Numerics of singularly perturbed differential equations

The main purpose of this report is to carry out the effect of the various numerical methods for solving singular perturbation problems on non-uniform meshes. When a small parameter epsilon known as the singular perturbation parameter is multiplied with the higher order terms of the differential equation, then the differential equation becomes singularly perturbed. In this type of problems, there are regions where the solution varies very rapidly known as boundary layers and the region where the solution varies uniformly known as the outer region. Standard finite difference/element methods are applied on the singularly perturbed differential equation on uniform mesh give unsatisfactory result as epsilon tends to zero. Due to presence of boundary layer, standard difference schemes unable to capture the layer behaviour until the mesh parameter and perturbation parameter are of the same size which results vast computational cost. In order to overcome this difficulty, we adapt non-uniform meshes. The Shishkin mesh and the adaptive mesh are two widely used special type of non-uniform meshes for solving singularly perturbed problem. Here, in this report singularly perturbed problems namely convection-diffusion and reaction-diffusion problems are considered and solved by various numerical techniques. The numerical solution of the problems are compared with the exact solution and the results are shown in the shape of tables and graphs to validate the theoretical bounds

Pengaruh Price Discount Framing Terhadap Purchase Intention Pada Ramayana Department Store, Jodoh, Batam

Penelitian ini menguji tentang pengaruh price discount framing terhadap purchase intention di Ramayana Department Store, Jodoh, Batam. Responden penelitian ini adalah pengunjung Ramayana Department Store  dengan kiteria pernah melakukan kunjungan minimal 2 kali, yaitu sebanyak 107 orang. Metode analisis data yang digunakan adalah analisis deskriptif dengan menggunakan regresi linear berganda, uji asumsi klasik, uji t dan uji F dengan taraf signifikansi sebesar 0,05 dan koefisien determinasi. Hasil dari penelitian ini adalah keempat variabel independen yaitu percentage discount, absolute saving, bonus pack dan special price secara parsial dan simultan berpengaruh positif signifikan terhadap purchase intention

Reaksi Metanolisis Limbah Minyak Ikan Menjadi Metil Ester Sebagai Bahan Bakar Biodiesel Dengan Menggunakan Katalis Naoh

Biodiesel merupakan bahan bakar alternatif yang produksinya dapat diperbaharui. Biodisel diperoleh dari minyak tumbuhan, lemak binatang atau minyak bekas melalui esterifikasi dengan alkohol. Biodiesel dapat digunakan tanpa modifikasi ulang mesin diesel. Minyak ikan dapat dimanfaatkan sebagai biodiesel karena mengandung asam lemak bebas. Peningkatan asam lemak bebas secara cepat terjadi karena adanya enzim lipase aktif pada saat proses pembuatan minyak ikan menjadi biodsel sehingga dapat dikonversi menjadi metil ester dengan proses esterifikasi. Esterifikasi adalah reaksi asam lemak bebas dengan alkohol membentuk ester dan air. Tujuan dari penelitian ini adalah untuk menghasilkan biodiesel dari limbah ikan dengan pengolahan limbah secara fisik, kimiawi, dan biologis, menentukan waktu reaksi optimum esterifikasi, serta menentukan banyaknya soda kaustik (NaOH) yang dibutuhkan agar didapatkan pemisahan antara gliserin dan metil ester yang optimum. Variabel tetap yang digunakan terdiri dari : berat minyak ikan 50 ml, waktu pemasakan 120 menit, perbandingan kadar minyak: metanol (1:6), % berat katalis, sedangkan variabel berubahnya terdiri dari : NaOH , dan waktu esterifikasi, variasi NaOH yang dipakai dalam penelitian ini adalah 3,5gr, 4,5gr, 5,5gr , dan 6,5gr dan variasi untuk waktu esterifikasinya adalah 30, 45, 60, dan 75 menit. Dapat disimpulkan bahwa pada waktu 75 menit, perbandingan minyak :methanol = 1:6 dan dengan penambahan NaOH 3,5 gram memberikan konversi maksimal yaitu 80,59%

A Demand Based Load Balanced Service Replication Model

Cloud computing allows service users and providers to access the applications, logical resources and files on any computer with ease. A cloud service has three distinct characteristics that differentiate it from traditional hosting. It is sold on demand, typically by the minute or the hour; it is elastic. It is a way to increase capacity or add capabilities on the fly without investing in new infrastructure, training new personnel, or licensing new software. It not only promises reliable services delivered through next-generation data centers that are built on compute and storage virtualization technologies but also addresses the key issues such as scalability, reliability, fault tolerance and file load balancing. The one way to achieve this is through service replication across different machines coupled with load balancing. Though replication potentially improves fault tolerance, it leads to the problem of ensuring consistency of replicas when certain service is updated or modified. However, fewer replicas also decrease concurrency and the level of service availability. A balanced synchronization between replication mechanism and consistency not only ensures highly reliable and fault tolerant system but also improves system performance significantly. This paper presents a load balancing based service replication model that creates a replica on other servers on the basis of number of service accesses. The simulation results indicate that the proposed model reduces the number of messages exchanged for service replication by 25-55% thus improving the overall system performance significantly. Also in case of CPU load based file replication, it is observed that file access time reduces by 5.56%-7.65%

Inclusion of the glucocorticoid receptor in a hypothalamic pituitary adrenal axis model reveals bistability

BACKGROUND: The body's primary stress management system is the hypothalamic pituitary adrenal (HPA) axis. The HPA axis responds to physical and mental challenge to maintain homeostasis in part by controlling the body's cortisol level. Dysregulation of the HPA axis is implicated in numerous stress-related diseases. RESULTS: We developed a structured model of the HPA axis that includes the glucocorticoid receptor (GR). This model incorporates nonlinear kinetics of pituitary GR synthesis. The nonlinear effect arises from the fact that GR homodimerizes after cortisol activation and induces its own synthesis in the pituitary. This homodimerization makes possible two stable steady states (low and high) and one unstable state of cortisol production resulting in bistability of the HPA axis. In this model, low GR concentration represents the normal steady state, and high GR concentration represents a dysregulated steady state. A short stress in the normal steady state produces a small perturbation in the GR concentration that quickly returns to normal levels. Long, repeated stress produces persistent and high GR concentration that does not return to baseline forcing the HPA axis to an alternate steady state. One consequence of increased steady state GR is reduced steady state cortisol, which has been observed in some stress related disorders such as Chronic Fatigue Syndrome (CFS). CONCLUSION: Inclusion of pituitary GR expression resulted in a biologically plausible model of HPA axis bistability and hypocortisolism. High GR concentration enhanced cortisol negative feedback on the hypothalamus and forced the HPA axis into an alternative, low cortisol state. This model can be used to explore mechanisms underlying disorders of the HPA axis

Analysis of waiting time for elective surgical procedures in neurosurgery department at a tertiary care teaching hospital in NCT, India

Background: Reported increases in waiting times for publicly-funded elective surgeries have intensified the need to decrease wait by healthcare providers and hence the study.Methods: Descriptive study done in neurosurgery department, to ascertain waiting times for its elective surgeries, included a retrospective analysis of admitted post-surgical patients and a prospective study using interviews with relevant stakeholders to do a process mapping.Results: Median time from decision of surgery to actual date of surgery was found to be 110.5 days. It was calculated that for optimum utilization of present available OTs, 19 extra beds are required and to address the existing load of patients waiting for their respective surgeries there is a need of 63 additional beds with 2 additional OTs functioning per day.Conclusions: The most common cause of waiting time was unavailability of vacant beds due to mismatch in demand-supply. The reason for postponement of surgery after admission was found to be lack of availability of theatre time followed by patient not being fit for surgery. Shortage of operating time was due to delayed start of operation theatre time. The study recommends improving admission process, restricting OPD time, standardized patient prioritization depending on relevant clinical criteria

Comparative evaluation of efficacy and safety of carboxymethylcellulose either alone or in combination with non-steroidal anti-inflammatory drug in the treatment of dry eye in a tertiary care teaching hospital

Background: Dry eye produces discomfort and reducedvision. The treatment of dry eyes has traditionally involved hydrating and lubricating artificial tears. The newer medications include non-steroidal anti-inflammatory drugs (NSAIDs) for the treatment of dry eye disorders. This study was designed to compare the effect of topical carboxymethylcellulose (CMC) alone or in combination with topical NSAID for the treatment of dry eye in a tertiary care teaching hospital.Methods: A total of 60 patients diagnosed with dry eye were enrolled for a study period of 1 year. Patient of either sex (male/female), age between 18 and 70 years, and all diagnosed cases of dry eye in ophthalmology outpatient department were selected. Patients (n=60) were stabilized on CMC for 2 weeks and thereafter divided into two groups. Group I (n=30) received only topical CMC; Group II (n=30) received CMC+NSAID. The patients were followed up to 12 weeks. Diagnostic tests included Schirmer’s test and tear break up time (TBUT). Ocular Surface Disease Index (OSDI) was used for assessing the Quality of Life. Analysis was done using GraphPad InStat software. p0.05) and TBUT test value (p>0.05) showed no significant difference while OSDI score revealed significant difference (p<0.05). Burning, stinging, blurring of vision, photophobia, and hyperemia were among the common adverse effects seen.Conclusion: Both groups showed significant improvement in Schirmer’s test and TBUT test value and OSDI score at the end of the study. Intergroup comparison showed a significant difference with reference to OSDI score. Patients receiving NSAID reported more adverse effects

Influence of cocoon stifling and storage on silk reeling performance and quality of muga raw silk

The hot air electrical stifling study has been conducted to evaluate the influence of electrical stifling temperature, stifling hours and duration of cocoon preservation on reeling performance and quality of muga silk . Muga cocoons are reeled on motorised muga silk reeling machine. Electrical hot air stifling has shown superior reeling performance in comparison to smoke stifled and sun dried cocoons. The study has shown that raw silk recovery from electrically hot air stifled cocoons is significantly high in comparison to flame-smoke-sun stifling with a gain of about 6.37%. Similarly there is gradual decline in raw silk recovery (RSR) percentage with increase in storage period of muga cocoon. Thus, RSR has declined by 14.32% in course of 6 months of cocoon storage. Tenacity is found higher in October crop (average 3.36 g/den), while it is average 2.83 g/den in crop of May month. Muga raw silk yarn has lost elongation with extended storage of yarn. In fresh muga raw silk yarn, elongation is found 37.55%, while in one year old stored muga raw silk yarn elongation has come down to 33.02%. Thus, the study recommends stifling muga cocoon by hot air stifling for four hours. Cocoon preservation time needs to be minimized and muga silk yarn of October (Kotia) crop with high tenacity should be used as warp yarn in weavin