1,801 research outputs found

    Evaluating the Location Efficiency of Arabian and African Seaports Using Data Envelopment Analysis (DEA)

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    In this paper the efficiency and performance is evaluated for 22 seaports in the region of East Africa and the Middle East. The aim of our study is to compare seaports situated on the maritime trade road between the East and the West. These are considered as middledistance ports at which goods from Europe and Far East/Australia can be exchanged and transhipped to all countries in the Middle East and East Africa. All these seaports are regional coasters, and dhow trade was built on these locations, leading this part of the world to become an important trade centre. Data was collected for 6 years (2000-2005) and a non-parametric linear programming method, DEA (Data Envelopment Analysis) is applied. The ultimate goal of our study is: 1) to estimate the performance levels of the ports under consideration. This will help in proposing solutions for better performance and developing future plans. 2) to select optimum transhipment locations.Middle East and East African Seaports; Data Envelopment Analysis; Seaports Efficiency; Performance measurement of Containers Ports; transshipment.

    On the numerical simulation of population dynamics with density-dependent migrations and the Allee effects

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    In this paper, the variational iteration method (VIM) and the Adomian decomposition method (ADM) are presented for the numerical simulation of the population dynamics model with density-dependent migrations and the Allee effects. The convergence of ADM is proved for the model problem. The results obtained by these methods are compared to the exact solution. It is found that these methods are always converges to the right solutions with high accuracy. Furthermore, VIM needs relative less computational work than ADM

    A Social Based Model For Genetic Algorithms.

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    Genetic algorithms (GAs), as a general search model, have proved its success in several applications, however, recently, several researchers have argued that they have slow convergence; this slowness is due to the randomness in all their operations. Therefore, recent researches have employed structured populations, in order to eliminate randomness, such as island models, cellular model, multinational evolutionary algorithms, etc. In this proposal, a social based GA is introduced; this model is trying to mimic the actual social behavior and the actual death and birth process. We will restrict the recombination for males to the only permitted females; we also divide the population into nearly separated subgroups (similar to the island model). Our motivation to such an approach is that we expect the nature to be more robust and optimal; hence the objectives of this work are to study the effects of these social rules and customs on the standard GA, and to investigate its effects on the speed of convergence of GA. The results will be analyzed according to parameters that depend on the social behavior and the natural birth and death models

    Therapies for tuberculosis and AIDS: Myeloid-derived suppressor cells in focus

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    The critical role of suppressive myeloid cells in immune regulation has come to the forefront in cancer research, with myeloid-derived suppressor cells (MDSCs) as a main oncology immunotherapeutic target. Recent improvement and standardization of criteria classifying tumor-induced MDSCs have led to unified descriptions and also promoted MDSC research in tuberculosis (TB) and AIDS. Despite convincing evidence on the induction of MDSCs by pathogen-derived molecules and inflammatory mediators in TB and AIDS, very little attention has been given to their therapeutic modulation or roles in vaccination in these diseases. Clinical manifestations in TB are consequences of complex host-pathogen interactions and are substantially affected by HIV infection. Here we summarize the current understanding and knowledge gaps regarding the role of MDSCs in HIV and Mycobacterium tuberculosis (co)infections. We discuss key scientific priorities to enable application of this knowledge to the development of novel strategies to improve vaccine efficacy and/or implementation of enhanced treatment approaches. Building on recent findings and potential for cross-fertilization between oncology and infection biology, we highlight current challenges and untapped opportunities for translating new advances in MDSC research into clinical applications for TB and AIDS

    Antiretroviral therapy does not reduce tuberculosis reactivation in a tuberculosis-HIV coinfection model

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    While the advent of combination antiretroviral therapy (ART) has significantly improved survival, tuberculosis (TB) remains the leading cause of death in the HIV-infected population. We used Mycobacterium tuberculosis/simian immunodeficiency virus-coinfected (M. tuberculosis/SIV-coinfected) macaques to model M. tuberculosis/HIV coinfection and study the impact of ART on TB reactivation due to HIV infection. Although ART significantly reduced viral loads and increased CD4+ T cell counts in blood and bronchoalveolar lavage (BAL) samples, it did not reduce the relative risk of SIV-induced TB reactivation in ART-treated macaques in the early phase of treatment. CD4+ T cells were poorly restored specifically in the lung interstitium, despite their significant restoration in the alveolar compartment of the lung as well as in the periphery. IDO1 induction in myeloid cells in the inducible bronchus-associated lymphoid tissue (iBALT) likely contributed to dysregulated T cell homing and impaired lung immunity. Thus, although ART was indispensable for controlling viral replication, restoring CD4+ T cells, and preventing opportunistic infection, it appeared inadequate in reversing the clinical signs of TB reactivation during the relatively short duration of ART administered in this study. This finding warrants the modeling of concurrent treatment of TB and HIV to potentially reduce the risk of reactivation of TB due to HIV to inform treatment strategies in patients with M. tuberculosis/HIV coinfection

    CXCL17 is a specific diagnostic biomarker for severe pandemic influenza A(H1N1) that predicts poor clinical outcome

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    The C-X-C motif chemokine ligand 17 (CXCL17) is chemotactic for myeloid cells, exhibits bactericidal activity, and exerts anti-viral functions. This chemokine is constitutively expressed in the respiratory tract, suggesting a role in lung defenses. However, little is known about the participation of CXCL17 against relevant respiratory pathogens in humans. Here, we evaluated the serum levels and lung tissue expression pattern of CXCL17 in a cohort of patients with severe pandemic influenza A(H1N1) from Mexico City. Peripheral blood samples obtained on admission and seven days after hospitalization were processed for determinations of serum CXCL17 levels by enzyme-linked immunosorbent assay (ELISA). The expression of CXCL17 was assessed by immunohistochemistry (IHQ) in lung autopsy specimens from patients that succumbed to the disease. Serum CXCL17 levels were also analyzed in two additional comparative cohorts of coronavirus disease 2019 (COVID-19) and pulmonary tuberculosis (TB) patients. Additionally, the expression of CXCL17 was tested in lung autopsy specimens from COVID-19 patients. A total of 122 patients were enrolled in the study, from which 68 had pandemic influenza A(H1N1), 24 had COVID-19, and 30 with PTB. CXCL17 was detected i

    Active and stable methane oxidation nano-catalyst with highly-ionized palladium species prepared by solution combustion synthesis

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    We report on the synthesis and testing of active and stable nano-catalysts for methane oxidation. The nano-catalyst was palladium/ceria supported on alumina prepared via a one-step solution-combustion synthesis (SCS) method. As confirmed by X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HTEM), SCS preparative methodology resulted in segregating both Pd and Ce on the surface of the Al 2 O 3 support. Furthermore, HTEM showed that bigger Pd particles (5 nm and more) were surrounded by CeO 2 , resembling a core shell structure, while smaller Pd particles (1 nm and less) were not associated with CeO 2 . The intimate Pd-CeO 2 attachment resulted in insertion of Pd ions into the ceria lattice, and associated with the reduction of Ce 4+ into Ce 3+ ions; consequently, the formation of oxygen vacancies. XPS showed also that Pd had three oxidation states corresponding to Pd0, Pd 2+ due to PdO, and highly ionized Pd ions (Pd (2+x)+ ) which might originate from the insertion of Pd ions into the ceria lattice. The formation of intrinsic Ce 3+ ions, highly ionized (Pd2+ species inserted into the lattice of CeO 2 ) Pd ions (Pd (2+x)+ ) and oxygen vacancies is suggested to play a major role in the unique catalytic activity. The results indicated that the Pd-SCS nano-catalysts were exceptionally more active and stable than conventional catalysts. Under similar reaction conditions, the methane combustion rate over the SCS catalyst was ~18 times greater than that of conventional catalysts. Full methane conversions over the SCS catalysts occurred at around 400 C but were not shown at all with conventional catalysts. In addition, contrary to the conventional catalysts, the SCS catalysts exhibited superior activity with no sign of deactivation in the temperature range between ~400 and 800 C. 2018 by the authors. Licensee MDPI, Basel, Switzerland.Acknowledgments: This paper was made possible by an NPRP Grant #6-290-1-059 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu

    Clinical and immunological factors that distinguish COVID-19 from pandemic influenza A(H1N1)

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    The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), is a global health threat with the potential to cause severe disease manifestations in the lungs. Although COVID-19 has been extensively characterized clinically, the factors distinguishing SARS-CoV-2 from other respiratory viruses are unknown. Here, we compared the clinical, histopathological, and immunological characteristics of patients with COVID-19 and pandemic influenza A(H1N1). We observed a higher frequency of respiratory symptoms, increased tissue injury markers, and a histological pattern of alveolar pneumonia in pandemic influenza A(H1N1) patients. Conversely, dry cough, gastrointestinal symptoms and interstitial lung pathology were observed in COVID-19 cases. Pandemic influenza A(H1N1) was characterized by higher levels of IL-1RA, TNF-α, CCL3, G-CSF, APRIL, sTNF-R1, sTNF-R2, sCD30, and sCD163. Meanwhile, COVID-19 displayed an immune profile distinguished by increased Th1 (IL-12, IFN-γ) and Th2 (IL-4, IL-5, IL-10, IL-13) cytokine levels, along with IL-1β, IL-6, CCL11, VEGF, TWEAK, TSLP, MMP-1, and MMP-3. Our data suggest that SARS-CoV-2 induces a dysbalanced polyfunctional inflammatory response that is different from the immune response against pandemic influenza A(H1N1). Furthermore, we demonstrated the diagnostic potential of some clinical and immune factors to differentiate both diseases. These findings might be relevant for the ongoing and future influenza seasons in the Northern Hemisphere, which are historically unique due to their convergence with the COVID-19 pandemic
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