NONPARAMETRIC ESTIMATION OF DERIVATIVES WITH APPLICATIONS

We review several nonparametric regression techniques and discuss their various strengths and weaknesses with an emphasis on derivative estimation and confidence band creation. We develop a generalized C(p) criterion for tuning parameter selection when interest lies in estimating one or more derivatives and the estimator is both linear in the observed responses and self-consistent. We propose a method for constructing simultaneous confidence bands for the mean response and one or more derivatives, where simultaneous now refers both to values of the covariate and to all derivatives under consideration. In addition we generalize the simultaneous confidence bands to account for heteroscedastic noise. Finally, we consider the characterization of nanoparticles and propose a method for identifying a proper subset of the covariate space that is most useful for characterization purposes

Manipulation of Surface Plasmon Resonance in Metal and Alloy Thin Films Using Dielectric Media

Surface plasmon polaritons are coherent electron oscillations that propagate along an interface between a Drude metal and a dielectric medium. The excitation of polaritons is highly dependent on the dielectric properties of the metal, the thickness of the metal, and the optical properties of the dielectric material. First, plasmonic activity is assessed for several thicknesses of silver and nickel chromium under He-Ne incidence. Relationships between film thickness and metal dielectric function are explored in both cases. To manipulate the plasmonic activity at the silver surfaces, two methods are explored. Silver oxide was grown on the surface of the silver films, and the resulting reflection curves are compared to the curves of the metal silver film alone. Next, a polymer was added to the top of the silver films, and the reflection curves were compared. Poling of the polymer is also discussed and attempted as a means of dynamically modulating the reflection curves. A weak relationship between the dielectric function of silver and the plasmonic activity was found. No definite relationship between the dielectric function of nickel chromium and plasmonic activity was found. Both dielectric media studied were found to alter the plasmonic activity at the metal-dielectric interface

Epicormic branching in Southern red oak (Quercus falcata Michx)--a measure of maximum degrade associated with reduced stocking in older stands

The objectives of the study were: (1) to quantify the relative loss in crop-tree lumber value resulting from increased epicormic branching brought on by stand density reduction, and (2) to quantify the time frame required for this loss to attain economic importance. The study was carried out in West Tennessee and examined the effect of a 13-year-old thinning in a seventy-six-year old hardwood stand dominated by Southern red oak (Quercus falcata Michx). Four sample trees were taken from a stand which had developed at a high level of stocking (127 sq. ft. basal area per acre) and compared to four sample trees from a contiguous part of the same forest stand which had been reduced from 85 to 60 sq. ft. of basal area in 1959. Data were collected regarding site characteristics and the density of surrounding stems, using sample trees as quarter-acre plot centers. Sample trees were logged and sawed, and lumber was graded and indexed to quadrants and log sequence including slab and board position; also, knots were examined to determine the character of their origin. The first boards sawed from the four quadrants of the lower 34 feet of sample trees were used in the lumber degrade comparison. Total firstboard volume was 665 board feet (321 bd. ft. and 344 bd. ft. from the low- and high-density areas, respectively), which was about one-fourth of the total scaled log volume of sample trees. Epicormic branch knots in sample trees showed a significant; (0.05 level) inverse relationship to understory density in all plot quadrants except the southeast. Epicormic branching in all logs above 8-1/2 feet also showed a definite inverse relationship to density of the understory. There were little differences in epicormic branching in the lower 8-1/2- ft. log between stand density areas, but differences began to appear in the second 8-1/2-ft. log and became greater with increasing height in the sample tree. The value difference per thousand board feet of first-board lumber between the two stand density areas was found to be about $50.00 at current prices, and to have been about one-fourth the market price of No. 1 Common red oak lumber for consecutive five-year periods during the past 25 years. The number of epicormic knots in lumber from the low-density area (average 111 per tree or nine times as many as in trees from the high stand density area) was felt to be more a result of early low stocking levels than attributable to the 1959 thinning. Because of the already high number of epicormics, devaluation attributable to the thinning was negligible. However, a similar thinning in the high stand density area probably would have resulted in potentially serious devaluation of subsequent wood production, up to$50.00 per MBF. Degrade of this magnitude would take at least 13 years to form, however, and would vary by the diameter growth rate and form of the individual tree, and by current lumber price levels

Design of a Small-Scale System for the Growth of Artificial Sea Ice

Sea ice plays a significant role in global climate systems, reflecting a significant portion of solar energy back into the atmosphere and maintaining ocean circulation currents. The effect of climate change on sea ice extent and seasonal changes is as yet unquantified. This is especially true for the initial growth processes and properties within the Antarctic Marginal Ice Zone (MIZ) front during the winter growth season. The Polar Engineering Research Group (PERG) at the University of Cape Town has conducted several research expeditions to the Antarctic MIZ along the 0° line of longitude, collecting samples of first year sea ice. Artificial sea ice has been used as a supplementary area of study because of the advanced control it provides over variables such as cooling rate or initial solution salinity. This allows for the effect of individual variables to be analysed through repeated experiments while adjusting only the variable of interest. Due to the complex nature and conditions of formation for Antarctic sea ice, this study focusses on the key properties of sea ice formed in predominantly calm conditions. These are observed as vertically elongated ice crystals with a c-axis located randomly within the horizontal plane. The profile of ice thickness over time displays a √ x shape. Brine inclusions are located in vertically orientated, interconnected channels, contained within the intracrystalline planes. The crystal planes have spacings of about 1 mm. Lastly, the salinity profile of the ice displays a characteristic c-shaped curve with depth, with higher values of salinity found at the top and bottom of the ice. Ice fitting this description is referred to as columnar S2 ice. The overall aim of this project is to design and test a small-scale system for the growth of artificial sea ice. This system will still enable method development of testing protocols for the testing of the Antarctic sea ice. Once this system has proven to reliably produce saline ice that can be termed as artificial sea ice with a columnar S2 structure, additional design implementations can then be undertaken to accomplish the growth of sea ice that more closely resembles the ice found in the Antarctic MIZ. The system is required to be large enough to produce samples of appropriate size and number to fit the testing protocols for mechanical testing set out by Schwarz et al. (1981), while being statistically sound. Secondary design objectives were to ensure the system is costeffective, portable and simple. A proof of design concept experiment, consisting of a 28 g kg−1 saline solution cooled at at a temperature of - 20 °C, was carried out in order to test the system design. The hypothesis is that the system design will be able to produce saline ice with properties similar to natural sea ice. Temperature profiles and ice growth within the tank were recorded, and ice samples were taken at the end of the run to determine in-ice salinity and crystal morphology. With some refinement of the system to identify the cause of the extended granular and transition layer, the system can be used to provide the necessary test samples for method development for the mechanical testing of sea ice samples collected from the Antarctic MIZ. Following on from this initial design, additional design implementations can be undertaken to accomplish the growth of sea ice that more closely resembles the ice found in the Antarctic MIZ. This will aid in the determination of sea ice properties and studies of the underlying growth processes that cause them

Spirituality and Suicidal Behavior: The Mediating Role of Self-Forgiveness and Psychache

Growing evidence for protective factors of spirituality against physical and mental health related outcomes has led to the consideration of spirituality as a protective factor for suicidal behaviors. Although initial support for this association is promising, spirituality has yet to be explored as it relates to psychache. Additionally, self-forgiveness has emerged as an important protective factor of suicidal behavior, but has not been explored in the context of psychache. Following a model developed by Webb, Hirsch, and Toussaint (2015), the current project explores the protective role of spirituality on suicidal behavior based on three dimensions of spirituality: ritualistic, theistic, and existential. A total of 262 individuals completed a self-report survey online through Amazon Mechanical Turk. Results indicate that only Existential Spirituality is related to suicidal behaviors. Further, self-forgiveness and psychache were found to be serial mediators of this relationship. Implications for clinical interventions and directions for future research are discussed

Relating evolutionary selection and mutant clonal dynamics in normal epithelia

Cancer develops from mutated cells in normal tissues. Whether somatic mutations alter normal cell dynamics is key to understanding cancer risk and guiding interventions to reduce it. An analysis of the first incomplete moment of size distributions of clones carrying cancer-associated mutations in normal human eyelid skin gives a good fit with neutral drift, arguing mutations do not affect cell fate. However, this suggestion conflicts with genetic evidence in the same dataset that argues for strong positive selection of a subset of mutations. This implies cells carrying these mutations have a competitive advantage over normal cells, leading to large clonal expansions within the tissue. In normal epithelium, clone growth is constrained by the limited size of the proliferating compartment and competition with surrounding cells. We show that if these factors are taken into account, the first incomplete moment of the clone size distribution is unable to exclude non-neutral behaviour. Furthermore, experimental factors can make a non-neutral clone size distribution appear neutral. We validate these principles with a new experimental data set showing that when experiments are appropriately designed, the first incomplete moment can be a useful indicator of non-neutral competition. Finally, we discuss the complex relationship between mutant clone sizes and genetic selection.Royal Society, Wellcome Trust, Clare Colleg