Pattern and Rate of Decline of a Population of Carolina Hemlock (Tsuga caroliniana Engelm.) in North Carolina

We monitored a population of Carolina Hemlocks in northwestern North Carolina for four years to examine the rate and pattern of decline in response to infestation by Adelges tsugae (Hemlock Woolly Adelgid). Our yearly census of hemlock condition and severity of the adelgid infestation included trees of all sizes. We estimated declines in condition as the portions of the leaf canopy that were lost. Initially, infestation occurred throughout the population but was severe in only a small cluster of individuals. Within 1 year, the area of severe infestation increased in size to encompass 48% of the population. In another region of the population, there was a cluster of relatively healthy individuals comprised largely of seedlings. Of the 4 size-classes of trees, sapling-sized individuals experienced the highest rates of decline in condition. Most trees declined to poor health within 3 years of an observation of moderate to severe infestation

Vascular Flora of the Rocky Fork Tract, Tennessee, USA, and Its Use in Conservation and Management

A flora of the 3800 ha Rocky Fork Tract in northeast Tennessee produced 749 species of which 19 were on the Tennessee Rare Plant List and 34 were on the Cherokee National Forest Species Viability List with 87 county records from Greene County and 217 from Unicoi County. Rare species were particularly numerous in the Cyperaceae and Orchidaceae. The tract serves as a refuge for several regionally uncommon species by supporting either large populations or metapopulations of these species. Exotic species comprised 15% of the flora and were most common in the Fabaceae and Poaceae. The most unique habitat was a heath bald dominated by Rhododendron catawbiense with abundant Xerophyllum asphodeloides in the herbaceous layer. While species richness was relatively high compared to regional sites of comparable area, diversity was limited by the absence of high elevation spruce-fir communities and the paucity of wetlands

High-Performance Silicon-Based Multiple Wavelength Source

We demonstrate a stable CMOS-compatible on-chip multiple-wavelength source by filtering and modulating individual lines from a frequency comb generated by a microring resonator optical parametric oscillator.. We show comb operation in a low-noise state that is stable and usable for many hours. Bit-error rate measurements demonstrate negligible power penalty from six independent frequencies when compared to a tunable diode laser baseline. Open eye diagrams confirm the fidelity of the 10 Gb/s data transmitted at the comb frequencies and the suitability of this device for use as a fully integrated silicon-based WDM source.Comment: 3 pages, 3 figure

Second-Harmonic Generation in Silicon Nitride Ring Resonators

The emerging field of silicon photonics seeks to unify the high bandwidth of optical communications with CMOS microelectronic circuits. Many components have been demonstrated for on-chip optical communications, including those that utilize the nonlinear optical properties of silicon[1, 2], silicon dioxide[3, 4] and silicon nitride[5, 6]. Processes such as second harmonic generation, which are enabled by the second-order susceptibility, have not been developed since the bulk $\chi^{(2)}$ vanishes in these centrosymmetric CMOS materials. Generating the lowest-order nonlinearity would open the window to a new array of CMOS-compatible optical devices capable of nonlinear functionalities not achievable with the?$\chi^{(3)}$ response such as electro-optic modulation, sum frequency up-conversion, and difference frequency generation. Here we demonstrate second harmonic (SH) generation in CMOS compatible integrated silicon nitride (Si3N4) waveguides. The $\chi^{(2)}$ response is induced in the centrosymmetric material by using the nanoscale structure to break the bulk symmetry. We use a high quality factor Q ring resonator cavity to enhance the efficiency of the nonlinear optical process and detect SH output with milliwatt input powers.Comment: 4 pages, 3 figure

Deidamia Inscriptum (lettered Sphinx Moth) Caterpillars Feeding on Oxydendrum Arboreum (sourwood) and Their Predation by Black Bears in Northeast Tennessee

An outbreak of Deidamia inscriptum (Lettered Sphinx Moth) caterpillars was noted in northeast Tennessee where Oxydendrum arboreum (Sourwood) trees were defoliated. Nearly all published literature and online resources list only plants in the grape family (Vitaceae) as larval food plants. Food-plant preference trials using fresh leaves of 3 woody plant species showed that Deidamiacaterpillars from this region had a preference for Sourwood over Parthenocissus quinquefolia(Virginia Creeper), and rejected Acer rubrum (Red Maple), a non-host species. Ursus americanus(Black Bear) were feeding on the caterpillars as evidenced by bent and broken Sourwood saplings bearing claw marks and by abundant sphingid remains in bear scat

Socrates' Praise and Blame of Eros

Thesis advisor: Christopher BruellIt is only in "erotic matters" that Plato's Socrates is wise, or so he claims at least on several occasions, and since his Socrates makes this claim, it is necessary for Plato's readers to investigate the content of Socrates' wisdom about eros. This dissertation undertakes such an investigation. Plato does not, however, make Socrates' view of eros easy to grasp. So diverse are Socrates' treatments of eros in different dialogues and even within the same dialogue that doubt may arise as to whether he has a consistent view of eros; Socrates subjects eros to relentless criticism throughout the Republic and his first speech in the Phaedrus, and then offers eros his highest praise in his second speech in the Phaedrus and a somewhat lesser praise in the Symposium. This dissertation takes the question of why Socrates treats eros in such divergent ways as its guiding thread and offers an account of the ambiguity in eros' character that renders it both blameworthy and praiseworthy in Socrates' estimation. The investigation is primarily of eros in its ordinary sense of romantic love for another human being, for Socrates' most extensive discussions of eros, those of the Phaedrus and Symposium, are primarily about romantic love. Furthermore, as this investigation makes clear, despite his references to other kinds of eros, Socrates distinguishes a precise meaning of eros, according to which eros is always love of another human being. Socrates' view of romantic love is then assessed through studies of the Republic, Phaedrus, and Symposium. These studies present a unified Socratic understanding of eros; despite their apparent differences, Socrates' treatment of eros in each dialogue confirms and supplements that of the others, each providing further insight into Socrates' complete view. In the Republic, Socrates' opposition to eros, as displayed in both his discussion of the communism of the family in book five and his account of the tyrannic soul in book nine, is traced to irrational religious beliefs to which he suggests eros is connected. Socrates then explains this connection by presenting romantic love as a source of such beliefs in the Phaedrus and Symposium. Because eros is such a source, this dissertation argues that philosophy is incompatible with eros in its precise sense, as Socrates subtly indicates even within his laudatory treatments of eros in the Phaedrus and Symposium. Thus, as a source of irrational beliefs, eros is blameworthy. Yet eros is also praiseworthy. Despite his indication that the philosopher would be free of eros in the precise sense, Socrates also argues that the experience of eros can be of great benefit in the education of a potential philosopher. Precisely as a source of irrational religious belief, the erotic experience includes a greater awareness of the longing for immortality and hence the concern with mortality that Socrates believes is characteristic of human beings, and by bringing lovers to a greater awareness of this concern, eros provides a first step towards the self-knowledge characteristic of the philosophic life.Thesis (PhD) — Boston College, 2010.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Political Science

Surface-Soil Properties of Alder Balds with Respect to Grassy and Rhododendron Balds on Roan Mountain, North Carolina—Tennessee

We analyzed soils in Alder Bald, Grassy Bald, and Rhododendron Bald communities on Roan Mountain to infer the influence of vegetation on soil and to help guide management strategies. In all vegetation types, soils were acid (pH = 4–5) sandy loams. We found vegetation-associated differences for organic content, cation exchange capacity, acidity, two plant macronutrients (K, Mg), and three cations (Fe, Na, Zn). We predicted that nitrogen compounds would be highest in the Alder Bald because Alnus viridis ssp. crispa (Green Alder) can harbor nitrogen-fixing bacteria. Organic content was highest at the alder-bald sites, ammonium was similar among vegetation types, and nitrate was high at only some sample sites. The unique soil properties of the Alder Bald community, its likely role in primary succession, and its documentation as a long-standing community type on Roan Mountain suggest that management should be directed towards its conservation

A Silicon-Based Monolithic Optical Frequency Comb Source

Recently developed techniques for generating precisely equidistant optical frequencies over broad wavelength ranges are revolutionizing precision physical measurement [1-3]. These frequency "combs" are produced primarily using relatively large, ultrafast laser systems. However, recent research has shown that broad-bandwidth combs can be produced using highly-nonlinear interactions in microresonator optical parametric oscillators [4-11]. Such devices not only offer the potential for developing extremely compact optical atomic clocks but are also promising for astronomical spectroscopy [12-14], ultrashort pulse shaping [15], and ultrahigh-speed communications systems. Here we demonstrate the generation of broad-bandwidth optical frequency combs from a CMOS-compatible integrated microresonator [16,17], which is a fully-monolithic and sealed chip-scale device making it insensitive to the surrounding environment. We characterize the comb quality using a novel self-referencing method and verify that the comb line frequencies are equidistant over a bandwidth that is nearly an order of magnitude larger than previous measurements. In addition, we investigate the ultrafast temporal properties of the comb and demonstrate its potential to serve as a chip-scale source of ultrafast (sub-ps) pulses