Nucleon momentum distribution in deuteron and other nuclei within the light-front dynamics method

The relativistic light-front dynamics (LFD) method has been shown to give a correct description of the most recent data for the deuteron monopole and quadrupole charge form factors obtained at the Jefferson Laboratory for elastic electron-deuteron scattering for six values of the squared momentum transfer between 0.66 and 1.7 (GeV/c)$^{2}$. The good agreement with the data is in contrast with the results of the existing non-relativistic approaches. In this work we firstly make a complementary test of the LFD applying it to calculate another important characteristic, the nucleon momentum distribution $n(q)$ of the deuteron using six invariant functions $f_{i}$ $(i=1,...,6)$ instead of two ($S$- and $D$-waves) in the nonrelativistic case. The comparison with the $y$-scaling data shows the decisive role of the function $f_{5}$ which at $q\geq$ 500 MeV/c exceeds all other $f$-functions (as well as the $S$- and $D$-waves) for the correct description of $n(q)$ of the deuteron in the high-momentum region. Comparison with other calculations using $S$- and $D$-waves corresponding to various nucleon-nucleon potentials is made. Secondly, using clear indications that the high-momentum components of $n(q)$ in heavier nuclei are related to those in the deuteron, we develop an approach within the natural orbital representation to calculate $n(q)$ in $(A,Z)$-nuclei on the basis of the deuteron momentum distribution. As examples, $n(q)$ in $^{4}$He, $^{12}$C and $^{56}$Fe are calculated and good agreement with the $y$-scaling data is obtained.Comment: 16 pages, 6 figures, corrected, to appear in Phys. Rev. C in February 200

Charge and matter distributions and form factors of light, medium and heavy neutron-rich nuclei

Results of charge form factors calculations for several unstable neutron-rich isotopes of light, medium and heavy nuclei (He, Li, Ni, Kr, Sn) are presented and compared to those of stable isotopes in the same isotopic chain. For the lighter isotopes (He and Li) the proton and neutron densities are obtained within a microscopic large-scale shell-model, while for heavier ones Ni, Kr and Sn the densities are calculated in deformed self-consistent mean-field Skyrme HF+BCS method. We also compare proton densities to matter densities together with their rms radii and diffuseness parameter values. Whenever possible comparison of form factors, densities and rms radii with available experimental data is also performed. Calculations of form factors are carried out both in plane wave Born approximation (PWBA) and in distorted wave Born approximation (DWBA). These form factors are suggested as predictions for the future experiments on the electron-radioactive beam colliders where the effect of the neutron halo or skin on the proton distributions in exotic nuclei is planned to be studied and thereby the various theoretical models of exotic nuclei will be tested.Comment: 26 pages, 11 figures, 3 tables, accepted for publication in Phys. Rev.

Idiopathic intracranial hypertension (IIH) - observations on 6 clinical cases

Идиапатичната интракраниална хипертензия (ИИХ) е неврологично заболяване, което клинически протича основно с офталмологична симптоматика.Цел: Да се направи литературен обзор и се представят дългосрочните наблюдения върху клинични случаи с ИИХ.Материал и методи: Литературният обзор е изграден на базата на търсене в 4057 заглавия в PubMed, от които 206 пълнотекстови статии от последните 5 г. Представят се и се обсъждат резултатите от дългосрочното наблюдение върху 6 клинични случая с различна динамика на заболяването в хода на лечението и проследяването.Резултати: Диагнозата се постави на базата на клиничната картина, наличието на едем на папилите и изключване на други заболявания, протичащи с интракраниална хипертензия (липса на промени в лабораторното изследване на лумбален пунктат и липсата на находка при КАТ и ЯМР на гл. мозък, отхвърляне на тромбоза на церебралните венозни синуси чрез ЯМР венография). При първите двама пациенти се проведе неврохирургично лечение (вентрикуло-перитонеален шънт), поради тежко протичане на заболяването. Дългосрочният резултат бе неблагоприятен. При останалите 4 пациента, поради по-леката тежест на заболяването, се проведе консервативно лечение с високи дoзи Acetazolamide и последващо титриране на дозата за минимум 9-12 месеца. При всички се постигна успех с възстановяване на зрителната функция, обратно развитие на едема на папилите и задържане на ефекта в рамките на 2-4 години.Заключение: Своевременната диагностика и лечение, както и добрата интердисциплинарна колаборация са основни фактори, които могат да предотвратят развитието на тежка двустранна необратима загуба на зрителна функция при пациенти с ИИХ.Idiopathic intracranial hypertension (IIH) is a neurological disease that has predominantly ophthalmological clinical signs.Aim: To perform review of literature and present the long-term observation results on clinical cases with IIH.Material and methods: The literature review is based on PubMed search of 4057 publications, among which 206 full text articles from the last 5 years. We present and discuss our observations on 6 clinical cases with different clinical characteristics and response to treatment in the long-term follow-up course.Results: The diagnosis was based on the clinical picture, presence of papilledema, and exclusion of other diseases that can cause intracranial hypertension (check-up of cerebrospinal fluid, cranial CTscan and MRI, exclusion of thrombosis of the cerebral venous sinuses - MRI venography). The first two presented patients underwent neurosurgical treatment (ventriculo-peritoneal shunting), because of the severe course of the disease. The long-term result was unfavorable. The rest 4 patients, due to the moderate severity of the disease, were treated conservatively with high dose Acetazolamide and titration of the dose for a minimum of 9-12 months. In all 4 patients there was successful recovery of visual function, absorbtion of the papilledema and retention of the result for a period of 2 to 4 years.Conclusion: The correct timely diagnosis and treatment, along with good interdisciplinary collaboration, are the main prerequisite factors that can prevent severe bilateral irreversible loss of visual function in patients with IIH

Regulation of peripheral blood flow in Complex Regional Pain Syndrome: clinical implication for symptomatic relief and pain management

Background. During the chronic stage of Complex Regional Pain Syndrome (CRPS), impaired microcirculation is related to increased vasoconstriction, tissue hypoxia, and metabolic tissue acidosis in the affected limb. Several mechanisms may be responsible for the ischemia and pain in chronic cold CPRS. Discussion. The diminished blood flow may be caused by either sympathetic dysfunction, hypersensitivity to circulating catecholamines, or endothelial dysfunction. The pain may be of neuropathic, inflammatory, nociceptive, or functional nature, or of mixed origin. Summary. The origin of the pain should be the basis of the symptomatic therapy. Since the difference in temperature between both hands fluctuates over time in cold CRPS, when in doubt, the clinician should prioritize the patient's report of a persistent cold extremity over clinical tests that show no difference. Future research should focus on developing easily applied methods for clinical use to differentiate between central and peripheral blood flow regulation disorders in individual patients

Extracellular vesicle sorting of α-Synuclein is regulated by sumoylation

Extracellular α-Synuclein has been implicated in interneuronal propagation of disease pathology in Parkinson’s Disease. How α-Synuclein is released into the extracellular space is still unclear. Here, we show that α-Synuclein is present in extracellular vesicles in the central nervous system. We find that sorting of α-Synuclein in extracellular vesicles is regulated by sumoylation and that sumoylation acts as a sorting factor for targeting of both, cytosolic and transmembrane proteins, to extracellular vesicles. We provide evidence that the SUMO-dependent sorting utilizes the endosomal sorting complex required for transport (ESCRT) by interaction with phosphoinositols. Ubiquitination of cargo proteins is so far the only known determinant for ESCRT-dependent sorting into the extracellular vesicle pathway. Our study reveals a function of SUMO protein modification as a Ubiquitin-independent ESCRT sorting signal, regulating the extracellular vesicle release of α-Synuclein. We deciphered in detail the molecular mechanism which directs α-Synuclein into extracellular vesicles which is of highest relevance for the understanding of Parkinson’s disease pathogenesis and progression at the molecular level. We furthermore propose that sumo-dependent sorting constitutes a mechanism with more general implications for cell biology.Instituto de Investigaciones Bioquímicas de La Plat