317 research outputs found
Investigation of Prediction Accuracy, Sensitivity, and Parameter Stability of Large-Scale Propagation Path Loss Models for 5G Wireless Communications
This paper compares three candidate large-scale propagation path loss models
for use over the entire microwave and millimeter-wave (mmWave) radio spectrum:
the alpha-beta-gamma (ABG) model, the close-in (CI) free space reference
distance model, and the CI model with a frequency-weighted path loss exponent
(CIF). Each of these models have been recently studied for use in standards
bodies such as 3GPP, and for use in the design of fifth generation (5G)
wireless systems in urban macrocell, urban microcell, and indoor office and
shopping mall scenarios. Here we compare the accuracy and sensitivity of these
models using measured data from 30 propagation measurement datasets from 2 GHz
to 73 GHz over distances ranging from 4 m to 1238 m. A series of sensitivity
analyses of the three models show that the physically-based two-parameter CI
model and three-parameter CIF model offer computational simplicity, have very
similar goodness of fit (i.e., the shadow fading standard deviation), exhibit
more stable model parameter behavior across frequencies and distances, and
yield smaller prediction error in sensitivity testing across distances and
frequencies, when compared to the four-parameter ABG model. Results show the CI
model with a 1 m close-in reference distance is suitable for outdoor
environments, while the CIF model is more appropriate for indoor modeling. The
CI and CIF models are easily implemented in existing 3GPP models by making a
very subtle modification -- by replacing a floating non-physically based
constant with a frequency-dependent constant that represents free space path
loss in the first meter of propagation.Comment: Open access available at:
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=743465
Overview of diagnosis and management of paediatric headache. Part I: diagnosis.
Headache is the most common somatic complaint in children and adolescents. The evaluation should include detailed history of children and adolescents completed by detailed general and neurological examinations. Moreover, the possible role of psychological factors, life events and excessively stressful lifestyle in influencing recurrent headache need to be checked. The choice of laboratory tests rests on the differential diagnosis suggested by the history, the character and temporal pattern of the headache, and the physical and neurological examinations. Subjects who have any signs or symptoms of focal/progressive neurological disturbances should be investigated by neuroimaging techniques. The electroencephalogram and other neurophysiological examinations are of limited value in the routine evaluation of headaches. In a primary headache disorder, headache itself is the illness and headache is not attributed to any other disorder (e.g. migraine, tension-type headache, cluster headache and other trigeminal autonomic cephalgias). In secondary headache disorders, headache is the symptom of identifiable structural, metabolic or other abnormality. Red flags include the first or worst headache ever in the life, recent headache onset, increasing severity or frequency, occipital location, awakening from sleep because of headache, headache occurring exclusively in the morning associated with severe vomiting and headache associated with straining. Thus, the differential diagnosis between primary and secondary headaches rests mainly on clinical criteria. A thorough evaluation of headache in children and adolescents is necessary to make the correct diagnosis and initiate treatment, bearing in mind that children with headache are more likely to experience psychosocial adversity and to grow up with an excess of both headache and other physical and psychiatric symptoms and this creates an important healthcare problem for their future life
Lipid residue analysis on Swifterbant pottery (c. 5000-3800 cal BC) in the Lower Rhine-Meuse area (the Netherlands) and its implications for human-animal interactions in relation to the Neolithisation process
This paper focuses on the functional analysis of Swifterbant pottery (c. 5000â3800 cal BC) in the Lower Rhine-Meuse area (the Netherlands). It examines pottery use across the transition to agriculture and aims to assess temporal changes in human-animal relations during the 5th millennium BC in the Lower Rhine-Meuse area through lipid residue analysis. We conducted lipid residue analysis of 49 samples from four Swifterbant sites: Hardinxveld-Giessendam Polderweg, Hardinxveld-Giessendam De Bruin, Brandwijk-het Kerkhof, and Hazendonk. A combined approach using both GC-MS and GC-C-IRMS of residues absorbed into the ceramic was employed to identify their context. Their context was then compared to published faunal datasets to present the relative abundance of taxa detected in the lipid residues. Evidence of processing freshwater fish was found in all sites, presenting that it was a continuous and primary function of Swifterbant pottery in the Lower Rhine-Meuse area starting from its first appearance at c. 5000 cal BC till the end of 5th millennium BC regardless of vessel form, size, decoration or temper. The results of our analysis also present temporal changes in the exploitation of food resources from the early to the late 5th millennium BC. From the mid 5th millennium BC onwards, vessels were also used to process different ranges of foodstuffs such as terrestrial resources and dairy products. The identification of dairy residue is the first direct evidence so far from Swifterbant pottery. We tentatively explain these results as an indication of presence of different culinary practices that had developed through the 5th millennium in the Lower Rhine-Meuse area and that the use of Swifterbant pottery is a direct reflection of changing cultural preferences on food preparation and consumption
A Pathway to Academic Resilience for Students Who Experience Trauma: A Structural Equation Modeling Approach
On the emission reduction through the application of an electrically heated catalyst to a diesel vehicle
Exhaust emissions from diesel engine powered vehicles are considerably high during cold start and warmâup, because of the poor catalyst performance due to the insufficient catalyst temperature. The controlled heat injection allowed by electrically heated catalysts can effectively reduce the catalyst lightâoff time with relatively moderate fuel penalty. This paper compares the exhaust temperature and emissions of a case study diesel vehicle in cold and warm start conditions, and proposes two electrically heated catalyst control strategies, which are evaluated in terms of emission reduction and energy consumption with different target temperature settings. In addition, a new performance indicator, that is, the specific emission reduction, is used to evaluate the afterâtreatment system and associated thermal management. For the worldwide harmonized light vehicle test cycle, the results without electrically heated catalyst show that from both cold and warm start conditions a large amount of operating points of the engine is located in the region of partial catalyst light off. Moreover, emissions, especially in terms of carbon monoxide and hydrocarbon, significantly decrease with the electrically heated catalyst implementation, for example, by at least 50% from cold start; however, they still tend to be rather substantial when the fuel is reâinjected after the engine cutoff phases. The exhaust temperature is lower than the target values in the sections of the driving cycle in which the electrically heated catalyst power is saturated according to the maximum level allowed by the device. The carbon dioxide penalty brought by the electrically heated catalyst ranges from 3.93% to 6.65% and from 6.49% to 9.35% for warm and cold start conditions, respectively
Pancreatic ductal deletion of Hnf1b disrupts exocrine homeostasis, leads to pancreatitis and facilitates tumorigenesis
BACKGROUND AND AIMS: The exocrine pancreas consists of acinar cells that produce digestive enzymes transported to the intestine through a branched ductal epithelium. Chronic pancreatitis is characterized by progressive inflammation, fibrosis and loss of acinar tissue. These changes of the exocrine tissue are risk factors for pancreatic cancer. The cause of chronic pancreatitis cannot be identified in one-quarter of patients. Here, we investigated how duct dysfunction could contribute to pancreatitis development. METHODS: The transcription factor Hnf1b, first expressed in pancreatic progenitors, is strictly restricted to ductal cells from late embryogenesis. We have previously shown that Hnf1b is crucial for pancreas morphogenesis but its postnatal role still remains unelucidated. To investigate the role of pancreatic ducts in exocrine homeostasis, we inactivated Hnf1b gene in vivo in mouse ductal cells. RESULTS: We uncovered that postnatal Hnf1b inactivation in pancreatic ducts leads to chronic pancreatitis in adults. Hnf1bÎduct mutants display dilatation of ducts, loss of acinar cells, acinar-to-ductal metaplasia (ADM) and lipomatosis. We deciphered the early events involved, with downregulation of cystic disease-associated genes, loss of primary cilia, upregulation of signaling pathways, especially Yap pathway involved in ADM. Remarkably, Hnf1bÎduct mutants developed pancreatic intraepithelial neoplasia and promote PanIN progression in concert with KRAS. We further showed that adult Hnf1b inactivation in pancreatic ducts is associated with impaired regeneration after injury, with persistent metaplasia and initiation of neoplasia. CONCLUSION: Loss of Hnf1b in ductal cells leads to chronic pancreatitis and neoplasia. This reveals that Hnf1b deficiency may contribute to diseases of the exocrine pancreas and could gain further insight into the etiology of pancreatitis and tumorigenesis.Support to CH was received from theCentre National de la Recherche Scientifique (CNRS), the Universite Pierre et Marie Curie (UPMC)- Sorbonne UniversitĂ© , the GEFLUC - Les entreprises contre le Cancer, the Societe Francophone du Diabete (SFD)-Ypsomed, the programme Emergence UPMC. EQ was supported by a PhD fellowship from the French MinistĂšre de la Recherche et de la Technologie. MF is an assistant engineer of the CNRS. TD and AS were supported by Sorbonne UniversitĂ©. MDV was supported by a PhD student fellowship from the European Marie Curie Initial Training Network (ITN)-Biology of Liver and Pancreatic Development and Disease (BOLD). O. O. was supported by a Master1 fellowship. RCP was supported by a postdoctoral fellowship from the American Heart Association (14POST20380262). MG was supported by the National Institutes of Health (U01 DK089540) and the Juvenile Diabetes Research Foundation (1-2011-592). CH is a permanent senior researcher of the Institut National de la Sante et de la Recherche Medicale (INSERM).S
Glial wingless/Wnt regulates glutamate receptor clustering and synaptic physiology at the Drosophila neuromuscular junction
Glial cells are emerging as important regulators of synapse formation, maturation, and plasticity through the release of secreted signaling molecules. Here we use chromatin immunoprecipitation along with Drosophila genomic tiling arrays to define potential targets of the glial transcription factor Reversed polarity (Repo). Unexpectedly, we identified wingless (wg), a secreted morphogen that regulates synaptic growth at the Drosophila larval neuromuscular junction (NMJ), as a potential Repo target gene. We demonstrate that Repo regulates wg expression in vivo and that local glial cells secrete Wg at the NMJ to regulate glutamate receptor clustering and synaptic function. This work identifies Wg as a novel in vivo glial-secreted factor that specifically modulates assembly of the postsynaptic signaling machinery at the Drosophila NMJ
Current practice and novel approaches in organ preservation
Organ transplantation remains the only treatment option for patients with end-stage organ failure. The last decade has seen a flurry of activity in improving organ preservation technologies, which promise to increase utilization in a dramatic fashion. They also bring the promise of extending the preservation duration significantly, which opens the doors to sharing organs across local and international boundaries and transforms the field. In this work, we review the recent literature on machine perfusion of livers across various protocols in development and clinical use, in the context of extending the preservation duration. We then review the next generation of technologies that have the potential to further extend the limits and open the door to banking organs, including supercooling, partial freezing, and nanowarming, and outline the opportunities arising in the field for researchers in the short and long term
An Intelligent Systems Approach to Primary Headache Diagnosis
In this study, the problem of primary headache diagnosis is considered, referring to multiple frames of reference, including the complexity characteristics of living systems, the limitation of human information processing, the enduring nature of headache throughout history, and the potential for intelligent systems paradigms to both broaden and deepen the scope of such diagnostic solutions. In particular, the use of machine learning is recruited for this study, for which a dataset of 836 primary headache cases was considered, originating from two medical centres located in Turkey. Five primary headache classes were derived from the data obtained, namely Tension Type Headache (TTH), Chronic Tension Type Headache (CTTH), Migraine With Aura (MwA), Migraine Without Aura (MwoA), followed by Trigeminal Autonomic Cephalalgia (TAC). A total of 9 machine learning based classi ers, ranging from linear to non-linear ensembles, in addition to 1 random baseline procedure, were evaluated within a supervised learning setting, yielding highest performance outcomes of AUC 0.985, sensitivity 1, and speci city 0.966. The study concludes that modern computing platforms represent a promising setting through which to realise intelligent solutions, which in turn support the space of analytical operations needed to drive forward diagnostic capability in the primary headache domain and beyond
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Whole Exome Sequencing Reveals DYSF, FKTN, and ISPD Mutations in Congenital Muscular Dystrophy Without Brain or Eye Involvement
Background: Congenital muscular dystrophies (CMDs) are a genetically and clinically heterogeneous group of neuromuscular disorders. Several genes encoding extracellular matrix, nuclear envelope, sarcolemmal proteins and glycosylation enzymes have been implicated in CMDs. The large overlap of clinical presentations due to mutations in different genes poses a challenge for clinicians in determining disease etiology for each patient. Objective: We investigated the use of whole exome sequencing (WES) in identifying the genetic cause of disease in 5 CMD patients from 3 families who presented with highly similar clinical features, including early-onset rapidly progressive weakness without brain or eye abnormalities. Methods: Whole exome sequencing was performed on DNA from affected individuals. Potential functional impacts of mutations were investigated by immunostaining on available muscle biopsies. Results: Pathogenic mutations in 3 different genes, DYSF, FKTN, and ISPD were identified in each family. Mutation in DYSF led to absence of dysferlin protein in patient muscle. Mutations in ISPD led to impaired ISDP function, as demonstrated by deficiency of α-dystroglycan glycosylation in patient muscle. Conclusions: This study highlights the benefit of unbiased genomic approaches in molecular diagnosis of neuromuscular disorders with high clinical heterogeneity, such as the phenotypes observed in our patients. Our results suggest that dysferlin deficiency should be in the differential diagnosis of congenital and rapidly progressive muscular dystrophy, and therefore dysferlin antibody should be in the standard immunohistochemistry panel for muscle biopsies in cases with suspected CMD
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