Nonlocal stabilization of nonlinear beams in a self-focusing atomic vapor

We show that ballistic transport of optically excited atoms in an atomic vapor provides a nonlocal nonlinearity which stabilizes the propagation of vortex beams and higher order modes in the presence of a self-focusing nonlinearity. Numerical experiments demonstrate stable propagation of lowest and higher order vortices over a hundred diffraction lengths, before dissipation leads to decay of these structures.Comment: 3 figure

Risk factors and clinical and neurological consequences of intraoperative rupture of brain aneurysms in microsurgical operations

Objective. to assess the frequency, risk factors and clinical and neurological consequences of intraoperative rupture of arterial aneurysm (AA) of the brain (B) in clipping operations of the B AA . Materials and approaches. A retrospective analysis of microsurgical operations clipping of cerebral aneurysms in 1449 (100%) patients for the period from 2011 to 2018 was performed, of which 141 (9.73%) cases had intraoperative rupture of the aneurysm (IORA). Preoperative examination: clinical and neurological examination, CT of the brain, cerebral angiography( CAG), duplex scanning of the main vessels of the head and neck. The analyzed criteria are risk factors of IORA: AA size, localization, shape, duration of surgery after the primary rupture of AA, the presence of hypertension and the patient's condition before surgery. Results. The frequency of IORA in clipping operations of B AA was 9.73% (141 patients) in a series of observations 1441 (100%). Most often IORA-141 (100%) was registered in clipping operations of AA of complex ACA-AcomA (86 (61%) cases out of 141 (100%)). IORA is possible at all stages of the operation with the maximum frequency of contact breaks – 135 (95.74%); the rarest-6 ( 4.26%)  -  non - contact IORA (at the stage of craniotomy)  was recorded. At the preoperative stage, the vast majority of patients with subsequent IORA were diagnosed with cerebral edema, AA of large size, atherosclerotic changes in the aneurysm-affected segment of the artery and cervical areas of the aneurysm, high blood pressure during surgery, adhesive arachnoid changes. At the time of discharge from the hospital, according to the Glasgow results scale: 69 (48.94%) full or partial restoration of labor activity, 18 (12.77%) had limited daily activities without the need for outside assistance, 37 (26 24%) deep disability ) Deaths were in the group of "contact" IORA -  17 (12.06%). At 6 ( 4.26%) of "non-contact" IORA,  a deepening of initial neurological symptoms was recorded with a suppression of the level of consciousness, the addition of pyramidal insufficiency, speech impairment and psycho-organic syndrome, and a deepening of the phenomena of initial cerebral arterial vasospasm. Conclusions. IORA is predominantly in contact with a frequency of occurrence-9.73 %. The most common risk factors for IORA were: cerebral edema, large AA, atherosclerotic changes in the aneurysm-affected artery segment and cervical aneurysm sites, high blood pressure during surgery, adhesions arachnoid changes. IORA leads to deepening of initial neurological symptoms, phenomena of initial vasospasm of cerebral arteries with the level of total mortality-17 (12.06%)

Congenital Adrenal Hyperplasia: Classification of Studies Employing Psychological Endpoints

Psychological outcomes in persons with congenital adrenal hyperplasia (CAH) have received substantial attention. The objectives of this paper were to (1) catalog psychological endpoints assessed in CAH outcome studies and (2) classify the conceptual/theoretical model shaping the research design and interpretation of CAH-related psychological effects. A total of 98 original research studies, published between 1955 and 2009, were categorized based on psychological endpoints examined as well as the research design and conceptual model guiding analysis and interpretation of data. The majority of studies (68%) investigated endpoints related to psychosexual differentiation. The preponderance of studies (76%) examined a direct relationship (i.e., inferring causality) between prenatal androgen exposure and psychological outcomes. Findings are discussed in relation to the observed imbalance between theoretical interest in the role of prenatal androgens in shaping psychosexual differentiation and a broader conceptual model that examines the role of other potential factors in mediating or moderating the influence of CAH pathophysiology on psychological outcomes in both affected females and males. The latter approach offers to identify factors amenable to clinical intervention that enhance both health and quality of life outcomes in CAH as well as other disorders of sex development

The Frontal Control of Stopping

Stopping is a critical aspect of brain function. Like other voluntary actions, it is defined by its context as much as by its execution. Its neural substrate must therefore reflect both. Here, we distinguish those elements of the underlying brain circuit that preferentially reflect contextual aspects of stopping from those related to its execution. Contextual complexity of stopping was modulated using a novel "Stop/Change-signal" task, which also allowed us to parameterize the duration of the stopping process. Human magnetoencephalographic activity and behavioral responses were simultaneously recorded. Whereas theta/alpha frequency activity in the right inferior frontal gyrus was most closely associated with the duration of the stopping process, earlier gamma frequency activity in the pre-supplementary motor area was unique in showing contextual modulation. These results differentiate the roles of 2 key frontal regions involved in stopping, a crucial aspect of behavioral control

Modulational instability in nonlocal nonlinear Kerr media

We study modulational instability (MI) of plane waves in nonlocal nonlinear Kerr media. For a focusing nonlinearity we show that, although the nonlocality tends to suppress MI, it can never remove it completely, irrespectively of the particular profile of the nonlocal response function. For a defocusing nonlinearity the stability properties depend sensitively on the response function profile: for a smooth profile (e.g., a Gaussian) plane waves are always stable, but MI may occur for a rectangular response. We also find that the reduced model for a weak nonlocality predicts MI in defocusing media for arbitrary response profiles, as long as the intensity exceeds a certain critical value. However, it appears that this regime of MI is beyond the validity of the reduced model, if it is to represent the weakly nonlocal limit of a general nonlocal nonlinearity, as in optics and the theory of Bose-Einstein condensates.Comment: 8 pages, submitted to Phys. Rev.

Resting state activity and connectivity of the nucleus basalis of Meynert and globus pallidus in Lewy body dementia and Parkinson's disease dementia

Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) are two related diseases which can be difficult to distinguish. There is no objective biomarker which can reliably differentiate between them. The synergistic combination of electrophysiological and neuroimaging approaches is a powerful method for interrogation of functional brain networks in vivo. We recorded bilateral local field potentials (LFPs) from the nucleus basalis of Meynert (NBM) and the internal globus pallidus (GPi) with simultaneous cortical magnetoencephalography (MEG) in six PDD and five DLB patients undergoing surgery for deep brain stimulation (DBS) to look for differences in underlying resting-state network pathophysiology. In both patient groups we observed spectral peaks in the theta (2–8 Hz) band in both the NBM and the GPi. Furthermore, both the NBM and the GPi exhibited similar spatial and spectral patterns of coupling with the cortex in the two disease states. Specifically, we report two distinct coherent networks between the NBM/GPi and cortical regions: (1) a theta band (2–8 Hz) network linking the NBM/GPi to temporal cortical regions, and (2) a beta band (13–22 Hz) network coupling the NBM/GPi to sensorimotor areas. We also found differences between the two disease groups: oscillatory power in the low beta (13–22Hz) band was significantly higher in the globus pallidus in PDD patients compared to DLB, and coherence in the high beta (22–35Hz) band between the globus pallidus and lateral sensorimotor cortex was significantly higher in DLB patients compared to PDD. Overall, our findings reveal coherent networks of the NBM/GPi region that are common to both DLB and PDD. Although the neurophysiological differences between the two conditions in this study are confounded by systematic differences in DBS lead trajectories and motor symptom severity, they lend support to the hypothesis that DLB and PDD, though closely related, are distinguishable from a neurophysiological perspective