514 research outputs found

    Constrained Secrecy Capacity of Finite-Input Intersymbol Interference Wiretap Channels

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    We consider reliable and secure communication over intersymbol interference wiretap channels (ISI-WTCs). In particular, we first examine the setup where the source at the input of an ISI-WTC is unconstrained and then, based on a general achievability result for arbitrary wiretap channels, we derive an achievable secure rate for this ISI-WTC. Afterwards, we examine the setup where the source at the input of an ISI-WTC is constrained to be a finite-state machine source (FSMS) of a certain order and structure. Optimizing the parameters of this FSMS toward maximizing the secure rate is a computationally intractable problem in general, and so, toward finding a local maximum, we propose an iterative algorithm that at every iteration replaces the secure rate function by a suitable surrogate function whose maximum can be found efficiently. Although the secure rates achieved in the unconstrained setup are potentially larger than the secure rates achieved in the constraint setup, the latter setup has the advantage of leading to efficient algorithms for estimating achievable secure rates and also has the benefit of being the basis of efficient encoding and decoding schemes.Comment: 32 pages, 6 figure

    We Choose to Call it 'Degenerative Cervical Myelopathy': Findings of AO Spine RECODE-DCM, an International and Multi-Stakeholder Partnership to Agree a Standard Unifying Term and Definition for a Disease

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    STUDY DESIGN Modified DELPHI Consensus Process. OBJECTIVE To agree a single unifying term and definition. Globally, cervical myelopathy caused by degenerative changes to the spine is known by over 11 different names. This inconsistency contributes to many clinical and research challenges, including a lack of awareness. METHOD AO Spine RECODE-DCM (Research objectives and Common Data Elements Degenerative Cervical Myelopathy). To determine the index term, a longlist of candidate terms and their rationale, was created using a literature review and interviews. This was shared with the community, to select their preferred terms (248 members (58%) including 149 (60%) surgeons, 45 (18%) other healthcare professionals and 54 (22%) People with DCM or their supporters) and finalized using a consensus meeting. To determine a definition, a medical definition framework was created using inductive thematic analysis of selected International Classification of Disease definitions. Separately, stakeholders submitted their suggested definition which also underwent inductive thematic analysis (317 members (76%), 190 (59%) surgeons, 62 (20%) other healthcare professionals and 72 (23%) persons living with DCM or their supporters). Using this definition framework, a working definition was created based on submitted content, and finalized using consensus meetings. RESULTS Degenerative Cervical Myelopathy was selected as the unifying term, defined in short, as a progressive spinal cord injury caused by narrowing of the cervical spinal canal. CONCLUSION A consistent term and definition can support education and research initiatives. This was selected using a structured and iterative methodology, which may serve as an exemplar for others in the future

    Clinical outcome of patients infected with hepatitis C virus infection on survival after primary liver transplantation under tacrolimus

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    The outcome of hepatitis C virus (HCV) infection on patient and graft survival after orthotopic liver transplantation (OLT) has been controversial. An earlier experience with a higher dose of tacrolimus (≥0.1 mg/kg/d intravenously and ≥0.2 mg/kg/d orally) was associated with a worse clinical outcome in patients infected with HCV. The clinical outcome of 183 liver transplant recipients with end-stage liver disease (ESLD) secondary to HCV infection (HCV group) was compared with a contemporary cohort of 556 patients with HCV infection who underwent transplantation for nonviral, nonmalignant ESLD (control group). All patients were prospectively screened for anti-HCV antibodies and HCV RNA by reverse-transcriptase polymerase chain reaction. All OLT patients were receiving low-dose tacrolimus immunosuppression. Cumulative patient survival rates for the HCV group were 80% after I year and 75% after 3 years compared with rates of 84% and 78%, respectively, in the control group (P = .452). Primary graft survival rates at the same time intervals for the HCV group and the control group were 72% and 77.5% at 1 year and 67% and 72% at 3 years, respectively (P = .144). The incidence of re-transplantation (re-OLT) in the HCV group and the control group was 12.6% and 10.4%, respectively (P = .42). Chronic HCV infection as an indication for OLT with a lower dose of tacrolimus immunosuppression (≤0.05 mg/kg/d intravenously and ≤0.1 mg/kg/d orally) is associated with a similar patient and graft survival as those without HCV infection

    Degenerative cervical myelopathy

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    Degenerative cervical myelopathy (DCM) is the most common cause of spinal cord dysfunction in adults. Its prevalence is increasing as a result of population aging. The diagnosis of DCM is often delayed or overlooked, resulting in secondary neurologic morbidity. The natural course of DCM typically presents as a gradual neurological deterioration, with symptoms ranging from muscle weakness to complete paralysis, with variable degrees of sensory deficits and sphincter dysfunction. Magnetic resonance imaging (MRI) and electrophysiological studies allow the assessment of spinal cord function and its structural damage to determine treatment and clinical outcomes. All patients with signs and symptoms consistent with DCM should be referred to a spine surgeon for assessment and tailored treatment. Those patients with mild DCM can be managed non-operatively but require close monitoring and education about potentially alarming signs and symptoms. Surgery is not currently recommended for asymptomatic patients with evidence of spinal cord compression or cervical spinal stenosis on MRI, but they require a structured follow-up. Patients with moderate or severe DCM require surgical decompression to avoid further progression. The objective of this review is to raise awareness of degenerative cervical myelopathy and its increasing prevalence as well as to aid non-surgical healthcare workers for a timely diagnosis and management of this disabling condition

    Current state of social media utilization in neurosurgery amongst European Association of Neurosurgical Societies (EANS) member countries.

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    BACKGROUND Social Media (SoMe) is becoming increasingly used in the medical community, and its use has been related with academic productivity. However, utilization of SoMe in the European neurosurgical community has not been assessed systematically. METHODS An online search was undertaken to discover SoMe accounts of (1) national and related neurosurgical societies listed on the EANS website, (2) neurosurgical journals present on EANS website, (3) neurosurgery centers within EANS member countries, as listed on their website. SoMe accounts of Facebook, Twitter, YouTube, and Instagram were searched for journals and societies, and Twitter, Instagram, and Facebook for neurosurgery departments. The number of likes/followers/subscribers was recorded. RESULTS Five (31%) neurosurgery journals had a SoMe presence. The highest number of followers, likes, and tweets was found for JNNP, and Journal of Neurological Surgery Part B had the most subscribers and video views. SoMe usage was identified for 11 national (28.2%) and 2 multi-national neurosurgical societies. From these, the French Society of Neurosurgery had the largest number of Facebook followers (> 2800) and Likes (> 2700), the Society of British Neurological Surgeons had the largest number of Twitter followers (> 2850), whereas EANS overall had the most followers on Twitter > 5100 and Facebook > 5450. A total of 87 SoMe neurosurgery center accounts were found on either Facebook, Instagram or Twitter, for 64 of 1000 centers (6.4%) in 22 of 40 different countries (55%). Of these 67% (n = 43/64) arose from 6 countries (England, Germany, Italy, Romania, Turkey, Ukraine). There were more Facebook accounts (n = 42) than Instagram accounts (n = 23) or Twitter accounts (n = 22). CONCLUSION SoMe use amongst neurosurgical societies and departments in Europe is very limited. From our perspective, explanations are lacking for the correlated numbers to the market shares of SoMe in the respective countries. Further research, including a survey, to follow up on this important topic should be undertaken among EANS members

    Changes of Serum Cytokines After the Long Term Immunotherapy with Japanese Hop Pollen Extracts

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    Japanese hop (Hop J) pollen has been considered as one of the major causative pollen allergens in the autumn season. We developed a new Hop J immunotherapy extract in collaboration with Allergopharma (Reinbeck, Germany) and investigated immunologic mechanisms during 3 yr immunotherapy. Twenty patients (13 asthma with rhinitis and 7 hay fever) were enrolled from Ajou University Hospital. Sera were collected before, 1 yr, and 3 yr after the immunotherapy. Changes of serum specific IgE, IgG1, and IgG4 levels to Hop J pollen extracts and serum IL-10, IL-12, TGFβ1 and soluble CD23 levels were monitored by ELISA. Skin reactivity and airway hyper-responsiveness to methacholine were improved during the study period. Specific IgG1 increased at 1 yr then decreased again at 3 yr, and specific IgG4 levels increased progressively (p<0.05, respectively), whereas total and specific IgE levels showed variable responses with no statistical significance. IL-10, TGF-β1 and soluble CD23 level began to decrease during first year and then further decreased during next two years with statistical significances. (p<0.05, respectively). In conclusion, these findings suggested the favorable effect of long term immunotherapy with Hop J pollen extracts can be explained by lowered IgE affinity and generation of specific IgG4, which may be mediated by IL-10 and TGF-β1

    Lack of association between HLA antigen DR3 and α<inf>1</inf> deficiency in liver transplant recipients

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    The relationship between α1-antitrypsin deficiency (α-ATD) and the HLA antigen system was studied in 32 liver transplant recipients. Despite previous reports of an association of HLA antigen DR3 with homozygosity for α-AT ZZ, no such association was seen in this population of α-ATD homozygous ZZ patients with advanced hepatic disease. Thus, the reported association of HLA class II antigens and homozygosity for the Z allele for α-AT may be an artifact of either a small study population or geographic inbreeding and a coincidental association of certain HLA antigens with the presence of homozygosity for the Z allele of α-AT. © 1993 Plenum Publishing Corporation
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