A Vulnerability Assessment of the East Tennessee State University Administrative Computer Network.

A three phase audit of East Tennessee State University\u27s administrative computer network was conducted during Fall 2001, Spring 2002, and January 2004. Nmap and Nessus were used to collect the vulnerability data. Analysis discovered an average of 3.065 critical vulnerabilities per host with a low of 2.377 in Spring 2001 to a high of 3.694 in Fall 2001. The number of unpatched Windows operating system vulnerabilities, which accounted for over 75% of these critical vulnerabilities, strongly argues for the need of an automated patch deployment system for the approximately 3,000 Windows-based systems at ETSU

Generalized Branching in Circle Packing

Circle packings are configurations of circle with prescribed patterns of tangency. They relate to a surprisingly diverse array of topics. Connections to Riemann surfaces, Apollonian packings, random walks, Brownian motion, and many other topics have been discovered. Of these none has garnered more interest than circle packings\u27 relationship to analytical functions. With a high degree of faithfulness, maps between circle packings exhibit essentially the same geometric properties as seen in classical analytical functions. With this as motivation, an entire theory of discrete analytic function theory has been developed. However limitations in this theory due to the discreteness of circle packings are shown to be unavoidable. This thesis explores methods to introduce continuous parameters for the purpose of overcoming these difficulties. Our topics include, packings with deep overlaps, fractional branching, and shift-points. Using the software package CirclePack, examples of some previously non-realizable discrete functions in circle packing are shown to computational exist using these techniques. Some necessary theory is developed including a generalization for overlapping packings and some results for expressing singularities associated with faces

Fractured Branched Circle Packings on the Plane

William Thurston first proposed that real circles could be used to approximate the underlying infinitesimal circles of conformal maps in 1985. Inspired pioneers developed Circle Packing into a very rich and deep field that can be used as a method for constructing discrete conformal maps of surfaces on different types of geometries. Offering the advantages of a computational method that lends itself to experimentation and the easy creation of visual models, Circle Packing has proven itself as valuable new tool in approaching both old and new problems. In particular, Circle Packing has been used to make discrete analogues of continuous functions; however existing methods are inadequate for certain classical functions. As a solution to this problem, Kenneth Stephenson has suggested using a branched circle packing where the extra angle sum is distributed amongst more than one circle. The purpose of this paper is to investigate the behavior of such circle packings on the plane. The result is the revelation of a subject worthy of interest beyond its potential aide to other problems. Normally, maps are made in Circle Packing are created by laying out circles adjacently to each other like a group of coins laid out on a table. Taking a group of circles similar to this, we can cut a slit from the exterior to a point in the center called the branch point. We can then wrap the cut edges around like a spiraling staircase by a multiple of 2π, creating a branched map. Branched maps are mostly similar to non-branched packings with the exception that they are necessarily globally non-univalent. Adding fractured multiples of 2π to more than a single point does not necessarily result in a map that makes any sense. Regardless of how complicated or simple our original map may be, most of these questions can be answered by surprisingly simple geometry. Furthermore, despite the difficulty that these unfamiliar terms may cause the non-mathematician, the visual nature of circle packing provides models and pictures that bring the concepts to life, making these ideas accessible to most anyone with a high school level understanding of geometry

A Revision of the Genus Elmas Blackwelder, 1952 (Coleoptera: Staphylinidae: Staphylininae: Xanthopygina), with a Preliminary Reconstructed Phylogeny of the Species1

The staphylinid genus Elmas Blackwelder 1952 (type.species: Selma modesta Sharp 1876 from Chontales, Nicaragua) is revised for the first time. The two previously described species, E. modesta (Sharp) from Nicaragua and E. strigella (Bernhauer) from Brazil, are redescribed. Fifteen species are described as new: Elmas brooksi from Ecuador; Elmas costaricensis from Costa Rica; Elmas elassos from Ecuador; Elmas esmeraldas from Ecuador; Elmas falini from Suriname; Elmas gigas from Peru; Elmas guianas from-French Guiana; Elmas hanleyi from Costa Rica; Elmas hibbsi from Ecuador; Elmas lambas from Brazil; Elmas lescheni from Peru; Elmas panamaensis from Panama; Elmas patillas from Costa Rica; Elmas spinosus from Bolivia; and Elmas windsori from Panama. A key and illustrations of structural features and aedeagi are provided for identification of the known species. The phylogenetic relationships of the species of Elmas species are only weakly resolved by the available dataset. Elmas is strongly supported to be a monophyletic lineage, and E. strigella is the most basal species followed by E. lambos and E. guianas respectively. E. spinosus + E. falini + E. gigas are strongly supported to be a monophyletic . group; E. hfbbsi is weakly supported to be the sister group to these three species. The lineage (E. windsori · + E. costaricensis) + (E. panamaensis + E. patillas) is weakly supported in all trees. The lineage E. elassos + E. hanleyi + E. esmeraldas is also weakly supported, and the successive approximation analysis hypothesizes that E. modesta is also a member of this lineage

The probable larva of an undescribed species of Edrabius (Coleoptera: Staphylinidae) and its implications for the systematics of the tribe Amblyopinini.

Larval staphylinids collected from the nest of the Chilean tuco-tuco, Ctenomys maulinus brunneus, are presumed to be those of an undescribed species of Edrabius, adults of which are known to occur on this host. These larvae are described and illustrations are provided for their identification. The larvae are characteristic of the subfamily Staphylininae; however, they do not have a combination of characteristics which allows unambiguous placement into one of the described tribes of this subfamily. Edrabius larvae share the greatest number of characteristics with larvae of the tribe Staphylinini, and, among these, with members of the subtribe Xanthopygina. Importantly, they differ from larvae of the tribe Quediini, to which the amblyopinines were believed to be related, in a number of significant ways. However, Edrabius may not be a part of a monophyletic lineage with the remainder of the South American amblyopinines

Learning-Induced Improvement in Encoding and Decoding of Specific Movement Directions by Neurons in the Primary Motor Cortex

Many recent studies describe learning-related changes in sensory and motor areas, but few have directly probed for improvement in neuronal coding after learning. We used information theory to analyze single-cell activity from the primary motor cortex of monkeys, before and after learning a local rotational visuomotor task. We show that after learning, neurons in the primary motor cortex conveyed more information about the direction of movement and did so with relation to their directional sensitivity. Similar to recent findings in sensory systems, this specific improvement in encoding is correlated with an increase in the slope of the neurons' tuning curve. We further demonstrate that the improved information after learning enables a more accurate reconstruction of movement direction from neuronal populations. Our results suggest that similar mechanisms govern learning in sensory and motor areas and provide further evidence for a tight relationship between the locality of learning and the properties of neurons; namely, cells only show plasticity if their preferred direction is near the training one. The results also suggest that simple learning tasks can enhance the performance of brain–machine interfaces

Cerebellar contributions to visual attention and working memory

Attention and working memory (WM) are processes that enable the efficient prioritization or storage of a subset of available information. Consequently, a substantial body of work has sought to determine the specific brain structures that support attention and WM. To date, this literature has predominantly focused on the contributions of a limited set of cortical areas referred to as the dorsal attention network (DAN). The cerebellum, a subcortical structure traditionally implicated in motor control, has received scant consideration as a locus of attentional control, despite findings of robust anatomical and functional connectivity between cerebellum and DAN areas. This project comprises several functional magnetic resonance imaging experiments aimed at elucidating the role of the cerebellum in attention and WM (n = 38; 20-38 years). The functional implications of cortico-cerebellar DAN connectivity have received only modest scientific attention. Experiment 1 examined the hypothesis that cortico-cerebellar DAN functional connectivity predicts recruitment by canonical visual WM and attention tasks. Task-driven responses of DAN-coupled cerebellar areas were found to mirror those of their cortical counterparts. These results argue for the reconceptualization of the DAN as a cortico-cerebellar network. Previous work indicates that the functional topography of the cerebellum is relatively coarse compared with cerebral cortex. Experiment 2 examined the organization of closely related aspects of visual attention and WM within the cerebellum, and found that spatial attention and visual WM recruit overlapping yet dissociable portions of cerebellar lobule VIIb/VIIIa. This functional organization was further shown to be predicted by fine-scale patterns of functional connectivity with occipito-parietal cortex. These findings indicate that the functional specificity of cerebellar cortex mirrors that of cerebral cortex and provides direct empirical support for the hypothesis that functional specialization within the cerebellum arises due to variation in afferent input. Experiment 3 tested the hypothesis that the cerebellum can be specifically implicated in the persistent representation of information in WM. Lobule VIIb/VIIIa delay-period activity patterns were shown to exhibit stimulus-selectivity, a critical marker of WM storage processes. These results indicate that lobule VIIb/VIIIa contains a robust representation of a stimulus stored in WM, thereby refuting long-standing cortico-centric models of WM maintenance.2021-02-10T00:00:00

Interacting Adaptive Processes with Different Timescales Underlie Short-Term Motor Learning

Multiple processes may contribute to motor skill acquisition, but it is thought that many of these processes require sleep or the passage of long periods of time ranging from several hours to many days or weeks. Here we demonstrate that within a timescale of minutes, two distinct fast-acting processes drive motor adaptation. One process responds weakly to error but retains information well, whereas the other responds strongly but has poor retention. This two-state learning system makes the surprising prediction of spontaneous recovery (or adaptation rebound) if error feedback is clamped at zero following an adaptation-extinction training episode. We used a novel paradigm to experimentally confirm this prediction in human motor learning of reaching, and we show that the interaction between the learning processes in this simple two-state system provides a unifying explanation for several different, apparently unrelated, phenomena in motor adaptation including savings, anterograde interference, spontaneous recovery, and rapid unlearning. Our results suggest that motor adaptation depends on at least two distinct neural systems that have different sensitivity to error and retain information at different rates

Disruption of State Estimation in the Human Lateral Cerebellum

The cerebellum has been proposed to be a crucial component in the state estimation process that combines information from motor efferent and sensory afferent signals to produce a representation of the current state of the motor system. Such a state estimate of the moving human arm would be expected to be used when the arm is rapidly and skillfully reaching to a target. We now report the effects of transcranial magnetic stimulation (TMS) over the ipsilateral cerebellum as healthy humans were made to interrupt a slow voluntary movement to rapidly reach towards a visually defined target. Errors in the initial direction and in the final finger position of this reach-to-target movement were significantly higher for cerebellar stimulation than they were in control conditions. The average directional errors in the cerebellar TMS condition were consistent with the reaching movements being planned and initiated from an estimated hand position that was 138 ms out of date. We suggest that these results demonstrate that the cerebellum is responsible for estimating the hand position over this time interval and that TMS disrupts this state estimate