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Studies of grand minima in sunspot cycles by using a flux transport solar dynamo model

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Research in Astronomy and Astrophysics 2013年第11期13卷 1339-1357页

作者： Bidya binay Karak Arnab rai Choudhuri Department of Physics Indian Institute of Science

We propose that grand minima in solar activity are caused by simultane- ous fluctuations in the meridional circulation and the Babcock-Leighton mechanism for the poloidal field generation in the flux transport dynamo model. We present the following results：（a） fluctuations in the meridional circulation are more effective in producing grand minima; （b） both sudden and gradual initiations of grand minima are possible; （c） distributions of durations and waiting times between grand minima seem to be exponential; （d） the coherence time of the meridional circulation has an effect on the number and the average duration of grand minima, with a coherence time of about 30 yr being consistent with observational data. We also study the occurrence of grand maxima and find that the distributions of durations and waiting times between grand maxima are also exponential, like the grand minima. Finally we address the question of whether the Babcock-Leighton mechanism can be operative during grand minima when there are no sunspots. We show that an a-effect restricted to the upper portions of the convection zone can pull the dynamo out of the grand minima and can match various observational requirements if the amplitude of this a-effect is suitably fine-tuned.

关键词： magnetic fields -- (magnetohydrodynamics:) MHD -- Sun: magneticfields -- (Sun:) sunspots

A possible explanation of the Maunder minimum from a flux transport dynamo model

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Research in Astronomy and Astrophysics 2009年第9期9卷 953-958页

作者： Arnab rai Choudhuri Bidya binay Karak Department of Physics Indian Institute of ScienceBangalore-560012India

We propose that the poloidal field at the end of the last sunspot cycle before the Maunder minimum fell to a very low value due to fluctuations in the Babcock-Leighton process. With this assumption, a flux transport dynamo model is able to explain various aspects of the historical records of the Maunder minimum remarkably well by suitably choosing the parameters of the model to give the correct growth time.

关键词： Sun: activity -- Sun: magnetic fields -- sunspots

Underground mining slurry transportation viability

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International Journal of Coal Science & Technology 2019年第3期6卷 430-437页

作者： binay Samanta Arun Baran Samaddar IIT (ISM) Dhanbad India NIT Ravangla India

Underground mining requires lot of water pumping to surface which increases cost. Because of safety, support, ventilation and environment costs underground mines are closing down gradually all over the world. This innovative paper is based on method studies by computer programming with realistic data. With development of electronic control systems, coal water slurry mix can be remote controlled for transport to surface Separator-bunker. Main consumers need powdered coal/mineral like thermal power stations, for feeding to Fuel Burners of boilers, generating power or in steel plants for feeding into coke ovens to make hard coke for charging into Blast Furnaces for making pig iron. Feed for coal washeries also require crushed coal and output of washed coal as slurry can be sent to coke ovens of steel plants directly. Production from mine faces should be taken through lump-breaker and conveyed to a mixing chamber, near panel sump, from where adequate capacity slurry pump will propel up to pit-top. The projected financial benefit can be several millions of Rupees per year, as compared to road, rail conveyor or winders is shown, by run of a computer program in Java, with realistic cost figures from mines.

关键词： Electronic control Slurry pumping Continuous miner Lump-breaker Panel sump Mixing chamber

Subcritical dynamo and hysteresis in a Babcock-Leighton type kinematic dynamo model

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Research in Astronomy and Astrophysics 2021年第10期21卷 250-256页

作者： Vindya Vashishth Bidya binay Karak Leonid Kitchatinov Department of Physics Indian Institute of Technology(BHU)Varanasi 221005India Institute of Solar-Terrestrial Physics SB RAS Lermontov Str.126A664033IrkutskRussia Pulkovo Astronomical Observatory Pulkovskoe Sh.65St.Petersberg196140Russia

In the Sun and Sun-like stars,it is believed that cycles of the large-scale magnetic field are produced due to the existence of differential rotation and helicity in the plasma flows in their convection zones(CZs).Hence,it is expected that for each star,there is a critical dynamo number for the operation of a large-scale *** a star slows down,it is expected that the large-scale dynamo ceases to operate above a critical rotation *** our study,we explore the possibility of the operation of the dynamo in the subcritical region using the Babcock–Leighton type kinematic dynamo *** some parameter regimes,we find that the dynamo shows hysteresis behavior,i.e.,two dynamo solutions are possible depending on the initial parameters—decaying solution if starting with weak field and strong oscillatory solution(subcritical dynamo)when starting with a strong ***,under large fluctuations in the dynamo parameter,the subcritical dynamo mode is unstable in some parameter ***,our study supports the possible existence of subcritical dynamo in some stars which was previously demonstrated in a mean-field dynamo model with distributedαand MHD turbulent dynamo simulations.

关键词： magnetic field Sun:activity Sun:magnetic fields stars:rotation stars:dynamo stars

Remediation of sulfidic wastewater by catalytic oxidation with hydrogen peroxide

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Journal of Environmental Sciences 2009年第12期21卷 1735-1740页

作者： Naveed Ahmad Saikat Maitra binay Kanti Dutta Farooq Ahmad Department of Chemical Engineering Universiti Teknologi PETRONAS Department of Chemical Engineering The Petroleum Institute

Oxidation of sulfide in aqueous solution by hydrogen peroxide was investigated in the presence of hydrated ferric oxide catalyst. The ferric oxide catalyst was synthesized by sol gel technique from ferric chloride and ammonia. The synthesized catalyst was characterized by Fourier transform infrared spectroscopy, X-Ray diffraction analysis, scanning electrom microscope and energy dispersive X-ray analysis. The catalyst was quite effective in oxidizing the sulfide by hydrogen peroxide. The effects of sulfide concentration, catalyst loading, H2O2 dosing and temperature on the kinetics of sulfide oxidation were investigated. Kinetic equations and activation energies for the catalytic oxidation reaction were calculated based on the experimental results.

关键词： catalytic oxidation wastewater kinetic equation hydrogen peroxide sodium sulfide remediation

Targeted therapy for leptomeningeal metastases in non-small cell lung cancer-Changing treatment paradigms

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Chinese Journal of Cancer Research 2017年第6期29卷 535-542页

作者： binay Kumar Shah Isaac Pak Nibash Budhathoki Kayla Buker binaytara Foundation BellinghamWA 98226USA Cancer Center PeaceHealth United General HospitalSedro WoolleyWA 98284USA pacific Northwest University School of Medicine YakimaWA 98901USA Department of Internal Medicine Interfaith Medical CenterBrooklynNY 11213USA Creighton University School of Medicine OmahaNebraska 68178USA

Leptomeningeal metastasis is an uncommon but serious complication in patients with advanced cancers. Leptomeningeal metastasis is diagnosed in approximately 5% of the patients, most commonly among patients with cancers of breast and lung, melanoma, and gastrointestinal malignancies. Treatment goal is to improve survival and quality of the patients. Use of targeted therapies and immunotherapy has led to improved survival of patients with non-small cell lung cancer （NSCLC）. In this article, we review emerging data on use of mutation-specific agents and immunotherapy in the treatment of leptomeningeal metastasis among patients with NSCLC.

关键词： Non-small cell hmg cancer leptomeningeal metastases immunotherapy

Pentoxifylline versus prednisolone for severe alcoholic hepatitis:A randomized controlled trial

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World Journal of Gastroenterology 2009年第13期15卷 1613-1619页

作者： binay Krishna De Subhabrata Gangopadhyay Deep Dutta Sumanta Das Baksi Adyapad Pani Pramit Ghosh Department of Medicine Medical College & Hospitals Department of Preventive and Social Medicine Medical College & Hospitals

AIM： To compare the efficacy of pentoxifylline and prednisolone in the treatment of severe alcoholic hepatitis, and to evaluate the role of different liver function scores in predicting prognosis.METHODS： Sixty-eight patients with severe alcoholic hepatitis （Maddrey score ≥ 32） received pentoxifylline （n = 34, group Ⅰ） or prednisolone （n = 34, group Ⅱ） for 28 d in a randomized double-blind controlled study, and subsequently in an open study （with a tapering dose of prednisolone） for a total of 3 mo, and were followed up over a period of 12 mo.RESULTS： Twelve patients in group Ⅱ died at the end of 3 mo in contrast to five patients in group Ⅰ. The probability of dying at the end of 3 mo was higher in group Ⅱ as compared to group Ⅰ （35.29% vs 14.71%, P = 0.04; log rank test）. Six patients in group I developed hepatorenal syndrome as compared to none in group Ⅰ. Pentoxifylline was associated with a significantly lower model for end-stage liver disease （MELD） score at the end of 28 d of therapy （15.53± 3.63 vs 17.78± 4.56, P=0.04）. Higher baseline Maddrey score was associated with increased mortality.CONCLUSION： Reduced mortality, improved risk-benefit profile and renoprotective effects of pentoxifylline compared with prednisolone suggest that pentoxifylline is superior to prednisolone for treatment of severe alcoholic hepatitis.

关键词： Alcoholic hepatitis Pentoxifylline Prednisolone Maddrey discriminant function score Model for end-stage liver disease score Glasgowalcoholic hepatitis score

Hemodynamic effects of propranolol with spironolactone in patients with variceal bleeds: A randomized controlled trial

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World Journal of Gastroenterology 2008年第12期14卷 1908-1913页

作者： binay K De Deep Dutta Rimi Som Pranab K Biswas Subrata K Pal Anirban Biswas Department of Medicine Medical College Calcutta 88 College Street Calcutta 700073 and Institute of Cardiovascular Sciences RG Kar Medical College Calcutta 32 Gorachand Road Kolkata 700014 India

AIM: To study the hemodynamic effects of spironolactone with propranolol vs propranolol alone in the secondary prophylaxis of variceal bleeding. METHODS: Thirty-five cirrhotics with variceal bleeding randomly received propranolol (n = 17: Group A) or spironolactone plus propranolol (n = 18: Group B). Hemodynamic assessment was performed at baseline and on the eighth day. RESULTS: Spironolactone with propranolol caused a greater reduction in the hepatic venous pressure gradient than propranolol alone (26.94% vs 10.2%; P < 0.01). Fourteen out of eighteen patients on the combination treatment had a reduction in hepatic venous pressure gradient to ≤ 12 mmHg or a 20% reduction from baseline in contrast to only six out of seventeen (6/17) on propranolol alone (P < 0.05). CONCLUSION: Spironolactone with propranolol results in a better response with a greater reduction in hepatic venous pressure gradient in the secondary prophylaxis of variceal bleeding. A greater number of patients may be protected by this combination therapy than by propranolol alone. Hence, this combination may be recommended for secondary prophylaxis in patients with variceal bleeding.

关键词： Hepatic venous pressure gradient Secondary prophylaxis Spironolactone Propranolol Varicealbleeding

Can Endarterectomy Be Useful in Peripheral Arterial Occlusive Disease with Critical Limb Ischemia?

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World Journal of Cardiovascular Surgery 2019年第11期9卷 163-169页

作者： binay Krishna Sarkar Pares Banerjee Department of Cardiovascular & Thoracic surgery Nil Ratan Sircar Medical College & Hospital Kolkata West Bengal India

Importance of?thrombendarterectomy (TEA) had declined with the advent of bypass techniques and availability of prosthetic grafts, in patients with Peripheral arterial occlusive disease (PAOD). Recently, there had been a significant shift towards lower limb revascularization using endoluminal techniques. However, previously available data evaluating the long leg bypass or combined endoluminal and bypass procedures have been too anatomically heterogeneous to be easily applied to patients with infrainguinal disease and tissue loss. Clinical decision making in Complex multilevel or diffuse peripheral arterial occlusive disease with multiple co-morbidities especially associated coronary arterial disease is challenging. We describe twelve patients of iliofemoral arterial occlusive disease with tibiopopliteal arterial occlusive disease along with multiple co-morbidities like coronary arterial disease and diabetes mellitus who showed marked improvement with minimal post-operative?morbidities after iliofemoral or ileopopliteal bypass grafting with endarterectomy of the tibiopopliteal segment and related review of the literature.

关键词： Peripheral Arterial Occlusive Disease Coronary Arterial Disease Thromboendarterectomy Tibiopopliteal Disease