We present the precision calibration of 35 Hamamatsu R11410-22 photomultiplier tubes (PMTs) with xenon scintillation light centred near 175 nm. This particular PMT variant was developed specifically ...for the LUX-ZEPLIN (LZ) dark matter experiment. A room-temperature xenon scintillation cell coupled to a vacuum cryostat was used to study the full-face PMT response at both room and low temperature \(\textrm{(\)\sim\( -100\)^\circ\(C)}\), in particular to determine the quantum efficiency (QE) and double photoelectron emission (DPE) probability in LZ operating conditions. For our sample with an average QE of \(\textrm{(32.4\)\pm\(2.9)%}\) at room temperature, we find a relative improvement of \(\textrm{(17.9\)\pm\(5.2)%}\) upon cooling (where uncertainty values refer to the sample standard deviation). The mean DPE probability in response to single vacuum ultraviolet (VUV) photons is \(\textrm{(22.6\)\pm\(2.0)%}\) at low temperature; the DPE increase relative to room temperature, measured here for the first time, was \(\textrm{(12.2\)\pm\(3.9)%}\). Evidence of a small triple photoelectron emission probability \(\textrm{(\)\sim\(0.6%)}\) has also been observed. Useful correlations are established between these parameters and the QE as measured by the manufacturer. The single VUV photon response is also measured for one ETEL D730/9829QB, a PMT with a more standard bialkali photocathode used in the ZEPLIN-III experiment, for which we obtained a cold DPE fraction of \(\textrm{(9.1\)\pm\(0.1)%}\). Hence, we confirm that this effect is not restricted to the low-temperature bialkali photocathode technology employed by Hamamatsu. This highlights the importance of considering this phenomenon in the interpretation of data from liquid xenon scintillation and electroluminescence detectors, and from many other optical measurements in this wavelength region.
We consider a model in which each individual belonging to an ethnic minority group is embedded in a network of relationships and decides whether she wants to be integrated in the society. Each ...individual wants her behavior to agree with her personal ideal preference for integration but also wants her behavior to be as close as possible to the average integration behavior of her peers. We show that there is always convergence to a steady-state and characterize it. We also show that different preferences for integration may emerge in steady state depending on the structure of the network. Then, we consider an optimal tax/subsidy policy which aim is to reach a certain level of integration in the population.
The practices of colostrum avoidance and prelacteal feeding, which are common in many developing countries, including Ethiopia, are firmly rooted in ancient traditions. The main objective of this ...work is to identify the prevalence of colostrum avoidance and study its associated factors among mothers of children aged less than 2 years old in the Oromia region of Ethiopia. A cross-sectional study on the practice of colostrum avoidance/prelacteal feeding was conducted in a rural community with 114 mothers of children under 2 years old. Our results reflected that colostrum avoidance and prelacteal feeding were practiced by 56.1% of mothers. The percentage of women who started breastfeeding in the first hour after birth, as recommended by the WHO, was 2.6%. Of the women who practiced colostrum avoidance, 67.2% gave birth at home, and 65.6% were attended by relatives. The likelihood of avoiding colostrum increases in mothers who have a lower educational level, who did not receive health care at the time of delivery, who think that colostrum is dirty and dangerous and who did not receive information about breastfeeding from healthcare professionals. The knowledge emanating from this work may be useful in designing new breastfeeding education programs and/or interventions in Ethiopia and other developing countries.
Abstract
Tumor heterogeneity includes variable and fluctuating oxygen concentrations, which result in the accumulation of hypoxic regions in most solid tumors. Tumor hypoxia leads to increased ...therapy resistance and has been linked to genomic instability. Here, we tested the hypothesis that exposure to levels of hypoxia that cause replication stress could increase APOBEC activity and the accumulation of APOBEC-mediated mutations. APOBEC-dependent mutational signatures have been well-characterized, although the physiological conditions which underpin them have not been described. We demonstrate that fluctuating/cyclic hypoxic conditions which lead to replication catastrophe induce the expression and activity of APOBEC3B. In contrast, stable/chronic hypoxic conditions which induce replication stress in the absence of DNA damage are not sufficient to induce APOBEC3B. Most importantly, the number of APOBEC-mediated mutations in patient tumors correlated with a hypoxia signature. Together, our data support the conclusion that hypoxia-induced replication catastrophe drives genomic instability in tumors, specifically through increasing the activity of APOBEC3B.
This paper explores theoretically the role of the ruling elites in the rise of progressive taxation in Western countries in the early 20th century. We focus on their interaction with the level of ...inequality between the elites and other citizens. We analyse a stylized political economy dynamic model where (wealthy) elite make a decision on the taxes to be paid by non-elite (poorer) citizens and by themselves. A fraction of citizens are fiscal-reciprocators: they experience positive (negative) reciprocity under a progressive (regressive) tax system. This proportion of citizens evolves over time according to their relative payoff compared to materialist citizens. We show that the choice of tax structure depends on the value for the elite of the public good generated by tax revenues, the proportion of fiscal-reciprocators and on the level of inequality between elite and citizen incomes. Our results show a dynamic complementarity between the level of reciprocity in society and tax progressivity. Indeed, this complementarity only operates if inequality is sufficiently low. In this case a progressive tax culture will be achieved, otherwise a regressive tax culture will prevail.
•The elite make a decision on taxes and citizens make a decision on their tax compliance.•Civic culture (reciprocity) evolves according to a payoff-monotonic dynamics.•Inequality between the elite and citizens plays a key role in the choice of tax system.•Under elite domination a high inequality reduces the progressivity of the tax system.•Dynamic complementarity between reciprocity and tax system gives rise to hysteresis.
ATM-mediated signaling in response to DNA damage is a barrier to tumorigenesis. Here we asked whether replication stress could also contribute to ATM signaling. We demonstrate that, in the absence of ...DNA damage, ATM responds to replication stress in a hypoxia-induced heterochromatin-like context. In certain hypoxic conditions, replication stress occurs in the absence of detectable DNA damage. Hypoxia also induces H3K9me3, a histone modification associated with gene repression and heterochromatin. Hypoxia-induced replication stress together with increased H3K9me3 leads to ATM activation. Importantly, ATM prevents the accumulation of DNA damage in hypoxia. Most significantly, we describe a stress-specific role for ATM in maintaining DNA replication rates in a background of increased H3K9me3. Furthermore, the ATM-mediated response to oncogene-induced replication stress is enhanced in hypoxic conditions. Together, these data indicate that hypoxia plays a critical role in the activation of the DNA damage response, therefore contributing to this barrier to tumorigenesis.
•In the absence of damage, ATM responds to replication stress in H3K9me3-rich contexts•The levels of ATM-S1981, H3K9me3, and hypoxia correlate well in vivo•ATM maintains DNA replication rates in hypoxia•ATM prevents the accumulation of DNA damage in hypoxic conditions
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