2,337 research outputs found
Impact of Solar Wind Depression on the Dayside Magnetosphere under Northward Interplanetary Magnetic Field
We present a follow up study of the sensitivity of the Earth's magnetosphere
to solar wind activity using a particles-in-cell model [Baraka and Ben Jaffel,
2007], but here during northward IMF. The formation of the magnetospheric
cavity and its elongation is obtained with the classical structure of a
magnetosphere with parallel lobes. An impulsive disturbance is then applied to
the system by changing the bulk velocity of the solar wind to simulate a
decrease in the solar wind dynamic pressure followed by its recovery. In
response to the imposed disturbance, a gap [abrupt depression] in the incoming
solar wind plasma appears moving toward the Earth. The gap's size is a ~15 RE
and is comparable to the sizes previously obtained for both Bz<0 and Bz =0.
During the initial phase of the disturbance, the dayside magnetopause (MP)
expands slower than the previous cases of IMF orientations as a result of the
depression. The size of the MP expands nonlinearly due to strengthening of its
outer boundary by the northward IMF. Also, during the initial 100 {\Delta}t,
the MP shrank down from 13.3 RE to ~9.2 RE before it started expanding; a
phenomenon that was also observed for southern IMF conditions but not during
the no IMF case. As soon as they felt the solar wind depression, cusps widened
at high altitude while dragged in an upright position. For the field's
topology, the reconnection between magnetospheric and magnetosheath fields is
clearly observed in both northward and southward cusps areas. Also, the tail
region in the northward IMF condition is more confined, in contrast to the
fishtail-shape obtained in the southward IMF case. An X-point is formed in the
tail at ~110 RE compared to ~103 RE and ~80 RE for Bz =0 and Bz <0
respectively. Our findings are consistent with existing reports from many space
observatories for which predictions are proposed to test furthermore our
simulation technique.Comment: 48 pages, 6 figures, 1 table, accepted for publication in Annales
Geophysicae (ANGEO Communicates
Large Scale Earth's Bow Shock with Northern IMF as simulated by PIC code in parallel with MHD model
In this paper, we propose a 3D kinetic model (Particle-in-Cell PIC ) for the
description of the large scale Earth's bow shock. The proposed version is
stable and does not require huge or extensive computer resources. Because PIC
simulations work with scaled plasma and field parameters, we also propose to
validate our code by comparing its results with the available MHD simulations
under same scaled Solar wind ( SW ) and ( IMF ) conditions. We report new
results from the two models. In both codes the Earth's bow shock position is
found to be ~14.8 RE along the Sun-Earth line, and ~ 29 RE on the dusk side.
Those findings are consistent with past in situ observations. Both simulations
reproduce the theoretical jump conditions at the shock. However, the PIC code
density and temperature distributions are inflated and slightly shifted sunward
when compared to the MHD results. Kinetic electron motions and reflected ions
upstream may cause this sunward shift. Species distributions in the foreshock
region are depicted within the transition of the shock (measured ~2
c/{\omega}pi for {\Theta}Bn =90o and MMS =4.7 ) and in the downstream. The size
of the foot jump in the magnetic field at the shock is measured to be (1.7
c/{\omega}pi ). In the foreshocked region, the thermal velocity is found equal
to 213 km.sec-1 at 15 RE and is equal to 63 km.sec-1at 12 RE (Magnetosheath
region). Despite the large cell size of the current version of the PIC code, it
is powerful to retain macrostructure of planets magnetospheres in very short
time, thus it can be used for a pedagogical test purposes. It is also likely
complementary with MHD to deepen our understanding of the large scale
magnetosphereComment: 26 pages, 8 figures, 1 table , 66 references, JOAA-D-16-00005/201
The Pattern of Oral and Maxillofacial Injuries Among Patients Attending Muhimbili National Hospital, Dar es salaam, Tanzania
To determine the pattern of oral and maxillofacial injuries among patients attended at the Muhimbili National Hospital, Dar es Salaam, Tanzania. Descriptive cross-sectional hospital based study. The study was done at oral and maxillofacial surgery firm and emergency medicine department of Muhimbili National Hospital (MNH). All patients who attended the Oral and Maxillofacial Surgery firm and Emergency Medicine departments of MNH for treatment of oral and maxillofacial injuries during the period of the study and consented were included in the study. An interview of the patients with oral and maxillofacial injuries was done through structured questionnaire to obtain relevant information from the patient. Social-demographic information (age, sex, address, education level and marital status), patient’s main complaint, type of injury, place where injury took place, cause of injury, general condition of patient immediately after injury and afterwards and the time interval from injury to reporting to hospital were recorded. Clinical findings were recorded as follows: type of injury, site of injury, single or multiple, soft tissue or hard tissue injury. Soft tissue injuries were categorized as bruises, abrasions, cut wound, contusion, lacerations, avulsions, and burn. Hard tissue injury was categorized as fracture of facial bones such as nasal bone, maxilla, mandible, zygoma, frontal palatal and orbital bones. Accompanying injuries to the TMJ were also recorded. Radiological investigations including plain skull radiography (posterior anterior view, Water’s view, submental vertex view), orthopantomograph and where necessary a computed tomography (CT) were ordered. The interpretation of the radiological investigations was done by the principal investigator with the assistance of an experienced clinician and was recorded in a special form as fracture or no fracture, site and type of fracture. Treatment offered and treatment outcomes were also recorded. For admitted patients the number of days spent in hospital was recorded against the type of injury and treatment done. The data was entered into computer and analysis was done using Statistical Package for Social Sciences programme (SPSS) Version 15. Association of maxillofacial injury parameters vii (demographic factors, aetiology, treatment and complications) and type of injuries was evaluated using Chi –square test (X2). Significant level p<0.05 was used to draw out conclusion. A total of 137 patients, 123 (89.8%) males and 14 (10.2%) females with the male- female ratio of 9:1 were included in this study. The age range was from 4 to 70 years with a mean age of 30.13 years. The 21-30 and 31-40 years age groups were the most affected. Road traffic accidents (RTA) were the most (64.2%) common causes of oral and maxillofacial injuries. The most common soft tissue injury was laceration in 63 (26.9%) patients followed by bruises in 57 (24.4%) and cut wounds in 54 (23.1%). Ninety-three patients (67.9%) had sustained fractures of either the mandible, mid face or both and of those 93 patients who sustained fracture, most had mandibular fractures 42 (45.2%). All patients received basic resuscitation procedures, for stabilization of the patient. Almost all (97.8%) patients with oral and maxillofacial injuries were given analgesics for pain control and prophylaxis antibiotics (96.4%). Surgical wound debridement and wound suturing were the most (62.8% and 53.3% respectively) common treatment for soft tissue injuries, while intermaxillary or mandibulomaxillary fixation was the most (51%) common hard tissue injuries treatment. A total of 27 (19.7%) patients suffered some complications after treatment. Infection was the most (59.3%) common complication followed by malunion (33.3%). This study showed that road traffic accidents were the most common cause of maxillofacial injuries. Assaults/interpersonal violence were the second most common cause of maxillofacial trauma. These findings should alert the authorities, particularly the government and the road safety commission to the need for improvement of our roads, enforcement of existing traffic laws, and improvement of socio-economic conditions of the general population
Kontsevich and Takhtajan construction of star product on the Poisson Lie group GL(2)
Comparing the star product defined by Takhtajan on the Poisson-Lie group
GL(2) and any star product calculated from the Kontsevich's graphs (any
''K-star product'') on the same group, we show, by direct computation, that the
Takhtajan star product on GL(2) can't be written as a K-star product.Comment: 19 pages, 10 figure
Geometrical construction of quantum groups representations
We describe geometrically the classical and quantum inhomogeneous groups
G_0=(SL(2, \BbbC)\triangleright \BbbC^2) and G_1=(SL(2, \BbbC)\triangleright
\BbbC^2)\triangleright \BbbC by studying explicitly their shape algebras as a
spaces of polynomial functions with a quadratic relations.Comment: 16 pages, 1 figur
Uncovering the stories behind the numbers : a case study of maternal death surveillance and response in Goma, Democratic Republic of Congo.
Globally, 303 000 women die each year from preventable causes related to pregnancy, with the Democratic Republic of Congo (DRC) having the tenth highest maternal mortality rate. Maternal Death Surveillance and Response (MDSR) is a surveillance-action cycle that aims to eliminate preventable maternal mortality by linking actionable data on maternal deaths with multi-level actions. While countries are increasingly adopting MDSR, there are research gaps on its implementation, outcomes, and best practices in developing countries including the DRC. This study assessed MDSR implementation in Goma Health Zone (HZ), DRC, specifically its structure, process, quality, outcomes, and influencing factors. A qualitative case study design was utilized, comprising semi-structured interviews with 15 key informants from seven sites, a review of 52 MDSR documents, and an observation of a maternal death review. Data analysis was conducted in Dedoose using the constant comparative method. Findings suggest that MDSR integration into an existing Integrated Disease Surveillance and Response system in the DRC has facilitated its acceptability and institutionalization in integrated (i.e. government-affiliated) health facilities in Goma HZ, where it is sustained by existing organizational resources. However, the MDSR system had weak community and private health sector linkages. Additionally, this study revealed a systematic implementation of early MDSR phases (notification-review) but gaps in completing advanced MDSR functions such as response implementation. With respect to quality, the MDSR system’s major strengths were its simplicity, acceptability, and timeliness in integrated health facilities, while its major challenges were its acceptability, data quality, and timeliness in communities and non-integrated facilities. The political commitment to MDSR and strong support from the HZ and facility leadership were key enablers of MDSR implementation, while unregulated private facilities and the links between MDSR and disciplinary action were the most prominent barriers. While MDSR in Goma HZ has yielded some improvements in the quality of care at HZ and facility levels, its overall impact on maternal health outcomes remains reportedly weak due to limited response implementation at higher levels of the health system.To strengthen Goma’s MDSR, this study suggests the need for a non-threatening MDSR environment, multisectoral partnerships, and mechanisms to follow-up on recommendations
In vitro anti-sickling effect of crude and partially purified fractions of methanolic extract of Steculia setigera leaf on human sickled red blood cells
Sickle cell anaemia is a very important genetic disease affecting populace of the sub Saharan Africa. There is a strong need for discovery of cheap and readily available remedies for management of this disease. This research work assesses the ability of the crude methanolic extract, ethylacetate, n-hexane, butanol, and aqueous fractions of Sterculia setigera to reverse sickled human red blood cells in vitro after inducing hypoxia in erythrocytes using sodium metabisulphite. Generally, the results showed that anti-sickling activity was both concentration- and time-dependent, except for some concentrations and time intervals where the percentage of unsickled erythrocytes were abnormally higher or lower than expected. These exceptions were reflected in crude methanolic extract at 0.3 mg/ml, n-hexane fraction at 0.1 mg/ml, ethylacetate fraction at 0.2 mg/ml, butanol fraction at 0.3 mg/ml, aqueous fraction at 0.3 mg/ml with percentage unsickled erythrocytes of 29.68±1.62 %, 15.39±2.81 %, 13.01±1.62 %, 21.73±1.4 %, and 8.68±1.83 %, respectively. At the lowest concentration of 0.1mg/ml, n-hexane fraction showed the highest number of percentage unsickled erythrocytes of 76.04±1.48 %. However, at 0.3 mg/ml, ethylacetate fraction seems to have the highest anti-sickling activity of 86.01±1.69 %. Qualitative phytochemical screening revealed the presence of important phytochemicals such as alkaloids, flavonoids, steroids, tannins, saponins and cardiac glycosides. However, anthraquinones were consistently absent in the extract and all the fractions. These results goes to show that S. Setigera leaf extract possess anti-sickling properties and hence validates the usefulness of this plant in the management of sickle cell anaemia by traditional healers.Keywords: S. setigera, Sickle cell anaemia, Erythrocyte, phytochemical screening, Antisickling effec
Diversity and community structure of the snail fauna (Mollusca,_Gastropoda) in the source area of the Cetina River
Glavni cilj ovog rada bio je odrediti sastav i strukturu zajednice slatkovodnih puževa izvorišnog područja rijeke Cetine. Odabrane su dvije postaje: Preočki most i Crveni most. Prva istraživana postaja nalazi se 1,5 km, a druga 2,5 km nizvodno od izvora Glavaš. Sakupljanje uzoraka makrozoobentosa obavljano je svaki drugi mjesec od listopada 2004. do kolovoza 2005. godine. Na svakoj postaji odabrane su tri različite podloge (mikrostaništa): valutice, makrovegetacija i sitni sediment. Nakon izdvajanja iz bentosa puževi su u laboratoriju determinirani do razine vrste. Iz dobivenih podataka o brojnosti jedinki za svaku vrstu utvrđena je abundancija, a na osnovu morfometrijskih mjerenja kućice prikazana je uzrasna struktura. Tijekom istraživanja ukupno su pronađene 3 vrsta puževa. Dominantna vrsta na obje postaje je Radomaniola curta germari, druga vrsta po zastupljenosti je Horatia klecakiana. Vrsta Ancylus fluviatilis pojavljuje se u malom broju primjeraka na postaji Preočki most, dok na postaji Crveni most nije zabilježena. Provedena analiza funkcionalnih hranidbenih grupa pokazala je da na istraživanim postajama podjednak udio strugača i detritivora. Najviše vrijednosti Shannonovog i Simpsonovog indeksa raznolikosti zabilježene su na makrovegetaciji postaje Preočki most, dok su najniže vrijednosti ovog indeksa utvrđene na sitnom sedimentu iste postaje. Klaster analiza sličnosti, koja je provedena prema tipu mikrostaništa, pokazala je najveću sličnost između mikrostaništa sa valuticama obaju postaja, dok je najmanja sličnost utvrđena između mikrostaništa karakteriziranih sitnim sedimentom. Dobiveni podaci značajan su doprinos boljem poznavanju faune slatkovodnih puževa rijeke Cetine.The main objective of this study was to determine the composition and structure of recommunities of freshwater snails in the source area of the Cetina River. Two locations were chosen: Preočki most and Crveni most. The first research location is located 1,5 km and the second one 2,5 km downstream from the source Glavas. Collection of macroinvertebrates samples took place every other month from October 2004 to August 2005. At each location three various substrates (microhabitats) were selected: pebbles, macrovegetation and sediment. Snails were separated from the benthos in the laboratory and were determined to the species level. Abundance of each species was determined based on the number of individuals, and age structure was based on morphometric measurements of their shells. During this study, a total of three snail species was found. The dominant species at both locations is Radomaniola curta germari. Horatia klecakiana is the second dominant species. Species Ancylus fluviatilis occurs in a small number of samples at the location Preočki most while at the location Crveni most was not recorded. The analysis of functional feeding guilds at researched sites showed equal share of the grazers and detritivora. Highest values of the Shannon and Simpson diversity indices were recorded at macrovegetation of Preočki most, while the lowest values of the indices were determined on the sediment of the same stations. Cluster analysis of similarity, which was carried out according to the type of habitat, showed the greatest similarity between microhabitats with pebbles of both stations, while the lowest similarity was found between microhabitats characterized by sediment. The obtained data are significant contribution to better understanding of the freshwater snail’s fauna of the Cetina River
Susceptibility of staphylococal biofilms to multiple combination of antimicrobials
Scientific supervisor: A.G. Dyachenk
Status Quo Bias: Is it Human Habit to Prefer the Current Situation and Abhor Changes?
Status quo bias is a cognitive bias found in many fields including business, economics, political science, sociology, and psychology just to mention a few. It is a situation where people choose to do nothing or maintain current or previous decisions without a change. However, in today’s world, change is one among the things that are constant; thus, organizations and individuals need to develop the capability to change so as to capitalize on new opportunities that emerge from changes. The study in this paper has used content analysis to arrive to its findings which were obtained from books, peer review journals, reports and Internet information sources. The research question to be examined is whether the preference of status quo bias is a human nature or the laziness of human consciousness on making sound decisions. Findings show that status quo bias, though preferred most does not help rational decision making when individuals choose among alternatives. Thus, in order to make rational and informed decisions, individuals shouldn’t have a bias towards sticking to the old but should show some characteristics that advance positive changes. Keywords: Status quo bias, Changes, Rational decision making
- …