Data Assimilation by Conditioning on Future Observations

Conventional recursive filtering approaches, designed for quantifying the state of an evolving uncertain dynamical system with intermittent observations, use a sequence of (i) an uncertainty propagation step followed by (ii) a step where the associated data is assimilated using Bayes' rule. In this paper we switch the order of the steps to: (i) one step ahead data assimilation followed by (ii) uncertainty propagation. This route leads to a class of filtering algorithms named \emph{smoothing filters}. For a system driven by random noise, our proposed methods require the probability distribution of the driving noise after the assimilation to be biased by a nonzero mean. The system noise, conditioned on future observations, in turn pushes forward the filtering solution in time closer to the true state and indeed helps to find a more accurate approximate solution for the state estimation problem

Approaching zero : temporal effects of a restrictive antibiotic policy on hospital-acquired Clostridium difficile, extended-spectrum β-lactamase-producing coliforms and meticillin-resistant Staphylococcus aureus

A restrictive antibiotic policy banning routine use of ceftriaxone and ciprofloxacin was implemented in a 450-bed district general hospital following an educational campaign. Monthly consumption of nine antibiotics was monitored in defined daily doses (DDDs) per 1000 patient-occupied bed-days (1000 pt-bds) 9 months before until 16 months after policy introduction. Hospital-acquired Clostridium difficile, meticillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum -lactamase (ESBL)- producing coliform cases per month/1000 pt-bds were identified and reviewed throughout the hospital. Between the first and final 6 months of the study, average monthly consumption of ceftriaxone reduced by 95% (from 46.213 to 2.129 DDDs/1000 pt-bds) and that for ciprofloxacin by 72.5% (109.804 to 30.205 DDDs/1000 pt-bds). Over the same periods, hospital-acquisition rates for C. difficile reduced by 77% (2.398 to 0.549 cases/1000 pt-bds), for MRSA by 25% (1.187 to 0.894 cases/1000 pt-bds) and for ESBL-producing coliforms by 17% (1.480 to 1.224 cases/1000 pt-bds). Time-lag modelling confirmed significant associations between ceftriaxone and C. difficile cases at 1 month (correlation 0.83; P < 0.005), and between ciprofloxacin and ESBL-producing coliform cases at 2 months (correlation 0.649; P = 0.002). An audit performed 3 years after the policy showed sustained reduction in C. difficile rates (0.259 cases/1000 pt-bds), with additional decreases for MRSA (0.409 cases/1000 pt-bds) and ESBL-producing coliforms (0.809 cases/1000 pt-bds). In conclusion, banning two antibiotics resulted in an immediate and profound reduction in hospital-acquired C. difficile, with possible longer-term effects on MRSA and ESBL-producing coliform rates. Antibiotic stewardship is fundamental in the control of major hospital pathogens

Biomechanical Analysis of an Interspinous Process Fixation Device with In Situ Shortening Capabilities: Does Spinous Process Compression Improve Segmental Stability?

OBJECTIVE: The objective of this study was to characterize the biomechanical implications of spinous process compression, via in situ shortening of a next-generation interspinous process fixation (ISPF) device, in the context of segmental fusion. METHODS: Seven lumbar cadaveric spines (L1-L4) were tested. Specimens were first tested in an intact state, followed by iterative instrumentation at L2-3 and subsequent testing. The order followed was 1) stand-alone ISPF (neutral height); 2) stand-alone ISPF (shortened in situ from neutral height; shortened); 3) lateral lumbar interbody fusion (LLIF) + ISPF (neutral); 4) LLIF + ISPF (shortened); 5) LLIF + unilateral pedicle screw fixation; 6) LLIF + bilateral pedicle screw fixation. A 7.5-Nm moment was applied in flexion/extension, lateral bending, and axial rotation via a kinematic test frame. Segmental range of motion (ROM) and lordosis were measured for all constructs. Comparative analysis was performed. RESULTS: Statistically significant flexion/extension ROM reductions: all constructs versus intact condition (P \u3c 0.01); LLIF + ISPF (neutral and shortened) versus stand-alone ISPF (neutral and shortened) (P \u3c 0.01); LLIF + USPF versus ISPF (neutral) (P = 0.049); bilateral pedicle screw fixation (BPSF) versus stand-alone ISPF (neutral and shortened) (P \u3c 0.01); LLIF + BPSF versus LLIF + unilateral pedicle screw fixation (UPSF) (P \u3c 0.01). Significant lateral bending ROM reductions: LLIF + ISPF (neutral and shortened) versus intact condition and stand-alone ISPF (neutral) (P \u3c 0.01); LLIF + UPSF versus intact condition and stand-alone ISPF (neutral and shortened) (P \u3c 0.01); LLIF + BPSF versus intact condition and all constructs (P \u3c 0.01). Significant axial rotation ROM reductions: LLIF + ISPF (shortened) and LLIF + UPSF versus intact condition and stand-alone ISPF (neutral) (P ≤ 0.01); LLIF + BPSF versus intact condition and all constructs (P ≤ 0.04). CONCLUSIONS: In situ shortening of an adjustable ISPF device may support increased segmental stabilization compared with static ISPF

Experimental restoration trials in Nakula Natural Area Reserve in preparation for reintroduction of Kiwikiu (Pseudonestor xanthophrys)

Reports were scanned in black and white at a resolution of 600 dots per inch and were converted to text using Adobe Paper Capture Plug-in.The native montane mesic forest in the Kahikinui region of Maui, Hawai‘i USA has been degraded by non-native ungulates for over a century. This has resulted in large areas of non-native grassland and savanna with small intact native forest patches, mainly in steep gulches. The Nakula Natural Area Reserve (NAR), on the southwestern slope of Haleakalā volcano, was selected as the site of the reintroduction of Kiwikiu (Pseudonestor xanthophrys), a critically endangered songbird currently found only in a small range on the northern slope of the volcano. This area was selected for the reintroduction because it is located within a mesic koa (Acacia koa) forest representing some of the best potential habitat outside of the current Kiwikiu range. Historic accounts noted the Kiwikiu’s affinity for koa as a foraging substrate, although little koa forest remains on Maui. Intensive forest restoration has created new habitat and enhanced the existing habitat in Nakula to the point where the reserve may now be capable of supporting a small population of Kiwikiu and other native birds. As a precursor to reintroduction efforts, we designed experimental trials to inform managers of the most efficient and effective techniques to restore the forest in Nakula NAR and surrounding region. Trial plots were established in open grass-dominated areas within a fenced, ungulate-free portion of the reserve to investigate natural regeneration, outplanting, and seed broadcast as restoration techniques under a number of conditions. Treatments to suppress and/or remove non-native grass were implemented as these grasses likely reduce germination of native seedlings and potentially influence outplanting success. Some plots were treated with herbicide and the dead grass biomass was removed to expose bare topsoil in a subset of these plots. Additional plots were established under mature koa trees to investigate natural recruitment and the success of these same restoration techniques in this microhabitat. In two years, natural regeneration was largely limited to ‘a‘ali‘i (Dodonea viscosa) and koa, and was enhanced by the application of herbicide followed by the removal of the grass biomass. Outplanting survivorship was high in most species, exceeding 80% after two years in five of seven species. Treatment application had little effect on survivorship, but the growth rates in four of the seven species planted was greatest in plots where herbicide was applied prior to planting. Seed broadcast was not found to be an effective treatment of producing seedlings. Based on our results, we recommend non-native grass biomass removal combined with outplanting as the primary method of forest restoration in Nakula NAR and the surrounding region.These trials could not have been conducted without the financial support of State of Hawai‘i Department of Land and Natural Resources (DLNR) Division of Forestry and Wildlife (DOFAW), University of Hawai‘i – Manoa, and American Bird Conservancy. We thank Native Nursery LLC for producing high-quality seedlings and preparing seeds for broadcast. We also thank DOFAW-Forestry and The Nature Conservancy for access to seed collection sites. We also thank J. Leary for aide with herbicide methodology and S. Yelenik for helpful comments and edits to this report

A Biomechanical Evaluation of a Next-Generation Integrated and Modular ACDF Device Possessing Full-Plate, Half-Plate, and No-Profile Fixation Iterations.

Study Design: In vitro biomechanical study. Objectives: The objective of this in vitro biomechanical range-of-motion (ROM) study was to evaluate spinal segmental stability following fixation with a novel anterior cervical discectomy and fusion (ACDF) device ( novel device ) that possesses integrated and modular no-profile, half-plate, and full-plate fixation capabilities. Methods: Human cadaveric (n = 18, C3-T1) specimens were divided into 3 groups (n = 6/group). Each group would receive one novel device iteration. Specimen terminal ends were potted. Each specimen was first tested in an intact state, followed by anterior discectomy (C5/C6) and iterative instrumentation. Testing order: (1) novel device (group 1, no-profile; group 2, half-plate; group 3, full-plate); (2) novel device (all groups) with lateral mass screws (LMS); (3) traditional ACDF plate + cage; (4) traditional ACDF plate + cage + LMS. A 2 N·m moment was applied in flexion/extension (FE), lateral bending (LB), and axial rotation (AR) via a kinematic testing machine. Segmental ROM was tracked and normalized to intact conditions. Comparative statistical analyses were performed. Results: Key findings: (1) the novel half- and full-plate constructs provided comparable reduction in FE and LB ROM to that of traditional plated ACDF ( Conclusions: The novel ACDF device may be a versatile alternative to traditional no-profile and independent plating techniques, as it provides comparable ROM reduction in all principle motion directions, across all device iterations

Did you see what I saw?: Comparing attentional synchrony during 360° video viewing in head mounted display and tablets

Advances in head mounted displays (HMDs) have increased the interest in cinematic virtual reality as an art form. However, the freedom of a viewer in 360 video presents challenges in ensuring that audiences do not inadvertently miss important events and locations. We examined whether the high level of immersion provided by HMDs encourages participants to synchronize their attention during viewing. Sixty-four participants watched the 360° documentary Clouds Over Sidra (VRSE.works, 2015) using either an HMD or via a flat screen tablet display. We used intersubject correlation (ISC) analysis to measure attentional synchrony over the course of the video and to examine whether spatial and temporal factors led to different amounts of correlation both within and between groups. We found significantly greater ISC for the HMD compared to the tablet group. This effect was greatest for scenes with a unidirectional focus and at the start of scenes. We discuss our results in terms of the visual properties and the motor affordances of HMDs versus tablets. Our results show the value of HMDs in increasing attentional synchrony and may provide producers of 360° content insight in how to encourage or discourage synchronization of viewing direction

Improved Blackbody Temperature Sensors for a Vacuum Furnace

Some improvements have been made in the design and fabrication of blackbody sensors (BBSs) used to measure the temperature of a heater core in a vacuum furnace. Each BBS consists of a ring of thermally conductive, high-melting-temperature material with two tantalum-sheathed thermocouples attached at diametrically opposite points. The name "blackbody sensor" reflects the basic principle of operation. Heat is transferred between the ring and the furnace heater core primarily by blackbody radiation, heat is conducted through the ring to the thermocouples, and the temperature of the ring (and, hence, the temperature of the heater core) is measured by use of the thermocouples. Two main requirements have guided the development of these BBSs: (1) The rings should have as high an emissivity as possible in order to maximize the heat-transfer rate and thereby maximize temperature-monitoring performance and (2) the thermocouples must be joined to the rings in such a way as to ensure long-term, reliable intimate thermal contact. The problem of fabricating a BBS to satisfy these requirements is complicated by an application-specific prohibition against overheating and thereby damaging nearby instrumentation leads through the use of conventional furnace brazing or any other technique that involves heating the entire BBS and its surroundings. The problem is further complicated by another application-specific prohibition against damaging the thin tantalum thermocouple sheaths through the use of conventional welding to join the thermocouples to the ring. The first BBS rings were made of graphite. The tantalum-sheathed thermocouples were attached to the graphite rings by use of high-temperature graphite cements. The ring/thermocouple bonds thus formed were found to be weak and unreliable, and so graphite rings and graphite cements were abandoned. Now, each BBS ring is made from one of two materials: either tantalum or a molybdenum/titanium/zirconium alloy. The tantalum-sheathed thermocouples are bonded to the ring by laser brazing. The primary advantage of laser brazing over furnace brazing is that in laser brazing, it is possible to form a brazed connection locally, without heating nearby parts to the flow temperature of the brazing material. Hence, it is possible to comply with the prohibition against overheating nearby instrumentation leads. Also, in laser brazing, unlike in furnace brazing, it is possible to exert control over the thermal energy to such a high degree that it becomes possible to braze the thermocouples to the ring without burning through the thin tantalum sheaths on the thermocouples. The brazing material used in the laser brazing process is a titanium-boron paste. This brazing material can withstand use at temperatures up to about 1,400 C. In thermal-cycling tests performed thus far, no debonding between the rings and thermocouples has been observed. Emissivity coatings about 0.001 in. (.0.025 mm) thick applied to the interior surfaces of the rings have been found to improve the performance of the BBS sensors by raising the apparent emissivities of the rings. In thermal-cycling tests, the coatings were found to adhere well to the rings

Swimming Upstream: Identifying student anxieties and solutions

This study explores some of the sources of stress faced by students in higher education. Research identifies an association between stress levels and students’ academic performance. This study aims to determine the sources, level and impact of perceived stresses among students in terms of age, gender, ethnicity, years of study and degree major. Participatory action research was explored as a means of developing strategies and solutions for students experiencing stress-related problems. Eleven undergraduate students were recruited initially as co-researchers with four academic staff and one research assistant. One student continued throughout the cycle with two others having to withdraw because of academic work pressures. A collaborative process took place using narrative storytelling and discussions alongside extra-sessional research. A range of outcomes is anticipated related to the students’ experience and academic achievements. Academic staff responsiveness and concern for student wellbeing and successful achievement will contribute to increased student satisfaction. Identification and development of systematic and effective ways of managing anxieties and sharing this with other HEIs will contribute to student wellbeing. In terms of academic outputs, a paper based on the pilot will be developed and acknowledgement of co-authorship appropriately made. A wider research proposal - inclusive of other universities and programmes can be developed for the future