Locked and Unlocked Chains of Planar Shapes

We extend linkage unfolding results from the well-studied case of polygonal linkages to the more general case of linkages of polygons. More precisely, we consider chains of nonoverlapping rigid planar shapes (Jordan regions) that are hinged together sequentially at rotatable joints. Our goal is to characterize the families of planar shapes that admit locked chains, where some configurations cannot be reached by continuous reconfiguration without self-intersection, and which families of planar shapes guarantee universal foldability, where every chain is guaranteed to have a connected configuration space. Previously, only obtuse triangles were known to admit locked shapes, and only line segments were known to guarantee universal foldability. We show that a surprisingly general family of planar shapes, called slender adornments, guarantees universal foldability: roughly, the distance from each edge along the path along the boundary of the slender adornment to each hinge should be monotone. In contrast, we show that isosceles triangles with any desired apex angle less than 90 degrees admit locked chains, which is precisely the threshold beyond which the inward-normal property no longer holds.Comment: 23 pages, 25 figures, Latex; full journal version with all proof details. (Fixed crash-induced bugs in the abstract.

Localizability of Wireless Sensor Networks: Beyond Wheel Extension

A network is called localizable if the positions of all the nodes of the network can be computed uniquely. If a network is localizable and embedded in plane with generic configuration, the positions of the nodes may be computed uniquely in finite time. Therefore, identifying localizable networks is an important function. If the complete information about the network is available at a single place, localizability can be tested in polynomial time. In a distributed environment, networks with trilateration orderings (popular in real applications) and wheel extensions (a specific class of localizable networks) embedded in plane can be identified by existing techniques. We propose a distributed technique which efficiently identifies a larger class of localizable networks. This class covers both trilateration and wheel extensions. In reality, exact distance is almost impossible or costly. The proposed algorithm based only on connectivity information. It requires no distance information

Characterizing the universal rigidity of generic frameworks

A framework is a graph and a map from its vertices to E^d (for some d). A framework is universally rigid if any framework in any dimension with the same graph and edge lengths is a Euclidean image of it. We show that a generic universally rigid framework has a positive semi-definite stress matrix of maximal rank. Connelly showed that the existence of such a positive semi-definite stress matrix is sufficient for universal rigidity, so this provides a characterization of universal rigidity for generic frameworks. We also extend our argument to give a new result on the genericity of strict complementarity in semidefinite programming.Comment: 18 pages, v2: updates throughout; v3: published versio

Interventions for improving clinical outcomes and health-related quality-of-life for people living with skeletal dysplasias: an evidence gap map

Purpose: Skeletal dysplasias are rare genetic disorders that are characterized by abnormal development of bone and cartilage. There are multiple medical and non-medical treatments for specific symptoms of skeletal dysplasias e.g. pain, as well as corrective surgical procedures to improve physical functioning. The aim of this paper was to develop an evidence-gap map of treatment options for skeletal dysplasias, and their impact on patient outcomes. Methods: We conducted an evidence-gap map to identify the available evidence on the impact of treatment options on people with skeletal dysplasias on clinical outcomes (such as increase in height), and dimensions of health-related quality of life. A structured search strategy was applied to five databases. Two reviewers independently assessed articles for inclusion in two stages: titles and abstracts (stage 1), and full text of studies retained at stage 2. Results: 58 studies fulfilled our inclusion criteria. The included studies covered 12 types of skeletal dysplasia that are non-lethal with severe limb deformities that could result in significant pain and numerous orthopaedic interventions. Most studies reported on the effect of surgical interventions (n = 40, 69%), followed by the effect of treatments on dimensions of health quality-of-life (n = 4, 6.8%) and psychosocial functioning (n = 8, 13.8%). Conclusion: Most studies reported on clinical outcomes from surgery for people living with Achondroplasia. Consequently, there are gaps in the literature on the full range of treatment options (including no active treatment), outcomes and the lived experience of people living with other skeletal dysplasias. More research is warranted to examine the impact of treatments on health-related quality-of-life of people living with skeletal dysplasias, including their relatives to enable them to make preference- and valued based decisions about treatment

Frailty exists in younger adults admitted as surgical emergency leading to adverse outcomes

Background: Frailty is prevalent in the older adult population (≥65 years of age) and results in adverse outcomes in the emergency general surgical population. Objective: To determine whether frailty exists in the younger adult emergency surgical population (<65 years) and what influence frailty may have on patient related outcomes. Design: Prospective observational cohort study. Setting: Emergency general surgical admissions. Participants: All patients ≥40 years divided into 2 groups: younger adults (40-64.9 years) and older adult comparative group (≥65). Measurements: Over a 6-month time frame the following data was collected: demographics; Scottish Index of Multiple Deprivation (SIMD); blood markers; multi-morbidities, polypharmacy and cognition. Frailty was assessed by completion of the Canadian Study of Health and Ageing (CSHA). Each patient was followed up for 90 days to allow determination of length of stay, re-admission and mortality. Results: 82 young adults were included and the prevalence of frailty was 16% (versus older adults 38%; p=0.001) and associated with: multi-morbidity; poly-pharmacy; cognitive impairment; and deprivation. Frailty in older adults was only significantly associated with increasing age. Conclusions: This novel study has found that frailty exists in 16% of younger adults admitted to emergency general surgical units, potentially leading to adverse short and long-term outcomes. Strategies need to be developed that identify and treat frailty in this vulnerable younger adult population

Complementary and Alternative Medical Therapies for Chronic Low Back Pain: What Treatments are Patients Willing to Try?

Background: Although back pain is the most common reason patients use complementary and alternative medical (CAM) therapies, little is known about the willingness of primary care back pain patients to try these therapies. As part of an effort to refine recruitment strategies for clinical trials, we sought to determine if back pain patients are willing to try acupuncture, chiropractic, massage, meditation, and t'ai chi and to learn about their knowledge of, experience with, and perceptions about each of these therapies. Methods: We identified English-speaking patients with diagnoses consistent with chronic low back pain using automated visit data from one health care organization in Boston and another in Seattle. We were able to confirm the eligibility status (i.e., current low back pain that had lasted at least 3 months) of 70% of the patients with such diagnoses and all eligible respondents were interviewed. Results: Except for chiropractic, knowledge about these therapies was low. Chiropractic and massage had been used by the largest fractions of respondents (54% and 38%, respectively), mostly for back pain (45% and 24%, respectively). Among prior users of specific CAM therapies for back pain, massage was rated most helpful. Users of chiropractic reported treatment-related "significant discomfort, pain or harm" more often (23%) than users of other therapies (5–16%). Respondents expected massage would be most helpful (median of 7 on a 0 to 10 scale) and meditation least helpful (median of 3) in relieving their current pain. Most respondents indicated they would be "very likely" to try acupuncture, massage, or chiropractic for their back pain if they did not have to pay out of pocket and their physician thought it was a reasonable treatment option. Conclusions: Most patients with chronic back pain in our sample were interested in trying therapeutic options that lie outside the conventional medical spectrum. This highlights the need for additional studies evaluating their effectiveness and suggests that researchers conducting clinical trials of these therapies may not have difficulties recruiting patients

Taxon-specific responses of Southern Ocean diatoms to Fe enrichment revealed by synchrotron radiation FTIR microspectroscopy

© 2014 Author(s). Photosynthesis by marine diatoms contributes substantially to global biogeochemical cycling and ecosystem productivity. It is widely accepted that diatoms are extremely sensitive to changes in Fe availability, with numerous in situ experiments demonstrating rapid growth and increased export of elements (e.g. C, Si and Fe) from surface waters as a result of Fe addition. Less is known about the effects of Fe enrichment on the phenotypes of diatoms, such as associated changes in nutritional value-furthermore, data on taxon-specific responses are almost non-existent. Enhanced supply of nutrient-rich waters along the coast of the subantarctic Kerguelen Island provide a valuable opportunity to examine the responses of phytoplankton to natural Fe enrichment. Here we demonstrate the use of synchrotron radiation Fourier Transform Infrared (SR-FTIR) microspectroscopy to analyse changes in the macromolecular composition of diatoms collected along the coast and plateau of Kerguelen Island, Southern Ocean. SR-FTIR microspectroscopy enabled the analysis of individual diatom cells from mixed communities of field-collected samples, thereby providing insight into in situ taxon-specific responses in relation to changes in Fe availability. Phenotypic responses were taxon-specific in terms of intraspecific variability and changes in proteins, amino acids, phosphorylated molecules, silicate/silicic acid and carbohydrates. In contrast to some previous studies, silicate/silicic acid levels increased under Fe enrichment, in conjunction with increases in carbohydrate stores. The highly abundant taxon Fragilariopsis kerguelensis displayed a higher level of phenotypic plasticity than Pseudo-nitzschia spp., while analysis of the data pooled across all measured taxa showed different patterns in macromolecular composition compared to those for individual taxon. This study demonstrates that taxon-specific responses to Fe enrichment may not always be accurately reflected by bulk community measurements, highlighting the need for further research into taxon-specific phenotypic responses of phytoplankton to environmental change

X-Ray Groups of Galaxies in the Aegis Deep and Wide Fields

We present the results of a search for extended X-ray sources and their corresponding galaxy groups from 800-ks Chandra coverage of the All-wavelength Extended Groth Strip International Survey (AEGIS). This yields one of the largest X-ray selected galaxy group catalogs from a blind survey to date. The red-sequence technique and spectroscopic redshifts allow us to identify 100$$ of reliable sources, leading to a catalog of 52 galaxy groups. The groups span the redshift range $z\sim0.066-1.544$ and virial mass range $M_{200}\sim1.34\times 10^{13}-1.33\times 10^{14}M_\odot$. For the 49 extended sources which lie within DEEP2 and DEEP3 Galaxy Redshift Survey coverage, we identify spectroscopic counterparts and determine velocity dispersions. We select member galaxies by applying different cuts along the line of sight or in projected spatial coordinates. A constant cut along the line of sight can cause a large scatter in scaling relations in low-mass or high-mass systems depending on the size of cut. A velocity dispersion based virial radius can more overestimate velocity dispersion in comparison to X-ray based virial radius for low mass systems. There is no significant difference between these two radial cuts for more massive systems. Independent of radial cut, overestimation of velocity dispersion can be created in case of existence of significant substructure and also compactness in X-ray emission which mostly occur in low mass systems. We also present a comparison between X-ray galaxy groups and optical galaxy groups detected using the Voronoi-Delaunay method (VDM) for DEEP2 data in this field.Comment: Accepted for publication in AP