Keyed Non-Parametric Hypothesis Tests

The recent popularity of machine learning calls for a deeper understanding of AI security. Amongst the numerous AI threats published so far, poisoning attacks currently attract considerable attention. In a poisoning attack the opponent partially tampers the dataset used for learning to mislead the classifier during the testing phase. This paper proposes a new protection strategy against poisoning attacks. The technique relies on a new primitive called keyed non-parametric hypothesis tests allowing to evaluate under adversarial conditions the training input's conformance with a previously learned distribution $\mathfrak{D}$. To do so we use a secret key $\kappa$ unknown to the opponent. Keyed non-parametric hypothesis tests differs from classical tests in that the secrecy of $\kappa$ prevents the opponent from misleading the keyed test into concluding that a (significantly) tampered dataset belongs to $\mathfrak{D}$.Comment: Paper published in NSS 201

Family Acculturation and Asthma Outcomes in Latino Children

Background: Asthma is the primary chronic disease diagnosed in children. California has had some of the highest asthma prevalence rates within the nation. The literature indicates that there is a poor understanding of asthma outcome and management. However, studies exploring the role of acculturation on such outcomes are limited. Thus, the goal of this research was to conduct a secondary analysis of the Child Questionnaire from the California Health Interview Survey (CHIS) 2007 and 2009 cross-sectional data to explore the determinants of asthma outcomes as it relates to family acculturation. Methodology: The quantitative data were analyzed using Stata. Descriptive statistics, univariate analyses, multivariable logistic regression analyses were used to evaluate whether family acculturation is associated with asthma outcomes, after adjusting for age (child and parent), gender (child and parent), socioeconomic status (family) and access to healthcare (child). Results: An annual population estimate of 237,802 children reported having an asthma diagnosis by a doctor and among such a population, 98,908 had an asthma attack in the past 12 months. Among those diagnosed with asthma, an annual population estimate of 99,013 children reported lacking asthma management resource. Low family acculturation was associated with children\u27s diagnosis of asthma (p \u3c .005) but not asthma attack (p \u3e .05) in bivariate analyses. In multivariate logistic regression models, low acculturation was associated with lower odds of asthma diagnosis (OR = 0.41,95% CI: 0.21, 0.79), and asthma attack in the last 12 months (OR = 0.40, 95% CI: 0.15,1.08), though the latter did not reach statistical significance. Low family acculturation was associated with families having asthma management plan (p \u3c .005) in bivariate analyses. In multivariate logistic regression models, low acculturation (speaking only Spanish at home) was associated with lower odds of having asthma management plan from doctor (unadjusted OR = 0.33), though it did not reach statistical significance upon adjusting for covariates. Additional outcomes could not he explored due to limited sample size or non significant associations based on bivariate analyses. Though the latter did not reach statistical significance, low family acculturation was associated with families having asthma management plan (p \u3c .005). Conclusion: Latinos are consistently reported to have lower asthma rates in California and the nation and yet little is known about the reasons for such outcomes. Moreover, asthma management is key to lower the burden of asthma and little research exists on factors associated with asthma management. Results from this study showed that low family acculturation was associated with lower odds of asthma diagnosis among children and lower odds of having an asthma management plan. Such results should further help health education specialists promote traditional values that are protective against asthma while improve patient-physician communication to ensure at-risk populations gain access to necessary asthma management plans

Preliminary assessment of terrestrial microalgae isolated from lichens as testing species for environmental monitoring: Lichen phycobionts present high sensitivity to environmental micropollutants

Bioassays constitute a tool for pollution analysis providing a holistic approach and high-quality indication of the toxicity. Microbioassays allow evaluating the toxicity of many samples, implying lower costs and enabling routine monitoring and pollution control. But tests conducted so far are limited to the use of a small number of taxa. Lichens are excellent bioindicators of pollution with great ecological significance. Studies show that the phycobiont is more sensitive to pollutants than the mycobiont. Phycobiont have features such as adaptation to anhydrobiosis and relatively rapid growth in vitro, making them suitable for microbioassays. Our aim is to determine the sensitivity of phycobionts to the pharmaceutical micropollutants carbamazepine and diclofenac as a preliminary step for the development of a toxicity microbioassay based on phycobionts. Optical dispersion and chlorophyll autofluorescence were used as endpoints of toxicity on two algal species showing that suspensions present cyclic and taxon specific patterns of aggregation. Trebouxia TR9 suspensions present a very high grade of aggregation while Asterochloris erici cells do not. Both micropollutants alter optical properties of the suspensions of both species. No significant alteration of chlorophyll autofluorescence by carbamazepine is observed. A. erici chlorophyll autofluorescence is extremely sensitive to diclofenac but the effect is not dependent on the drug concentration or on the time of exposure. Differently, TR9 only shows punctual chlorophyll alterations. Fluctuations in optical dispersion may indicate changes in the population structure of the species, including reproductive strategy. A. erici seems more sensitive to micropollutants, is better characterized and is available from commercial collections

Presence of multiple group I introns closely related to bacteria and fungi in plastid 23S rRNAs of lichen-forming Trebouxia

The chloroplast-encoded large subunit ribosomal RNA gene of several free-living green algae contains group I introns at Escherichia coli genic positions 1917, 1931, 1951, and 2449. Herein we report the presence of group I introns at these positions within the chloroplast-encoded large subunit ribosomal RNA gene of several lichen-forming green algae belonging to the Trebouxia genus. In contrast to the introns inserted at position 2449, all introns inserted at positions 1917, 1931, and 1951 contained LAGLIDADG homing endonuclease genes. Phylogenetic analyses show that: (i) introns inserted at positions 1917, 1931, and 1951 are closely related to introns located at homologous insertion sites in bacterial rDNA genes; and (ii) introns inserted at position 2449 are closely related to fungal introns located at homologous insertion sites in mitochondrial rDNA genes. The symbiogenetic thalli of some lichens are proposed as the likely setting of horizontal transfer of genetic material among distantly related organisms such as bacteria, fungi, and green [email protected]; [email protected]

Photobiont diversity in lichen symbioses from extreme environments

Fungal–algal relationships—both across evolutionary and ecological scales—are finely modulated by the presence of the symbionts in the environments and by the degree of selectivity and specificity that either symbiont develop reciprocally. In lichens, the green algal genus Trebouxia Puymaly is one of the most frequently recovered chlorobionts. Trebouxia species-level lineages have been recognized on the basis of their morphological and phylogenetic diversity, while their ecological preferences and distribution are still only partially unknown. We selected two cosmopolitan species complexes of lichen-forming fungi as reference models, i.e., Rhizoplaca melanophthalma and Tephromela atra, to investigate the diversity of their associated Trebouxia spp. in montane habitats across their distributional range worldwide. The greatest diversity of Trebouxia species-level lineages was recovered in the altitudinal range 1,000–2,500 m a.s.l. A total of 10 distinct Trebouxia species-level lineages were found to associate with either mycobiont, for which new photobionts are reported. One previously unrecognized Trebouxia species-level lineage was identified and is here provisionally named Trebouxia “A52.” Analyses of cell morphology and ultrastructure were performed on axenically isolated strains to fully characterize the new Trebouxia “A52” and three other previously recognized lineages, i.e., Trebouxia “A02,” T. vagua “A04,” and T. vagua “A10,” which were successfully isolated in culture during this study. The species-level diversity of Trebouxia associating with the two lichen-forming fungi in extreme habitats helps elucidate the evolutionary pathways that this lichen photobiont genus traversed to occupy varied climatic and vegetative regimes

Detection of small murine lung tumours by FDG-PET

[Abstract] AMI International Conference 2003, September 21 - 27, Madrid, Spain: "High Resolution Molecular Imaging: from Basic Science to Clinical Applications"The functional information provided by 2-deoxy-2- [18F]fluoro-D-Glucose (FDG) positron emission tomography (PET) is commonly used to detect primary tumours and metastases in clinical studies. The aim of this work is to assess the possibilities of FDG-PET studies to detect small lung tumour lesions in mice, using a dedicated small animal PET scannerPublicad

Effects of MDMA on blood glucose levels and brain glucose metabolism

Purpose This study was designed to assess changes in glucose metabolism in rats administered single or repeated doses of MDMA. Methods Two different experiments were performed: (1) A single-dose study with four groups receiving 20 mg/kg, 40 mg/kg, saline or heat, and (2) a repeated-dose study with two groups receiving three doses, at intervals of 2 h, of 5 mg/kg or saline. Rats were imaged using a dedicated small-animal PET scanner 1 h after single-dose administration or 7 days after repeated doses. Glucose metabolism was measured in 12 cerebral regions of interest. Rectal temperature and blood glucose were monitored. Results Peak body temperature was reached 1 h after MDMA administration. Blood glucose levels decreased significantly after MDMA administration. In the single-dose experiment, brain glucose metabolism showed hyperactivation in cerebellum and hypo-activation in the hippocampus, amygdala and auditory cortex. In the repeated-dose experiment, brain glucose metabolism did not show any significant change at day 7. Conclusion These results are the first to indicate that MDMA has the potential to produce significant hypoglycaemia. In addition, they show that MDMA alters glucose metabolism in components of the motor, limbic and somatosensory systems acutely but not on a long-term basisPublicad

Security Evaluation of Support Vector Machines in Adversarial Environments

Support Vector Machines (SVMs) are among the most popular classification techniques adopted in security applications like malware detection, intrusion detection, and spam filtering. However, if SVMs are to be incorporated in real-world security systems, they must be able to cope with attack patterns that can either mislead the learning algorithm (poisoning), evade detection (evasion), or gain information about their internal parameters (privacy breaches). The main contributions of this chapter are twofold. First, we introduce a formal general framework for the empirical evaluation of the security of machine-learning systems. Second, according to our framework, we demonstrate the feasibility of evasion, poisoning and privacy attacks against SVMs in real-world security problems. For each attack technique, we evaluate its impact and discuss whether (and how) it can be countered through an adversary-aware design of SVMs. Our experiments are easily reproducible thanks to open-source code that we have made available, together with all the employed datasets, on a public repository.Comment: 47 pages, 9 figures; chapter accepted into book 'Support Vector Machine Applications

Detection of rat brain activation using statistical parametric mapping analysis in FDG-PET studies

[Abstract] AMI International Conference 2003, September 21 - 27, Madrid, Spain: High Resolution Molecular Imaging: from Basic Science to Clinical ApplicationsStatistical parametric mapping (SPM) is an analysis technique long been used in clinical research to detect subtle activity changes in brain; it is an excellent exploratory tool as it does not require a priori assumptions about the expected brain region activations. Research in animal imaging may also take benefit from this technique, if properly adapted to the new scenario. This is the case of brain activation studies in murine models using PET tracers and dedicated imaging devices. This work proposes the use of an SPM methodology adapted to the analysis of 2-deoxy-2-[18F] fluoro-D-Glucose (FDG) positron emission tomography (PET) scans of rat brains. Advantages over conventional region of interest (ROI) based analysis were assessed in an experiment addressing the detection of brain activation in of rats which underwent three different visual stimulation paradigmsPublicad