An Empirical Comparison of Real-time Dense Stereo Approaches for use in the Automotive Environment

In this work we evaluate the use of several real-time dense stereo algorithms as a passive 3D sensing technology for potential use as part of a driver assistance system or autonomous vehicle guidance. A key limitation in prior work in this area is that although significant comparative work has been done on dense stereo algorithms using de facto laboratory test sets only limited work has been done on evaluation in real world environments such as that found in potential automotive usage. This comparative study aims to provide an empirical comparison using automotive environment video imagery and compare this against dense stereo results drawn on standard test sequences in addition to considering the computational requirement against performance in real-time. We evaluate five chosen algorithms: Block Matching, Semi-Global Matching, No-Maximal Disparity, Cross-Based Local Approach, Adaptive Aggregation with Dynamic Programming. Our comparison shows a contrast between the results obtained on standard test sequences and those for automotive application imagery where a Semi-Global Matching approach gave the best empirical performance. From our study we can conclude that the noise present in automotive applications, can impact the quality of the depth information output from more complex algorithms (No-Maximal Disparity, Cross-Based Local Approach, Adaptive Aggregation with Dynamic Programming) resulting that in practice the disparity maps produced are comparable with those of simpler approaches such as Block Matching and Semi-Global Matching which empirically perform better in the automotive environment test sequences. This empirical result on automotive environment data contradicts the comparative result found on standard dense stereo test sequences using a statistical comparison methodology leading to interesting observations regarding current relative evaulation approaches

Structural change in the impact of income on food consumption in China, 1989-1993

Change has not always been steady in China, and evidence of increased poverty among some subpopulation groups exists. For example, among the rural poor in some areas there has been an increase in chronic energy deficiency, while, particularly among higher-income groups, the incidences of high-fat diets and obesity have increased rapidly. There has been a marked shift not only in obesity but also in other diet-related chronic diseases such as cardiovascular disease, diabetes, and certain types of cancers. These are rapidly becoming major health problems in the higher-income population. In this article we first present the overall picture with a cross-country analysis of changes in the dietary structure, and we explore the income-fat and diet-obesity relationships. Then we present data from China that demonstrate the trend in the dietary structure. This is followed by a more rigorous examination and testing of the income-food consumption relationship. The behavioral changes that we uncover in the income-food relationship have important implications for the formulation of future nutrition policies in China. We explore some of these implications in the concluding section

Anterior Cervical Infection: Presentation and Incidence of an Uncommon Postoperative Complication.

STUDY DESIGN: Retrospective multi-institutional case series. OBJECTIVE: The anterior cervical discectomy and fusion (ACDF) affords the surgeon the flexibility to treat a variety of cervical pathologies, with the majority being for degenerative and traumatic indications. Limited data in the literature describe the presentation and true incidence of postoperative surgical site infections. METHODS: A retrospective multicenter case series study was conducted involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network, selected for their excellence in spine care and clinical research infrastructure and experience. Medical records for 17 625 patients who received cervical spine surgery (levels from C2 to C7) between January 1, 2005, and December 31, 2011, inclusive, were reviewed to identify the occurrence of 21 predefined treatment complications. Patients who underwent an ACDF were identified in the database and reviewed for the occurrence of postoperative anterior cervical infections. RESULTS: A total of 8887 patients were identified from a retrospective database analysis of 21 centers providing data for postoperative anterior cervical infections (17/21, 81% response rate). A total of 6 postoperative infections after ACDF were identified for a mean rate of 0.07% (range 0% to 0.39%). The mean age of patients identified was 57.5 (SD = 11.6, 66.7% female). The mean body mass index was 22.02. Of the total infections, half were smokers (n = 3). Two patients presented with myelopathy, and 3 patients presented with radiculopathic-type complaints. The mean length of stay was 4.7 days. All patients were treated aggressively with surgery for management of this complication, with improvement in all patients. There were no mortalities. CONCLUSION: The incidence of postoperative infection in ACDF is exceedingly low. The management has historically been urgent irrigation and debridement of the surgical site. However, due to the rarity of this occurrence, guidance for management is limited to retrospective series

Endoscopist biopsy rate as a quality indicator for outpatient gastroscopy: a multicenter cohort study with validation.

BACKGROUND AND AIMS: The diagnosis of gastric premalignant conditions (GPCs) relies on endoscopy with mucosal sampling. We hypothesized that the endoscopist biopsy rate (EBR) might constitute a quality indicator for EGD, and we have analyzed its association with GPC detection and the rate of missed gastric cancers (GCs). METHODS: We analyzed EGD databases from 2 high-volume outpatient units. EBR values, defined as the proportion of EGDs with ≥1 biopsy to all examinations were calculated for each endoscopist in Unit A (derivation cohort) and divided by the quartile values into 4 groups. Detection of GPC was calculated for each group and compared using multivariate clustered logistic regression models. Unit B database was used for validation. All patients were followed in the Cancer Registry for missed GCs diagnosed between 1 month and 3 years after EGDs with negative results. RESULTS: Sixteen endoscopists in Unit A performed 17,490 EGDs of which 15,340 (87.7%) were analyzed. EBR quartile values were 22.4% to 36.7% (low EBR), 36.8% to 43.7% (moderate), 43.8% to 51.6% (high), and 51.7% and 65.8% (very-high); median value 43.8%. The odds ratios for the moderate, high, and very-high EBR groups of detecting GPC were 1.6 (95% confidence interval [CI], 1.3-1.9), 2.0 (95% CI, 1.7-2.4), and 2.5 (95% CI, 2.1-2.9), respectively, compared with the low EBR group (P < .001). This association was confirmed with the same thresholds in the validation cohort. Endoscopists with higher EBR (≥43.8%) had a lower risk of missed cancer compared with those in the lower EBR group (odds ratio, 0.44; 95% CI, 0.20-1.00; P = .049). CONCLUSIONS: The EBR parameter is highly variable among endoscopists and is associated with efficacy in GPC detection and the rate of missed GCs

Misplaced Cervical Screws Requiring Reoperation.

STUDY DESIGN: A multicenter, retrospective case series. OBJECTIVE: In the past several years, screw fixation of the cervical spine has become commonplace. For the most part, this is a safe, low-risk procedure. While rare, screw backout or misplaced screws can lead to morbidity and increased costs. We report our experiences with this uncommon complication. METHODS: A multicenter, retrospective case series was undertaken at 23 institutions in the United States. Patients were included who underwent cervical spine surgery from January 1, 2005, to December 31, 2011, and had misplacement of screws requiring reoperation. Institutional review board approval was obtained at all participating institutions, and detailed records were sent to a central data center. RESULTS: A total of 12 903 patients met the inclusion criteria and were analyzed. There were 11 instances of screw backout requiring reoperation, for an incidence of 0.085%. There were 7 posterior procedures. Importantly, there were no changes in the health-related quality-of-life metrics due to this complication. There were no new neurologic deficits; a patient most often presented with pain, and misplacement was diagnosed on plain X-ray or computed tomography scan. The most common location for screw backout was C6 (36%). CONCLUSIONS: This study represents the largest series to tabulate the incidence of misplacement of screws following cervical spine surgery, which led to revision procedures. The data suggest this is a rare event, despite the widespread use of cervical fixation. Patients suffering this complication can require revision, but do not usually suffer neurologic sequelae. These patients have increased cost of care. Meticulous technique and thorough knowledge of the relevant anatomy are the best means of preventing this complication

Physiological concentrations of bile acids down-regulate agonist induced secretion in colonic epithelial cells

In patients with bile acid malabsorption, high concentrations of bile acids enter the colon and stimulate Cl− and fluid secretion, thereby causing diarrhoea. However, deoxycholic acid (DCA), the predominant colonic bile acid, is normally present at lower concentrations where its role in regulating transport is unclear. Thus, the current study set out to investigate the effects of physiologically relevant DCA concentrations on colonic epithelial secretory function. Cl− secretion was measured as changes in short-circuit current across voltage-clamped T84 cell monolayers. At high concentrations (0.5–1 mM), DCA acutely stimulated Cl− secretion but this effect was associated with cell injury, as evidenced by decreased transepithelial resistance (TER) and increased lactate dehydrogenase (LDH) release. In contrast, chronic (24 hrs) exposure to lower DCA concentrations (10–200 μM) inhibited responses to Ca2+ and cAMP-dependent secretagogues without altering TER, LDH release, or secretagogue-induced increases in intracellular second messengers. Other bile acids – taurodeoxycholic acid, chenodeoxycholic acid and cholic acid – had similar antisecretory effects. DCA (50 μM) rapidly stimulated phosphorylation of the epidermal growth factor receptor (EGFr) and both ERK and p38 MAPKs (mitogen-activated protein kinases). The EGFr inhibitor, AG1478, and the protein synthesis inhibitor, cycloheximide, reversed the antisecretory effects of DCA, while the MAPK inhibitors, PD98059 and SB203580, did not. In summary, our studies suggest that, in contrast to its acute prosecretory effects at pathophysiological concentrations, lower, physiologically relevant, levels of DCA chronically down-regulate colonic epithelial secretory function. On the basis of these data, we propose a novel role for bile acids as physiological regulators of colonic secretory capacity

Epithelial ovarian carcinoma diagnosis by desorption electrospray ionization mass spectrometry imaging

Ovarian cancer is highly prevalent among European women, and is the leading cause of gynaecological cancer death. Current histopathological diagnoses of tumour severity are based on interpretation of, for example, immunohistochemical staining. Desorption electrospray mass spectrometry imaging (DESI-MSI) generates spatially resolved metabolic profiles of tissues and supports an objective investigation of tumour biology. In this study, various ovarian tissue types were analysed by DESI-MSI and co-registered with their corresponding haematoxylin and eosin (H&E) stained images. The mass spectral data reveal tissue type-dependent lipid profiles which are consistent across the n = 110 samples (n = 107 patients) used in this study. Multivariate statistical methods were used to classify samples and identify molecular features discriminating between tissue types. Three main groups of samples (epithelial ovarian carcinoma, borderline ovarian tumours, normal ovarian stroma) were compared as were the carcinoma histotypes (serous, endometrioid, clear cell). Classification rates >84% were achieved for all analyses, and variables differing statistically between groups were determined and putatively identified. The changes noted in various lipid types help to provide a context in terms of tumour biochemistry. The classification of unseen samples demonstrates the capability of DESI-MSI to characterise ovarian samples and to overcome existing limitations in classical histopathology

Characterization of the material response in the granular ratcheting

The existence of a very special ratcheting regime has recently been reported in a granular packing subjected to cyclic loading \cite{alonso04}. In this state, the system accumulates a small permanent deformation after each cycle. After a short transient regime, the value of this permanent strain accumulation becomes independent on the number of cycles. We show that a characterization of the material response in this peculiar state is possible in terms of three simple macroscopic variables. They are defined that, they can be easily measured both in the experiments and in the simulations. We have carried out a thorough investigation of the micro- and macro-mechanical factors affecting these variables, by means of Molecular Dynamics simulations of a polydisperse disk packing, as a simple model system for granular material. Biaxial test boundary conditions with a periodically cycling load were implemented. The effect on the plastic response of the confining pressure, the deviatoric stress and the number of cycles has been investigated. The stiffness of the contacts and friction has been shown to play an important role in the overall response of the system. Specially elucidating is the influence of the particular hysteretical behavior in the stress-strain space on the accumulation of permanent strain and the energy dissipation.Comment: 13 pages, 20 figures. Submitted to PR

Spontaneous polymerization of benzofulvene monomers bearing a 4-Pyri- dylacetylene substituent in different positions of the benzofulvene scaffold

Two benzofulvene derivatives bearing a 4-pyridylacetylene substituent in different positions (i. e. 2 and 6) of the benzofulvene scaffold are designed and synthesized to evaluate the effects on the spontaneous solid-state polymerization of the presence of the same substituent in two different key positions of the 3-phenylbenzoful-vene moiety. Both the benzofulvene derivatives showed the tendency to polymerize spontaneously in the consequence of solvent removal under reduced pressure without the addition of catalysts or initiators. The macromolecular structure of the stemming polymeric materials was investigated by NMR spectroscopy and MALDI-TOF mass spectrometry. Both NMR and MALDI-TOF studies confirmed the polymeric nature of the materials and suggested for the polybenzofulvene derivative bearing the 4-pyridylacetylene substituent in po-sitions 6 a higher structural homogeneity with respect to the one bearing the same substituent in position 2. The photophysical characterization of the most homogeneous polybenzofulvene derivative led to the discovery of its outstanding hole mobility value, which was found to be around one order of magnitude higher than that pre-viously measured for two oligothiophene-based polybenzofulvene derivatives and almost two orders of magni-tude higher than that of poly(vinylcarbazole), commonly used as hole-transporter matrix. This result places the new polybenzofulvene derivative in an outstanding position as a promising material for field-effect transistor (FET) device applications