An Optimal Linear Time Algorithm for Quasi-Monotonic Segmentation

Monotonicity is a simple yet significant qualitative characteristic. We consider the problem of segmenting a sequence in up to K segments. We want segments to be as monotonic as possible and to alternate signs. We propose a quality metric for this problem using the l_inf norm, and we present an optimal linear time algorithm based on novel formalism. Moreover, given a precomputation in time O(n log n) consisting of a labeling of all extrema, we compute any optimal segmentation in constant time. We compare experimentally its performance to two piecewise linear segmentation heuristics (top-down and bottom-up). We show that our algorithm is faster and more accurate. Applications include pattern recognition and qualitative modeling.Comment: This is the extended version of our ICDM'05 paper (arXiv:cs/0702142

An optical fiber hydrogen sensor using a palladium-coated ball lens

A self-referenced optical fiber refractometer using a ball lens as a sensor head has been developed and characterized. A 350-μm ball lens created at the tip of a single mode fiber has been coated with a 40-nm optically thin layer of palladium that reacts with hydrogen to form a hydride, which has a lower reflectivity than pure palladium. Optical reflectance measurements from the tip of the ball lens were performed to determine the hydrogen response. The change in reflectivity is proportional to the hydrogen concentration in the range 0% to 1% hydrogen in air with a detection limit down to 10 ppm (1σ) in air. This technique offers a simple sensor head arrangement, with a larger sampling area (~40 times) than a typical single-mode fiber core. A statistical image analysis of a palladium film, with cracks created by accelerated failure, confirms that the anticipated sensor area for a ball lens sensor head has a more predictable reflectivity than that of a bare fiber core

Urban transportation: Perspectives on mobility and choice

A study of urban transportation systems are presented characterized by intensive scrutiny of many ideas, philosophies, and academic perspectives. This report is intended to communicate some dimensions of the urban transportation problem to the general public

Magnetoresistance and magnetic breakdown in the quasi-two-dimensional conductors (BEDT-TTF)2_2MHg(SCN)4_4[M=K,Rb,Tl]

The magnetic field dependence of the resistance of (BEDT-TTF)$_2$MHg(SCN)$_4$[M=K,Rb,Tl] in the density-wave phase is explained in terms of a simple model involving magnetic breakdown and a reconstructed Fermi surface. The theory is compared to measurements in pulsed magnetic fields up to 51 T. The value implied for the scattering time is consistent with independent determinations. The energy gap associated with the density-wave phase is deduced from the magnetic breakdown field. Our results have important implications for the phase diagram.Comment: 5 pages, RevTeX + epsf, 3 figures. To appear in Physical Review B, Rapid Communications, September 15, 199

The scatter about the "Universal" dwarf spheroidal mass profile: A kinematic study of the M31 satellites, And V and And VI

While the satellites of the Milky Way (MW) have been shown to be largely consistent in terms of their mass contained within one half--light radius (M_{half}) with a "Universal" mass profile, a number of M31 satellites are found to be inconsistent with such relations, and seem kinematically colder in their central regions than their MW cousins. In this work, we present new kinematic and updated structural properties for two M31 dSphs, And V and And VI using data from the Keck Low Resolution Imaging Spectrograph (LRIS) and the DEep Imaging Multi-Object Spectrograph (DEIMOS) instruments and the Subaru Suprime-Cam imager. We measure systemic velocities of v_r=-393.1+/-4.2km/s and -344.8+/-2.5km/s, and dispersions of sigma_v=11.5{+5.3}{-4.4}km/s and sigma_v=9.4{+3.2}{-2.4}km/s for And V and And VI respectively, meaning these two objects are consistent with the trends in sigma_v and r_{half} set by their MW counterparts. We also investigate the nature of this scatter about the MW dSph mass profiles for the "Classical" (i.e. M_V<-8) MW and M31 dSphs. When comparing both the "classical" MW and M31 dSphs to the best--fit mass profiles in the size--velocity dispersion plane, we find general scatter in both the positive (i.e. hotter) and negative (i.e. colder) directions from these profiles. However, barring one exception (CVnI) only the M31 dSphs are found to scatter towards a colder regime, and, excepting the And I dSph, only MW objects scatter to hotter dispersions. We also note that the scatter for the combined population is greater than expected from measurement errors alone. We assess this divide in the context of the differing disc-to-halo mass (i.e. stars and baryons to total virial mass) ratios of the two hosts and argue that the underlying mass profiles for dSphs differ from galaxy to galaxy, and are modified by the baryonic component of the host.Comment: 15 pages, 8 figures. Small modifications made for referee report. Accepted for publication in MNRAS (29/06/2011

The High Magnetic Field Phase Diagram of a Quasi-One Dimensional Metal

We present a unique high magnetic field phase of the quasi-one dimensional organic conductor (TMTSF)$_2$ClO$_4$. This phase, termed "Q-ClO$_4$", is obtained by rapid thermal quenching to avoid ordering of the ClO$_4$ anion. The magnetic field dependent phase of Q-ClO$_4$ is distinctly different from that in the extensively studied annealed material. Q-ClO$_4$ exhibits a spin density wave (SDW) transition at $\approx$ 5 K which is strongly magnetic field dependent. This dependence is well described by the theoretical treatment of Bjelis and Maki. We show that Q-ClO$_4$ provides a new B-T phase diagram in the hierarchy of low-dimensional organic metals (one-dimensional towards two-dimensional), and describe the temperature dependence of the of the quantum oscillations observed in the SDW phase.Comment: 10 pages, 4 figures, preprin

Correlation between Fermi surface transformations and superconductivity in the electron-doped high-TcT_c superconductor Nd2−x_{2-x}Cex_xCuO4_4

Two critical points have been revealed in the normal-state phase diagram of the electron-doped cuprate superconductor Nd$_{2-x}$Ce$_x$CuO$_4$ by exploring the Fermi surface properties of high quality single crystals by high-field magnetotransport. First, the quantitative analysis of the Shubnikov-de Haas effect shows that the weak superlattice potential responsible for the Fermi surface reconstruction in the overdoped regime extrapolates to zero at the doping level $x_c = 0.175$ corresponding to the onset of superconductivity. Second, the high-field Hall coefficient exhibits a sharp drop right below optimal doping $x_{\mathrm{opt}} = 0.145$ where the superconducting transition temperature is maximum. This drop is most likely caused by the onset of long-range antiferromagnetic ordering. Thus, the superconducting dome appears to be pinned by two critical points to the normal state phase diagram.Comment: 9 pages; 7 figures; 1 tabl

Pancreas preserving distal duodenectomy: a versatile operation for a range of infra-papillary pathologies

AIM To investigate the range of pathologies treated by pancreas preserving distal duodenectomy (PPDD) and present the outcome of follow-up. METHODS Neoplastic lesions of the duodenum are treated conventionally by pancreaticoduodenectomy. Lesions distal to the major papilla may be suitable for a pancreas-preserving distal duodenectomy, potentially reducing morbidity and mortality. We present our experience with this procedure. Selective intraoperative duodenoscopy assessed the relationship of the papilla to the lesion. After duodenal mobilisation and confirmation of the site of the lesion, the duodenum was transected distal to the papilla and beyond the duodenojejunal flexure and a side-to-side duodenojejunal anastomosis was formed. Patients were identified from a prospectively maintained database and outcomes determined from digital health records with a dataset including demographics, co-morbidities, mode of presentation, preoperative imaging and assessment, nutritional support needs, technical operative details, blood transfusion requirements, length of stay, pathology including lymph node yield and lymph node involvement, length of follow-up, complications and outcomes. Related published literature was also reviewed. RESULTS Twenty-four patients had surgery with the intent of performing PPDD from 2003 to 2016. Nineteen underwent PPDD successfully. Two patients planned for PPDD proceeded to formal pancreaticoduodenectomy (PD) while three had unresectable disease. Median post-operative follow-up was 32 mo. Pathologies resected included duodenal adenocarcinoma (n = 6), adenomas (n = 5), gastrointestinal stromal tumours (n = 4) and lipoma, bleeding duodenal diverticulum, locally advanced colonic adenocarcinoma and extrinsic compression (n = 1 each). Median postoperative length of stay (LOS) was 8 d and morbidity was low [pain and nausea/vomiting (n = 2), anastomotic stricture (n = 1), pneumonia (n = 1), and overwhelming postsplenectomy sepsis (n = 1, asplenic patient)]. PPDD was associated with a significantly shorter LOS than a contemporaneous PD series [PPDD 8 (6-14) d vs PD 11 (10-16) d, median (IQR), P = 0.026]. The 30-d mortality was zero and 16 of 19 patients are alive to date. One patient died of recurrent duodenal adenocarcinoma 18 mo postoperatively and two died of unrelated disease (at 2 mo and at 8 years respectively). CONCLUSION PPDD is a versatile operation that can provide definitive treatment for a range of duodenal pathologies including adenocarcinoma

N=2 Supersymmetric Model with Dirac-Kahler Fermions from Generalized Gauge Theory in Two Dimensions

We investigate the generalized gauge theory which has been proposed previously and show that in two dimensions the instanton gauge fixing of the generalized topological Yang-Mills action leads to a twisted N=2 supersymmetric action. We have found that the R-symmetry of N=2 supersymmetry can be identified with the flavour symmetry of Dirac-Kahler fermion formulation. Thus the procedure of twist allows topological ghost fields to be interpreted as the Dirac-Kahler matter fermions.Comment: 22 pages, LaTe