Linearity of Outphasing Radio Transmitters

The outphasing transmitter is a promising technique, which can simultaneously achieve high linearity and power efficiency, thereby addressing the major design requirements of next generation transmitters. It employs highly non-linear power amplifier (PA) classes in a linear manner, in principle transmitting a distortion-free signal. Due to symmetric nature of the outphasing architecture, its linearity performance is constrained by any mismatches and non-linear effects encountered in the RF paths. This thesis analyzes the linearity performance of outphasing transmitters (in terms of ACLR specification) for LTE base station applications, under the non-linear effects and tolerances present in practical implementations. The system-level model, built in Matlab software, investigates the important non-linear effects present in outphasing transmitters, including gain and phase imbalance, IQ modulator mismatches, delay imbalance, and the non-linear effects of PAs and Chireix combiners. The path and delay mismatches result in only partial cancellation of the wideband quadrature signal, and thus create interference in both the in-band and out-of-band frequency regions. The misalignment in IQ modulators, such as gain/phase imbalance and carrier leakage, introduces amplitude and phase modulation in the outphased signals. The quadrature modulator mismatches, in conjunction with amplifier nonlinearity, result in spectral regrowth around the carrier frequency. The transmitter linearity performance is also affected by mismatches in the non-linear characteristics of the PAs. Realistic square-wave signals, exhibiting finite rise- and fall- time, also create spectral leakage for distinct rise/fall times in each outphasing branch. Furthermore, the Chireix combiner severely degrades the linearity of outphasing transmitters; it produces ACLR well below the specified limit for LTE base stations. This makes mandatory the compensation of Chireix combiner induced non-linearity in outphasing transmitters. The strict linearity requirements (for LTE downlink applications) present a small tolerance window for mismatches experienced in practical circuits. The relatively small tolerance margin indicates the need of linearization and compensation techniques in outphasing transmitters

Prognostically Significant Fusion Oncogenes and Gene Mutations in Pakistani AML Patients

Background: The onset and progression of leukemia is associated with many genetic abnormalities including gene mutations and production of fusion oncogenes. Molecular studies on fusion oncogenes and mutations in different populations have been done. However, not much research on correlation of the fusion oncogenes with acute myeloid leukemia have been done in Pakistan.Methods: Genetic analysis of 105 AML patients was done to investigate AML1-ETOand CBFB-MYH11 fusion oncogenes and mutations in NPM1 and NRAS genes. The genomic DNA and cDNA were subjected to amplification, electrophoresis, and Sanger sequencing.Results: The frequency of AML1-ETO was 26% in AML patients and 34.2% in AML-M2 patients. CBFB-MYH11 was present in 11.4% AML patients. A total of six mutations in 4 regions of NPM1 gene and 2 regions of NRAS gene were detected. 3’UTR of NPMI gene had three variants; g.1128C>T (57.1%), g.1185-/T insertion (80.95%), and g.1163A>T (57.14%) while c.867_871subGTGGA >CAAGTTTGC (2.86%) was present in exon 12. NRAS gene had two mutations c.12C>T (51.4%) and c.33A>T (11.43%) in exon 2. c.867_871subGTGGA >CAAGTTTGC , and g.1163A>T in NPM1 gene and c.33A>T in NRAS gene were the novel findings in this ethnic population.Conclusion: This genetic analysis may help to modulate the treatment strategies and improve survival of patients.Keywords: Acute Myeloid Leukemia; Fusion Oncogenes; AML; AML1-ETO; CBFB-MYH11; AML-M2; Nucleophosmin, NPM1; NRAS

Jatropha curcas L. and Pongamia pinnata L. exhibited differential growth and bioaccumulation pattern irrigated with wastewater

Pakistan currently faces an acute shortage of water, which has increasingly been devastating for the past few decades. In order to mitigate water scarcity, agriculture sector of the country started using wastewater discharged from various industries. The present study aims to assess the impact of fertilizer industry effluent on Jatropha curcas L. and Pongamia pinnata L., which are popular biofuel tree species. Initially, one-year-old saplings were acclimatized in pots, then wastewater was applied in diluted concentrations of effluent using 20 and 40 mL L-1 to the treatment group while control plants were irrigated with tap water. The physico-chemical properties of the effluent showed high values 179 mg L-1 for biological oxygen demand (BOD), 257 mg L-1 for chemical oxygen demand (COD) and 1200 mg L-1 for total dissolved solid (TDS), respectively. Surprisingly, high concentrations of arsenic (15 µg L-1) and cadmium (0.78 mg L-1) were present but chromium (Cr) concentration was found within permissible limit to WHO. The levels applied caused a significant (p≤0.05) increase in plant growth and biomass. The extent of membrane damage assessed via malondialdehyde (MDA) production was also greater in the roots of P. pinnata while reverse was true for shoots of J. curcas. A more profound (p≤0.05) reduction in photosynthetic pigments and carotenoids was observed in P. pinnata at concentrated level of effluent. Overall, the study signifies a 2-folds potential of biofuel tree species for efficient reuse of wastewater, as well as for remediation of metals from wastewater and soil

A 6–20 GHz 400-MHz Modulation-Bandwidth CMOS Transmitter IC

This paper presents a transmitter IC with two identical signal paths, including base-band amplifier, up-converting mixer, and power amplifier (PA) stages. The design is focused on wide modulation bandwidth, and the use of a resonatorless small die-area class-D power amplifier at cm-wave frequencies. This work also incorporates a local oscillator (LO) signal distribution network with phase tuning elements. The circuit is implemented in a 22-nm CMOS process, and the active die area is 0.8 mm2. Operation over the 6–20 GHz range of carrier frequencies through the transmission of both continuous wave (CW) and wideband quadrature phase shift keying (QPSK) modulated signals were verified with measurements. Results with 20/40/100, and 400 MHz modulation bandwidths are presented, and for instance for a 20-MHz QPSK modulated input signal the measured adjacent channel leakage ratio (ACLR) of the transmitter is 28 dBc and error vector magnitude (EVM) is 5%.acceptedVersionPeer reviewe

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

Global, regional, and national burden of disorders affecting the nervous system, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BackgroundDisorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021.MethodsWe estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, COVID-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined.FindingsGlobally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378–521), affecting 3·40 billion (3·20–3·62) individuals (43·1%, 40·5–45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7–26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6–38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5–32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7–2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer.InterpretationAs the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed

Linearity of Outphasing Radio Transmitters

The outphasing transmitter is a promising technique, which can simultaneously achieve high linearity and power efficiency, thereby addressing the major design requirements of next generation transmitters. It employs highly non-linear power amplifier (PA) classes in a linear manner, in principle transmitting a distortion-free signal. Due to symmetric nature of the outphasing architecture, its linearity performance is constrained by any mismatches and non-linear effects encountered in the RF paths. This thesis analyzes the linearity performance of outphasing transmitters (in terms of ACLR specification) for LTE base station applications, under the non-linear effects and tolerances present in practical implementations. The system-level model, built in Matlab software, investigates the important non-linear effects present in outphasing transmitters, including gain and phase imbalance, IQ modulator mismatches, delay imbalance, and the non-linear effects of PAs and Chireix combiners. The path and delay mismatches result in only partial cancellation of the wideband quadrature signal, and thus create interference in both the in-band and out-of-band frequency regions. The misalignment in IQ modulators, such as gain/phase imbalance and carrier leakage, introduces amplitude and phase modulation in the outphased signals. The quadrature modulator mismatches, in conjunction with amplifier nonlinearity, result in spectral regrowth around the carrier frequency. The transmitter linearity performance is also affected by mismatches in the non-linear characteristics of the PAs. Realistic square-wave signals, exhibiting finite rise- and fall- time, also create spectral leakage for distinct rise/fall times in each outphasing branch. Furthermore, the Chireix combiner severely degrades the linearity of outphasing transmitters; it produces ACLR well below the specified limit for LTE base stations. This makes mandatory the compensation of Chireix combiner induced non-linearity in outphasing transmitters. The strict linearity requirements (for LTE downlink applications) present a small tolerance window for mismatches experienced in practical circuits. The relatively small tolerance margin indicates the need of linearization and compensation techniques in outphasing transmitters

Integrated Radio Frequency LO Circuits for Beamforming Receivers

5th generation (5G) New Radio (NR) demands high data-rate connections for wireless channels that are crowded by interference signals, especially the frequency range 1 (FR1). On the other hand, the desire to integrate more functionality on the same integrated circuit (IC) calls for receivers to operate over a band of several GHz without off-chip channel filters. Beamforming is one effective way to reduce interference and improve the signal-to-noise ratio to enable higher data-rate connections. The choice of beamforming approach impacts the footprint of the receiver's signal chain, and the required dynamic range for blocks before summation. Analog beamforming is a strong candidate for the 5G NR either as a standalone solution or as part of hybrid beamforming, because it reduces the footprint and dynamic range requirements, particularly for the analog-to-digital converters (ADCs). This thesis concentrates on the design of local oscillator (LO) circuits for phase-tuning and true-time-delay beamforming receivers. This is because it can maintain orthogonal gain and phase-tuning, simplify the calibration procedure as well as conserve the linearity and noise figure of the radio frequency (RF) signal path. The research presented in this thesis is based on three receiver front-ends, the focus being the development of LO circuits to enable beamforming. Design 1 is a 2-5.5 GHz 4-element beamforming receiver front-end that applied LO phase-tuning with a >7-bit phase-resolution and 360 degree tuning range. The developed delay line provides divider-less I/Q generation and a compact design (0.008 mm square) with moderate power consumption (2.23-5.6 mW for the reported range) favoring integration of a higher number of beamforming elements. The phase calibration scheme includes pilot-signal generation and baseband detection, being able to measure phase mismatches up to 1 degree (detection through external devices). Design 2 introduces a new true-time-delay (TTD) beamforming architecture that applies RF re-sampling to generate time-delay through discrete-time signal processing. The pulse-skipped LO concept was developed to empower TTD beamforming for large arrays. The implemented LO chain's delay-tuning range with pulse-skipping extends to 3 carrier cycles suitable for an 8-element TTD array. The receiver, operating in degree 6-4 GHz, achieved squint-free beamforming for modulation bandwidth as large as 40% of the LO frequency. Design 3 concentrates on developing LO circuits with mixed-signal techniques for operation at 12-25 GHz to drive the Gilbert cell mixer of the first stage of a heterodyne receiver. The LO chain comprises pulse generation and varactor based phase-tuning blocks. The measurements demonstrate that rail-to-rail LO signalling can be generated, processed and propagated up to 25 GHz in deep submicron processes

Radiological Aspect of COVID-19 Pneumonia: How CT Chest Findings Help in Diagnosis?

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