A Method for Detection of Local Dimension in Point Cloud Data

We have invented a method that uses the mathematical idea of local homology to calculate the local dimension (one-dimensional, two-dimensional, mixed dimension of varying types) of an underlying object in two-dimensional space from a point cloud approximation. Motivated by the need to find an efficient method for computing local homology, we define a new mathematical object -- the Local Complex, and some variations of this idea -- that we show to be exactly related to the Vietoris-Rips complex under some settings. This concept captures the essence of the local homology of point cloud data at any scale. We provide a computationally tractable heuristic -- the simplex arc projection on a particular variation of the Local Complex -- the Acute Local Complex -- to produce yet another object, simply called the simplex arc projections. Homology computation for this latter class of objects is then described. This homology is then related to the true local homology, by example. This relationship is not tight (as we show by counter-example), and conditions under which it holds are the subject of future extensions to this research. Our method also includes mechanisms for detecting whether a particular dimensionality analysis is mathematically more meaningful (in technical terms, ``persistent\u27\u27) and not just a function of a choice of parameters. We also provide implementation and experimental results on synthetic data as well as a subset of the Sloan Digital Sky Survey data

Biology of "peak" and "late" nesting Ring-billed gulls, Granite Island, Lake Superior

Late-nesting Ring-billed Gulls in this study laid fewer and smaller eggs and hatched fewer young than earlier nesting pairs. Birds nesting late in the season appeared to lack sufficient stimuli for incubation, as indicated by their increased restlessness on the nest and higher desertion rates. Factors affecting their behavior include physical condition and social and environmental stimuli. Late-nesting gulls had a lower body weight and condition index than peak-nesting gulls. Their smaller egg size was attributable to decreased amounts of albumen. Analyses of blood metabolites and hormones were inconclusive. It is suggested that the low reproductive success experienced by "late"-nesting Ring-billed Gulls in this study results predominantly from factors during the incubation period

The FIRST-Optical-VLA Survey for Lensed Radio Lobes

We present results from a survey for gravitationally lensed radio lobes. Lensed lobes are a potentially richer source of information about galaxy mass distributions than lensed point sources, which have been the exclusive focus of other recent surveys. Our approach is to identify radio lobes in the FIRST catalog and then search optical catalogs for coincident foreground galaxies, which are candidate lensing galaxies. We then obtain higher-resolution images of these targets at both optical and radio wavelengths, and obtain optical spectra for the most promising candidates. We present maps of several radio lobes that are nearly coincident with galaxies. We have not found any new and unambiguous cases of gravitational lensing. One radio lobe in particular, FOV J0743+1553, has two hot spots that could be multiple images produced by a z=0.19 spiral galaxy, but the lensing interpretation is problematic.Comment: 38 pages, 18 figures, aastex, accepted to A

Pitch perception and production in congenital amusia: evidence from Cantonese speakers

This study investigated pitch perception and production in speech and music in individuals with congenital amusia (a disorder of musical pitch processing) who are native speakers of Cantonese, a tone language with a highly complex tonal system. Sixteen Cantonese-speaking congenital amusics and 16 controls performed a set of lexical tone perception, production, singing, and psychophysical pitch threshold tasks. Their tone production accuracy and singing proficiency were subsequently judged by independent listeners, and subjected to acoustic analyses. Relative to controls, amusics showed impaired discrimination of lexical tones in both speech and non-speech conditions. They also received lower ratings for singing proficiency, producing larger pitch interval deviations and making more pitch interval errors compared to controls. Demonstrating higher pitch direction identification thresholds than controls for both speech syllables and piano tones, amusics nevertheless produced native lexical tones with comparable pitch heights/contours and intelligibility as controls. Significant correlations were found between pitch threshold and lexical tone perception, music perception and production, but not between lexical tone perception and production for amusics. These findings provide further evidence that congenital amusia is domain-general language-independent pitch-processing deficit that is associated with severely impaired music perception and production, mildly impaired speech perception, and largely intact speech production

How integrated are neurology and palliative care services? Results of a multicentre mapping exercise

Background: Patients affected by progressive long-term neurological conditions might benefit from specialist palliative care involvement. However, little is known on how neurology and specialist palliative care services interact. This study aimed to map the current level of connections and integration between these services. Methods: The mapping exercise was conducted in eight centres with neurology and palliative care services in the United Kingdom. The data were provided by the respective neurology and specialist palliative care teams. Questions focused on: i) catchment and population served; ii) service provision and staffing; iii) integration and relationships. Results: Centres varied in size of catchment areas (39-5,840 square miles) and population served (142,000-3,500,000). Neurology and specialist palliative care were often not co-terminus. Service provisions for neurology and specialist palliative care were also varied. For example, neurology services varied in the number and type of provided clinics and palliative care services in the settings they work in. Integration was most developed in Motor Neuron Disease (MND), e.g., joint meetings were often held, followed by Parkinsonism (made up of Parkinson’s Disease (PD), Multiple-System Atrophy (MSA) and Progressive Supranuclear Palsy (PSP), with integration being more developed for MSA and PSP) and least in Multiple Sclerosis (MS), e.g., most sites had no formal links. The number of neurology patients per annum receiving specialist palliative care reflected these differences in integration (range: 9–88 MND, 3–25 Parkinsonism, and 0–5 MS). Conclusions: This mapping exercise showed heterogeneity in service provision and integration between neurology and specialist palliative care services, which varied not only between sites but also between diseases. This highlights the need and opportunities for improved models of integration, which should be rigorously tested for effectiveness

Simulating rewetting events in intermittent rivers and ephemeral streams: a global analysis of leached nutrients and organic matter

Climate change and human pressures are changing the global distribution and extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56‐98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached organic matter. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events

Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter

Climate change and human pressures are changing the global distribution and the ex‐ tent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (precon‐ ditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experi‐ mentally simulated, under standard laboratory conditions, rewetting of leaves, river‐ bed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative character‐ istics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dis‐ solved substances during rewetting events (56%–98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contrib‐ uted most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental vari‐ ables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached sub‐ stances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying event

Identifying Miscanthus in Iowa

Do you know the difference between the Miscanthus species? One species of Miscanthus is now being evaluated for its bioenergy potential. However, two other species of Miscanthus are becoming invasive in the United States. Due to the invasive risk, this resource will help you learn to identify each species.</p

Food Webs and Trophic Interactions in Intermittent Rivers and Ephemeral Streams

The contraction of aquatic, and expansion of terrestrial, habitats in association with flow cessation and drying in intermittent rivers and ephemeral streams (IRES) fundamentally affect interactions among IRES organisms. Drying alters the relative contributions of autotrophy and heterotrophy to food webs because shredders, microbes, and autotrophs are affected, which often leads heterotrophy to become dominant. Changes in ecosystem dimensions, conditions, and resources fundamentally alter the types, sizes, and abundance of organisms present. Spatial and temporal fragmentation of habitats constrains, compresses, and sometimes expands trophic interactions, often substantially altering interaction strengths due to disproportional effects on large top predators. Drying and rewetting alter the trophic linking of aquatic and terrestrial habitats laterally, longitudinally, and vertically, with the form of food web modification in IRES related to regional differences in climate, biota, and riparian structure. Overall, drying reduces aquatic food chain length and trophic diversity, and often culminates in collapse of aquatic food webs; however, it can also trigger transitions toward terrestrial energy pathways and likely expands terrestrial food web dimensions. Given that hysteresis effects and strong, destabilizing interactions have been observed in drying stream food webs, global changes that exacerbate or produce unnatural drying are likely to have deleterious influences in IRES