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Distributed denial of service (DDoS) attacks : classification, attacks, challenges, and countermeasures
The complexity and severity of the Distributed Denial of Service (DDoS) attacks are increasing day-by-day. The Internet has a highly inconsistent structure in terms of resource distribution. Numerous technical solutions are available, but those involving economic aspects have not been given much consideration. The book, DDoS Attacks - Classification, Attacks, Challenges, and Countermeasures, provides an overview of both types of defensive solutions proposed so far, exploring different dimensions that would mitigate the DDoS effectively and show the implications associated with them. Features: Covers topics that describe taxonomies of the DDoS attacks in detail, recent trends and classification of defensive mechanisms on the basis of deployment location, the types of defensive action, and the solutions offering economic incentives. Introduces chapters discussing the various types of DDoS attack associated with different layers of security, an attacker's motivations, and the importance of incentives and liabilities in any defensive solution. Illustrates the role of fair resource-allocation schemes, separate payment mechanisms for attackers and legitimate users, negotiation models on cost and types of resources, and risk assessments and transfer mechanisms. DDoS Attacks - Classification, Attacks, Challenges, and Countermeasures is designed for the readers who have an interest in the cybersecurity domain, including students and researchers who are exploring different dimensions associated with the DDoS attack, developers and security professionals who are focusing on developing defensive schemes and applications for detecting or mitigating the DDoS attacks, and faculty members across different universities.
Book
An optimized method for ^sup 15^N R^sub 1^ relaxation rate measurements in non-deuterated proteins
^sup 15^N longitudinal relaxation rates are extensively used for the characterization of protein dynamics; however, their accurate measurement is hindered by systematic errors. ^sup 15^N CSA/^sup 1^H-^sup 15^N dipolar cross-correlated relaxation (CC) and amide proton exchange saturation transfer from water protons are the two main sources of systematic errors in the determination of ^sup 15^N R^sub 1^ rates through ^sup 1^H-^sup 15^N HSQC-based experiments. CC is usually suppressed through a train of 180° proton pulses applied during the variable ^sup 15^N relaxation period (T), which can perturb water magnetization. Thus CC cancellation is required in such a way as to minimize water saturation effects. Here we examined the level of water saturation during the T period caused by various types of inversion proton pulses to suppress CC: (I) amide-selective IBURP-2; (II) cosine-modulated IBURP-2; (III) Watergate-like blocks; and (IV) non-selective hard. We additionally demonstrate the effect of uncontrolled saturation of aliphatic protons on ^sup 15^N R^sub 1^ rates. In this paper we present an optimized pulse sequence that takes into account the crucial effect of controlling also the saturation of the aliphatic protons during ^sup 15^N R^sub 1^ measurements in non-deuterated proteins. We show that using cosine-modulated IBURP-2 pulses spaced 40 ms to cancel CC in this optimized pulse program is the method of choice to minimize systematic errors coming from water and aliphatic protons saturation effects.
Journal Article
0941 Sleep Apnea Testing in Hospitalized Patients: Are Patients Following Up?
Introduction Obstructive sleep apnea (OSA) can often be recognized in an inpatient setting where patients are continuously monitored. Although an unattended portable sleep study can successfully diagnose OSA in many inpatients, allowing for earlier intervention, a loss to follow up can compromise effective treatment. This study aims to determine the rate of hospital follow-up in patients who are diagnosed with OSA on a portable inpatient sleep study. Methods We included adult inpatients who underwent portable sleep studies from 2013 to 2022. This is a retrospective study design. Individual charts were reviewed to determine demographics including age, gender, and race. Co-morbidities and length of stay were recorded. Sleep study data analyzed included total recording time, total estimated sleep time, overall apnea-hypopnea index (AHI) and nadir oxygen saturation. Primary outcome was percentage of patients with AHI 5/h with scheduled follow up visit. Secondary outcome was percentage of patients with AHI 5/h completed outpatient follow-up visit. Results 104 patients were included for analysis. Majority were middle aged (55.2 SD15.9 years-old), black (n=71, 68.2%) and male gender (n=64, 62%). A minority identified as Hispanic (n=7, 6.7%). The total number of sleep studies with AHI 5/h was 95 (91.3%) and the mean AHI was in the severe range (42.8 SD31.4/h) with significant associated oxygen desaturations (mean nadir oxygen saturation 77.1 SD10.6%). Primary outcome: the number of patients with a positive sleep study for OSA (AHI 5/h) who had scheduled for follow-up at discharge was 57 (60%). Secondary outcome: 54.4% of patients with positive sleep study and scheduled follow-up completed the outpatient visit. Conclusion The percentage of patients lost to follow-up is high despite diagnosing OSA successfully with an inpatient portable sleep study. Close to half of the patients had no scheduled follow-up, and the “no show” rate remained high (close to 50%) in those who had a sleep medicine appointment. Future studies should explore effective interventions to improve the follow-up rate and overall adherence to treatment. Support (if any)
Journal Article
0507 A wireless patch-based polysomnography system for conducting in-lab sleep studies
Introduction Current attended in-lab polysomnographic sleep studies are time-consuming and costly, primarily due to the time required to “hook-up” a patient to multiple electrodes and sensors and meet the quality assurance and safety requirements of an in-lab study. We developed a wireless PSG system (Onera STS - Onera Health, NL) consisting of four disposable patches and reusable pods to record full polysomnography that may reduce hook-up time while preserving standards of an attended polysomnography in the lab. Methods We used the Onera STS system for monitoring EEG, EOG, EMG, forehead reflectance SaO2, ECG, bioimpedance derived respiratory airflow and effort, airflow via nasal cannula, snoring sounds, body position, actigraphy, and leg movements, and accessory online monitoring of finger SaO2, ECG, nasal cannula airflow and video via RemLogic 4.0 or REM logic MPR system for Q/A and safety monitoring. Seventeen subjects (8 male, 9 female, age 18-to-75 yrs, BMI 29.9±6.0 kg/m2) were monitored for the evaluation of sleep apnea. We measured hook-up times and observed oxygen saturation and cardiac rhythm throughout the night. Results Mean hook-up time for the Onera STS was 5:22±1:17 minutes and for the additional on-line sensors (Finger SaO2, ECG and nasal cannula) was 3:15±1:10 minutes, resulting in an average hook-up time of less than 10 minutes. Onera PSG data revealed a mean oxygen desaturation event rate of >3% (ODI3) of 8.8 (SD 18.6) and a mean fall of oxygen saturation (ΔSaO2/event) of 4.4 (SD 1.2). The accessory online SaO2, ECG and video monitoring showed that no subjects demonstrated sustained nocturnal hypoxia, severe cardiac arrhythmia or parasomnia events that would have required interventions. Conclusion The Onera STS system substantially lowers the burden to conduct attended polysomnographic sleep studies. In combination with standard monitoring of SaO2, ECG and video, it meets the safety requirements for attended sleep studies while reducing the overall operational and capital equipment costs. The ease of application together with the reduced hook-up time makes it now possible to implement polysomnographic sleep studies in the hospital setting, particularly in addition to conventional bedside monitoring units such as ICU-, step-down unit- or hospital beds. Support (if any)
Journal Article
A new model for zircon saturation in silicate melts
A new model describing zircon saturation in silicate melts is presented that combines the results of 196 data from new experiments with data from previous experimental studies. In the new experiments, the concentration of Zr in melts coexisting with zircon was determined at temperatures between 800 and 1500 °C for 21 compositions (with alumina saturation index, ASI, from 0.20 to 1.15), containing ~ 1 to 16 wt % FeOT and, for a subset of these conditions, at variable pressure (0.0001 to 4.0 GPa) and water content (0 to 15 wt %). The collated dataset contains 626 data, with 430 from 26 literature studies, and covers conditions from 750 to 1620 °C, (including 45 new data and 106 literature data for temperatures < 1000 °C), ASI 0.20 to 2.00, 0.0001 to 4.0 GPa and 0 to 17 wt % H2O. A limitation of previous models of zircon saturation is the choice of parameter used to describe the silicate melt, which may not be appropriate for all compositions and can result in differences in predicted temperatures of over 200 °C for granitic systems. Here we use optical basicity (Λ), which can be easily calculated from the major oxide components of a melt, to parameterise the composition. Using a non-linear least-squares multiple regression, the new zircon saturation model is:logZr=0.96(5)-5790(95)/T-1.28(8)P+12.39(35)Λ+0.83(9)x.H2O+2.06(16)PΛwhere Zr is in ppm, T is temperature in K, P is pressure in GPa, Λ is the optical basicity of the melt, x.H2O is the mole fraction of water in the melt, and the errors are 1σ. This model confirms that temperature and melt composition are the dominant controls on zircon solubility. In addition, pressure and melt water content exert small but resolvable effects on the solubility and are included, for the first time, in a model. Using this new calibration, 92% of the predicted temperatures are within 10% of the experimental temperatures for the collated dataset (with an average temperature difference of 57 °C), while predicted temperatures for only 78 and 62% of the collated dataset are within 10% of the experimental temperature (with average temperature differences > 80 °C) using the widely cited Watson and Harrison (Earth Planet Sci Lett 64:295–304, 1983) and Boehnke et al. (Chem Geol 351:324–334, 2013) models, respectively. This new model can be extrapolated to temperatures below those included in the calibration with greater accuracy and when applied to melt inclusions from the Bishop Tuff, gives temperatures that are in excellent agreement with independent estimates.
Journal Article
Contributors to contrast between glioma and brain tissue in chemical exchange saturation transfer sensitive imaging at 3Tesla
Off-resonance saturation transfer images have shown intriguing differences in intensity in glioma compared to normal brain tissues. Interpretation of these differences is complicated, however, by the presence of multiple sources of exchanging magnetization including amide, amine, and hydroxyl protons, asymmetric magnetization transfer contrast (MTC) from macromolecules, and various protons with resonances in the aliphatic spectral region. We report a study targeted at separating these components and identifying their relative contributions to contrast in glioma. Off-resonance z-spectra at several saturation powers and durations were obtained from 6 healthy controls and 8 patients with high grade glioma. Results indicate that broad macromolecular MTC in normal brain tissue is responsible for the majority of contrast with glioma. Amide exchange could be detected with lower saturation power than has previously been reported in glioma, but it was a weak signal source with no detectable contrast from normal brain tissue. At higher saturation powers, amine proton exchange was a major contributor to the observed signal but showed no significant difference from normal brain. Robust acquisition strategies that effectively isolate the contributions of broad macromolecular MTC asymmetry from amine exchange were demonstrated that may provide improved contrast between glioma and normal tissue.
•We describe robust methods to measure chemical exchange saturation transfer (CEST).•We separated amine and amide CEST effects from magnetization transfer (MT) asymmetry.•We measured CEST and MT asymmetry signal in patients with recurrent glioma.•MT asymmetry is mostly responsible for the contrast between glioma and normal brain.
Journal Article
An H2O–CO2 mixed fluid saturation model compatible with rhyolite-MELTS
A thermodynamic model for estimating the saturation conditions of H
2
O–CO
2
mixed fluids in multicomponent silicate liquids is described. The model extends the capabilities of rhyolite-MELTS (Gualda et al. in J Petrol 53:875–890,
2012a
) and augments the water saturation model in MELTS (Ghiorso and Sack in Contrib Mineral Petrol 119:197–212,
1995
). The model is internally consistent with the fluid-phase thermodynamic model of Duan and Zhang (Geochim Cosmochim Acta 70:2311–2324,
2006
). It may be used independently of rhyolite-MELTS to estimate intensive variables and fluid saturation conditions from glass inclusions trapped in phenocrysts. The model is calibrated from published experimental data on water and carbon dioxide solubility, and mixed fluid saturation in silicate liquids. The model is constructed on the assumption that water dissolves to form a hydroxyl melt species, and that carbon dioxide both a molecular species and a carbonate ion, the latter complexed with calcium. Excess enthalpy interaction terms in part compensate for these simplistic assumptions regarding speciation. The model is restricted to
natural composition liquids
over the pressure range 0–3 GPa. One characteristic of the model is that fluid saturation isobars at pressures greater than ~100 MPa always display a maximum in melt CO
2
at nonzero H
2
O melt concentrations, regardless of bulk composition. This feature is universal and can be attributed to the dominance of hydroxyl speciation at low water concentrations. The model is applied to four examples. The first involves estimation of pressures from H
2
O–CO
2
-bearing glass inclusions found in quartz phenocrysts of the Bishop Tuff. The second illustrates H
2
O and CO
2
partitioning between melt and fluid during fluid-saturated equilibrium and fractional crystallization of MORB. The third example demonstrates that the position of the quartz–feldspar cotectic surface is insensitive to melt CO
2
contents, which facilitates geobarometry using phase equilibria. The final example shows the effect of H
2
O and CO
2
on the crystallization paths of a high-silica rhyolite composition representative of the late-erupted Bishop Tuff. Software that implements the model is available at ofm-research.org, and the model is incorporated into the latest version (1.1+) of rhyolite-MELTS.
Journal Article
Estimation of Pressure Pain in the Lower Limbs Using Electrodermal Activity, Tissue Oxygen Saturation, and Heart Rate Variability
Quantification of pain or discomfort induced by pressure is essential for understanding human responses to physical stimuli and improving user interfaces. Pain research has been conducted to investigate physiological signals associated with discomfort and pain perception. This study analyzed changes in electrodermal activity (EDA), tissue oxygen saturation (StO2), heart rate variability (HRV), and Visual Analog Scale (VAS) under pressures of 10, 20, and 30 kPa applied for 3 min to the thigh, knee, and calf in a seated position. Twenty participants were tested, and relationships between biosignals, pressure intensity, and pain levels were evaluated using Friedman tests and post-hoc analyses. Multiple linear regression models were used to predict VAS and pressure, and five machine learning models (SVM, Logistic Regression, Random Forest, MLP, KNN) were applied to classify pain levels (no pain: VAS 0, low: VAS 1–3, moderate: VAS 4–6, high: VAS 7–10) and pressure intensity. The results showed that higher pressure intensity and pain levels affected sympathetic nervous system responses and tissue oxygen saturation. Most EDA features and StO2 significantly changed according to pressure intensity and pain levels, while NN interval and HF among HRV features showed significant differences based on pressure intensity or pain level. Regression analysis combining biosignal features achieved a maximum R2 of 0.668 in predicting VAS and pressure intensity. The four-level classification model reached an accuracy of 88.2% for pain levels and 81.3% for pressure intensity. These results demonstrated the potential of EDA, StO2, HRV signals, and combinations of biosignal features for pain quantification and prediction.
Journal Article
Targeted, random mutagenesis of plant genes with dual cytosine and adenine base editors
Targeted saturation mutagenesis of crop genes could be applied to produce genetic variants with improved agronomic performance. However, tools for directed evolution of plant genes, such as error-prone PCR or DNA shuffling, are limited1. We engineered five saturated targeted endogenous mutagenesis editors (STEMEs) that can generate de novo mutations and facilitate directed evolution of plant genes. In rice protoplasts, STEME-1 edited cytosine and adenine at the same target site with C > T efficiency up to 61.61% and simultaneous C > T and A > G efficiency up to 15.10%. STEME-NG, which incorporates the nickase Cas9-NG protospacer-adjacent motif variant, was used with 20 individual single guide RNAs in rice protoplasts to produce near-saturated mutagenesis (73.21%) for a 56-amino-acid portion of the rice acetyl-coenzyme A carboxylase (OsACC). We also applied STEME-1 and STEME-NG for directed evolution of the OsACC gene in rice and obtained herbicide resistance mutations. This set of two STEMEs will accelerate trait development and should work in any plants amenable to CRISPR-based editing.Saturation mutagenesis using dual base editors improves the herbicide resistance of rice.
Journal Article
A Simple Accurate Formula for Calculating Saturation Vapor Pressure of Water and Ice
It is necessary to calculate the saturation vapor pressure of water and of ice for some purposes in many disciplines. A number of formulas are available for this calculation. These formulas either are tedious or are not very accurate. In this study, a new formula has been developed by integrating the Clausius–Clapeyron equation. This new formula is simple and easy to remember. In comparison with the International Association for the Properties of Water and Steam reference dataset, the mean relative errors from this new formula are only 0.001% and 0.006% for the saturation vapor pressure of water and of ice, respectively, within a wide range of temperatures from −100° to 100°C. In addition, this new formula yields a mean relative error of 0.0005% within the commonly occurring temperature range (10°–40°C). Therefore, this new formula has significant advantages over the improved Magnus formula and can be used to calculate the saturation vapor pressure of water and of ice in a wide variety of disciplines.
Journal Article