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The performance of fixed-wing micro air vehicles (MAVs) is impaired due to their small size, operating speeds, and altitude leading to limited lift, aerodynamic efficiency (lift-to-drag ratio), and low gust resilience. Nonslender delta wings have high stall angle and maneuverability, which are desirable features for MAVs. However, the aerodynamic efficiency of delta-winged MAVs is low, thus impacting the overall performance. We optimize the aerodynamic efficiency of a flat-plate delta wing using the adjoint-based aerodynamic shape optimization method coupled with incompressible Reynolds-averaged Navier–Stokes equations. The optimization improves the aerodynamic efficiency from 6.2 to 10.2 at 5° angle of attack while satisfying lift and moment constraints. The optimized wing is significantly cambered, and the axial cross section reveals that a circular arc can approximate the optimized wing airfoil. A parametric study of the circular camber delta wings with a 0–7.5% camber-to-chord ratio reveals that an increase in camber leads to linear growth in the lift, whereas the drag shows a quadratic growth. Consequently, an optimum camber exists at 2.5% for maximizing the aerodynamic efficiency (9.3); the wing has aerodynamic characteristics closely resembling the optimized wing, thus revealing that the essence of the efficiency optimization process is to identify the optimal camber distribution.

Acute lymphoblastic leukemia (ALL) diagnosed during pregnancy is rare and causes ethical and therapeutic challenges. We performed a retrospective search of ALL patients (n = 202) treated at our institution from 2015 to 2020 and found five patients diagnosed during pregnancy. In this report, we discuss the individual patients in detail and the challenges faced during their treatment. The use of established lymphoblastic leukemia treatment protocols and the modifications made therein to prevent untoward chemotherapy-related toxicities to the fetus are discussed in this study. We report the second use of rasburicase during pregnancy in literature with favorable maternal and fetal outcomes. We also present an extensive literature review of 41 cases of ALL in pregnancy previously reported. It is important to note that there is a dearth of guidelines for the treatment of these complex situations, and although certain general principles can be established, an individualized approach is needed in most cases of leukemia diagnosed during pregnancy.

This file contains Supplementary Table 1 and provides hazard ratios for recurrence free survival and overall survival for polyploidy and clinical variables using a Cox proportional hazard model.

This file contains supplementary figures S1-S4. These illustrate correlation of ploidy from chromosome 17 FSIH versus 6-chromosome FISH, chromosome spreads of cell lines, additional dose-response curves, and data demonstrating DPBQ does not operate by binding DNA or by inhibiting topoisomerase II.

Supplemental Figure 3. Genetic ablation of AXL enhances HNSCC cell line response to cisplatin, cetuximab, and radiation

Supplemental Figure Legends

Supplemental Figure 1. AXL knockdown inhibits the migration of HNSCC cell lines

Supplemental Table 2. Clinical parameters and median progression-free survival in relation to AXL expression among patients with HNSCC

Supplemental Materials and Methods

Supplemental Figure 2. HNSCC cell proliferation and apoptosis are not significantly impacted 24 hours post R428 treatment

Supplemental Table 3. Fractional cell proliferation analysis for drug combination synergy

Supplemental Table 1. Clinical information describing HNSCC cohort

Supplemental Table 4. Clinical characteristics of patients prior to surgery and PDX establishment

Purpose: Head and neck squamous cell carcinoma (HNSCC) represents the eighth most common malignancy worldwide. Standard-of-care treatments for patients with HNSCC include surgery, radiation, and chemotherapy. In addition, the anti-EGFR monoclonal antibody cetuximab is often used in combination with these treatment modalities. Despite clinical success with these therapeutics, HNSCC remains a difficult malignancy to treat. Thus, identification of new molecular targets is critical.Experimental Design: In the current study, the receptor tyrosine kinase AXL was investigated as a molecular target in HNSCC using established cell lines, HNSCC patient-derived xenografts (PDX), and human tumors. HNSCC dependency on AXL was evaluated with both anti-AXL siRNAs and the small-molecule AXL inhibitor R428. Furthermore, AXL inhibition was evaluated with standard-of-care treatment regimens used in HNSCC.Results: AXL was found to be highly overexpressed in several models of HNSCC, where AXL was significantly associated with higher pathologic grade, presence of distant metastases, and shorter relapse-free survival in patients with HNSCC. Further investigations indicated that HNSCC cells were reliant on AXL for cellular proliferation, migration, and invasion. In addition, targeting AXL increased HNSCC cell line sensitivity to chemotherapy, cetuximab, and radiation. Moreover, radiation-resistant HNSCC cell line xenografts and PDXs expressed elevated levels of both total and activated AXL, indicating a role for AXL in radiation resistance.Conclusions: This study provides evidence for the role of AXL in HNSCC pathogenesis and supports further preclinical and clinical evaluation of anti-AXL therapeutics for the treatment of patients with HNSCC. Clin Cancer Res; 21(11); 2601–12. ©2015 AACR.

Some of the existing challenges of fixed-wing micro aerial vehicle designs at low Reynolds number are low lift and reduced aerodynamic efficiency. Delta wings, despite their characteristic maneuver...

Timely administration of appropriate empirical antibiotics in febrile neutropenia is crucial for favourable patient outcomes. There are guidelines in place recommending such antibiotics. However, regional variations and local epidemiological data must be evaluated to tailor the antibiotics for best possible and rational use. In this study, we audited the clinical and microbiological data of febrile neutropenic episodes occurring at a tertiary care haematology institution. Three hundred and ninety-three febrile neutropenic episodes occurring in 123 patients over a 1-year period were analysed for microbial profile, sensitivity and resistance patterns, and finally clinical outcomes. Gram-negative bacilli (GNB) blood stream infections (46.9%) were more prevalent as compared to gram-positive infections (41.9%). Overall mortality due to complicated neutropenic sepsis was 19.5% (24/123 patients). Increased resistance to carbapenems, beta-lactam beta-lactamase inhibitor combinations, aminoglycosides, fluoroquinolones, and cephalosporins were observed. Cefepime and tigecycline resistance were seen in 20% and 15% GNB isolates, respectively. Chest was the most frequent focus of infection, and acute myeloid leukaemia (AML) was the most common underlying disorder which correlated with the likelihood of death (p < 0.01). Multidrug-resistant GNB (esp. Klebsiella sp.) are still most worrisome isolates in neutropenic patients. Single-agent cefepime or piperacillin-tazobactam/tigecycline combination may be considered empirical agents. Chest infections and AML were independent predictors of poor clinical outcome in neutropenic patients. Regular audit of infections and antibiotic susceptibility data is needed to improve clinical outcomes in patients with febrile neutropenia.

Beta thalassemia is the commonest inherited monogenic disorder and India forms a major part of the thalassemia belt in the world. Effective screening programmes and proper prenatal diagnosis are the only ways to eradicate the disease. Haemoglobin high-pressure liquid chromatography (HPLC) is the screening method employed for detection of thalassemia carriers. The aim of this paper was to investigate the prevalence and demographic profiles of thalassemia carriers in Eastern India. Haemogram data was used to develop a novel haematological index for thalassemia carrier detection. This was a retrospective analysis of data collected from 21,695 individuals at thalassemia screening camps. The prevalence of the common hemoglobinopathies and their regional variations were noted. Using stepwise discriminant analysis, RBC indices were analysed to develop a novel formula to help distinguish β-thalassemia carriers from normal individuals. Out of the total population analysed, β-hemoglobinopathy carrier prevalence was around 10%. HbE was the commonest hemoglobinopathy in the region. There was no difference in the prevalence rates of thalassemia carriers amongst religious communities. The formula generated was expressed as outcome = RBCx6.59 + MCHx0.527 − (HCTx0.782 + MCHCx0.395 + RDWx0.02 + 1.365). Any integer value more than 0.5 indicated the probability of carrier status while a value less than 0.5 was normal. The formula had a negative predictive value of > 96% and an accuracy of 89%. This study provides an audit of the common β-hemoglobinopathies in Eastern India. The regional variations and prevalence of hemoglobinopathies highlighted here may guide public health efforts. The formula generated from RBC indices can be used to screen individuals prior to HPLC testing, thereby reducing overall costs of thalassemia screening in the country.

Wind energy is anticipated to play a vital role to fulfill the worldwide energy requirements, whereas existing bare wind turbines can convert only a fraction of flow energy into electricity. To bridge the gap between the escalating demand and the generation capability, we propose a shrouded-twin-rotor turbine design, whose power coefficient exceeds the Betz-Joukowsky limit. We analyze the flow through the wind turbine assembly, using the actuator disk theory, and estimate the power output for a pair of rotor-loading coefficients. We find the existence of two regimes in which the proposed design performs better than the single-rotor configuration: (a) a turbine-turbine mode where both rotors work as turbines and (b) a turbine-fan mode where one rotor is a turbine while the other is a fan- an idea proposed by Betz (A. Betz, Wind-Energie und ihre Ausnutzung durch Windmuhlen, Vandenhoeck, 1926). Both modes enable achieving maximum power for multiple combinations of the loading coefficient pair. Moreover, power output depends solely on a single parameter, defined using the area weighted sum of the loading coefficients. We derive the optimum performance criterion and present the effects of the shroud geometry, back pressure, and flow-efficiency parameters on the power output and the performance envelope.

International audience; Air exchange between people has emerged in the COVID-19 pandemic as the important vector for transmission of the SARS-CoV-2 virus. We study the airflow and exchange between two unmasked individuals conversing face-to-face at short range, which can potentially transfer a high dose of a pathogen, because the dilution is small when compared to long-range airborne transmission. We conduct flow visualization experiments and direct numerical simulations of colliding respiratory jets mimicking the initial phase of a conversation. The evolution and dynamics of the jets are affected by the vertical offset between the mouths of the speakers. At low offsets the head-on collision of jets results in a 'blocking effect', temporarily shielding the susceptible speaker from the pathogen carrying jet, although, the lateral spread of the jets is enhanced. Sufficiently large offsets prevent the interaction of the jets. At intermediate offsets (8-10 cm for 1 m separation), jet entrainment and the inhaled breath assist the transport of the pathogen-loaded saliva droplets towards the susceptible speaker's mouth. Air exchange is expected, in spite of the blocking effect arising from the interaction of the respiratory jets from the two speakers.

The flight of a golf ball is majorly governed by aerodynamic forces acting on the ball. Since these forces depend on the relative airspeed of the ball, wind has a direct impact of the golf ball’s trajectory. Moreover, the impact of wind is much more significant than that of other parameters like ball speed, spin rate and launch angle. Therefore, the effect of wind becomes a vital subject in the game of golf. In this chapter, we present a detailed quantitative analysis of the variation in wind-induced deviations with respect to three parameters that govern the ball’s trajectory: wind conditions, launch conditions and aerodynamic characteristics. We find that the effect of headwind is more profound than that of a tailwind of the same magnitude. Also, the wind-induced deviations are higher for more lobbed shots compared to flat shots. Finally, the trajectory of a golf ball having hexagonal dimples undergoes a higher deflection in the presence of wind, as compared to that of a conventional golf ball having circular dimples.

In this chapter, we view the results obtained from the quantitative analysis in Chap. 4 from the perspective of a golfer. First, we describe the common techniques used by the golfer to adapt his launch conditions such that the wind-induced deviation is nullified. We explain how these techniques work through simulations of realistic golf shots and also discuss their limitations. Next, we discuss how wind impacts a real golf game by simulating golf shots under the effect of wind in modelled environments of three real golf courses having different design styles: (1) hole 17 of Tournament Players’ Club in Florida (penal style), (2) hole 8 of Muirfield Golf Club in Scotland (strategic style) and (3) hole 18 of Pebble Beach Golf Links in California (heroic style). We find that wind has a decisive effect on the gameplay strategy in each of the courses, wherein wind tends to enhance the key characteristic of the course and hence helps in clearly distinguishing between amateurs and experts.

In this chapter, we discuss various physical models that govern the motion of a golf ball. The flight of a golf ball is governed by the laws of aerodynamics and projectile motion. The dimples on the ball’s surface help the ball fly over a larger distance by reducing the drag, while the backspin enhances the upward Magnus force acting on it due to its airspeed. On the other hand, bouncing and rolling motions are governed by the ball’s material properties, the grass type and the local terrain profile. The ball’s interaction with the golf course plays a vital role in the gameplay. Therefore, it is essential to understand and model the golf course architecture itself. The local wind conditions are modelled using a logarithmic velocity profile, that captures the effect of the atmospheric boundary layer. Finally, we end with a discussion on various design styles and par rating of a golf course.

In this chapter, we discuss the algorithm and numerical techniques that we use to simulate a golf ball’s motion in a synthesised golf course environment. The physical models that govern the motion of the ball are integrated with the golf course environment in the form of a computer algorithm which comprises of four subroutines: flight, bounce, roll and validity check. In the flight subroutine, the ball’s flight trajectory is computed as an initial value problem using numerical schemes. When the ball hits the ground, the bounce subroutine computes the rebound velocity and spin rate vector from the impact velocity and spin rate vector. When the balls motion transitions from bouncing to pure rolling, the roll subroutine takes over and numerically computes the motion. Finally, we describe the procedure we use to model a real or an arbitrary golf course and explain how we incorporate it in the simulation programme so that the ball interacts with it.

Advancements in the field of aerial robotics and micro aerial vehicles (MAVs) have increased the demand for high payload capabilities. Closed wing designs like the annular wing, the joined wing, the box wing and spiroid tip devices improve the aerodynamic performance by suppressing the wingtip vortices along with an enhanced lift coefficient. A box wing may be defined as a wing that effectively has two main planes which merge at their ends so that there are no conventional wingtips. We propose the implementation of box wings as the main lifting surface for such systems. Box wings have a potential of generating lift with considerably less induced drag and delayed stall angles than monoplane wings. We study the aerodynamic aspects of a box wing model using wind tunnel tests and numerical simulations. We conducted Computational Fluid Dynamics (CFD) simulation subjecting the model to a steady flow and later analysed the vortex core using CFD tools. Wind tunnel measurements of the forces were obtained using sting balance. Furthermore, polyester thread tufts and smoke flow visualisation were performed to understand the qualitative behaviour of the scaled model in the open to atmosphere, suction type tunnel. Our results reveal an increase in the lift to drag (L/D) ratio of the wing by 25 % and a delay in the model’s stall angle by +6° compared to a monoplane; implying a lower stalling speed for mini unmanned aerial vehicles (UAVs) and MAVs. These advancements if applied could revolutionize the capabilities of intelligent flying systems by enabling them to carry better sensors, computational units and other payloads as per the mission.

After deep venous thrombosis (DVT), many patients have impaired quality of life (QOL). We aimed to assess whether pharmacomechanical catheter-directed thrombolysis (PCDT) improves short-term or long-term QOL in patients with proximal DVT and whether QOL is related to extent of DVT.The Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) trial was an assessor-blinded randomized trial that compared PCDT with no PCDT in patients with DVT of the femoral, common femoral, or iliac veins. QOL was assessed at baseline and 1 month, 6 months, 12 months, 18 months, and 24 months using the Venous Insufficiency Epidemiological and Economic Study on Quality of Life/Symptoms (VEINES-QOL/Sym) disease-specific QOL measure and the 36-Item Short Form Health Survey (SF-36) physical component summary (PCS) and mental component summary general QOL measures. Change in QOL scores from baseline to assessment time were compared in the PCDT and no PCDT treatment groups overall and in the iliofemoral DVT and femoral-popliteal DVT subgroups.Of 692 ATTRACT patients, 691 were analyzed (mean age, 53 years; 62% male; 57% iliofemoral DVT). VEINES-QOL change scores were greater (ie, better) in PCDT vs no PCDT from baseline to 1 month (difference, 5.7; P = .0006) and from baseline to 6 months (5.1; P = .0029) but not for other intervals. SF-36 PCS change scores were greater in PCDT vs no PCDT from baseline to 1 month (difference, 2.4; P = .01) but not for other intervals. Among iliofemoral DVT patients, VEINES-QOL change scores from baseline to all assessments were greater in the PCDT vs no PCDT group; this was statistically significant in the intention-to-treat analysis at 1 month (difference, 10.0; P .0001) and 6 months (8.8; P .0001) and in the per-protocol analysis at 18 months (difference, 5.8; P = .0086) and 24 months (difference, 6.6; P = .0067). SF-36 PCS change scores were greater in PCDT vs no PCDT from baseline to 1 month (difference, 3.2; P = .0010) but not for other intervals. In contrast, in femoral-popliteal DVT patients, change scores from baseline to all assessments were similar in the PCDT and no PCDT groups.Among patients with proximal DVT, PCDT leads to greater improvement in disease-specific QOL than no PCDT at 1 month and 6 months but not later. In patients with iliofemoral DVT, PCDT led to greater improvement in disease-specific QOL during 24 months.

Inflammation, and the organization of collagen in the breast tumor microenvironment, is an important mediator of breast tumor progression. However, a direct link between markers of inflammation, collagen organization, and patient outcome has yet to be established. A tumor microarray of 371 invasive breast carcinoma biopsy specimens was analyzed for expression of inflammatory markers, including cyclooxygenase 2 (COX-2), macrophages, and several collagen features in the tumor nest (TN) or the tumor-associated stroma (TS). The tumor microarray cohort included females, aged 18 to 80 years, with a median follow-up of 8.4 years. High expression of COX-2 (TN), CD68 (TS), and CD163 (TN and TS) predicted worse patient overall survival (OS). This notion was strengthened by the finding from the multivariate analysis that high numbers of CD163(+) macrophages in the TS is an independent prognostic factor. Overall collagen deposition was associated with high stromal expression of COX-2 and CD163; however, total collagen deposition was not a predictor for OS. Conversely, local collagen density, alignment and perpendicular alignment to the tumor boundary (tumor-associated collagen signature-3) were predictors of OS. These results suggest that in invasive carcinoma, the localization of inflammatory cells and aligned collagen orientation predict poor patient survival. Additional clinical studies may help validate whether therapy with selective COX-2 inhibitors alters expression of CD68 and CD163 inflammatory markers.

Facial fractures after motor vehicle collisions are a significant source of facial trauma in patients seen at trauma centers. With recent changes in use of seat belts and advances in airbag technology, new patterns in the incidence of facial fractures after motor vehicle collisions have yet to be quantified.To evaluate the incidence of facial fractures and assess the influence of protective device use in motor vehicle collisions in patients treated at trauma centers in the United States.Using a data set from the National Trauma Data Bank, we retrospectively assessed facial fractures in motor vehicle collisions occurring from 2007 through 2012, reported by level I, II, III, and IV trauma centers. Data analysis was performed from March 13 to September 22, 2015.We characterized the data set by subsite of facial injury using International Classification of Diseases, Ninth Revision codes including mandible, midface, and nasal fractures. We assessed the influence of variables such as age, sex, race/ethnicity, crash occupant (driver or passenger), use of protective device, and presence or suspicion of alcohol use.A total of 518 106 patients required assessment at a trauma center after a motor vehicle collision, with 56 422 (10.9%) experiencing at least 1 facial fracture. Nasal fracture was the most common facial fracture (5.6%), followed by midface (3.8%), other (3.2%), orbital (2.6%), mandible (2.2%), and panfacial fractures (0.8%). Of the subset sustaining at least 1 facial fracture, 5.8% had airbag protection only, 26.9% used a seat belt only, and 9.3% used both protective devices, while 57.6% used no protective device. Compared with no protective device, the use of an airbag alone significantly reduced the likelihood of facial fracture after a motor vehicle collision (odds ratio, 0.82; 95% CI, 0.79-0.86); use of a seat belt alone had a greater effect (odds ratio, 0.57; 95% CI, 0.56-0.58) and use of both devices provided the greatest odds reduction (odds ratio, 0.47; 95% CI, 0.45-0.48). Younger age, male sex, and alcohol use significantly increased the likelihood of facial fracture.For patients who presented to US trauma centers after motor vehicle collisions between 2007 and 2012, airbags, seat belts, and the combination of the 2 devices incrementally reduced the likelihood of facial fractures.3.

Background Estrogen receptor beta (ERβ) is expressed by 50% to 80% of triple-negative breast cancers (TNBC). Agonism of ERβ has antiproliferative effects in TNBC cells expressing ERβ. This phase 2 study evaluated single-agent high-dose estradiol in patients with advanced TNBC. Patients and Methods Adult women with measurable advanced TNBC were treated with estradiol 10 mg oral 3 times daily provided continuously for 28-day cycles. A Simon optimal 2-stage design was used. The primary end point was objective response (OR). Secondary end points included progression-free survival (PFS), clinical benefit (CB), and safety. OR, CB, and PFS by ERβ status were also examined. Results Seventeen evaluable women were enrolled. Median age was 58 years (range, 34-90 years); the median number of prior systemic therapies was 2 (range, 0-6). One patient had a confirmed partial response (OR rate, 5.9%) and remained on the study for > 24 weeks. Three patients had stable disease, with one lasting more than 16 weeks. ERβ expression was detected in 77% (13 patients). The CB rate at 16 weeks was 15% (2 of 13) in ERβ-positive patients and 0% (0 of 4) in ERβ-negative patients ( P = 1). PFS was poor (median, 1.9 months) and not statistically significantly different between ERβ-positive versus -negative patients. No new adverse events from estradiol were identified. The study closed after the first stage as a result of limited responses in these unselected patients. Conclusion In unselected TNBC, high-dose estradiol has limited efficacy. However, further evaluation of ERβ selective agonists in TNBC selected by ERβ expression may be warranted.

BACKGROUND Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) are commonly used antihypertensive medications that have been reported to affect aberrant angiogenesis and the dysregulated inflammatory response. Because of such mechanisms, it was hypothesized that these medications might affect the tumor response to neoadjuvant radiation in patients with rectal cancer. METHODS One hundred fifteen patients who were treated with neoadjuvant radiation at the University of Wisconsin (UW) between 1999 and 2012 were identified. Univariate analyses were performed with anonymized patient data. In a second independent data set, 186 patients with rectal cancer who were treated with neoadjuvant radiation at the Queen's Medical Center of the University of Hawaii (UH) between 1995 and 2010 were identified. These data were independently analyzed as before. Multivariate analyses were performed with aggregate data. RESULTS Among patients taking ACEIs/ARBs in the UW data set, a significant 3-fold increase in the rate of pathologic complete response (pCR) to neoadjuvant therapy (52% vs 17%, P = .001) was observed. This finding was confirmed in the UH data set, in which a significant 2-fold–increased pCR rate (24% vs 12%, P = .03) was observed. Identified patient and treatment characteristics were otherwise balanced between patients taking and not taking ACEIs/ARBs. No significant effect was observed on pCR rates with other medications, including statins, metformin, and aspirin. Multivariate analyses of aggregate data identified ACEI/ARB use as a strong predictor of pCR (odds ratio, 4.02; 95% confidence interval, 2.06-7.82; P < .001). CONCLUSIONS The incidental use of ACEIs/ARBs among patients with rectal cancer is associated with a significantly increased rate of pCR after neoadjuvant treatment. Cancer 2016;122:2487–95. © 2016 American Cancer Society.

Limited data are currently available to direct treatment recommendations in the management of leptomeningeal metastases (LM). Here we review treatment modalities clinicians should understand in order to manage patients with LM. We first describe our institution's experience with the treatment of LM and use this dataset to frame the discussion of LM management. Between 1999 and 2014, 1361 patients with central nervous system metastases were reviewed, 124 (9.1%) had radiographic evidence of LM, and these patients form the cohort for this analysis. Mean age at diagnosis of LM was 52years. Median survival for the entire cohort was 2.3months. The most common primary malignancies were non-small cell lung cancer (25.8%), breast cancer (17.7%), small cell lung cancer (16.9%) and melanoma (8.9%). Univariate analyses demonstrated that greater Karnofsky Performance Status (KPS) (p=0.001) and administration of systemic chemotherapy (p

An accurate numerical solution of the Laplace equation and Poisson equation is desirable in physical problems related to fluid flows, and spectral methods are well suited towards this goal. However, in the presence of an interface, the solution is discontinuous owing to the interface jump conditions and thus the numerical approximation is susceptible to the Gibbs-Wilbraham phenomenon, leading to a reduced solution accuracy. In order to resolve the discontinuity at the interface, we propose a reconstruction technique wherein the approximate solution is expressed as the sum of an infinitely-differentiable smooth function and a modified Heaviside function. The smooth function is composed of Chebyshev polynomials while the modified Heaviside function is expressed in a weak form using the jump conditions across the interface. The reconstruction framework allows us to impose the interfacial conditions exactly. To motivate further application of the technique, we first present the underlying rationale by revisiting the work of Wilbraham (1848) [13] , followed by the numerical implementation. We present numerical solution of four equations to illustrate the application of the proposed technique: (i) an ordinary differential equation (ODE), (ii) the Euler-Bernoulli equation; (iii) the Laplace equation and (iv) the Poisson equation. The Laplace and Poisson equation are solved on a square domain embedded with complex interfacial geometries in two-dimensions and on a cube with a spherical interface in three-dimensions. The method achieves error in the maximum norm ∼ O ( 10 − 14 ) using approximately 30 modes in each direction and requires a computational time of less than a second for all the problems. We also conduct a sensitivity analysis to demonstrate the robustness of the algorithm under sub-grid scale perturbations to interface location. An alternate derivation for the modified Heaviside function is proposed that is distinct from the Taylor series expansion used to treat interface conditions in difference methods. The pointwise error plots are subsequently presented to demonstrate that the Gibbs-Wilbraham phenomenon is accurately resolved. Finally, we present concluding thoughts on the potential applications of the reconstruction technique.

The Stefan problem represents a large class of physical phenomena ranging from heat diffusion during phase change to the shoreline movement problem. The numerical solution of the Stefan problem requires special attention to the accuracy of the scheme to restrict the propagation of error and consequently avoid non-physical solutions or an increased computational cost. We propose a novel fixed grid scheme using pseudospectral methods, referred to as the spectral reconstruction technique, to obtain an accurate solution of the one-dimensional single-phase Stefan problem with constant coefficients. The technique requires the solution in the spatial or the temporal direction to be decomposed into an infinitely-differentiable smooth function and a step function centered at the interface. The infinitely-differentiable smooth function is treated as a sum of Chebyshev polynomials, while a weighted Heaviside step function is used to impose the Stefan condition at the interface exactly. The weighting function is expressed in a weak form using the interface jump conditions. In this article, we use the spectral reconstruction technique in the spatial direction and two schemes for the temporal direction. At first, the Crank-Nicolson method is used for temporal discretization and then the spectral reconstruction technique. Three instances of the one dimensional Stefan problem, where the solution varies within one of the phases only, are studied: the Stefan melting problem, the Frank sphere solidification problem, and the variable flux shoreline movement problem. We present quantitative comparisons of the computed interface location with existing literature for the melting and the shoreline movement problem. The convergence of the numerical method is clarified via presenting the errors in the maximum norm for the spectral discretization scheme. Between the two temporal schemes, the Crank-Nicolson time integration is easier to implement and requires less memory, but yields algebraic convergence along with non-physical oscillations during interface grid crossing. The spectral reconstruction temporal scheme achieves exponential convergence in the maximum norm while requiring variable grid time integration.

Security has undeniably been a major concern for people in all aspects and implementations of computer science. Be it a website, database, or any other software, every application needs security to prevent any possible attack on them. One of the many popular attacks is Denial of Service (DoS), which is widely used to slow down, and even stop, many applications from processing any request. In this paper, we present a method, an algorithm, which can essentially prevent DoS and peer attacks like Distributed Denial of Service (DDoS). We use storage Data Structures like tries and process IP Addresses as they make any new request to the server. In multiple stages of IP processing and IP scrutinizing, any possible malicious request made by potential DoS attackers will be detected and, essentially, all normal requests will be separated, allowing them normal access, whereas, the attackers will be denied access to the application.

Mixing in numerous medical and chemical applications, involving overly long microchannels, can be enhanced by inducing flow instabilities. The channel length is thus shortened in the inertial microfluidics regime due to the enhanced mixing, thereby making the device compact and portable. Motivated by the emerging applications of a lab on a compact disk based microfluidic devices, we analyze the linear stability of rotationally actuated microchannel flows commonly deployed for biochemical and biomedical applications. The solution of the coupled system of Orr-Sommerfeld and Squire equations yields the growth rate and the neutral curves for the Coriolis force-driven instability. We report on the existence of four different types of unstable modes ( Type-I to Type-IV) at low rotation numbers. Furthermore, Types-I and II exhibit competing characteristics, signifying that Type-II can play an important role in the transition to turbulence. Type-III and Type-IV modes have relatively lower growth rates, but the associated normal velocity has an oscillatory nature near the center of the channel. Thus, we infer that Types-III and IV might cause strong mixing locally by virtue of strong velocity perturbation in proximity to the various point depths. Moreover, the situation is reliable if the channel is too short to allow for the amplification of Types-I and II. We quantify the potential of all the unstable modes to induce such localized mixing near an imaginary interface (near a hyphothetical interface) inside the flow using the notion of penetration depth. This study also presents an instability regime diagram obtained from the parametric study over a range of Reynolds numbers, rotation numbers, and streamwise and spanwise wavenumbers to assist the design of efficient microchannels. Further insight into the mechanism of energy transfer, drawn from the evaluation of the kinetic-energy budget, reveals how the Reynolds stress first transfers energy from the mean flow to the streamwise velocity fluctuations. The Coriolis force, thereafter, redistributes the axial momentum into spanwise and wall-normal directions, generating the frequently observed roll-cell structures. A qualitative comparison of our predictions with the reported experiments on roll-cells indicates a good agreement.