1,933 research outputs found
Regional Governance Institutions and Interlocal Cooperation for Service Delivery
Fragmentation of authority defines a first-order problem by creating economies of scale and positive and negative externalities in the provision of local public services. Resolving first-order problems leads to the second-order collective action problem of developing regional institutions that alter the first-order problem in a manner that improves joint outcomes. This paper investigates how regional councils of governments facilitate service cooperation by reducing transaction costs in interlocal service contracting. I focus on the role of the regional governance organizations, the characteristics of services, and political institutions while controlling for service markets and community characteristics. The results suggest that local governments in metropolitan areas can take advantage of regional governance institutions to overcome the barriers to intergovernmental service cooperation. This analysis also reports that interlocal contracting is an important service delivery arrangement for asset specific and difficult to measure services and for council manager cities and mayor council cities with a professional manager position. After discussing the limitations of these analyses, I describe follow-up work focusing on Florida metropolitan cities that address these issues
The Antitumor Agent, Arglabin-DMA, Preferentially Induces Apoptosis in Human Colon Tumor Cells
Arglabin-DMA, an analog of farnesyl pyrophosphate (FPP), reportedly inhibits farnesyltransferase (FTase) directly by competitively blocking the binding of Ras protein and its posttranslational modification, as suggested in previous studies. But, the mechanisms by which Arglabin-DMA inhibits tumor growth in vivo and in vitro are still relatively poorly characterized. To determine the mechanism by which this drug inhibits tumor growth, the effects of Arglabin-DMA in two human colon tumor cell lines (mutant K-ras HCT 116 and wild-type ras HT-29) were explored on cell proliferation, apoptosis, and cell cycle kinetics in vitro. In cell viability studies, we showed that Arglabin-DMA had striking morphological and physiological effects on the two human colon tumor cell lines, possibly more so than those of other anticancer drugs. Also, Arglabin-DMA exhibited less harm to normal cells (Hs27) which retained their potential for cell growth. An add-back experiment showed that Arglabin-DMA had no effect on the isoprenoid biosynthetic pathway. The drug not only affects the mutant K-ras human colon tumor cell line, but also the wild-type ras human colon tumor cell line. It may therefore inhibit one or more non-Ras proteins to exert its antitumor effects. Gel electrophoresis, TUNEL assay, Annexin V assay, apoptosis dye-uptake assay, and morphological criteria were used to characterize apoptosis. Adherent cells and freely floating detached cells in Arglabin-DMA treatment were treated as two distinct populations We demonstrated that the detached cells caused by Arglabin-DMA exposure exhibited increased apoptosis in a p53-independent manner. Cell cycle effects were studied using flow cytometry. After Arglabin-DMA was added, the proportion of the two human colon tumor cells in G2/M phase increased, indicating a block in either G2 or M phase. We conclude that Arglabin-DMA has specific cytotoxic effects in two human colon tumor cell lines, and less cytotoxicity to normal cells. It induces arrest at the G2/M phase of the cell cycle. After treatment with Arglabin-DMA, rounded and detached cells enter apoptosis. This mechanism may be analogous to anoikis, which is the induction of apoptosis in response to loss of cell contact. The utility of this drug in combating cancer remains an attractive, though complex possibility
Automatic Internal Stray Light Calibration of AMCW Coaxial Scanning LiDAR Using GMM and PSO
In this paper, an automatic calibration algorithm is proposed to reduce the
depth error caused by internal stray light in amplitude-modulated continuous
wave (AMCW) coaxial scanning light detection and ranging (LiDAR). Assuming that
the internal stray light generated in the process of emitting laser is static,
the amplitude and phase delay of internal stray light are estimated using the
Gaussian mixture model (GMM) and particle swarm optimization (PSO).
Specifically, the pixel positions in a raw signal amplitude map of calibration
checkboard are segmented by GMM with two clusters considering the dark and
bright image pattern. The loss function is then defined as L1-norm of
difference between mean depths of two amplitude-segmented clusters. To avoid
overfitting at a specific distance in PSO process, the calibration check board
is actually measured at multiple distances and the average of corresponding L1
loss functions is chosen as the actual loss. Such loss is minimized by PSO to
find the two optimal target parameters: the amplitude and phase delay of
internal stray light. According to the validation of the proposed algorithm,
the original loss is reduced from tens of centimeters to 3.2 mm when the
measured distances of the calibration checkboard are between 1 m and 4 m. This
accurate calibration performance is also maintained in geometrically complex
measured scene. The proposed internal stray light calibration algorithm in this
paper can be used for any type of AMCW coaxial scanning LiDAR regardless of its
optical characteristics
Highly precise AMCW time-of-flight scanning sensor based on digital-parallel demodulation
In this paper, a novel amplitude-modulated continuous wave (AMCW)
time-of-flight (ToF) scanning sensor based on digital-parallel demodulation is
proposed and demonstrated in the aspect of distance measurement precision.
Since digital-parallel demodulation utilizes a high-amplitude demodulation
signal with zero-offset, the proposed sensor platform can maintain extremely
high demodulation contrast. Meanwhile, as all cross correlated samples are
calculated in parallel and in extremely short integration time, the proposed
sensor platform can utilize a 2D laser scanning structure with a single photo
detector, maintaining a moderate frame rate. This optical structure can
increase the received optical SNR and remove the crosstalk of image pixel
array. Based on these measurement properties, the proposed AMCW ToF scanning
sensor shows highly precise 3D depth measurement performance. In this study,
this precise measurement performance is explained in detail. Additionally, the
actual measurement performance of the proposed sensor platform is
experimentally validated under various conditions
Patterns, temporal trends and methodological associations in the measurement and valuation of childhood health utilities
Purpose
To systematically assess patterns and temporal changes in the measurement and valuation of childhood health utilities and associations between methodological factors.
Methods
Studies reporting childhood health utilities using direct or indirect valuation methods, published by June 2017, were identified through PubMed, Embase, Web of Science, PsycINFO, EconLit, CINAHL, Cochrane Library, and PEDE. The following were explored: patterns in tariff application; linear trends in numbers of studies/samples and paediatric cost-utility analyses (CUAs) and associations between them; changes in proportions of studies/samples within characteristic-based categories over pre-specified periods; impact of National Institute for Health and Care Excellence (NICE) guidance on primary UK research; and associations between valuation method, age and methodological factors.
Results
335 studies with 3,974 samples covering all ICD-10 chapters, 23 valuation methods, 12 respondent types, and 42 countries were identified by systematic review. 34.0% of samples using indirect methods compatible with childhood applied childhood-derived tariffs. There was no association between numbers of studies/samples and numbers of CUAs. Compared to 1990-2008, 2009-June 2017 saw a significant fall in the proportion of studies using case series; significant compositional changes across ICD-10 chapters; and significantly higher sample proportions using childhood/adolescent-specific and adult-specific indirect valuation methods, and based on pre-adolescents, self-assessment, self-administration and experienced health states. NICE guidance was weakly effective in promoting reference methods. Associations between valuation method, age and methodological factors were significant.
Conclusion
1990-2017 witnessed significant changes in primary research on childhood health utilities. Health technology assessment agencies should note the equivocal effect of methodological guidance on primary research methods
A systematic review and meta-analysis of childhood health utilities
Background:
A common feature of most reviews or catalogues of health utilities has been their focus on adult health states or derivation of values from adult populations. More generally, utility measurement in or on behalf of children has been constrained by a number of methodological concerns. The objective of this study was to conduct the first comprehensive systematic review and meta-analysis of primary utility data for childhood conditions and descriptors and to determine the effects of methodological factors on childhood utilities.
Methods:
The review followed PRISMA guidelines. PubMed, Embase, Web of Science, PsycINFO, EconLit, CINAHL and Cochrane Library were searched for primary studies reporting health utilities for childhood conditions or descriptors using direct or indirect valuation methods. The Pediatric Economic Database Evaluation (PEDE) was also searched for cost-utility analyses with primary utility values. Mean or median utilities for each of the main samples were catalogued, whilst weighted averages of utilities for each health condition were estimated, by valuation method. Mixed-effects meta-regression using hierarchical linear modelling was conducted for the most common valuation methods to estimate the utility decrement for each health condition category relative to general childhood population health, as well as the independent effects of methodological factors.
Results:
The literature searches resulted in 272 eligible studies. These yielded 3,414 utilities when all sub-groups were considered, covering all ICD-10 chapters relevant to childhood health, 19 valuation methods, 12 respondent types, 8 modes of administration, and data from 36 countries. A total of 1,191 utility values were obtained when only main study samples were considered and these were catalogued by health condition or descriptor, and methodological characteristics. 1,073 mean utilities for main samples were used for fixed-effects meta-analysis by health condition and valuation method. Mixed-effects meta-regressions estimated that 53 of 76 ICD-10 delineated health conditions valued using the HUI3 were associated with statistically significant utility decrements relative to general population health, whilst 38 of 57 valued using a Visual Analogue Scale (VAS) were associated with statistically significant VAS decrements. For both methods, parental proxy-assessment was associated with overestimation of values, whilst adolescents reported lower values than children under 12 years. VAS responses were more heavily influenced by mode of administration than the HUI3
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