117 research outputs found

    A Review Of Econometric Approaches For The Oil Price-Exchange Rate Nexus: Lessons For ASEAN-5 Countries

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    This paper reviews alternative econometric approaches the literature has used to examine the connectedness between oil prices and exchange rates and illustrates their application using quarterly data from 1970: Q1 to 2022: Q1 for ASEAN-5 countries, which are as follows: Indonesia, Malaysia, the Philippines, Singapore, and Thailand. Although most studies examining the impact of oil prices and exchange rates apply the Ordinary Least Squares (OLS) approach with symmetry, the quantile regression (QR) method is shown to offer a thorough investigation of the connectedness. For ASEAN-5 countries, we present a comparative analysis of both methodologies (OLS and QR) with and without asymmetry. Our findings suggest that asymmetric effects triggered by oil prices are noticeably heterogeneous across quantiles. Hence, future studies should allow for asymmetry in the oil price by decomposing the price into positive and negative changes to further investigate the connectedness between oil prices and exchange rates

    Variability Study of High Current Junctionless Silicon Nanowire Transistors

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    Silicon nanowires have numerous potential applications, including transistors, memories, photovoltaics, biosensors and qubits [1]. Fabricating a nanowire with characteristics required for a specific application, however, poses some challenges. For example, a major challenge is that as the transistors dimensions are reduced, it is difficult to maintain a low off-current (Ioff) whilst simultaneously maintaining a high on-current (Ion). This can be the result of quantum mechanical tunnelling, short channel effects or statistical variability [2]. A variety of new architectures, including ultra-thin silicon-on-insulator (SOI), double gate, FinFETs, tri-gate, junctionless and gate all-around (GAA) nanowire transistors, have therefore been developed to improve the electrostatic control of the conducting channel. This is essential since a low Ioff implies low static power dissipation and it will therefore improve power management in the multi-billion transistor circuits employed globally in microprocessors, sensors and memories

    Notes on the Economics of Residential Hybrid Energy System

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    Despite advances in small-scale hybrid renewable energy technologies, there are limited economic frameworks that model the different decisions made by a residential hybrid system owner. We present a comprehensive review of studies that examine the techno-economic feasibility of small-scale hybrid energy systems, and we find that the most common approach is to compare the annualized life-time costs to the expected energy output and choose the system with the lowest cost per output. While practical, this type of benefit—cost analysis misses out on other production and consumption decisions that are simultaneously made when adopting a hybrid energy system. In this paper, we propose a broader and more robust theoretical framework–based on production and utility theory–to illustrate how the production of renewable energy from multiple sources affects energy efficiency, energy services, and energy consumption choices in the residential sector. Finally, we discuss how the model can be applied to guide a hybrid-prosumer\u27s decision-making in the US residential sector. Examining hybrid renewable energy systems within a solid economic framework makes the study of hybrid energy more accessible to economists, facilitating interdisciplinary collaborations

    Experimental and Simulation Study of a High Current 1D Silicon Nanowire Transistor Using Heavily Doped Channels

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    Silicon nanowires have numerous potential applications, including transistors, memories, photovoltaics, biosensors and qubits [1]. Fabricating a nanowire with the required characteristics for a specific application, however, poses some challenges. For example, a major challenge is that, as the transistors dimensions are reduced, it is difficult to maintain a low off-current (Ioff) whilst simultaneously maintaining a high on-current (Ion). Some sources of this parasitic leakage current include quantum mechanical tunnelling, short channel effects and statistical variability [2, 3]. A variety of new architectures, including ultra-thin silicon-on-insulator (SOI), double gate, FinFETs, tri-gate, junctionless and gate all-around (GAA) nanowire transistors, have therefore been developed to improve the electrostatic control of the conducting channel. This is essential since a low Ioff implies low static power dissipation and it will therefore improve power management in the multi-billion transistors circuits employed globally in microprocessors, sensors and memories

    Experimental and simulation study of 1D silicon nanowire transistors using heavily doped channels

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    The experimental results from 8 nm diameter silicon nanowire junctionless field effect transistors with gate lengths of 150 nm are presented that demonstrate on-currents up to 1.15 mA/m for 1.0 V and 2.52 mA/m for 1.8 V gate overdrive with an off-current set at 100 nA/m. On- to off-current ratios above 108 with a subthreshold slope of 66 mV/dec are demonstrated at 25 oC. Simulations using drift-diffusion which include densitygradient quantum corrections provide excellent agreement with the experimental results. The simulations demonstrate that the present silicon-dioxide gate dielectric only allows the gate to be scaled to 25 nm length before short-channel effects significantly reduce the performance. If high-K dielectrics replace some parts of the silicon dioxide then the technology can be scaled to at least 10 nm gatelength

    Perforated red blood cells enable compressible and injectable hydrogels as therapeutic vehicles

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    Hydrogels engineered for medical use within the human body need to be delivered in a minimally invasive fashion without altering their biochemical and mechanical properties to maximize their therapeutic outcomes. In this regard, key strategies applied for creating such medical hydrogels include formulating precursor solutions that can be crosslinked in situ with physical or chemical cues following their delivery or forming macroporous hydrogels at sub-zero temperatures via cryogelation prior to their delivery. Here, we present a new class of injectable composite materials with shape recovery ability. The shape recovery is derived from the physical properties of red blood cells (RBCs) that are first modified via hypotonic swelling and then integrated into the hydrogel scaffolds before polymerization. The RBCs' hypotonic swelling induces the formation of nanometer-sized pores on their cell membranes, which enable fast liquid release under compression. The resulting biocomposite hydrogel scaffolds display high deformability and shape-recovery ability. The scaffolds can repeatedly compress up to ~87% of their original volumes during injection and subsequent retraction through syringe needles of different sizes; this cycle of injection and retraction can be repeated up to ten times without causing any substantial mechanical damage to the scaffolds. Our biocomposite material system and fabrication approach for injectable materials will be foundational for the minimally invasive delivery of drug-loaded scaffolds, tissue-engineered constructs, and personalized medical platforms that could be administered to the human body with conventional needle-syringe systems

    Impact of quantum confinement on transport and the electrostatic driven performance of silicon nanowire transistors at the scaling limit

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    In this work we investigate the impact of quantum mechanical effects on the device performance of n-type silicon nanowire transistors (NWT) for possible future CMOS applications at the scaling limit. For the purpose of this paper, we created Si NWTs with two channel crystallographic orientations <110> and <100> and six different cross-section profiles. In the first part, we study the impact of quantum corrections on the gate capacitance and mobile charge in the channel. The mobile charge to gate capacitance ratio, which is an indicator of the intrinsic performance of the NWTs, is also investigated. The influence of the rotating of the NWTs cross-sectional geometry by 90o on charge distribution in the channel is also studied. We compare the correlation between the charge profile in the channel and cross-sectional dimension for circular transistor with four different cross-sections diameters: 5nm, 6nm, 7nm and 8nm. In the second part of this paper, we expand the computational study by including different gate lengths for some of the Si NWTs. As a result, we establish a correlation between the mobile charge distribution in the channel and the gate capacitance, drain-induced barrier lowering (DIBL) and the subthreshold slope (SS). All calculations are based on a quantum mechanical description of the mobile charge distribution in the channel. This description is based on the solution of the Schrödinger equation in NWT cross sections along the current path, which is mandatory for nanowires with such ultra-scale dimensions

    Prevalence of Trachoma in Benishangul Gumuz Region, Ethiopia: Results of Seven Population-Based Surveys from the Global Trachoma Mapping Project.

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    PURPOSE: Trachoma is a major cause of blindness in Ethiopia, and targeted for elimination as a public health problem by the year 2020. Prevalence data are needed to plan interventions. We set out to estimate the prevalence of trachoma in each evaluation unit of grouped districts ("woredas") in Benishangul Gumuz region, Ethiopia. METHODS: We conducted seven cross-sectional community-based surveys, covering 20 woredas, between December 2013 and January 2014, as part of the Global Trachoma Mapping Project (GTMP). The standardized GTMP training package and methodologies were used. RESULTS: A total of 5828 households and 21,919 individuals were enumerated in the surveys. 19,583 people (89.3%) were present when survey teams visited. A total of 19,530 (99.7%) consented to examination, 11,063 (56.6%) of whom were female. The region-wide age- and sex-adjusted trichiasis prevalence in adults aged ≥15 years was 1.3%. Two evaluation units covering four woredas (Pawe, Mandura, Bulen and Dibate) with a combined rural population of 166,959 require implementation of the A, F and E components of the SAFE strategy (surgery, antibiotics, facial cleanliness and environmental improvement) for at least three years before re-survey, and intervention planning should begin for these woredas as soon as possible. CONCLUSION: Both active trachoma and trichiasis are public health problems in Benishangul Gumuz, which needs implementation of the full SAFE strategy

    Assessment of animal African trypanosomiasis (AAT) vulnerability in cattle-owning communities of sub-Saharan Africa

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    Background: Animal African trypanosomiasis (AAT) is one of the biggest constraints to livestock production and a threat to food security in sub-Saharan Africa. In order to optimise the allocation of resources for AAT control, decision makers need to target geographic areas where control programmes are most likely to be successful and sustainable and select control methods that will maximise the benefits obtained from resources invested. Methods: The overall approach to classifying cattle-owning communities in terms of AAT vulnerability was based on the selection of key variables collected through field surveys in five sub-Saharan Africa countries followed by a formal Multiple Correspondence Analysis (MCA) to identify factors explaining the variations between areas. To categorise the communities in terms of AAT vulnerability profiles, Hierarchical Cluster Analysis (HCA) was performed. Results: Three clusters of community vulnerability profiles were identified based on farmers’ beliefs with respect to trypanosomiasis control within the five countries studied. Cluster 1 communities, mainly identified in Cameroon, reported constant AAT burden, had large trypanosensitive (average herd size = 57) communal grazing cattle herds. Livestock (cattle and small ruminants) were reportedly the primary source of income in the majority of these cattle-owning households (87.0 %). Cluster 2 communities identified mainly in Burkina Faso and Zambia, with some Ethiopian communities had moderate herd sizes (average = 16) and some trypanotolerant breeds (31.7 %) practicing communal grazing. In these communities there were some concerns regarding the development of trypanocide resistance. Crops were the primary income source while communities in this cluster incurred some financial losses due to diminished draft power. The third cluster contained mainly Ugandan and Ethiopian communities which were mixed farmers with smaller herd sizes (average = 8). The costs spent diagnosing and treating AAT were moderate here. Conclusions: Understanding how cattle-owners are affected by AAT and their efforts to manage the disease is critical to the design of suitable locally-adapted control programmes. It is expected that the results could inform priority setting and the development of tailored recommendations for AAT control strategies
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