Efficient and Robust Bayesian Selection of Hyperparameters in Dimension Reduction for Visualization

We introduce an efficient and robust auto-tuning framework for hyperparameter selection in dimension reduction (DR) algorithms, focusing on large-scale datasets and arbitrary performance metrics. By leveraging Bayesian optimization (BO) with a surrogate model, our approach enables efficient hyperparameter selection with multi-objective trade-offs and allows us to perform data-driven sensitivity analysis. By incorporating normalization and subsampling, the proposed framework demonstrates versatility and efficiency, as shown in applications to visualization techniques such as t-SNE and UMAP. We evaluate our results on various synthetic and real-world datasets using multiple quality metrics, providing a robust and efficient solution for hyperparameter selection in DR algorithms.Comment: 20 pages, 16 figure

Endoscope and System and Method of Operation Thereof

An endoscope including a rigid section having opposed first and second ends and an opening situated between the first and second ends, the rigid section defining a longitudinal axis; a handle portion coupled to a first end of the rigid section and having first and second scissor-type handles suitable for grasping by a user; and a base part situated at the second end of the rigid section and coupled to the first handle of the scissor-type handles such that displacement of the first handle causes a rotation of the base part

Adjustable-Viewing-Angle Endoscopic Tool for Skull Base and Brain Surgery

The term Multi-Angle and Rear Viewing Endoscopic tooL (MARVEL) denotes an auxiliary endoscope, now undergoing development, that a surgeon would use in conjunction with a conventional endoscope to obtain additional perspective. The role of the MARVEL in endoscopic brain surgery would be similar to the role of a mouth mirror in dentistry. Such a tool is potentially useful for in-situ planetary geology applications for the close-up imaging of unexposed rock surfaces in cracks or those not in the direct line of sight. A conventional endoscope provides mostly a frontal view that is, a view along its longitudinal axis and, hence, along a straight line extending from an opening through which it is inserted. The MARVEL could be inserted through the same opening as that of the conventional endoscope, but could be adjusted to provide a view from almost any desired angle. The MARVEL camera image would be displayed, on the same monitor as that of the conventional endoscopic image, as an inset within the conventional endoscopic image. For example, while viewing a tumor from the front in the conventional endoscopic image, the surgeon could simultaneously view the tumor from the side or the rear in the MARVEL image, and could thereby gain additional visual cues that would aid in precise three-dimensional positioning of surgical tools to excise the tumor. Indeed, a side or rear view through the MARVEL could be essential in a case in which the object of surgical interest was not visible from the front. The conceptual design of the MARVEL exploits the surgeon s familiarity with endoscopic surgical tools. The MARVEL would include a miniature electronic camera and miniature radio transmitter mounted on the tip of a surgical tool derived from an endo-scissor (see figure). The inclusion of the radio transmitter would eliminate the need for wires, which could interfere with manipulation of this and other surgical tools. The handgrip of the tool would be connected to a linkage similar to that of an endo-scissor, but the linkage would be configured to enable adjustment of the camera angle instead of actuation of a scissor blade. It is envisioned that thicknesses of the tool shaft and the camera would be less than 4 mm, so that the camera-tipped tool could be swiftly inserted and withdrawn through a dime-size opening. Electronic cameras having dimensions of the order of millimeters are already commercially available, but their designs are not optimized for use in endoscopic brain surgery. The variety of potential endoscopic, thoracoscopic, and laparoscopic applications can be expected to increase as further development of electronic cameras yields further miniaturization and improvements in imaging performance

Gestational Weight Gain Prior to Glucola and Risk of Gestational Diabetes Mellitus

Background: Gestational diabetes mellitus (GDM) complicates 4–7% of U.S. pregnancies. Diabetes and obesity rates are consistently higher in Hispanics compared to non-Hispanic whites. Early-to-mid gestational weight gain (GWG) has been thought to be associated with GDM risk; however, the Institute of Medicine (IOM) found insufficient evidence when re-examining GWG guidelines in 2009. Objective: To investigate associations of GWG adherence per 2009 IOM guidelines prior to 1-hr 50g Glucose Tolerance Test (GTT), or glucola, with GDM diagnoses in Latinas. Methods: The study is a retrospective chart review of all Hispanic women delivered by UMass Memorial faculty between 4/1/06-3/31/11 and received prenatal care at faculty-resident practices (n=1163). Pre-pregnancy weight and height, weight and gestational age (GA) most proximate to glucola and 100g GTT where appropriate, lab results and relevant demographics were abstracted. Weight gain was categorized as inadequate, appropriate or excessive according to 2009 IOM Guidelines with adjustment for gestational age. Mean and standard deviation (SD) and frequency measures reported for continuous and categorical variables, respectively. Comparisons were evaluated with chi-squared tests with statistical significance set at p\u3c0.05. Results: Data for 1115 subjects was analyzed. Preliminary cohort was mean age 25.3 years (sd±6.0), mean gravidity 2.8 (sd±1.8) and 72.1% English and 26.4% Spanish-speaking. Eleven subjects excluded for pregestational diabetes. BMI calculable for 858 subjects (5.4% underweight, 40.3% normal, 26.0% overweight and 28.3% obese); 70 subjects missing GWG prior to glucola. Seven hundred eighty-eight subjects had complete data, on which remainder of analyses were performed. By 2009 IOM guidelines, 174 (22.1%), 193 (24.5%) and 421 (53.4%) gained inadequately, appropriately and excessively as per BMI criteria, respectively. Overall, 86 of 788 diagnosed with GDM (10.9%). According to weight gain adherence, 14 of 174 (8.0%) inadequate-gainers, 20 of 193 (10.4%) appropriate-gainers and 52 of 421 (12.4%) excessive-gainers were diagnosed with GDM. Of subjects with GDM diagnosis (n=86), 16.3%, 23.3% and 60.5% were inadequate, appropriate and excessive-gainers, respectively. Compared to appropriate gainers, the crude odds ratio and 95% CI for GDM diagnosis was 1.22 (0.71-2.11) for excessive-gainers and 0.76 (0.37-1.55) for inadequate-gainers. No statistically significant association between pre-glucola GWG and GDM detected (p=0.3). Conclusion: The rate of GDM in this cohort of Latina women is almost double that of the general population. Though no statistically significant association was identified, the majority of patients diagnosed with GDM were classified as excessive-gainers as per pre-glucola GWG adherence. The trend warrants further evaluation of this population at increased risk for GDM as well as analysis within high-risk subgroups

Nanotunneling Junction-based Hyperspectal Polarimetric Photodetector and Detection Method

A photodetector, detector array, and method of operation thereof in which nanojunctions are formed by crossing layers of nanowires. The crossing nanowires are separated by a few nm thick electrical barrier layer which allows tunneling. Each nanojunction is coupled to a slot antenna for efficient and frequency-selective coupling to photo signals. The nanojunctions formed at the intersection of the crossing wires defines a vertical tunneling diode that rectifies the AC signal from a coupled antenna and generates a DC signal suitable for reforming a video image. The nanojunction sensor allows multi/hyper spectral imaging of radiation within a spectral band ranging from terahertz to visible light, and including infrared (IR) radiation. This new detection approach also offers unprecedented speed, sensitivity and fidelity at room temperature

Endoscope and System and Method of Operation Thereof

An endoscope including a rigid section having opposed first and second ends and an opening situated between the first and second ends, the rigid section defining a longitudinal axis; a handle portion coupled to a first end of the rigid section and having first and second scissor-type handles suitable for grasping by a user; and a base part situated at the second end of the rigid section and coupled to the first handle of the scissor-type handles such that displacement of the first handle causes a rotation of the base part

High-Sensitivity GaN Microchemical Sensors

Systematic studies have been performed on the sensitivity of GaN HEMT (high electron mobility transistor) sensors using various gate electrode designs and operational parameters. The results here show that a higher sensitivity can be achieved with a larger W/L ratio (W = gate width, L = gate length) at a given D (D = source-drain distance), and multi-finger gate electrodes offer a higher sensitivity than a one-finger gate electrode. In terms of operating conditions, sensor sensitivity is strongly dependent on transconductance of the sensor. The highest sensitivity can be achieved at the gate voltage where the slope of the transconductance curve is the largest. This work provides critical information about how the gate electrode of a GaN HEMT, which has been identified as the most sensitive among GaN microsensors, needs to be designed, and what operation parameters should be used for high sensitivity detection

Bump Bonding Using Metal-Coated Carbon Nanotubes

Bump bonding hybridization techniques use arrays of indium bumps to electrically and mechanically join two chips together. Surface-tension issues limit bump sizes to roughly as wide as they are high. Pitches are limited to 50 microns with bumps only 8-14 microns high on each wafer. A new process uses oriented carbon nanotubes (CNTs) with a metal (indium) in a wicking process using capillary actions to increase the aspect ratio and pitch density of the connections for bump bonding hybridizations. It merges the properties of the CNTs and the metal bumps, providing enhanced material performance parameters. By merging the bumps with narrow and long CNTs oriented in the vertical direction, higher aspect ratios can be obtained if the metal can be made to wick. Possible aspect ratios increase from 1:1 to 20:1 for most applications, and to 100:1 for some applications. Possible pitch density increases of a factor of 10 are possible. Standard capillary theory would not normally allow indium or most other metals to be drawn into the oriented CNTs, because they are non-wetting. However, capillary action can be induced through the ability to fabricate oriented CNT bundles to desired spacings, and the use of deposition techniques and temperature to control the size and mobility of the liquid metal streams and associated reservoirs. This hybridization of two technologies (indium bumps and CNTs) may also provide for some additional benefits such as improved thermal management and possible current density increases

Carbon Nanotube Bonding Strength Enhancement Using Metal "Wicking" Process

Carbon nanotubes grown from a surface typically have poor bonding strength at the interface. A process has been developed for adding a metal coat to the surface of carbon nano tubes (CNTs) through a wicking process, which could lead to an enhanced bonding strength at the interface. This process involves merging CNTs with indium as a bump-bonding enhancement. Classical capillary theory would not normally allow materials that do not wet carbon or graphite to be drawn into the spacings by capillary action because the contact angle is greater than 90 degrees. However, capillary action can be induced through JPL's ability to fabricate oriented CNT bundles to desired spacings, and through the use of deposition techniques and temperature to control the size and mobility of the liquid metal streams and associated reservoirs. A reflow and plasma cleaning process has also been developed and demonstrated to remove indium oxide, and to obtain smooth coatings on the CNT bundles

How restorative landscapes can benefit psychological and physiological responses: a pilot study of human–naturerelationships in Sweden and Taiwan

Restorative landscapes provide people with the opportunity to experience nature. This pilot study aimed to determine whether cultural differences affect psychological and physiological responses to restorative landscapes. Two populations, one in Taiwan and one in Sweden, were experimentally compared by showing them photos of restorative landscapes from each country. The results showed that restorativeness was affected more by photos of the restorative landscape in Sweden than in Taiwan. The results showed that restorativeness in terms of psychological and physiological responses was affected. A significant variation in heart rate was observed between the populations: Taiwanese participants experienced higher heart rates when viewing unfamiliar and novel scenery when compared to Swedish participants. No significant differences between the populations were observed regarding attention capacity, working memory, and muscle tension. The psychological and physiological responses to the two countries’ distinctive restorative landscapes may have implications for designing such landscapes in urban green spaces