•A direct-coupled PV system with batteries was studied.•A model for direct-coupled PV systems with batteries was developed.•Number of serial connected PV cells was considered as main factor affecting ...the PV system.•Other factors like solar radiation and air temperatures were also considered.•The range of optimal number of serial connected PV cells was selected.
In the designing of solar photovoltaic (PV) systems, which are directly coupled to batteries, it is of great importance to consider voltage-operating points of PV modules and batteries. Usually, batteries operating points are supposed to be near to the PV maximum power points to maximize the PV output.
PV output voltage is affected by incident radiation, air temperature, shading, module orientation, PV technology; tilt angle and number of serial connected PV cells. This paper presents a PV model, which takes into account the number of PV cells connected in series, incident solar radiation and temperature as main factors affecting PV systems that are directly coupled to the batteries. The developed model was then validated by conducting some laboratory tests.
In this study, an amorphous silicon thin film PV module was used. Electrical load data collected in Dodoma, Tanzania and lead acid battery with 24 V were also used in the designing and simulation of PV systems.
Optimization and the laboratory test results have revealed how good the optimization tool is. The tool can select the optimal number of PV cells required for the given system. The selected optimal number of PV cells in series always matches with the battery operating voltage, which helps in the reduction of losses that usually occur in direct-coupled systems, hence maximizing PV output.
The results presented in this paper are based on solar home system simulated in Dodoma, Tanzania; however, the model can be adapted to any other region and any type of PV module by changing input data like solar radiation, air temperature, longitude, latitude, load profile and STC parameters of the PV module respectively.
This book offers an accessible and inclusive overview of the major debates in the philosophy of action. It covers the distinct approaches taken by Donald Davidson, G.E.M. Anscombe, and numerous ...others to answering questions like "what are intentional actions?" and "how do reasons explain actions?" Further topics include intention, practical knowledge, weakness and strength of will, self-governance, and collective agency. With introductions, conclusions, and annotated suggested reading lists for each of the ten chapters, it is an ideal introduction for advanced undergraduates as well as any philosopher seeking a primer on these issues.
Uncoupling protein 1 (UCP1) mediates nonshivering thermogenesis and, upon cold exposure, is induced in brown adipose tissue (BAT) and subcutaneous white adipose tissue (iWAT). Here, by ...high-throughput screening using the UCP1 promoter, we identify Zfp516 as a transcriptional activator of UCP1 as well as PGC1α, thereby promoting a BAT program. Zfp516 itself is induced by cold and sympathetic stimulation through the cAMP-CREB/ATF2 pathway. Zfp516 directly binds to the proximal region of the UCP1 promoter, not to the enhancer region where other transcription factors bind, and interacts with PRDM16 to activate the UCP1 promoter. Although ablation of Zfp516 causes embryonic lethality, knockout embryos still show drastically reduced BAT mass. Overexpression of Zfp516 in adipose tissue promotes browning of iWAT even at room temperature, increasing body temperature and energy expenditure and preventing diet-induced obesity. Zfp516 may represent a future target for obesity therapeutics.
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•Zfp516 binds UCP1 promoter to drive transcription•Zfp516 expression is regulated by cold/sympathetic stimuli•Zfp516 promotes the browning of iWAT and prevents diet-induced obesity•Zfp516 ablation leads to defective brown fat formation in mice
Using high-throughput screening, Dempersmier et al. identify Zfp516 as a cold-inducible regulator of UCP1 transcription. Using both transgenic and knockout mouse models, they show that Zfp516 promotes browning of iWAT to prevent diet-induced obesity and is required for BAT development.
Plan B Paul, Sarah K.
Australasian Journal of Philosophy,
07/2022, Letnik:
100, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We sometimes strive to achieve difficult goals when our evidence suggests that success is unlikely-not just because it will require strength of will, but because we are targets of prejudice and ...discrimination or because success will require unusual ability. Optimism about one's prospects can be useful for persevering in these cases. With that said, excessive optimism can be dangerous; when our evidence is unfavourable, we should be at most agnostic about whether we will succeed. This paper explores the nature and rational significance of agnostic practical commitments. Most importantly, the rationality of striving against the odds can depend on investing in a plan for failure-a plan B. I aim to make headway on an account of what backup plans are, how they are related to primary plans, and whether the standard norms of plan rationality apply to our agnostic commitments.
•Comparison between off grid PV systems has been done.•Optimization of SHS and VPPS has been done.•Direct coupled PV system depends on the battery operation voltages.•Use of MPPT for small PV systems ...is irrelevant.•SHS with NCA battery has a lower LCOE.•It is better to change from SHS to VPPS.
Solar home systems (SHS) and solar photovoltaic village power supply systems can play an important role in the supply of electrical energy to off-grid areas. This paper presents a comparison of solar home systems and village power supply systems using two different types of battery technologies, namely lithium nickel cobalt aluminum oxide (NCA) and lead-acid (Pb) batteries. The developed models were implemented in Matlab/Simulink where solar radiation, temperature and electrical load data from Dodoma, the capital of Tanzania were used as model inputs.
Two topologies were analyzed for SHS: A system which is directly coupled to the battery and another system which uses a Maximum Power Point Tracker (MPPT) charge controller. The main idea of analyzing these two topologies was to find an affordable solution for off-grid population, but at the same time the selected topology should have the ability of extracting maximum output from the PV panel.
Since most of the off-grid settlements in Tanzania today use SHS with lead-acid batteries as storage, analysis was carried out for SHS with lead-acid batteries and SHS with lithium-ion batteries by simulating and optimizing the systems for 20 years. The levelized cost of electricity (LCOE) for both storage systems was compared and it was found that the SHS with lithium-ion (NCA) battery generally had a lower LCOE compared to the SHS with lead-acid battery. This is mainly due to both the longer life time of NCA batteries and the reduction of the price of NCA batteries as a result of significantly increasing global production scales.
For the case of solar photovoltaic village power supply systems, an energy management system was implemented to optimize power flows in a hybrid storage system containing both lead-acid and lithium-ion batteries. Optimization of this “hybrid” system led to a selection of both types of batteries with small capacity of lead-acid battery (0.24kW h) compared to NCA battery (1.44kW h) backed up with diesel generator. Further analysis was done regarding the benefits of village power supply systems over individual SHS, and it was found that the LCOE for solar PV village power supply systems was lower than the LCOE for single SHS.
In light of increasing cannabis use among pregnant women, the US Surgeon General recently issued an advisory against the use of marijuana during pregnancy.
To evaluate whether cannabis use during ...pregnancy is associated with adverse outcomes among offspring.
In this cross-sectional study, data were obtained from the baseline session of the ongoing longitudinal Adolescent Brain and Cognitive Development Study, which recruited 11 875 children aged 9 to 11 years, as well as a parent or caregiver, from 22 sites across the United States between June 1, 2016, and October 15, 2018.
Prenatal cannabis exposure prior to and after maternal knowledge of pregnancy.
Symptoms of psychopathology in children (ie, psychotic-like experiences PLEs and internalizing, externalizing, attention, thought, and social problems), cognition, sleep, birth weight, gestational age at birth, body mass index, and brain structure (ie, total intracranial volume, white matter volume, and gray matter volume). Covariates included familial (eg, income and familial psychopathology), pregnancy (eg, prenatal exposure to alcohol and tobacco), and child (eg, substance use) variables.
Among 11 489 children (5997 boys 52.2%; mean SD age, 9.9 0.6 years) with nonmissing prenatal cannabis exposure data, 655 (5.7%) were exposed to cannabis prenatally. Relative to no exposure, cannabis exposure only before (413 3.6%) and after (242 2.1%) maternal knowledge of pregnancy were associated with greater offspring psychopathology characteristics (ie, PLEs and internalizing, externalizing, attention, thought and, social problems), sleep problems, and body mass index, as well as lower cognition and gray matter volume (all |β| > 0.02; all false discovery rate FDR-corrected P < .03). Only exposure after knowledge of pregnancy was associated with lower birth weight as well as total intracranial volume and white matter volumes relative to no exposure and exposure only before knowledge (all |β| > 0.02; all FDR-corrected P < .04). When including potentially confounding covariates, exposure after maternal knowledge of pregnancy remained associated with greater PLEs and externalizing, attention, thought, and social problems (all β > 0.02; FDR-corrected P < .02). Exposure only prior to maternal knowledge of pregnancy did not differ from no exposure on any outcomes when considering potentially confounding variables (all |β| < 0.02; FDR-corrected P > .70).
This study suggests that prenatal cannabis exposure and its correlated factors are associated with greater risk for psychopathology during middle childhood. Cannabis use during pregnancy should be discouraged.
Zfp516, a brown fat (BAT)-enriched and cold-inducible transcription factor, promotes transcription of UCP1 and other BAT-enriched genes for non-shivering thermogenesis. Here, we identify ...lysine-specific demethylase 1 (LSD1) as a direct binding partner of Zfp516. We show that, through interaction with Zfp516, LSD1 is recruited to UCP1 and other BAT-enriched genes, such as PGC1α, to function as a coactivator by demethylating H3K9. We also show that LSD1 is induced during brown adipogenesis and that LSD1 and its demethylase activity is required for the BAT program. Furthermore, we show that LSD1 ablation in mice using Myf5-Cre alters embryonic BAT development. Moreover, BAT-specific deletion of LSD1 via the use of UCP1-Cre impairs the BAT program and BAT development, making BAT resemble WAT, reducing thermogenic activity and promoting obesity. Finally, we demonstrate an in vivo requirement of the Zfp516-LSD1 interaction for LSD1 function in BAT gene activation.
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•Zfp516 recruits LSD1 at the UCP1 promoter, where it demethylates H3K9•LSD1 cooperates with Zfp516 to activate BAT genes and to promote thermogenesis•LSD1 ablation in brown adipose precursors impairs embryonic development of BAT•LSD1 ablation prevents browning of subcutaneous WAT induced by Zfp516
Sambeat et al. report that Zfp516, critical for activation of BAT gene program and thermogenesis, directly interacts with LSD1 for recruitment to BAT-enriched thermogenic genes. LSD1 demethylates H3K9 at the promoter regions of BAT-enriched genes. The authors also show that LSD1 is required during embryonic BAT development and for Zfp516-induced browning of WAT.
ABSTRACT
Aposematic theory has historically predicted that predators should select for warning signals to converge on a single form, as a result of frequency‐dependent learning. However, widespread ...variation in warning signals is observed across closely related species, populations and, most problematically for evolutionary biologists, among individuals in the same population. Recent research has yielded an increased awareness of this diversity, challenging the paradigm of signal monomorphy in aposematic animals. Here we provide a comprehensive synthesis of these disparate lines of investigation, identifying within them three broad classes of explanation for variation in aposematic warning signals: genetic mechanisms, differences among predators and predator behaviour, and alternative selection pressures upon the signal. The mechanisms producing warning coloration are also important. Detailed studies of the genetic basis of warning signals in some species, most notably Heliconius butterflies, are beginning to shed light on the genetic architecture facilitating or limiting key processes such as the evolution and maintenance of polymorphisms, hybridisation, and speciation. Work on predator behaviour is changing our perception of the predator community as a single homogenous selective agent, emphasising the dynamic nature of predator–prey interactions. Predator variability in a range of factors (e.g. perceptual abilities, tolerance to chemical defences, and individual motivation), suggests that the role of predators is more complicated than previously appreciated. With complex selection regimes at work, polytypisms and polymorphisms may even occur in Müllerian mimicry systems. Meanwhile, phenotypes are often multifunctional, and thus subject to additional biotic and abiotic selection pressures. Some of these selective pressures, primarily sexual selection and thermoregulation, have received considerable attention, while others, such as disease risk and parental effects, offer promising avenues to explore. As well as reviewing the existing evidence from both empirical studies and theoretical modelling, we highlight hypotheses that could benefit from further investigation in aposematic species. Finally by collating known instances of variation in warning signals, we provide a valuable resource for understanding the taxonomic spread of diversity in aposematic signalling and with which to direct future research. A greater appreciation of the extent of variation in aposematic species, and of the selective pressures and constraints which contribute to this once‐paradoxical phenomenon, yields a new perspective for the field of aposematic signalling.
Resource availability during development shapes not only adult phenotype but also the phenotype of subsequent offspring. When resources are absent and periods of starvation occur in early life, such ...developmental stress often influences key life-history traits in a way that benefits individuals and their offspring when facing further bouts of starvation. Here we investigated the impacts of different starvation regimes during larval development on life-history traits and measures of consumption in the turnip sawfly, Athalia rosae (Hymenoptera: Tenthredinidae). We then assessed whether offspring of starved and non-starved parents differed in their own life-history if reared in conditions that either matched that of their parents or were a mismatch. Early life starvation effects were more pronounced within than across generations in A. rosae, with negative impacts on adult body mass and increases in developmental time, but no effects on adult longevity in either generation. We found some evidence of higher growth rates in larvae having experienced starvation, although this did not ameliorate the overall negative effect of larval starvation on adult size. However, further work is necessary to disentangle the effects of larval size and instar from those of starvation treatment. Finally, we found weak evidence for transgenerational effects on larval growth, with intra-generational larval starvation experience being more decisive for life-history traits. Our study demonstrates that intra-generational effects of starvation are stronger than transgenerational effects on life-history traits and consumption measures in A. rosae.
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