University of Malaya

About: University of Malaya is a education organization based out in Kuala Lumpur, Malaysia. It is known for research contribution in the topics: Population & Fiber laser. The organization has 25087 authors who have published 51491 publications receiving 1036791 citations. The organization is also known as: UM & Universiti Malaya.

Microplastics in Sediment Cores from Asia and Africa as Indicators of Temporal Trends in Plastic Pollution

Abstract: Microplastics (<5 mm) were extracted from sediment cores collected in Japan, Thailand, Malaysia, and South Africa by density separation after hydrogen peroxide treatment to remove biofilms were and identified using FTIR. Carbonyl and vinyl indices were used to avoid counting biopolymers as plastics. Microplastics composed of variety of polymers, including polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethyleneterphthalates (PET), polyethylene-polypropylene copolymer (PEP), and polyacrylates (PAK), were identified in the sediment. We measured microplastics between 315 µm and 5 mm, most of which were in the range 315 µm–1 mm. The abundance of microplastics in surface sediment varied from 100 pieces/kg-dry sediment in a core collected in the Gulf of Thailand to 1900 pieces/kg-dry sediment in a core collected in a canal in Tokyo Bay. A far higher stock of PE and PP composed microplastics in sediment compared with surface water samples collected in a canal in Tokyo Bay suggests that sediment is an important sink for microplastics. In dated sediment cores from Japan, microplastic pollution started in 1950s, and their abundance increased markedly toward the surface layer (i.e., 2000s). In all sediment cores from Japan, Thailand, Malaysia, and South Africa, the abundance of microplastics increased toward the surface, suggesting the global occurrence of and an increase in microplastic pollution over time.

Factors associated with return to work of breast cancer survivors: a systematic review

Abstract: Background The breast cancer survival rate is the highest among all types of cancers, and survivors returning to work after completing treatment is extremely important in regards to economy and rehabilitation. The aim of this systematic review study is to identify the prevalence of breast cancer survivors who return to work (RTW) and the factors associated to RTW.

Extraction and validation of a new set of CMS pythia8 tunes from underlying-event measurements

Abstract: New sets of CMS underlying-event parameters (“tunes”) are presented for the pythia8 event generator. These tunes use the NNPDF3.1 parton distribution functions (PDFs) at leading (LO), next-to-leading (NLO), or next-to-next-to-leading (NNLO) orders in perturbative quantum chromodynamics, and the strong coupling evolution at LO or NLO. Measurements of charged-particle multiplicity and transverse momentum densities at various hadron collision energies are fit simultaneously to determine the parameters of the tunes. Comparisons of the predictions of the new tunes are provided for observables sensitive to the event shapes at LEP, global underlying event, soft multiparton interactions, and double-parton scattering contributions. In addition, comparisons are made for observables measured in various specific processes, such as multijet, Drell–Yan, and top quark-antiquark pair production including jet substructure observables. The simulation of the underlying event provided by the new tunes is interfaced to a higher-order matrix-element calculation. For the first time, predictions from pythia8 obtained with tunes based on NLO or NNLO PDFs are shown to reliably describe minimum-bias and underlying-event data with a similar level of agreement to predictions from tunes using LO PDF sets.

Fuzzy-Logic-Controller-Based SEPIC Converter for Maximum Power Point Tracking

Abstract: This paper presents a fuzzy logic controller (FLC)-based single-ended primary-inductor converter (SEPIC) for maximum power point tracking (MPPT) operation of a photovoltaic (PV) system. The FLC proposed presents that the convergent distribution of the membership function offers faster response than the symmetrically distributed membership functions. The fuzzy controller for the SEPIC MPPT scheme shows high precision in current transition and keeps the voltage without any changes, in the variable-load case, represented in small steady-state error and small overshoot. The proposed scheme ensures optimal use of PV array and proves its efficacy in variable load conditions, unity, and lagging power factor at the inverter output (load) side. The real-time implementation of the MPPT SEPIC converter is done by a digital signal processor (DSP), i.e., TMS320F28335. The performance of the converter is tested in both simulation and experiment at different operating conditions. The performance of the proposed FLC-based MPPT operation of SEPIC converter is compared to that of the conventional proportional-integral (PI)-based SEPIC converter. The results show that the proposed FLC-based MPPT scheme for SEPIC can accurately track the reference signal and transfer power around 4.8% more than the conventional PI-based system.