Magnetic Gradient Survey at the M. S. Roberts (41HE8) Site in Henderson County, Texas

The M. S. Roberts site is located in Henderson County, Texas and it represents one of the few known Caddo mound sites in the upper Neches River Basin in northeast Texas (Figure 1). The site is situated along Caddo Creek – an eastward-flowing tributary of the Neches River (Perttula et al. 2016; Perttula 2016; Perttula and Walters 2016). The site is located southeast of Athens, Texas. When first recorded, the single mound at the site was approximately 24 m long and 20 m wide and roughly 1.7 m in height (Pearce and Jackson 1931). Directly west of the mound was a large depression, which has since been mostly filled, and likely represents the borrow pit for mound fill. The mound is situated at the southern end of an elevated alluvial landform. The site was first reported to Dr. J. E. Pearce of the University of Texas in September 1931. In October of the same year, archaeologists from the University of Texas began investigating the mound and defining the extent of the associated settlement (Pearce and Jackson 1931). Researchers obtained a surface collection from the site and excavated an unknown number of trenches in the mound where portions of at least one burned and buried Caddo structure was identified. Their excavation notes document that the mound began as a 25 cm deposit of yellow sand constructed on the undisturbed brown sandy loam that defines the alluvial landform. A structure had been built on the yellow sand and then at some point had been burned. The burned structure was then covered with mound fill at least a meter in depth. Materials collected from the surface as part of the 1931 investigations indicate the presence of a Caddo habitation area surrounding the mound and suggest the site was occupied from the fourteenth to the early fifteenth centuries (Perttula et al. 2016; Perttula 2016; Perttula and Walters 2016). At that time, the landscape around the mound was a used as a cotton field and subject to extensive plowing. Today, the landscape is part of a residential ranch development where landowners are stewards of the site with a focus on preservation and research. In January 2015, with the permission of the landowners, renewed interested in the site began with a surface collection and the examination of the artifact collections from the 1931 work held by the Texas Archeological Research Laboratory (Perttula et al. 2016; Perttula 2016; Perttula and Walters 2016). A series of shovel tests and auger holes were then dug in the mound and surrounding habitation area in mid-2015. Shovel tests and auger holes documented organically-stained and charcoal-rich areas within the mound that were thought to represent the remains of several burned Caddo structures, and also identified non-mound habitation deposits at the site. An initial aerial survey was also conducted to map the landform topography, estimate the extent of the current mound dimensions and borrow pit, and to reconstruct changes in the shape and size of the mound since it was first recorded in 1931 (Perttula et al. 2016). The survey employed a small Unmanned Aerial Vehicle (UAV) to map the roughly 20-acre property surrounding the site at a 2 cm per pixel resolution. The aerial survey of the mound and surrounding landscape and the creation of a high-resolution digital elevation model reveal that the mound dimensions have changed significantly from what was reported in 1931 (Perttula et al. 2016). For example, aerial data document both the mound and borrow pit features and show that the mound measures 43 m North-South and 26 m East-West, and is roughly 1 meter above the surrounding terrace surface (Perttula et al. 2016). The aerial survey demonstrates that the mound has elongated over the last century since it was first recorded, likely related to historic landscape modification. In January 2016, the site was again revisited. The purpose of the fieldwork was to better define the spatial extent of archaeological deposits in the non-mounded habitation area and investigate the stratigraphy of mound deposits, identify cultural features in the mound, and hopefully obtain charred plant remains or unburned animal bones from these deposits for AMS dating. To help evaluate and identify the distribution of cultural features in the mound and the surrounding non-mounded habitation area, an area just over 1 hectare or 2.8 acres was surveyed using magnetic gradient and a second aerial survey was completed to refine the overall landscape topography (Figure 2). The magnetic gradient results document the subsurface location of at least two interpreted structures within the mound, the possible locations of three 1931 UT trenches, and several possible pit features proximate to the mound. The combination of aerial and geophysical data and the excavation results are revising our understanding of the archaeological remains and preservation conditions of the site

Local solutions of the optimal power flow problem

The existence of locally optimal solutions to the AC optimal power flow problem (OPF) has been a question of interest for decades. This paper presents examples of local optima on a variety of test networks including modified versions of common networks. We show that local optima can occur because the feasible region is disconnected and/or because of nonlinearities in the constraints. Standard local optimization techniques are shown to converge to these local optima. The voltage bounds of all the examples in this paper are between ±5% and ±10% off-nominal. The examples with local optima are available in an online archive (http://www.maths.ed.ac.uk/optenergy/LocalOpt/) and can be used to test local or global optimization techniques for OPF. Finally we use our test examples to illustrate the behavior of a recent semi-definite programming approach that aims to find the global solution of OPF

MILP formulation for controlled islanding of power networks

This paper presents a flexible optimization approach to the problem of intentionally forming islands in a power network. A mixed integer linear programming (MILP) formulation is given for the problem of deciding simultaneously on the boundaries of the islands and adjustments to generators, so as to minimize the expected load shed while ensuring no system constraints are violated. The solution of this problem is, within each island, balanced in load and generation and satisfies steady-state DC power flow equations and operating limits. Numerical tests on test networks up to 300 buses show the method is computationally efficient. A subsequent AC optimal load shedding optimization on the islanded network model provides a solution that satisfies AC power flow. Time-domain simulations using second-order models of system dynamics show that if penalties were included in the MILP to discourage disconnecting lines and generators with large flows or outputs, the actions of network splitting and load shedding did not lead to a loss of stability

Radio Astronomical Polarimetry and Point-Source Calibration

A mathematical framework is presented for use in the experimental determination of the polarimetric response of observatory instrumentation. Elementary principles of linear algebra are applied to model the full matrix description of the polarization measurement equation by least-squares estimation of non-linear, scalar parameters. The formalism is applied to calibrate the center element of the Parkes Multibeam receiver using observations of the millisecond pulsar, PSR J0437-4715, and the radio galaxy, 3C 218 (Hydra A).Comment: 8 pages, 4 figures, to be published in ApJ

An image-based search for pulsars among Fermi unassociated LAT sources

We describe an image-based method that uses two radio criteria, compactness, and spectral index, to identify promising pulsar candidates among Fermi Large Area Telescope (LAT) unassociated sources. These criteria are applied to those radio sources from the Giant Metrewave Radio Telescope all-sky survey at 150 MHz (TGSS ADR1) found within the error ellipses of unassociated sources from the 3FGL catalogue and a preliminary source list based on 7 yr of LAT data. After follow-up interferometric observations to identify extended or variable sources, a list of 16 compact, steep-spectrum candidates is generated. An ongoing search for pulsations in these candidates, in gamma rays and radio, has found 6 ms pulsars and one normal pulsar. A comparison of this method with existing selection criteria based on gamma-ray spectral and variability properties suggests that the pulsar discovery space using Fermi may be larger than previously thought. Radio imaging is a hitherto underutilized source selection method that can be used, as with other multiwavelength techniques, in the search for Fermi pulsars

The Rising Light Curves of Type Ia Supernovae

We present an analysis of the early, rising light curves of 18 Type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF) and the La Silla-QUEST variability survey (LSQ). We fit these early data flux using a simple power-law $(f(t) = {\alpha\times t^n})$ to determine the time of first light $({t_0})$, and hence the rise-time $({t_{rise}})$ from first light to peak luminosity, and the exponent of the power-law rise ($n$). We find a mean uncorrected rise time of $18.98 {\pm} 0.54$ days, with individual SN rise-times ranging from $15.98$ to $24.7$ days. The exponent n shows significant departures from the simple 'fireball model' of $n = 2$ (or ${f(t) \propto t^2}$) usually assumed in the literature. With a mean value of $n = 2.44 {\pm} 0.13$, our data also show significant diversity from event to event. This deviation has implications for the distribution of 56Ni throughout the SN ejecta, with a higher index suggesting a lesser degree of 56Ni mixing. The range of n found also confirms that the 56Ni distribution is not standard throughout the population of SNe Ia, in agreement with earlier work measuring such abundances through spectral modelling. We also show that the duration of the very early light curve, before the luminosity has reached half of its maximal value, does not correlate with the light curve shape or stretch used to standardise SNe Ia in cosmological applications. This has implications for the cosmological fitting of SN Ia light curves.Comment: 19 pages, 19 figures, accepted for publication in MNRA

A systematic map of evidence on the contribution of forests to poverty alleviation

This is the final version. Available from the publisher via the DOI in this record.Background: Forests provide an essential resource to the livelihoods of an estimated 20% of the global population. The contribution of forest ecosystems and forest-based resources to poverty reduction is increasingly emphasized in international policy discourse and conservation and development investments. However, evidence measuring the effect of forest-based activities on poverty outcomes remains scattered and unclear. Lack of systematic understanding of forest-poverty relationships, in turn, inhibits research, policymaking, and efficient financial resource allocation. Methods: To identify relevant studies for inclusion in this systematic map we searched six bibliographic databases, 15 organizational websites, eight systematic evidence syntheses (reviews and maps), and solicited information from key informants. Search results were screened for relevance against predefined inclusion criteria at title, abstract, and full text levels, according to a published protocol. Included articles were coded using a predefined framework. Trends in the evidence, knowledge gaps and relatively well-researched sub-topics are reported in a narrative synthesis. Occurrence and extent of existing evidence about links between interventions and outcomes are presented in a visual heatmap. Data are available through the open access Evidence for Nature and People Data Portal (http://www.natureandpeopleevidence.org). Results: A total of 242 articles were included in the systematic map database. Included articles measured effects of 14 forest-based intervention types on 11 poverty dimensions. The majority of the evidence base (72%) examined links between productivity-enhancement strategies (e.g. forest management, agroforestry, and habitat management) and monetary income and/or social capital outcomes. Other areas with high occurrence of articles include linkages between interventions involving governance, individual rights/empowerment or linked enterprises/livelihood alternatives with impacts on monetary income from direct sale of goods. A key knowledge gap was on the impacts of investment-based interventions (i.e. enhancing produced, human, and social capitals). Another was the impacts of forest-based interventions on financial capital (savings, debt), non-monetary benefits, and health. Conclusions: The evidence base on forest-based productive activities and poverty alleviation is growing but displays a number of biases in the distribution of articles on key linkages. Priorities for future systematic reviews and evaluations include in-depth examinations into the impacts of rights-based activities (e.g. governance, empowerment) on poverty dimensions; and productivity-enhancing activities on social capital. More comprehensive and robust evidence is needed to better understand the synergies and trade-offs among the different objectives of forest conservation and management and variation in outcomes for different social groups in different social-ecological contexts

Altered hippocampal function in major depression despite intact structure and resting perfusion

Background: Hippocampal volume reductions in major depression have been frequently reported. However, evidence for functional abnormalities in the same region in depression has been less clear. We investigated hippocampal function in depression using functional magnetic resonance imaging (fMRI) and neuropsychological tasks tapping spatial memory function, with complementing measures of hippocampal volume and resting blood flow to aid interpretation. Method: A total of 20 patients with major depressive disorder (MDD) and a matched group of 20 healthy individuals participated. Participants underwent multimodal magnetic resonance imaging (MRI): fMRI during a spatial memory task, and structural MRI and resting blood flow measurements of the hippocampal region using arterial spin labelling. An offline battery of neuropsychological tests, including several measures of spatial memory, was also completed. Results: The fMRI analysis showed significant group differences in bilateral anterior regions of the hippocampus. While control participants showed task-dependent differences in blood oxygen level-dependent (BOLD) signal, depressed patients did not. No group differences were detected with regard to hippocampal volume or resting blood flow. Patients showed reduced performance in several offline neuropsychological measures. All group differences were independent of differences in hippocampal volume and hippocampal blood flow. Conclusions: Functional abnormalities of the hippocampus can be observed in patients with MDD even when the volume and resting perfusion in the same region appear normal. This suggests that changes in hippocampal function can be observed independently of structural abnormalities of the hippocampus in depression

Insects for breakfast and whales for dinner: the diet and body condition of dingoes on Fraser Island (K’gari)

Top-predators play stabilising roles in island food webs, including Fraser Island, Australia. Subsidising generalist predators with human-sourced food could disrupt this balance, but has been proposed to improve the overall health of the island’s dingo (Canis lupus dingo) population, which is allegedly ‘starving’ or in ‘poor condition’. We assess this hypothesis by describing the diet and health of dingoes on Fraser Island from datasets collected between 2001 and 2015. Medium-sized mammals (such as bandicoots) and fish were the most common food items detected in dingo scat records. Stomach contents records revealed additional information on diet, such as the occurrence of human-sourced foods. Trail camera records highlighted dingo utilisation of stranded marine fauna, particularly turtles and whales. Mean adult body weights were higher than the national average, body condition scores and abundant-excessive fat reserves indicated a generally ideal-heavy physical condition, and parasite loads were low and comparable to other dingo populations. These data do not support hypotheses that Fraser Island dingoes have restricted diets or are in poor physical condition. Rather, they indicate that dingoes on Fraser Island are capable of exploiting a diverse array of food sources which contributes to the vast majority of dingoes being of good-excellent physical condition