Multivariate spacings based on data depth: I. Construction of nonparametric multivariate tolerance regions

This paper introduces and studies multivariate spacings. The spacings are developed using the order statistics derived from data depth. Specifically, the spacing between two consecutive order statistics is the region which bridges the two order statistics, in the sense that the region contains all the points whose depth values fall between the depth values of the two consecutive order statistics. These multivariate spacings can be viewed as a data-driven realization of the so-called ``statistically equivalent blocks.'' These spacings assume a form of center-outward layers of ``shells'' (``rings'' in the two-dimensional case), where the shapes of the shells follow closely the underlying probabilistic geometry. The properties and applications of these spacings are studied. In particular, the spacings are used to construct tolerance regions. The construction of tolerance regions is nonparametric and completely data driven, and the resulting tolerance region reflects the true geometry of the underlying distribution. This is different from most existing approaches which require that the shape of the tolerance region be specified in advance. The proposed tolerance regions are shown to meet the prescribed specifications, in terms of $\beta$-content and $\beta$-expectation. They are also asymptotically minimal under elliptical distributions. Finally, a simulation and comparison study on the proposed tolerance regions is presented.Comment: Published in at http://dx.doi.org/10.1214/07-AOS505 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

cis-regulatory circuits regulating NEK6 kinase overexpression in transformed B cells Are super-enhancer independent

Alterations in distal regulatory elements that control gene expression underlie many diseases, including cancer. Epigenomic analyses of normal and diseased cells have produced correlative predictions for connections between dysregulated enhancers and target genes involved in pathogenesis. However, with few exceptions, these predicted cis-regulatory circuits remain untested. Here, we dissect cis-regulatory circuits that lead to overexpression of NEK6, a mitosis-associated kinase, in human B cell lymphoma. We find that only a minor subset of predicted enhancers is required for NEK6 expression. Indeed, an annotated super-enhancer is dispensable for NEK6 overexpression and for maintaining the architecture of a B cell-specific regulatory hub. A CTCF cluster serves as a chromatin and architectural boundary to block communication of the NEK6 regulatory hub with neighboring genes. Our findings emphasize that validation of predicted cis-regulatory circuits and super-enhancers is needed to prioritize transcriptional control elements as therapeutic targets

A primal--dual algorithm as applied to optimal control problems

We propose a primal--dual technique that applies to infinite dimensional equality constrained problems, in particular those arising from optimal control. As an application of our general framework, we solve a control-constrained double integrator optimal control problem and the challenging control-constrained free flying robot optimal control problem by means of our primal--dual scheme. The algorithm we use is an epsilon-subgradient method that can also be interpreted as a penalty function method. We provide extensive comparisons of our approach with a traditional numerical approach

Short-wavelength-band tunable high-power Tm-doped fiber laser

In this work, we realized broadly tunable mode-locking operation from 1730 nm to 1815 nm in normal dispersion regime employing an acousto-optic tunable fiber (AOTF) in a Tm-doped dispersion-managed fiber laser. The AOTF worked as a multifunctional component in laser cavity suppressing undesired wavelength lasing and introducing a frequency shifting, which improved the stability of laser operation. The hybrid mode-locking incorporated by nonlinear polarization rotation (NPR) effect and frequency shifting effect ensured self-starting stable pulsed operation. The pulse spectral widths ranged from 17 nm to 25 nm. The stretching-free direct amplification in two-cascaded fiber amplifier enabled power scaling up to 310 mW and pulse energy of 19 nJ. Pulse duration was compressed down to 282 fs by a pair of gratings. The seed laser is further optimized. The optimized seed laser enhances output power about 5 times. The laser system was designed for multiphoton imaging of bladder cancer in the third biological window to demonstrate the recently discovered nonlinear effect resulting in improvement of signal contrast at the deeper tissue level.Peer reviewe

How Hands Free Always On (HFAO) Technology Will Affect Classrooms

Hands Free Always On (HFAO) technology, such as the next generation of smart glasses, will likely become undetectable, turn up in classrooms in the near future and change teaching and learning. This paper is an exploratory study that analyzes two focus groups with faculty members at a research university. Participants were former and current NJIT instructors who have taught at an undergraduate and/or graduate level. The focus group process and the analysis of the information collected were guided by our four research questions: (1) How will HFAO technology affect students’ learning? (2) How will it affect professors’ teaching? (3) How will it affect assessment? (4) What would make faculty embrace this technology? From the insights provided by the participants we found that the perceived effects of HFAO technology were mixed. Future work aims to conduct additional focus groups with instructors and students at the graduate and undergraduate levels

Porous stainless steel for biomedical applications

Porous 316L austenitic stainless steel was synthesized by powder metallurgy with relative density of 0.50 and 0.30 using 15 and 30 wt. (%) respectively of ammonium carbonate and ammonium bicarbonate as foaming agents. The powders were mixed in a planetary ball mill at 60 rpm for 10 minutes. The samples were uniaxially pressed at 287 MPa and subsequently vacuum heat treated in two stages, the first one at 200 ºC for 5 hours to decompose the carbonate and the second one at 1150 ºC for 2 hours to sinter the steel. The sintered samples had a close porous structure and a multimodal pore size distribution that varied with the foaming agent and its concentration. The samples obtained by addition of 30 wt. (%) of foaming agents had a more homogeneous porous structure than that obtained with 15 wt. (%). The MTT cytotoxicity test (3-[4,5-dimethylthiazol]-2,5-diphenyltetrazolium bromide) was used to evaluate the mitochondrial activity of L929 cells with samples for periods of 24, 48, and 72 hours. The cytotoxicity test showed that the steel foams were not toxic to fibroblast culture. The sample with the best cellular growth, therefore the most suitable for biomedical applications among those studied in this work, was produced with 30 wt. (%) ammonium carbonate. In this sample, cell development was observed after 48 hours of incubation, and there was adhesion and spreading on the material after 72 hours. Electrochemical experiments using a chloride-containing medium were performed on steel foams and compared to massive steel. The massive steel had a better corrosion performance than the foams as the porosity contributes to increase the surface area exposed to the corrosive medium.Universidade do Vale do Paraíba Instituto de Pesquisa e DesenvolvimentoUniversidade Federal de São Paulo (UNIFESP) Instituto de Ciência e TecnologiaUNIFESP, Instituto de Ciência e TecnologiaSciEL

Examining the representativeness of home outdoor PM2.5, EC, and OC estimates for daily personal exposures in Southern California

Recent studies have linked acute respiratory and cardiovascular outcomes to measurements or estimates of traffic-related air pollutants at homes or schools. However, few studies have evaluated these outdoor measurements and estimates against personal exposure measurements. We compared measured and modeled home outdoor concentrations with personal measurements of traffic-related air pollutants in the Los Angeles air basin (Whittier and Riverside). Personal exposure of 63 children with asthma and 15 homes were assessed for particulate matter with an aerodynamic diameter less than 2.5μm (PM2.5), elemental carbon (EC), and organic carbon (OC) during sixteen 10-day monitoring runs. Regression models to predict daily home outdoor PM2.5, EC, and OC were constructed using home outdoor measurements, geographical and meteorological parameters, as well as CALINE4 estimates at outdoor home sites, which represent the concentrations from local traffic sources. These home outdoor models showed the variance explained (R 2) was 0.97 and 0.94 for PM2.5, 0.91 and 0.83 for OC, and 0.76 and 0.87 for EC in Riverside and Whittier, respectively. The PM2.5 outdoor estimates correlated well with the personal measurements (Riverside R 2 = 0.65 and Whittier R 2 = 0.69). However, excluding potentially inaccurate samples from Riverside, the correlation between personal exposure to carbonaceous species and home outdoor estimates in Whittier was moderate for EC (R 2 = 0.37) and poor for OC (R 2 = 0.08). The CALINE4 estimates alone were not correlated with personal measurements of EC or other pollutants. While home outdoor estimates provide good approximations for daily personal PM2.5 exposure, they may not be adequate for estimating daily personal exposure to EC and O