second, and third generation Holocaust survivors

The current study explored the possible relationship between disclosure of Holocaust related narratives and emotional well-being among Holocaust survivors as well as children and grandchildren of Holocaust survivors. This study further considered how methods of disclosure and number of disclosure methods used related to emotional wellbeing and overall benefit or harm of the disclosure experience among first, second, and third generation Holocaust survivors. A sample of 147 Holocaust survivors and descendants completed an online survey consisting of Likert scales to rate the perceived benefit or harm of their disclosure experience and opportunities to offer narrative describing their disclosure experience. Three groups formed based on participant survivor status: first generation (n=29), second generation (n=74), and third generation (n=11). Results showed the vast majority of participants disclosed their Holocaust related narratives; however, disclosure did not relate to overall emotional wellbeing. Approximately 86% rated their disclosure experience at least beneficial; the more methods of disclosure used related to participants’ rating disclosure as more beneficial. This study also discovered the both/ and influence of an audience (i.e. telling family/friends, speaking at a community event, etc.) to the disclosed narrative – a receptive audience related to great benefit while a skeptical audience related to great harm. While preliminary in nature, these findings reflect the importance of considering the environment that will hear the trauma narrative before attempting disclosure. This research indicates the need for further exploration of factors predicting the benefits of disclosure

Battery-Operated Atomic Force Microscope

The design of a battery-operated atomic force microscope (AFM) using a piezoresistive cantilever is described. The AFM is designed so that all power to drive the scanning tube and detection electronics comes from a self-contained battery. The prototype AFM uses a 6 V, Ni–Cd, camcorder battery, however, any battery that supplies between 6 and 12 V may be used. Scanner control and data acquisition are implemented using commercially available software running on an external computer. The prototype AFM achieves a scan area of 53 by 53 μm, consumes 1.8 W of power, and can scan continuously for about 7 h on a single battery charge