Optimal Trading Execution with Nonlinear Market Impact: An Alternative Solution Method

We consider the optimal trade execution strategies for a large portfolio of single stocks proposed by Almgren (2003). This framework accounts for a nonlinear impact of trades on average market prices. The execution strategy of Almgren (2003) is based on the assumption that no shares per unit of time are trade at the beginning of the period. We use a general solution method that accomodates the case of positive initial trades. Our results are twofold. First of all, we show that the problem admits a solution with no trading in the opening period only if additional parametric restrictions are imposed. Second, with positive initial trading, the optimal execution time depends on trading activity in the initial period.

Experiments on the Helicopter-Obstacle Aerodynamic Interference in Absence of External Wind

The rotor-obstacle interaction has become a challenging research topic in the last few years. In the present paper a comprehensive experimental survey carried out at University of Glasgow is described, taking advantage of two di↵erent rotor rigs and several experimental techniques. The results are then compared with those already obtained for a similar investigation at Politecnico di Milano. The experimental database comprises load measurements on the rotor (in order to assess the rotor performance for di↵erent positions with respect to a cubic obstacle), Laser Doppler Anemometry (LDA) measurements of the rotor inflow and Stereoscopic Particle Image Velocimetry (SPIV) measurements in the region between the rotor and the obstacle. Despite a few slight di↵erences in geometry and test conditions, the two databases show several similarities that are analysed in the paper

Experiments on the Helicopter-Obstacle Aerodynamic Interference in Absence of External Wind

The rotor-obstacle interaction has become a challenging research topic in the last few years. In the present paper a comprehensive experimental survey carried out at University of Glasgow is described, taking advantage of two di↵erent rotor rigs and several experimental techniques. The results are then compared with those already obtained for a similar investigation at Politecnico di Milano. The experimental database comprises load measurements on the rotor (in order to assess the rotor performance for di↵erent positions with respect to a cubic obstacle), Laser Doppler Anemometry (LDA) measurements of the rotor inflow and Stereoscopic Particle Image Velocimetry (SPIV) measurements in the region between the rotor and the obstacle. Despite a few slight di↵erences in geometry and test conditions, the two databases show several similarities that are analysed in the paper

Wind Tunnel Investigation of a Helicopter Model in Shipboard Operations

The paper presents the wind tunnel simulation of a helicopter model in shipboard operations. The test rig consists of a scaled helicopter model and a simplified ship model, based on the geometry of the Simple Frigate Shape 1. In the first phase of the experiment, pressure and Particle Image Velocimetry survey of the flow field on the flight deck were performed without the presence of the helicopter, to study the flow features on the ship deck, for several wind conditions obtained modifying the wind speed and direction. The influence of Atmospheric Boundary Layer was investigated as well. Then, the rotorcraft was positioned in a series of points representative of both a typical fore-aft landing trajectory toward the deck, and a vertical descent on the deck. Loads generated by the rotor were monitored by means of a six-axis load cell. Particle Image Velocimetry of the ship wake and of the helicopter inflow were carried out in order to have a better understanding of how the interacting flow fields affected the helicopter performance. The test showed a significant effect of the mutual aerodynamic influence between the helicopter and the ship model and a limited effect of the Atmospheric Boundary Layer

The Vortex Ring State of a Shrouded Rotor

An experimental investigation into the flow field produced by a shrouded rotor, operating in axial descent is presented. Laser Doppler Anemometry (LDA) was used to determine the induced velocity of the rotors, whilst Particle Image Velocimetry (PIV) was applied to investigate the dynamics of the unsteady flow field produced. Tests were repeated using the same rotor, without the shroud, to assess its influence on the observed phenomena. At low descent velocity ratios, the mean flow field resembled that produced by a shrouded rotor operating in hover. At slightly higher descent velocity ratios, the wake from the shrouded rotor broke down, leading to the formation of a large region of recirculation outboard of the shroud which aperiodically sheds into the free stream. Further increases in descent velocity lead the centre of recirculation to form around the external surface of the shroud. The flow topology appears to be generally similar to the one arising from an isolated rotor operating in descent flight, however the results suggest that the presence of the shroud might slightly delay the onset of the Vortex Ring State (VRS)

Non-Stationary Outcome of Alternating Hemiplegia of Childhood into Adulthood

Background Although described as non-progressive, alternating hemiplegia of childhood (AHC) can display a sudden deterioration, anecdotally reported mainly in childhood. Outcome in adulthood is uncertain. Objectives Aim of this study is to describe the long-term follow-up of neurological function in adults with AHC. Methods Seven adults with AHC were included in this retrospective single-center study. Clinical history and previous investigation data were gathered from the review of medical records. Video-documented neurological examination was performed at the last follow-up visit in four out of the seven reported indivisuals. Results Over a median follow-up of 16 years, neurological outcome and trajectories were heterogeneous. All individuals showed new neurological signs or symptoms. Three experienced a serious irreversible neurological deterioration after prolonged quadriplegic episodes and/or status epilepticus in their second or third decade. One patient died at age 29. Conclusions This video-series suggests that AHC in adulthood is not stationary; larger cohorts are needed to identify genotype–phenotype correlations and clinically useful outcome predictors

Wind Tunnel Investigation of a Helicopter Model in Shipboard Operations

The paper presents the wind tunnel simulation of a helicopter model in shipboard operations. The test rig consists of a scaled helicopter model and a simplified ship model, based on the geometry of the Simple Frigate Shape 1. In the first phase of the experiment, pressure and Particle Image Velocimetry survey of the flow field on the flight deck were performed without the presence of the helicopter, to study the flow features on the ship deck, for several wind conditions obtained modifying the wind speed and direction. The influence of Atmospheric Boundary Layer was investigated as well. Then, the rotorcraft was positioned in a series of points representative of both a typical fore-aft landing trajectory toward the deck, and a vertical descent on the deck. Loads generated by the rotor were monitored by means of a six-axis load cell. Particle Image Velocimetry of the ship wake and of the helicopter inflow were carried out in order to have a better understanding of how the interacting flow fields affected the helicopter performance. The test showed a significant effect of the mutual aerodynamic influence between the helicopter and the ship model and a limited effect of the Atmospheric Boundary Layer

RANTES correlates with inflammatory activity and synaptic excitability in multiple sclerosis

BACKGROUND: Alterations of synaptic transmission induced by inflammatory activity have been linked to the pathogenic mechanisms of multiple sclerosis (MS). Regulated upon activation, normal T-cell expressed, and secreted (RANTES) is a pro-inflammatory chemokine involved in MS pathophysiology, potentially able to regulate glutamate release and plasticity in MS brains, with relevant consequences on the clinical manifestations of the disease. OBJECTIVE: To assess the role of RANTES in the regulation of cortical excitability. METHODS: We explored the association of RANTES levels in the cerebrospinal fluid (CSF) of newly diagnosed MS patients with magnetic resonance imaging (MRI) and laboratory measures of inflammatory activity, as well its role in the control of cortical excitability and plasticity explored by means of transcranial magnetic stimulation (TMS), and in hippocampal mouse slices in vitro. RESULTS: CSF levels of RANTES were remarkably high only in active MS patients and were correlated with the concentrations of interleukin-1β. RANTES levels were associated with TMS measures of cortical synaptic excitability, but not with long-term potentiation (LTP)-like plasticity. Similar findings were obtained in mouse hippocampal slices in vitro, where we observed that RANTES enhanced basal excitatory synaptic transmission with no effect on LTP. CONCLUSION: RANTES correlates with inflammation and synaptic excitability in MS brains

Cardiac investigations in sudden unexpected death in DEPDC5-related epilepsy

Objective: Germline loss-of-function mutations in DEPDC5, and in its binding partners (NPRL2/3) of the mammalian target of rapamycin (mTOR) repressor GATOR1 complex, cause focal epilepsies and increase the risk of sudden unexpected death in epilepsy (SUDEP). Here, we asked whether DEPDC5 haploinsufficiency predisposes to primary cardiac defects that could contribute to SUDEP and therefore impact the clinical management of patients at high risk of SUDEP. Methods: Clinical cardiac investigations were performed in 16 patients with pathogenic variants in DEPDC5, NPRL2, or NPRL3. Two novel Depdc5 mouse strains, a human HA-tagged Depdc5 strain and a Depdc5 heterozygous knockout with a neuron-specific deletion of the second allele (Depdc5c/−), were generated to investigate the role of Depdc5 in SUDEP and cardiac activity during seizures. Results: Holter, echocardiographic, and electrocardiographic (ECG) examinations provided no evidence for altered clinical cardiac function in the patient cohort, of whom 3 DEPDC5 patients succumbed to SUDEP and 6 had a family history of SUDEP. There was no cardiac injury at autopsy in a postmortem DEPDC5 SUDEP case. The HA-tagged Depdc5 mouse revealed expression of Depdc5 in the brain, heart, and lungs. Simultaneous electroencephalographic–ECG records on Depdc5c/− mice showed that spontaneous epileptic seizures resulting in a SUDEP-like event are not preceded by cardiac arrhythmia. Interpretation: Mouse and human data show neither structural nor functional cardiac damage that might underlie a primary contribution to SUDEP in the spectrum of DEPDC5-related epilepsies. ANN NEUROL 2022;91:101–11