46 research outputs found
The Fermi Bubble as a Source of Cosmic Rays in the Energy Range > 10E15 eV
The {\it Fermi} Large Area Telescope has recently discovered two giant
gamma-ray bubbles which extend north and south of the Galactic center with
diameters and heights of the order of kpc. We suggest that the
periodic star capture processes by the Galactic supermassive black hole Sgr
A, with a capture rate of
yr and an energy release of erg per capture, can
result in hot plasma injecting into the Galactic halo at a wind velocity of
cm s. The periodic injection of hot plasma can produce a
series of shocks. Energetic protons in the bubble are re-accelerated when they
interact with these shocks. We show that for energy larger than
eV, the acceleration process can be better described by the stochastic
second-order Fermi acceleration.
We propose that hadronic cosmic rays (CRs) within the ``knee'' of the
observed CR spectrum are produced by Galactic supernova remnants distributed in
the Galactic disk. Re-acceleration of these particles in the Fermi Bubble
produces CRs beyond the knee. With a mean CR diffusion coefficient in this
energy range in the bubble cm s, we can
reproduce the spectral index of the spectrum beyond the knee and within. The
conversion efficiency from shock energy of the bubble into CR energy is about
10\%. This model provides a natural explanation of the observed CR flux,
spectral indices, and matching of spectra at the knee.Comment: 43 pages, 8 figues, to be published in the Astrophysical Journal;
version 2, 45 pages, 8 figures, added references and corrected typo
Від глобальної тектоніки до глобальної геодинаміці
Observations suggest that global (plate) tectonics operates on the Earth. The most characteristic features of the global tectonics are ocean floor spreading in mid-ocean ridges and subduction in deep-sea trenches. These processes imply the existence of mantle flow. However, within the framework of the plate tectonics, it is impossible to build a consistent quantitative theory of mantle convection because one cannot answer the question of where the tectonic plate “terminates”. From a mathematical point of view, the difficulty of global tectonics is that there are no boundary and initial conditions that would allow one to consider the evolution of some isolated part of the planet (e. g., the upper mantle). Therefore, to obtain a physically justified answer to the questions about the causes and energy sources of mantle motions, it is necessary to consider an evolution of the planet as a single whole. This formulation of the problem leads to the global geodynamics. Unlike the global tectonics, which in fact ignores the existence of the Earth’s core, for the global geodynamics the liquid outer and solid inner core, as well as the processes at the boundary between them and at the boundary between the core and the mantle, which decisively influence the mantle dynamics, are the main objects of the study. In this review, we confine ourselves to the global heat balance of the Earth. In the coming years, the results of the geoneutrino experiment will make it possible to obtain a reliable estimate of the total rate of radiogenic heat production in the Earth and to estimate the heat flow from the core to the mantle. Even this alone will significantly narrow the choice of models describing processes in the core. An ascertainment of the temperature at the inner/outer core interface and an elucidation of the mixing nature in the outer core will allow one to reduce an uncertainty of the temperature at the base of the mantle and to formulate a boundary condition problem for the mantle flow dynamics. Thus, a bridge from global geodynamics to global tectonics will be thrown and the conceptions of the latter will be put on a firm physical basis.Согласно наблюдениям, на Земле функционирует глобальная (плитовых) тектоника, характерными признаками которой являются спрединг океанского дна в серединно- океанических хребтах и субдукция в глубоководных желобах. Наличие этих процессов свидетельствует о существовании мантийных течений. Однако построить последовательную количественную теорию мантийной конвекции, оставаясь в рамках плитовых тектоники, невозможно, потому что невозможно ответить на вопрос, где "заканчивается" тектоническая плита. С математической точки зрения, трудностью глобальной тектоники является отсутствие граничных и начальных условий, использование которых дало бы возможность рассматривать задачу об эволюции некоторой выделенной части планеты (например, верхней мантии). Поэтому для получения физически обоснованного ответа на вопрос о причинах и источники энергии мантийных движений следует рассматривать эволюцию планеты как единое целое. Такая постановка задачи и ведет к глобальной геодинамики. В отличие от глобальной тектоники, которая фактически игнорирует существование ядра Земли, для глобальной геодинамики жидкое внешнее и твердое внутреннее ядра, а также процессы на границе между ними и на границе между ядром и мантией, решительно влияют на мантийную динамику, являются основными о объектами исследования. В этом обзоре рассмотрены только проблему глобального теплового баланса Земли. Уже в ближайшие годы по результатам нейтринного эксперимента будет надежно оценен полной мощности радиогенного тепловыделения на Земле и оценены поток тепла из ядра в мантию. Уже одно это существенно сузит выбор моделей, описывающих процессы в ядре. Уточнение температуры на границе внутреннего и внешнего ядер и характера перемешивания во внешнем ядре позволит уменьшить неопределенность температуры на нижней границе мантии и сформулировать краевую задачу динамики мантийных течений. Тем самым будет перекинут мост от глобальной геодинамики к глобальной тектоники и поставлено на прочную физическую основу представления последней.Згідно зі спостереженнями, на Землі функціонує глобальна (плитова) тектоніка, найхарактернішими ознаками якої є спрединг океанського дна у серединно- океанічних хребтах і субдукція у глибоководних жолобах. Наявність цих процесів засвідчує існування мантійних течій. Однак побудувати послідовну кількісну теорію мантійної конвекції, залишаючись у рамках плитової тектоніки, неможливо, тому що неможливо відповісти на питання, де "закінчується" тектонічна плита. З математичної точки зору, трудністю глобальної тектоніки є відсутність граничних і початкових умов, використання яких дало би змогу розглядати задачу про еволюцію деякої виділеної частини планети (наприклад, верхньої мантії). Тому для отримання фізично обґрунтованої відповіді на питання про причини і джерела енергії мантійних рухів слід розглядати еволюцію планети як єдине ціле. Така постановка задачі і веде до глобальної геодинаміки. На відміну від глобальної тектоніки, яка, фактично, ігнорує існування ядра Землі, для глобальної геодинаміки рідке зовнішнє і тверде внутрішнє ядра, а також процеси на межі між ними і на межі між ядром і мантією, що рішуче впливають на мантійну динаміку, є основними об'єктами дослідження. У цьому огляді розглянуто лише проблему глобального теплового балансу Землі. Вже у найближчі роки за результатами нейтринного експерименту буде надійно оцінено повну потужность радіогенного тепловиділення в Землі й оцінено потік тепла з ядра в мантію. Вже одне це суттєво звузить вибір моделей, що описують процеси в ядрі. Уточнення температури на межі внутрішнього і зовнішнього ядер і характеру перемішування у зовнішньому ядрі дасть змогу зменшити невизначеність температури на нижній межі мантії і сформулювати крайову задачу динаміки мантійних течій. Тим самим буде перекинуто міст від глобальної геодинаміки до глобальної тектоніки і поставлено на міцну фізичну основу уявлення останньої
Interaction of mantle convection with the lithosphere and the origin of kimberlites
Thermobarometry of xenolites/xenocrysts from 39 kimberlites of Eurasia, Africa, and North America demonstrates that the deepest xenolites, as well as all the other, are exhumed from the depleted lithosphere implying in agreement with petrologic and geochemical data that the kimberlite sources are situated within the limits of the depleted lithosphere. It follows from the thermobarometric data that the deepest xenolite depth decreases with increasing reference heat flow (RHF) characterizing a lithospheric geotherm. Conditions controlling formation of a rheological sublayer at the lithosphere-astenosphere boundary have been studied. In agreement with observations, a geodynamic model implies that the mantle convection reaches the base of depleted lithosphere of a "cratonic" thickness (> 130-150 km) during the post-Archean. The rheological sublayer partially penetrates the lithosphere. As a result, a layer of strongly sheared rocks form, wherefrom deepest and severely deformed xenoliths with fluidal microstructure similar to that of crustal mylonites seem to be entrained by kimberlites. The relation between the depleted lithosphere thickness and the reference heat flow predicted by the model agrees well with the thermobarometry data. In whole, the present results support the model of the kimberlite genesis assuming that the kimberlite magmatism originates from an interaction of the plume "head" with lithosphere. While this "head" propagates laterally, it follows the re-lief of the lithosphere base, metasomatizes lithosphere, and initiates melting with the melt composition depending on pressure at the lithosphere base. Particularly, under the conditions of the cratonic lithosphere base the melts have kimberlitic composition
"Clifford's Rule" and the geodynamics of kimberlite magmatism
The Clifford rule emphasizes the association of kimberlite magmatism with the crust areas of Archean and Early Proterozoic age. Though there are diamantiferous and highly productive primary diamond deposits outside Archean cratons, the Clifford rule is valid for most cases. However, from the geodynamics viewpoint the rule is not consistent because the kimberlites have a deep origin, and crustal structures can not affect the formation of protokimberlite melts. The extended Clifford rule associates the primary diamonds deposits not with the Archean crust but with the thick depleted lithosphere. It is geodynamically justified and has almost no exceptions. Besides, with such an interpretation of the Clifford rule the association of the kimberlite magmatizm with the ancient structures becomes self-evident because a lithosphere characteristic of Archean cratons could not be formed later due to a decrease of the potential temperature of the convecting mantle since Archean. Therefore the cooling of the convecting mantle is in fact the primary physical reason underlying the validity of the Clifford rule
Spatiotemporal correlations between traps, carbonatites and kimberlites
Based upon the most complete modern plateau basalt, carbonatite and kimberlite databases, we show the existence of spatiotemporal correlations between these three types of intraplate magmatism. These correlations are evident everywhere in Eurasia and Africa but they are absent in North America. A probable cause of such correlations is an interaction of a giant plume «head» with the lithosphere, which generates almost simultaneous magmatic activity over a territory of a few thousand kilometers across with magma volume and composition depending on the tectonic structure and thermal state of lithosphere. A distinction of Eurasia and Africa on one side and North America on the other is probably related to the fact that during the last 350 M years North America in contrast to Eurasia and Africa were not situated above the African and Pacific zones of plume generation
ANTIBACTERIAL PREVENTION OF INFLAMMATORY COMPLICATIONS IN INTERVENTIONAL URORADIOLOGY
Introduction. Hospital strains of microorganisms are characterized by multiple drug resistance, which significantly complicates treatment of infectious and inflammatory diseases acquired by patients during hospitalization, especially in the postoperative period. One of the methods of decreasing the level of hospital-acquired urinary tract infections (HAUTI) in urological in-patient facilities is antibacterial prevention prior to various interventions and surgeries.The study objective is to investigate the effectiveness of pre- and postoperative use of fluoroquinolones in prevention of inflammatory complications of interventional and focal treatment methods in uro-andrology.Materials and methods. The study included 32 patients aged 18 to 70 years (mean age 48.9 ± 12 years). All patients received antibacterial prevention in the pre- and postoperative periods. The patients were divided into 3 groups. In the 1st group (n = 10), all patients underwent prostate biopsy, including transrectal multifocal biopsy in 5 patients, template biopsy in 3 patients, and fusion biopsy in 2 patients. In the 2nd group (n = 12), all patients underwent prostatic artery embolization for benign prostatic hyperplasia and intermediate-to-severe lower urinary tract symptoms. In the 3rd group, 10 patients with nephrolithiasis underwent nephrolithotomy without retrograde pyelography.Results. In the 1st group, mean patient age was 66 ± 5.4 years (59–78 years); total score per the International Scoring Prognostic System (IPSS) was 18.7 ± 3.4; mean leukocyte count was 3.2 ± 1.1 per field of vision (FOV); score per the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) for evaluation of chronic prostatitis/chronic pelvic pain syndrome was 19.3 ± 5.7; score per the visual analog scale (VAS) was 4.3 ± 1.2. In 7 patients (70 %), prostate fluid (PF) contained more than 10–15 leukocytes per FOV, in 3 patients (10 %) less than 10 leukocytes. Positive inoculations were observed in 6 patients, Enterobacteriaceae family microorganism sensitivity (microbial count 105 CFU/ml) – in 2, E. сoli sensitivity (105) – in 2, Staphylococcus aureus sensitivity (104) – in 2; the rest of inoculations were negative. PF examination revealed 10–15 leukocytes per FOV in 4 patients, less than 10 leukocytes in 5 patients. In the 2nd group, PF inoculations demonstrated the following positive reactions: E. сoli (104) in 3 patients, Staphylococcus aureus (104) in 2 patients; in other inoculations no microflora growth was observed. No inflammatory complications in the postoperative period were evident. Macrohematuria developed in 3 patients, transient blood in stool in 2 patients. In the postoperative period, there weren’t any data on the presence of flora from patients. The 3rd group included 6 men and 4 women with nephrolithiasis (aged from 34 to 58 years, mean age 47 ± 7.4 years), who underwent percutaneous nephrolithotomy. The patients displayed various concrements in the kidneys (2 recurrent) and ureter. In most patients (8), leukocyturia was diagnosed: from 15 leukocytes per FOV to “dense, whole FOV”; positive inoculations in 7 patients; flora sensitivity to Lefokcin in 5 patients; Enterobacteriaceae family microorganism sensitivity (105) – in 2, E. сoli sensitivity (105) – in 2, Staphylococcus aureus sensitivity (104) – in 1; no microflora growth was observed in other inoculations.Conclusion. Treatment effectiveness in the studied groups was associated with eradication of the causative agent (empirical antibacterial therapy with correction after inoculation (fluoroquinolones), high safety profile, inhibiting concentration in the urologic organs (hematoprostatic and hematotesticular barriers) [1], wide spectrum of action, low probability of development of torpid forms of causative agents, and low level of side effects (hepatotoxicity, effect on spermatogenesis)). Empirical therapy, i.e. treatment until acquirement of microbiological data for a certain patient, plays a crucial role in treatment of urogenital infections. Choice of starting regimen of antibacterial therapy must be based on the local microbiological monitoring data and take into account the spectrum of urinary infection causative agents and their resistance to antibiotics. On the pharmaceutical market, levofloxacin is represented by several drugs, one of which is Lefokcin manufactured by Shreya Life Sciences. It’s an effective antibacterial drug for prevention and postoperative management of patients who underwent interventional and focal diagnostic and treatment procedures of uro-andrology