An intelligent assistant for exploratory data analysis

In this paper we present an account of the main features of SNOUT, an intelligent assistant for exploratory data analysis (EDA) of social science survey data that incorporates a range of data mining techniques. EDA has much in common with existing data mining techniques: its main objective is to help an investigator reach an understanding of the important relationships ina data set rather than simply develop predictive models for selectd variables. Brief descriptions of a number of novel techniques developed for use in SNOUT are presented. These include heuristic variable level inference and classification, automatic category formation, the use of similarity trees to identify groups of related variables, interactive decision tree construction and model selection using a genetic algorithm

The effect of multiple sclerosis on carotid baroreflex control of heart rate and blood pressure

Multiple sclerosis (MS) is marked by conduction abnormalities within the central nervous system that can lead to impaired blood pressure regulation. However, the impact of this disease on dynamic neural control—responsiveness and timing (i.e., latency)—of blood pressure has not been examined. Utilizing a variable neck chamber system, we tested the hypothesis that patients with MS (MS: n=4) exhibit an altered response following baroreflex perturbation compared to sex and age matched healthy controls (CON: n=4). At rest, 5-sec pulses of neck suction (NS; -60 Torr) and neck pressure (NP; +40 Torr) were applied to simulate carotid hypertension and hypotension, respectively. Mean arterial pressure (MAP; Finometer) and heart rate (HR) were continuously measured in response to the perturbations. Carotid baroreflex (CBR) latencies (i.e., time-to-peak responses) were examined using carotid-cardiac (peak HR responses), carotid-vasomotor (peak MAP responses), and change in MAP at the peak HR response of the corresponding stimuli (MAP@HRpeak), all of which were not significant for both NP and NS. Following NS, responses in MAP (MS: -12±5, CON: -10±3 mmHg; p=0.43) and HR (MS: -9±3, CON: -8±4 BPM; p=0.58) were similar between groups. Following administration of NP, HR responses (MS: 4±2, CON: 5±4 BPM; p=0.47) were no different. However, the differences found in MAP were significant (MS: 5±2, CON: 8±2 mmHg; p=0.05), providing some evidence that baroreceptor responsiveness may be compromised when faced with a hypotensive challenge

Modularity and community detection in bipartite networks

The modularity of a network quantifies the extent, relative to a null model network, to which vertices cluster into community groups. We define a null model appropriate for bipartite networks, and use it to define a bipartite modularity. The bipartite modularity is presented in terms of a modularity matrix B; some key properties of the eigenspectrum of B are identified and used to describe an algorithm for identifying modules in bipartite networks. The algorithm is based on the idea that the modules in the two parts of the network are dependent, with each part mutually being used to induce the vertices for the other part into the modules. We apply the algorithm to real-world network data, showing that the algorithm successfully identifies the modular structure of bipartite networks.Comment: RevTex 4, 11 pages, 3 figures, 1 table; modest extensions to conten

Reduced Muscle Sympathetic Nerve Activity Response to a Cold Pressor Test in Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative autoimmune disease characterized by demyelination in the central nervous system leading to potential impairments in the autonomic control of cardiovascular function. We have previously demonstrated individuals with MS exhibit a diminished ability to increase blood pressure in response to a hypotensive stimulus compared with healthy controls likely due to impaired sympathetic modulation of the vasculature. PURPOSE: The aim of the current investigation was to test the hypothesis that muscle sympathetic nerve activity (MSNA) responses to a cold pressor test (CPT) are reduced in individuals with MS compared to healthy controls. METHODS: Four patients with relapsing-remitting MS (2 females/2 males, EDSS \u3c 4) and 4 sex-, age- and mass-matched controls were instrumented for MSNA (peroneal nerve), mean arterial blood pressure (MAP; Finometer), and heart rate (HR). Subjects were exposed to a CPT by immersing a hand in ice water for 2 min. Mean cardiovascular and MSNA responses (burst frequency) at baseline and at 30 sec intervals during the CPT were compared between groups. RESULTS: Heart rate (P\u3c0.001) and MAP (P\u3c0.001) responses increased from baseline throughout the CPT but no group differences were observed (P=0.10 and P=0.78, respectively). At baseline, MSNA was similar between groups (MS: 2 ± 2 vs. CON: 14 ± 9 bursts/min; P=0.239). However, individuals with MS had blunted MSNA responses to CPT compared to healthy controls at 60 seconds (MS: 18 ± 14 vs. CON: 42 ± 10 bursts/min; P=0.033), at 90 seconds (MS: 16 ± 12 vs. CON: 44 ± 10 bursts/min; P=.017) and at 120 seconds (MS: 13 ± 12 vs. CON: 43 ± 13 bursts/min; P=.012). CONCLUSION: Individuals with MS appear to have an attenuated muscle sympathetic response to CPT. However, MAP appears to respond similarly to healthy controls potentially through other compensatory mechanisms

Diagnostic Performance of Receptor-Specific Surgical Specimen Staining Correlates with Receptor Expression Level

Intraoperative margin assessment is imperative to cancer cure but is a continued challenge to successful surgery. Breast conserving surgery is a relevant example, where a cosmetically improved outcome is gained over mastectomy, but re-excision is required in \u3e25  %   of cases due to positive or closely involved margins. Clinical translation of margin assessment modalities that must directly contact the patient or required administered contrast agents are time consuming and costly to move from bench to bedside. Tumor resections provide a unique surgical opportunity to deploy margin assessment technologies including contrast agents on the resected tissues, substantially shortening the path to the clinic. However, staining of resected tissues is plagued by nonspecific uptake. A ratiometric imaging approach where matched targeted and untargeted probes are used for staining has demonstrated substantially improved biomarker quantification over staining with conventional targeted contrast agents alone. Our group has developed an antibody-based ratiometric imaging technology using fluorescently labeled, spectrally distinct targeted and untargeted antibody probes termed dual-stain difference specimen imaging (DDSI). Herein, the targeted biomarker expression level and pattern are evaluated for their effects on DDSI diagnostic potential. Epidermal growth factor receptor expression level was correlated to DDSI diagnostic potential, which was found to be robust to spatial pattern expression variation. These results highlight the utility of DDSI for accurate margin assessment of freshly resected tumor specimens

Statistical Confirmation of Empirical Observations Concerning Tool Mark Striae

Toolmarks produced by 44 sequentially manufactured screwdriver tips have been characterized for surface roughness using a profilometer. Toolmarks were produced in lead at angles of 30°, 60°, and 85°. A computer program developed to compare and match the profilometer data has been used to show that marks from a single tip produced at similar angles yield much higher correlation values than marks produced from the same tip but at different angles. This analysis provides statistical support for the widely-accepted empirical observation that toolmark striae must be reproduced at similar angles in order to be unambiguously identified as being made by a particular tool

Natural hybridization between divergent lineages in a selfing hermaphroditic fish.

By definition, mating between individuals is infrequent in highly selfing organisms, and so too, therefore, hybridization should be rare between genetically divergent lineages in predominantly self-fertilizing species. Notwithstanding these expectations, here we report a remarkable case of natural hybridization between highly diverged phylogeographic lineages of the mangrove rivulus, a small killifish that reproduces predominantly by self-fertilization and typically is found as highly homozygous lines in most parts of its extensive geographical range. Two distinctive genetic lineages (Kryptolebias marmoratus and a 'Central clade' closely related to K. hermaphroditus) previously were not known in sympatry, but were found by us to co-occur on San Salvador, Bahamas. Genetic analyses of a mitochondrial and multiple nuclear markers determined the direction of a cross producing a hybrid fish. Furthermore, we show that this hybrid individual was viable, as it successfully reproduced by self-fertilization for two generations. Additional sampling of this population will be necessary to determine if backcrossing of hybrids to the parental lineages occurs in nature and to analyse whether such backcross progeny are viable. Application of the biological species concept (BSC) is traditionally difficult in clonally reproducing organisms. Our results show that although mangrove rivulus fish are mostly highly selfing in nature (resulting in isogenic, effectively clonal and homozygous progeny), classification within this taxonomic complex need not be incompatible with the BSC

Generalized Entanglement as a Natural Framework for Exploring Quantum Chaos

We demonstrate that generalized entanglement [Barnum {\em et al.}, Phys. Rev. A {\bf 68}, 032308 (2003)] provides a natural and reliable indicator of quantum chaotic behavior. Since generalized entanglement depends directly on a choice of preferred observables, exploring how generalized entanglement increases under dynamical evolution is possible without invoking an auxiliary coupled system or decomposing the system into arbitrary subsystems. We find that, in the chaotic regime, the long-time saturation value of generalized entanglement agrees with random matrix theory predictions. For our system, we provide physical intuition into generalized entanglement within a single system by invoking the notion of extent of a state. The latter, in turn, is related to other signatures of quantum chaos.Comment: clarified and expanded version accepted by Europhys. Let