Multi-party Poisoning through Generalized pp-Tampering

In a poisoning attack against a learning algorithm, an adversary tampers with a fraction of the training data $T$ with the goal of increasing the classification error of the constructed hypothesis/model over the final test distribution. In the distributed setting, $T$ might be gathered gradually from $m$ data providers $P_1,\dots,P_m$ who generate and submit their shares of $T$ in an online way. In this work, we initiate a formal study of $(k,p)$-poisoning attacks in which an adversary controls $k\in[n]$ of the parties, and even for each corrupted party $P_i$, the adversary submits some poisoned data $T'_i$ on behalf of $P_i$ that is still "$(1-p)$-close" to the correct data $T_i$ (e.g., $1-p$ fraction of $T'_i$ is still honestly generated). For $k=m$, this model becomes the traditional notion of poisoning, and for $p=1$ it coincides with the standard notion of corruption in multi-party computation. We prove that if there is an initial constant error for the generated hypothesis $h$, there is always a $(k,p)$-poisoning attacker who can decrease the confidence of $h$ (to have a small error), or alternatively increase the error of $h$, by $\Omega(p \cdot k/m)$. Our attacks can be implemented in polynomial time given samples from the correct data, and they use no wrong labels if the original distributions are not noisy. At a technical level, we prove a general lemma about biasing bounded functions $f(x_1,\dots,x_n)\in[0,1]$ through an attack model in which each block $x_i$ might be controlled by an adversary with marginal probability $p$ in an online way. When the probabilities are independent, this coincides with the model of $p$-tampering attacks, thus we call our model generalized $p$-tampering. We prove the power of such attacks by incorporating ideas from the context of coin-flipping attacks into the $p$-tampering model and generalize the results in both of these areas

Assessment Of Soft Tissue Facial Profile, Nasal Airway Morphology And Dental Arch Features In Adult Malay Obstructive Sleep Apnea Patients Using Geometric Morphometric Analysis.

Masalah tidur apnea obstruktif (OSA) telah dikenal pasti sebagai satu masalah yang memberi impak kepada masyarakat setanding dengan masalah merokok. Obstructive sleep apnea (OSA) has been described as a public health problem comparable to smoking in its impacts upon society

Fractals analysis of cardiac arrhythmias

Heart rhythms are generated by complex self-regulating systems governed by the laws of chaos. Consequently, heart rhythms have fractal organization, characterized by self-similar dynamics with long-range order operating over multiple time scales. This allows for the self-organization and adaptability of heart rhythms under stress. Breakdown of this fractal organization into excessive order or uncorrelated randomness leads to a less-adaptable system, characteristic of aging and disease. With the tools of nonlinear dynamics, this fractal breakdown can be quantified with potential applications to diagnostic and prognostic clinical assessment. In this paper, I review the methodologies for fractal analysis of cardiac rhythms and the current literature on their applications in the clinical context. A brief overview of the basic mathematics of fractals is also included. Furthermore, I illustrate the usefulness of these powerful tools to clinical medicine by describing a novel noninvasive technique to monitor drug therapy in atrial fibrillation

Fast Iterative Solver for the 2-D Convection-Diffusion Equations

In this paper, we introduce the preconditioned Explicit Decoupled Group (EDG) for solving the two dimensional Convection-Diffusion equation with initial and Dirichlet boundary conditions. The purpose of this paper is to accelerate the convergence rate of the Explicit Decoupled Group (EDG) method by using suitable preconditioned iterative scheme for solving the Convection-Diffusion. The robustness of these new formulations over the existing EDG scheme demonstrated through numerical experiments

Habits of Juvenile Fishes in Two Rhode Island Estuaries

The basic purpose of this work was to gain information on the possible role of some Rhode Island estuaries as nursery grounds for young migrant and resident species of fishes. The areas selected were, the lower Pettaquamscutt River and the lower Point Judith Pond, both in the town of Narragansett, Rhode Island. The seining operations were carried through summer and early fall of 1962 when these estuaries are heavily used as nursery grounds. Major features of the occurrence, abundance and distribution of young fishes were deduced by examining samples from seine hauls. Thirty-six species were recorded from the lower river while only twenty-four species occurred in the lower pond. The abundance of fishes rose with a rise in temperature and declined with decreasing temperature, but no correlation was observed between maximum temperature and maximum number of individuals occurring at any time. The number of species and the abundance of individual fish were highest at the seaward station (Sta. II) in the lower river. Among the selected species, the abundance of Menidia menidia was two to three times higher at Middle Bridge (Sta. II) than at any other station. The behavior of Pseudopleuronectes americanus, found primarily at seaward stations, and the migrant species Brevoortia tyrannus observed at landward stations, is discussed. The species P. americanus grew at the rate of 10 mm per month, but exhibited no variation in growth in the two estuarine systems. The populations of B. tyrannus from the lower Pettaquamscutt River had a growth rate that was almost twice that of populations in the lower Point Judith Pond. The growth rate of these species in Rhode lsland waters compare favorably with similar data from other studies. The juvenile M. menidia demonstrated a higher rate of growth at seaward stations in both the areas, especially in the lower river. Forty-three types of prey organisms belonging to diverse taxonomic groups were identified from stomach contents of P. americanus and thirty-nine types were noted in the gut contents of M. menidia. Amlysis of the degree of fullness indicated markedly high percentage of full stomachs in the two study areas. However the degree of fullness was comparatively less in fish occurring in the lower pond. The scarcity of food in the lower pond, apparently forced M. menidia (51-80 mm) to feed upon phytoplankton as a substitute food or “forced diet”. In P. americanus and M. menidia a change in diet was noted with change in size. The taxon, B. tyrannus, which depended upon phytoplankton and suspended organic matter, did not show any change in food with change in body size. While no effective predation was observed, an infection by the sporozoan parasites, Glugea hertwigi, was marked in both Osmerus mordax and P. americanus. Low catches of P. americanus were perhaps due to higher infection. A comparison of the parameters of abundance, growth and food habits reveal that the two estuarine systems are suitable nursery grounds, and that the lower river is a more favorable nursery than the lower pond

Habits of Juvenile Fishes in Two Rhode Island Estuaries

The basic purpose of this work was to gain information on the possible role of some Rhode Island estuaries as nursery grounds for young migrant and resident species of fishes. The areas selected were, the lower Pettaquamscutt River and the lower Point Judith Pond, both in the town of Narragansett, Rhode Island. The seining operations were carried through summer and early fall of 1962 when these estuaries are heavily used as nursery grounds. Major features of the occurrence, abundance and distribution of young fishes were deduced by examining samples from seine hauls. Thirty-six species were recorded from the lower river while only twenty-four species occurred in the lower pond. The abundance of fishes rose with a rise in temperature and declined with decreasing temperature, but no correlation was observed between maximum temperature and maximum number of individuals occurring at any time. The number of species and the abundance of individual fish were highest at the seaward station (Sta. II) in the lower river. Among the selected species, the abundance of Menidia menidia was two to three times higher at Middle Bridge (Sta. II) than at any other station. The behavior of Pseudopleuronectes americanus, found primarily at seaward stations, and the migrant species Brevoortia tyrannus observed at landward stations, is discussed. The species P. americanus grew at the rate of 10 mm per month, but exhibited no variation in growth in the two estuarine systems. The populations of B. tyrannus from the lower Pettaquamscutt River had a growth rate that was almost twice that of populations in the lower Point Judith Pond. The growth rate of these species in Rhode lsland waters compare favorably with similar data from other studies. The juvenile M. menidia demonstrated a higher rate of growth at seaward stations in both the areas, especially in the lower river. Forty-three types of prey organisms belonging to diverse taxonomic groups were identified from stomach contents of P. americanus and thirty-nine types were noted in the gut contents of M. menidia. Amlysis of the degree of fullness indicated markedly high percentage of full stomachs in the two study areas. However the degree of fullness was comparatively less in fish occurring in the lower pond. The scarcity of food in the lower pond, apparently forced M. menidia (51-80 mm) to feed upon phytoplankton as a substitute food or “forced diet”. In P. americanus and M. menidia a change in diet was noted with change in size. The taxon, B. tyrannus, which depended upon phytoplankton and suspended organic matter, did not show any change in food with change in body size. While no effective predation was observed, an infection by the sporozoan parasites, Glugea hertwigi, was marked in both Osmerus mordax and P. americanus. Low catches of P. americanus were perhaps due to higher infection. A comparison of the parameters of abundance, growth and food habits reveal that the two estuarine systems are suitable nursery grounds, and that the lower river is a more favorable nursery than the lower pond

Optimal Portfolio Construction for Oil-Based Sovereign Wealth Funds

Chapter 1 of this dissertation delves into the economic challenges faced by oil-exporting countries that rely heavily on a single income source, with a particular focus on Saudi Arabia as a case study. The primary objective is to examine the efforts of Saudi Arabia\u27s sovereign wealth fund in diversifying revenue streams and mitigating risks associated with an excessive dependence on oil. To achieve this, the study proposes an adaptation of the subset-optimization algorithm within the mean-variance model, aiming to enhance portfolio construction in sovereign wealth funds. Chapter 2 of the dissertation conducts a comparative analysis between portfolios constructed using the subset-optimization algorithm and a benchmark portfolio that does not employ the algorithm. The findings show that the subset-optimized portfolios outperform the benchmark across various performance metrics. Notably, these portfolios exhibit higher Sharpe ratios, greater investor utility, and lower volatility compared to the benchmark. Additionally, the use of the algorithm leads to reduced exposure to oil beta across different subset sizes. Notably, as the subset size decreases, the portfolio\u27s volatility also decreases, suggesting the algorithm\u27s effectiveness in diversification. In Chapter 3, the research explores advanced estimation strategies for portfolio construction, considering two distinct cases. The first case incorporates a four-factor model, including the Carhart four-factor model, along with an additional factor specifically related to oil. The second case uses the Bayesian-shrinkage estimator for estimating the variance–covariance matrix and incorporates an informative prior within a Bayesian framework to estimate expected returns. Comparisons among the different models and inputs demonstrate that these advanced estimation techniques lead to improved portfolio performance. Specifically, the Sharpe ratio and investor utility are enhanced, indicating the contribution of these cutting-edge techniques to the creation of more effective and efficient portfolios. Overall, the findings highlight the algorithm\u27s potential to enhance risk-adjusted returns, reduce exposure to specific market factors such as oil, and ultimately contribute to the overall enhancement of portfolio management

Effect of halloysite aluminosilicate clay nanotube incorporation into bonding agents on shear bond strength to human dentin

Indiana University-Purdue University Indianapolis (IUPUI)In adhesive dentistry, obtaining a good bond is a fundamental goal. It has been suggested that filler addition to the adhesives would increase the bonding strength of the adhesive layer. Halloysite aluminosilicate nanotubes (HNTs) are biocompatible, hydrophilic, durable, and have high mechanical strength. These advantages make them good candidates to be used as reinforcing agents for improving the properties of dental adhesives. The objective of this study was to evaluate the effect of incorporating HNTs into a commercial two-step etch-and-rinse adhesive system or one-step self-etch adhesive system on dentin shear bond strength. HNTs were incorporated into the two commercial adhesive systems in 0 wt%, 5 wt%, 10 wt%, and 20 wt%. The commercial control adhesives and the experimental adhesives were used to bond occlusal dentin of 120 extracted human molar teeth and then tested for shear bond strength by a universal testing machine with a semi-circular edge at a crosshead speed of 1.0 mm/min. Debonded specimens were examined under light microscopy to evaluate the fracture pattern. Resin-dentin interface were evaluated under scanning electron microscopy (SEM) after bonding dentin slabs using commercial control adhesives and experimental adhesive that showed numerically highest shear bond strength from each adhesive system. Two-way ANOVA was used to evaluate the effects of adhesive system and nanofiller content on shear bond strength. Pair-wise comparisons between groups were made using Fisher's (LSD) (p < 0.05). For the self-etch adhesive system, only incorporation of 5 wt% showed a significant increase in shear bond strength to dentin compared with the commercial control group. For the etch-and-rinse adhesive system, there was no significant difference in shear bond strength between HNTs filled adhesives groups and the commercial control group. Resin-dentin interface SEM evaluation showed nanotubes infiltrated into dentinal tubules. In conclusion, incorporating the self-etch adhesive system with 5 wt% HNTs increased the bond strength to dentin. Incorporation of up to 10 wt% filler concentration into both the self-etch and the etch-and-rinse adhesive systems did not adversely affect the bond strength to dentin or the handling properties. HNTs can penetrate along with resin tags into dentinal tubules, which could expand the use of their unique properties