Deep Learning for Frame Error Probability Prediction in BICM-OFDM Systems

In the context of wireless communications, we propose a deep learning approach to learn the mapping from the instantaneous state of a frequency selective fading channel to the corresponding frame error probability (FEP) for an arbitrary set of transmission parameters. We propose an abstract model of a bit interleaved coded modulation (BICM) orthogonal frequency division multiplexing (OFDM) link chain and show that the maximum likelihood (ML) estimator of the model parameters estimates the true FEP distribution. Further, we exploit deep neural networks as a general purpose tool to implement our model and propose a training scheme for which, even while training with the binary frame error events (i.e., ACKs / NACKs), the network outputs converge to the FEP conditioned on the input channel state. We provide simulation results that demonstrate gains in the FEP prediction accuracy with our approach as compared to the traditional effective exponential SIR metric (EESM) approach for a range of channel code rates, and show that these gains can be exploited to increase the link throughput.Comment: Submitted to 2018 IEEE International Conference on Acoustics, Speech and Signal Processin

Convergence in wing coloration between orange underwing moths (Archiearis spp.) and tortoiseshell butterflies (Aglais spp.)

We analysed the wing coloration of the orange underwing moth Archiearis parthenias (Geometridae, Archiearinae) in comparison with the small tortoiseshell butterfly Aglais urticae (Nymphalidae). Both species fly in early spring and occur sympatrically in the northern Palaearctic. Aglais, the more common species, has a longer flight period and uses a broader range of habitats. Both species show a camouflaged colour pattern on surfaces exposed at rest but a bright orange signal in flight. Although the evolution of its coloration is constrained by its geometrid morphology, Archiearis is functionally similar to Aglais both while resting and in flight. Archiearis has presumably evolved from nocturnal geometrid ancestors. Its shift to diurnality has included a change in the predator defence system from one based on ultrasonic hearing, functional against bats, to one presumably functional against birds. Preliminary palatability tests showed that Aglais is distasteful to birds (chicken), while Archiearis seems to be palatable. The function of the convergent coloration is unknown, but several possibilities are discussed

Cerebrospinal fluid markers before and after shunting in patients with secondary and idiopathic normal pressure hydrocephalus

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to explore biochemical changes in the cerebrospinal fluid (CSF) induced by shunt surgery and the relationship between these changes and clinical improvement.</p> <p>Methods</p> <p>We measured clinical symptoms and analysed lumbar CSF for protein content, neurodegeneration and neurotransmission markers in patients with secondary (SNPH, n = 17) and idiopathic NPH (INPH, n = 18) before and 3 months after shunt surgery. Patients were divided into groups according to whether or not there was improvement in clinical symptoms after surgery.</p> <p>Results</p> <p>Preoperatively, the only pathological findings were elevated neurofilament protein (NFL), significantly more so in the SNPH patients than in the INPH patients, and elevated albumin content. Higher levels of NFL correlated with worse gait, balance, wakefulness and neuropsychological performance. Preoperatively, no differences were seen in any of the CSF biomarkers between patients that improved after surgery and those that did not improve. Postoperatively, a greater improvement in gait and balance performance correlated with a more pronounced reduction in NFL. Levels of albumin, albumin ratio, neuropeptide Y, vasoactive intestinal peptide and ganglioside GD3 increased significantly after shunting in both groups. In addition, Gamma amino butyric acid increased significantly in SNPH and tau in INPH.</p> <p>Conclusion</p> <p>We conclude that a number of biochemical changes occur after shunt surgery, but there are no marked differences between the SNPH and INPH patients. The results indicate that NFL may be a marker that can predict a surgically reversible state in NPH.</p

White matter pathology in normal pressure hydrocephalus and subcortical arteriosclerotic encephalopathy. Clinical, CSF and MRI aspects

Normal pressure hydrocephalus (NPH) and subcortical arteriosclerotic encephalopathy (SAE) are common causes of gait disturbance, cognitive impairment and urinary incontinence in the elderly. In spite of a primarily different pathogenesis with a potentially reversible CSF dynamic disturbance in NPH and an irreversible microangiopathy in SAE, patients with NPH and SAE can present with similar symptoms and exhibit white matter changes that are difficult to distinguish, constituting a diagnostic and therapeutic challenge.The aim of this thesis was to evaluate the diagnostic, predictive and pathophysiological significance of white matter pathology in NPH and SAE by analysis of MR images and biochemical CSF markers reflecting white matter alterations. We analysed CSF markers reflecting demyelination, axonal degeneration, gliosis and neurotransmission. MR images were analysed by two separate methods; 1) A novel visual rating protocol registering the location, the extension and the shape of periventricular hyperintensities (PVH) and deep white matter hyperintensities (DWMH), the number of subcortical and cortical infarctions, the flow void sign and the width of the ventricular system; 2) An objective, rule-based, semiautomatic segmentation method for quantification of PVH and DWMH. Neurological signs and symptoms and psychometric test score were quantified in all patients and in the NPH patients also three months after shunt surgery. Clinical variables were standardised and used for calculating the outcome of treatment. We included 124 patients with NPH and 19 patients with SAE. Eighty-three percent of the NPH patients improved after shunt surgery. In spite of the refined quantification of white matter changes, only minor differences were found between NPH and SAE patients. They also shared the major part of the quantified symptoms. CSF Sulfatide, a demyelination marker, was increased in all SAE patients, distinguishing between SAE and NPH patients with a sensitivity of 74% and a specificity of 94%, making it a potential diagnostic marker. Abundant PVH and DWMH preoperatively correlated with clinical improvement after shunt surgery, as did postoperative reduction in PVH, supporting the prognostic value of MRI in NPH. High CSF levels of neurofilament protein (NFL), a marker of neuronal degeneration, correlated with the severity of symptoms and with a favourable outcome after surgery which may imply that the symptoms in NPH are related to periventricular white matter changes. CSF sulfatide correlated with the amount of DWMH and NFL with both PVH and DWMH, suggesting that DWMH might relate to demyelination and PVH to neuronal axonal dysfunction. Our results of similarities in symptomatology and white matter MRI changes in NPH and SAE consequently indicate some common pathophysiological mechanism. The difference in sulfatide levels, however, suggests abundant demyelination in SAE but not in NPH. Thus, NPH and SAE, probably initiated by different pathogenic mechanisms, may in later stages comprise a common pathophysiological pathway of white matter degeneration that could further enhance the subcortical white matter pathology. The results of this study will probably improve the medical car

A Learning Approach for Optimal Codebook Selection in Spatial Modulation Systems

For spatial modulation (SM) systems that utilize multiple transmit antennas/patterns with a single radio front-end, we propose a learning approach to predict the average symbol error rate (SER) conditioned on the instantaneous channel state. We show that the predicted SER can he used to lower the average SER over Rayleigh fading channels by selecting the optimal codebook in each transmission instance. Further by exploiting that feedforward artificial neural networks (ANNs) trained with a mean squared error (MSE) criterion estimate the conditional a posteriori probabilities, we maximize the expected rate for each transmission instance and thereby improve the link spectral efficiency.QC 20190603</p

Reduced regional cerebral blood flow in non-psychotic violent offenders

The present study was designed to replicate previously reported findings of abnormal frontal and/or temporal cerebral blood flow in violent offenders and to control for the influence of major mental disorder (MMD), substance abuse, and current medication. HMPAO-SPECT-CBF and MRI scans from pretrial forensic psychiatric investigations of 21 subjects convicted of impulsive violent crimes were retrospectively re-evaluated. In 16/21 subjects, visual assessment of SPECT scans showed some hypoperfusion in the temporal and/or frontal lobes. MRI showed no corresponding structural damage. Quantified regional cerebral blood flow (rCBF) in defined regions of interest was compared between index cases and 11 healthy control subjects. Index subjects had significant reductions in the right angular gyrus and the right medial temporal gyrus, bilaterally in the hippocampus, and in the left white frontal matter, but they had significantly increased rCBF in the parietal association cortex bilaterally. The aberrations were as frequent and severe among the subjects without MMD, substance abuse, and current medication (n=7) as in the entire group of index subjects

Physical Capacity and Activity in Patients With Idiopathic Normal Pressure Hydrocephalus

Introduction: Most patients with idiopathic normal pressure hydrocephalus (iNPH) improve gait after surgery. However, knowledge on physical capacity and activity after shunt surgery is limited. One of the aims of this study was to evaluate the effect of shunt surgery in patients with iNPH on short-distance walking, functional exercise capacity, functional strength, and variables of activity and sleep, 3 and 6 months postoperatively. Another aim was to evaluate the effect of a physical exercise program. Additionally, we studied how changes in short-distance walking were correlated with functional exercise capacity and voluntary walking.&amp; nbsp;Methods: In total, 127 patients were consecutively included and randomized to the exercise group (n = 62) or the control group (n = 65). Participants in the exercise group underwent the supervision of a 12-week exercise program. All patients were assessed before surgery, at 3 and 6 months postoperatively with the 10-m walk test (10MWT), the 6-min walk test (6MWT), 30-s chair stand test (30sCST), and with the actigraphic recordings of activity variables measured for a total of 24 h/day for at least 3 days.&amp; nbsp;Results: All patients improved at 3 months postoperatively in the 10MWT (p &amp;lt; 0.001), 6MWT (p &amp;lt; 0.001), and 30sCST (p &amp;lt; 0.001). These results were maintained after 6 months. Actigraphic recordings for voluntary walking (steps per minute) were improved and nighttime sleep (%) increased after 6 months (p = 0.01, p = 0.04). There were no significant differences between the exercise group and the control group, except for the postoperative change in the proportion of daytime sleep after 3 months, which was slightly more reduced compared to baseline in the exercise group (p = 0.04). Changes after 3 months in the 10MWT and 6MWT were moderately correlated (rho= -0.49, p = 0.01) whereas the correlation between the 10MWT and voluntary walking was weak (rho = -0.34, p = 0.01).&amp; nbsp;Conclusion: Shunt surgery improved short-distance walking, functional exercise capacity, functional strength, and voluntary walking. An exercise program did not affect these outcomes. Short-distance walking was weakly correlated with voluntary walking, indicating improved physical capacity does not directly translate to increased physical activity. Further research should address how interventions should be tailored to promote physical activity after shunt surgery.Funding Agencies|Region Ostergotland; Ella Stahls Foundation; Rune and Ulla Amlov Foundation; Edit Jacobson Foundation; Foundation Hjalmar Svenssons Forskningsfond; Swedish Government; County Councils [ALFGBG 720121]</p