1,854 research outputs found
Causes of the failure of the state in Syria (2010-2019)
What broke out as the Arab Spring in Tunisia in 2010 stroke Egypt and shed its light on the Middle East, including Syria. During the first few days of demonstrations in Syria, the spring turned into a bloody fall and a full-scale civil war. Political-security crises and economic and social problems that had dominated the country during Assad's family rule left the state in deep defeat. Meanwhile, the arena of war turned into the scene of conflict between different political forces and their regional and international supporters, caused Syria to encounter immense foreign intervention. In this regard, this article attempts to figure out the answer to this question, "What are the causes for the Syrian state of failing during 2010-19?" The authors hypothesize that "the state in Syria has failed since the beginning of the protests due to persistent social, economic and political-security crises that led to the militarization of the country by the opposition and insurgent groups." The findings also indicate that the Syrian state faced historical crises after 2010 in economic imbalance and decline, demographic and environmental pressures, political-administrative corruption, and weak public services, which deepened after 2011, and it spread to other areas such as ethnic-religious violence
Two-qutrit Entanglement Witnesses and Gell-Mann Matrices
The Gell-Mann matrices for Lie algebra su(3) are the natural basis
for the Hilbert space of Hermitian operators acting on the states of a
three-level system(qutrit). So the construction of EWs for two-qutrit states by
using these matrices may be an interesting problem. In this paper, several
two-qutrit EWs are constructed based on the Gell-Mann matrices by using the
linear programming (LP) method exactly or approximately. The decomposability
and non-decomposability of constructed EWs are also discussed and it is shown
that the -diagonal EWs presented in this paper are all decomposable
but there exist non-decomposable ones among -non-diagonal EWs.Comment: 25 page
Influence of core stability exercise on lumbar vertebral instability in patients presented with chronic low back pain: A randomized clinical trial
Background: Excessive lumbar vertebrae translation and rotation in sagittal plane has been attributed as an associated factor of lumbar segmental instability (LSI) and low back pain (LBP). Reduction of these abnormalities improves back pain. The aim of this study was to investigate the effect of core stability exercise on the translation and rotation of lumbar vertebrae in sagittal plane in patients with nonspecific chronic LBP (NSCLBP). Methods: In this randomized clinical trial, 30 patients with NSCLBP due to LSI were included. The participants were randomly divided into two groups of treatment and control. The treatment group received general exercises plus core stability exercise for 8 weeks whereas; the control group received only general exercises. The magnitude of translation (mm) and rotation (deg) of lumbar vertebrae in the sagittal plane was determined by radiography in flexion and extension at baseline and after intervention. The primary outcome measures were to determine the mean changes from baseline in translation and rotation of the lumbar vertebrae in the sagittal plane after 8 weeks of intervention in each group. The secondary outcome was to compare the two groups in regard to translation and rotation of the lumbar vertebrae at the end of the study period. Data were analyzed using paired t-test and independent t-test. Results: Thirty patients aged 18-40 years old with clinical diagnosis of NSCLBP entered the study. Compared with baseline values, mean value of translation and rotation of the lumbar vertebra reduced significantly in both groups (P<0.05), except L3 translation in the control group. At the endpoint, mean translation value of L4 (P=0.04) and L5 (P=0.001) and rotation of the L5 (P=0.01) in the treatment group was significantly lower than the control group. Conclusion: These findings indicate that in patients presented with NSCLBP due to lumbar segmental instability, core stability exercises plus general exercises are more efficient than general exercises alone in the improvement of excessive lumbar vertebrae translation and rotation
Gracilaria corticata cultivation in fiberglass tanks and Agar extraction
In order to culture the G. corticata for further agar extraction, during one year study (2001), 3 treatments with 3 different densities of 500, 1000 and 2000 g/m^2 and 3 replicates were cultured in fiberglass tanks. During the culture period the parameters of temperature, pH and salinity were measured and 30-40 percent of water was exchanged once every two days. The aeration activity was constantly done and also 0.5g urea added into the water after exchanging the water. The biometric measurement of algae was carried out every week and ultimately end of the period culture, the daily growth and net production (wet weight) was calculated in proportion to g/m2. Also, amount of extracted agar (dry weight) estimated seasonally. In winter, the daily growth (%), net production and agar extracted (%) were estimated 1.46±0.11, 11.5±3.57 and 17.5%, in which these figures for three other seasons of spring, summer and autumn were: 3.74±0.31, 38.3±5.4, 19.3 and 1.5±0.28, 12.43±3.3, 14% and 3.11±0.04, 26.9±0.61 and 15%, respectively. Some epiphytes and grazers were recognized in algae cultivation tanks such as Navicula, Nitzschia, Oscillatoria, Peridinium, Chaetoceros, Enteromorpha, Ulva, and Isopoda, Nemertine and Nereis. Two seasons of spring and autumn showed the best daily growth and net production, and also the 500 g/m^2 treatment was recognized the best culture treatment
Tropical Dominating Sets in Vertex-Coloured Graphs
Given a vertex-coloured graph, a dominating set is said to be tropical if
every colour of the graph appears at least once in the set. Here, we study
minimum tropical dominating sets from structural and algorithmic points of
view. First, we prove that the tropical dominating set problem is NP-complete
even when restricted to a simple path. Then, we establish upper bounds related
to various parameters of the graph such as minimum degree and number of edges.
We also give upper bounds for random graphs. Last, we give approximability and
inapproximability results for general and restricted classes of graphs, and
establish a FPT algorithm for interval graphs.Comment: 19 pages, 4 figure
Orbital Ferromagnetism and Quantum Collapse in Stellar Plasmas
The possibility of quantum collapse and characteristics of nonlinear
localized excitations is examined in dense stars with Landau orbital
ferromagnetism in the framework of conventional quantum magnetohydrodynamics
(QMHD) model including Bohm force and spin-orbit polarization effects.
Employing the concepts of effective potential and Sagdeev pseudopotential, it
is confirmed that the quantum collapse and Landau orbital ferromagnetism
concepts are consistent with the magnetic field and mass-density range present
in some white dwarf stars. Furthermore, the value of ferromagnetic-field found
in this work is about the same order of magnitude as the values calculated
earlier. It is revealed that the magnetosonic nonlinear propagations can behave
much differently in the two distinct non-relativistic and relativistic
degeneracy regimes in a ferromagnetic dense astrophysical object. Current
findings should help to understand the origin of the most important mechanisms
such as gravitational collapse and the high magnetic field present in many
compact stars.Comment: To appear in journal Physics of Plasma
Quantum collapse in ground-state Fermi-Dirac-Landau plasmas
It is revealed that in a relativistically degenerate dense highly-magnetized
electron-ion plasma the effective quantum-potential due to the total
quantum-force acting on fermions may cancel-out causing a quantum transverse
collapse in the ground-state Fermi-Dirac-Landau (GSFDL) plasma. The condition
for the plasma transverse collapse is found to be restricted to the minimum
relativistic degeneracy parameter and minimum impressed magnetic field strength
values satisfied for many superdense astrophysical objects such as white dwarfs
and neutron stars. In such plasmas, the magnetization pressure is shown to
cancel the lateral electron degeneracy pressure counteracting the existing
gravitational pressure. Furthermore, using the Sagdeev pseudopotential method
in the framework of quantum magnetohydrodynamics (QMHD) model including spin
magnetization it is confirmed that the quantum pressure due to spin-orbit
polarization and the electron relativistic degeneracy has significant effects
on the existence criteria and the propagation of localized magnetosonic density
excitations in GSFDL plasmas. Current findings can have important implications
for the density excitations mechanism and gravitational collapse of the highly
magnetized astrophysical relativistically dense objects such as white-dwarfs,
neutron stars, magnetars and pulsars.Comment: To be Published in Journal Physics of Plasma
Multi-qubit stabilizer and cluster entanglement witnesses
One of the problems concerning entanglement witnesses (EWs) is the
construction of them by a given set of operators. Here several multi-qubit EWs
called stabilizer EWs are constructed by using the stabilizer operators of some
given multi-qubit states such as GHZ, cluster and exceptional states. The
general approach to manipulate the multi-qubit stabilizer EWs by
exact(approximate) linear programming (LP) method is described and it is shown
that the Clifford group play a crucial role in finding the hyper-planes
encircling the feasible region. The optimality, decomposability and
non-decomposability of constructed stabilizer EWs are discussed.Comment: 57 pages, 2 figure
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