Thermal-based early breast cancer detection using inception V3, inception V4 and modified inception MV4

Breast cancer is one of the most significant causes of death for women around the world. Breast thermography supported by deep convolutional neural networks is expected to contribute significantly to early detection and facilitate treatment at an early stage. The goal of this study is to investigate the behavior of different recent deep learning methods for identifying breast disorders. To evaluate our proposal, we built classifiers based on deep convolutional neural networks modelling inception V3, inception V4, and a modified version of the latter called inception MV4. MV4 was introduced to maintain the computational cost across all layers by making the resultant number of features and the number of pixel positions equal. DMR database was used for these deep learning models in classifying thermal images of healthy and sick patients. A set of epochs 3–30 were used in conjunction with learning rates 1 9 10–3, 1 9 10–4 and 1 9 10–5, Minibatch 10 and different optimization methods. The training results showed that inception V4 and MV4 with color images, a learning rate of 1 9 10–4, and SGDM optimization method, reached very high accuracy, verified through several experimental repetitions. With grayscale images, inception V3 outperforms V4 and MV4 by a considerable accuracy margin, for any optimization methods. In fact, the inception V3 (grayscale) performance is almost comparable to inception V4 and MV4 (color) performance but only after 20–30 epochs. inception MV4 achieved 7% faster classification response time compared to V4. The use of MV4 model is found to contribute to saving energy consumed and fluidity in arithmetic operations for the graphic processor. The results also indicate that increasing the number of layers may not necessarily be useful in improving the performance

Phonon features in terahertz photoconductivity spectra due to data analysis artifact: A case study on organometallic halide perovskites

We propose a simple scenario where the superimposed phonon modes on the photoconductive spectra are experimental artifacts due to the invalid formula used in data analysis. By use of experimental and simulated data of CH_3NH_3PbI_3 perovskites as a case study, we demonstrate that a correction term must be included in the approximated thin-film formula used in the literature; otherwise, parts of the spectra with high background permittivity near the phonon-mode resonances might interfere with the transient photoconductivity. The implication of this work is not limited to perovskites but other materials with strong vibrational modes within the THz spectral range

Elucidating the role of disorder and free-carrier recombination kinetics in CH_3NH_3PbI_3 perovskite films

Apart from broadband absorption of solar radiation, the performance of photovoltaic devices is governed by the density and mobility of photogenerated charge carriers. The latter parameters indicate how many free carriers move away from their origin, and how fast, before loss mechanisms such as carrier recombination occur. However, only lower bounds of these parameters are usually obtained. Here we independently determine both density and mobility of charge carriers in a perovskite film by the use of time-resolved terahertz spectroscopy. Our data reveal the modification of the free carrier response by strong backscattering expected from these heavily disordered perovskite films. The results for different phases and different temperatures show a change of kinetics from two-body recombination at room temperature to three-body recombination at low temperatures. Our results suggest that perovskite-based solar cells can perform well even at low temperatures as long as the three-body recombination has not become predominant

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Poly(3-hexylthiophene) nanofibers for organic photovoltaic applications

Dwindling non-renewable energy resources, as well as global warming and air pollution, have forced human beings to seek for alternative resources. Solar energy is one of the most attractive candidates to replace fossil fuels in years to come. Therefore, the research into improving the efficiency, the lifetime and the cost of solar cells has gained momentum worldwide in recent years. Organic solar cells are highly viable as cheaper options for energy harvesting. At present, the best power conversion efficiency (PCE) of close to 10% has been demonstrated although further development is still required to push the efficiency beyond the limit required for commercialization. The application of one-dimensional organic nano-structures based on conjugated polymers for organic solar cells has gained some interest recently. These nanostructures enable highly efficient solar cell devices, through improved photon harvesting and enhanced charge transport. In particular, solar cell devices based on the nanostructures of poly(3-alkylthiophene) derivatives have exhibited PCEs in the range of 3 – 4%. Nevertheless, the performance of organic nanostructure devices generally falls below those that undergo the conventional thermal annealing. The work presented in this thesis focuses on poly(3-hexylthiophene) (P3HT) nanofibers and their applications for organic solar cells, and is expected to drive the research of other organic nanostructures with high aspect ratios. The optical, electrical and morphological characterizations of the P3HT nanofiber blends reveal the potential as well as the limitations of the organic nanostructure system. It was found that the morphology of the blends of P3HT nanofibers and fullerene molecules should be optimized to reduce holes recombination prior to extraction to external electrodes. The poorer device performance could be attributed to the poor interconnectivity between the nanofibers. Subsequently, with the application of solvent additives with high boiling points and with the suitable interaction energies with the active materials, improvement in the morphology results in a better-connected nanofiber blend. The benefit of organic nanostructures is more pronounced in an all-polymer blend system, which may suffer either a more severe phase separation or intermixing. It is shown that the pre-formed P3HT nanofibers could maintain their crystallinity in the all-polymer blend, thus enabling improved blend absorption, exciton dissociation and charge transport. Besides all-polymer blends, in terms of morphological stability, organic nanostructures also have an edge for ternary blend systems. The negative impact of the dopant molecules on the original blends is moderated when the active materials are transformed into the more morphologically stable organic nanostructures.DOCTOR OF PHILOSOPHY (MSE

PROTOTYPE SISTEM PENDATAAN KELUAR-MASUK KENDARAAN PADA KLUSTER DENGAN MENGGUNAKAN RFID UHF

PROTOTYPE SISTEM PENDATAAN KELUAR-MASUK KENDARAAN PADA KLUSTER DENGAN MENGGUNAKAN RFID UHF - RFID UHF, Kluster, Sistem Pendataan Kendaraa

Transparent electronic and photoelectric synaptic transistors based on the combination of an InGaZnO channel and a TaOx gate dielectric

A transparent thin film transistor (TFT) based on the combination of an InGaZnO channel and a high-κ (the dielectric constant is about 42.6) TaOx gate dielectric layer is fabricated. The TFT shows robust anticlockwise hysteresis under DC voltage sweep and synaptic behaviors (i.e., excitatory postsynaptic current, short-term memory plasticity, short-term memory to long-term memory transition, and potentiation and depression) under voltage pulse stimulus. In addition, the TFT shows high responsivity to illumination of light with various wavelengths (ultraviolet and visible light). Synaptic behaviors in response to light pulse stimuli, which could be employed in vision-based neuromorphic applications, are demonstrated. Large conductance change (Gmax/Gmin > 10) and ultra-low non-linearity (α < 0.5) of the potentiation and depression can be inspired by either gate bias pulses or photoelectric pulses with short pulse widths and small amplitudes.Ministry of Education (MOE)Published versionThe research of the project was supported by the Ministry of Education, Singapore, under grant AcRF TIER 1-2020-T1-002- 008 (RG144/20)

A facile method to evaluate the influence of trap densities on perovskite solar cell performance

This work discusses how the behaviour of the fill factor (FF) of devices calculated from current-voltage (I-V) measurements at different light intensities can be used as a basis to assess the trap density of methylammonium lead triiodide (MAPbI₃) solar cells. Solar cells with different trap densities are prepared using varying molar ratios of methylammonium iodide (MAI) and lead iodide (PbI₂) precursors. Excess MAI in the precursor solution yields more traps/defects in perovskite films and when the trap density increases, trap-filling is the dominant loss mechanism, which results in a low FF in perovskite solar cells with excess MAI; this is especially the case at low light intensities. The FF of perovskite solar cells with excess MAI also shows a non-monotonic dependence on light intensity: the FF first increases, followed by a decrease with increasing light intensity. This non-monotonic dependence of the FF on light intensity suggests that both trap-filling and bimolecular recombination are involved in the determination of the FF in perovskite solar cells in cases where a high density of traps exists. Furthermore, we also observed that a stoichiometric precursor solution could lead to a monotonic light intensity-dependence for the FF in perovskite solar cells: the FF continuously decreases as the light intensity is increased from 1.7 to 100 mW cm⁻². This monotonic dependence of the FF on light intensity implies that bimolecular recombination is the main reason for the loss in FF in perovskite solar cells when a low density of trap states exists. In addition, the peak light intensity (Ppeak), at which the FF shows the highest value, would shift to a smaller value when the amount of excess MAI in the precursor solution is decreased and it approaches the stoichiometric ratio of one. These results suggest that by looking at how the FF varies with light intensity we can deduce the contribution of traps in the performance of perovskite solar cells. This will help tremendously in focusing on areas for improvement for such solar cells.Ministry of Education (MOE)Nanyang Technological UniversityY. M. L. acknowledges financial support from grants from Innovation Fund Denmark (ALTCELL) and Ministry of Education, Singapore, Tier 1 Funding (RG105/18). We would like to acknowledge the Facility for Analysis, Characterization, Testing and Simulation (FACTS), Nanyang Technological University, Singapore, for use of their electron microscopy, Auger Electron Spectroscopy and XRD facilities