Soft microenvironments promote the early neurogenic differentiation but not self-renewal of human pluripotent stem cells

Human pluripotent stem cells (hPSCs) are of great interest in biology and medicine due to their ability to self-renew and differentiate into any adult or fetal cell type. Important efforts have identified biochemical factors, signaling pathways, and transcriptional networks that regulate hPSC biology. However, recent work investigating the effect of biophysical cues on mammalian cells and adult stem cells suggests that the mechanical properties of the microenvironment, such as stiffness, may also regulate hPSC behavior. While several studies have explored this mechanoregulation in mouse embryonic stem cells (mESCs), it has been challenging to extrapolate these findings and thereby explore their biomedical implications in hPSCs. For example, it remains unclear whether hPSCs can be driven down a given tissue lineage by providing tissue-mimetic stiffness cues. Here we address this open question by investigating the regulation of hPSC neurogenesis by microenvironmental stiffness. We find that increasing extracellular matrix (ECM) stiffness in vitro increases hPSC cell and colony spread area but does not alter self-renewal, in contrast to past studies with mESCs. However, softer ECMs with stiffnesses similar to that of neural tissue promote the generation of early neural ectoderm. This mechanosensitive increase in neural ectoderm requires only a short 5-day soft stiffness “pulse,” which translates into downstream increases in both total neurons as well as therapeutically relevant dopaminergic neurons. These findings further highlight important differences between mESCs and hPSCs and have implications for both the design of future biomaterials as well as our understanding of early embryonic development

Development and Wind Tunnel Evaluation of a SMA Based Trim Tab Actuator for a Civil Aircraft

This paper presents about the development and wind tunnel evaluation of an SMA based smart trim tab for a typical 2 seater civil aircraft. SMA actuator was housed in the port side of the elevator for actuating the trim tab. Wind tunnel tests were conducted on a full scale Horizontal Tail model with Elevator and Trim Tab at free stream speeds of 25, 35 & 45 m/sec and also for a number of deflections of the elevator (30° up, 0° neutral & 25° down) and trim-tab 11° & 21° up and 15° & 31° down). To measure the hinge moment experienced by the trim-tab at various test conditions, two miniaturized balances were designed and fabricated. Gain scheduled proportional integral controller was developed to control the SMA actuated smart trim tab. It was confirmed during the tests that the trim-tab could be controlled at the desired position against the aerodynamic loads acting on it for the various test conditions

3D Printed V8 Engine Model

The improvements on accuracy, speed and quality of materials in 3D printing technology have opened new doors for it to move beyond the use of 3D printing in the modeling process and actually move it to manufacturing strategy. 3D printing can be particularly useful in research labs and industrial design

Electromagnetic pulse technology : biological and terahertz applications

Since the mid-1970s, the field of Electromagnetic Pulse (EMP) technology has extended to include High-Power Electromagnetic (HPE) sources/antennas. Two such EMP/HPE antennas, designed to address unique applications, are presented in this dissertation. The first is the Prolate-Spheroidal Impulse-Radiating Antenna (PSIRA). Such an antenna uses a prolate-spheroidal reflector and has two foci. A fast (\u3c= 100 ps), high-voltage (\u3e 100 kV) pulse launched from the first focal point is focused into a target located at the second focal point (near-field). It has been found that these pulses are useful for a variety of biological applications, such as accelerated wound healing and skin cancer (melanoma) treatment. Two lens designs for the PSIRA are explored. The first lens, called the focusing lens, is used at the second focal point of the PSIRA to better match the focused pulses into the (biological) target medium. Analytical calculations, numerical simulations and experimental results on a five-layer, hemispherical, dielectric focusing lens are detailed. The second lens, called the launching lens, is used at the first focal point of the PSIRA. For input voltages of 100 kV or more, a switch system, i.e., switch cones, pressure vessel, hydrogen chamber and launching lens, are required to effectively launch a spherical TEM wave from the first focal point. Various switch configurations are explored. It is shown that the pressure vessel can also serve as the launching lens, which considerably simplifies the design of the switch system. Spherical and cylindrical pressure vessel designs are investigated. The second is the Switched Oscillator (SwO) antenna. A SwO is essentially an electrical, shock-excited resonant structure. The SwO is adopted as a high-power antenna to radiate high-energy pulses in the terahertz frequency range. The primary focus is to use these pulses for secure communications. Analytical calculations for the SwO are detailed. Numerical simulations are used to optimize and more thoroughly study the antenna. Various characteristic relations obtained are used to provide a deeper insight into the working of the SwO radiator

Prevalence of Talon cusp in Indian population

Aim: To investigate the prevalence of the talon cusps in a sample of Indian dental patients and their distribution among different types of teeth. To determine the presence of other dental anomalies associated with the talon cusps. Methodology: 2740 out patients (1523 males and 1217 females) attending Oral Medicine department from November 2010 to January 2011 were screened for the presence of talon cusps and were subjected to Intra Oral Peri-apical (IOPA) radiograph to rule out any associated anomalies or peri-apical changes. Results: Talon cusps were detected in 16 out of 2740 patients (person prevalence 0.58%). Thirty one teeth were found to have talon cusp. Maxillary lateral incisors were the most commonly affected teeth (54.8%, 17 teeth), followed by maxillary central incisors and canines (16.12%, 5 teeth).Talon cusp was found in two mandibular central incisors (6.45%) and one each in mandibular second and third molar (3.22% each). Seventeen teeth in 7 patients (54.83%) were found to be associated with anomalies like dens invagination (6 teeth, 19.35%), impacted 13, 23 (6 teeth, 19.35%), partial anodontia (3 teeth, 9.67%), geographic and fissured tongue (2 teeth, 6.45%). Peri-apical granuloma was found in one tooth with talon cusp associated with dens invaginatus. None of the patients were found to be associated with any syndromes. Conclusion: Attention should be paid to the presence of the talon cusp and the associated anomalies. Early diagnosis of the talon cusp can help the clinician in preventing the further complications