Probabilistic metrology or how some measurement outcomes render ultra-precise estimates

We show on theoretical grounds that, even in the presence of noise, probabilistic measurement strategies (which have a certain probability of failure or abstention) can provide, upon a heralded successful outcome, estimates with a precision that exceeds the deterministic bounds for the average precision. This establishes a new ultimate bound on the phase estimation precision of particular measurement outcomes (or sequence of outcomes). For probe systems subject to local dephasing, we quantify such precision limit as a function of the probability of failure that can be tolerated. Our results show that the possibility of abstaining can set back the detrimental effects of noise.Comment: Improved version of arXiv:1407.6910 with an extended introduction where we clarify our approach to metrology, and probabilistic metrology in particular. Changed titl

Birth of the first stars amidst decaying and annihilating dark matter

The first stars are expected to form through molecular-hydrogen (H$_2$) cooling, a channel that is especially sensitive to the thermal and ionization state of gas, and can thus act as a probe of exotic energy injection from decaying or annihilating dark matter (DM). Here, we use a toy halo model to study the impact of DM-sourced energy injection on the H$_2$ content of the first galaxies, and thus estimate the threshold mass required for a halo to form stars at high redshifts. We find that currently allowed DM models can significantly change this threshold, producing both positive and negative feedback. In some scenarios, the extra heating of the gas raises the halo mass required for collapse, whereas in others, energy injection lowers the threshold by increasing the free-electron fraction and catalyzing H$_2$ formation. The direction of the effect can be redshift-dependent. We also bracket the uncertainties from self-shielding of halos from Lyman-Werner radiation. Hence, exotic energy injection can both delay and accelerate the onset of star formation; we show how this can impact the timing of 21cm signals at cosmic dawn. We encourage detailed simulation follow-ups in the most promising regions of parameter space identified in this work.Comment: 32 pages, 13 figures, 3 table

Effect of anthropogenic pollution on the fitness of tetracycline sensitive Shigella flexneri in Thames river water

Urban rivers may be source of antibiotics contamination that could support spread of antibiotic resistant bacteria (ARB) to the population. It is important to understand to what extent the presence of pollutants in urban rivers influences fitness of ARB. In an exercise to estimate this contribution, microcosms were generated from Thames river (London, UK) from different locations: upstream and downstream the city center. The concentration of the polycyclic aromatic hydrocarbons (PAHs) benzo(a)pyrene, pyrene and phenantrene was found to be 128, 171 and 128 times higher in downstream sector when compared to upstream sector, respectively. Filtered microcosms for each sector were enriched with tetracycline at lethal (10 μg/mL) and sub-lethal (10 ng/mL) concentrations and the fitness of an isogenic pair of Shigella flexneri 2a YSH6000 (tetR) and S. flexneri 2a 1363 (tetS) was then measured. In the presence of selective pressure in upstream microcosms, the resistant strain outcompeted the sensitive one, as expected. In contrast, sensitive S. flexneri tetS was found to significantly compete with resistant S. flexneri tetR at lethal concentrations of tetracycline in downstream microcosms, where levels of PAHs were the highest. Further experiments showed that PAHs rendered the resistant S. flexneri tetR ∼20% more sensitive to tetracycline. Sensitive S. flexneri tetS strain was able to persist at lethal concentration of tetracycline in downstream microcosms, at higher concentrations of PAHs. Our findings suggest that in a polluted river sensitive S. flexneri cells may still thrive in presence of selective pressure. Fitness tests provide an additional tool to measure bioavailability

Occupational Therapy for Adults With Cancer: Why It Matters

Adults with cancer may be at risk for limitations in functional status and quality of life (QOL). Occupational therapy is a supportive service with the specific mission to help people functionally engage in life as safely and independently as possible with the primary goal of improving QOL. Unfortunately, for people with cancer, occupational therapy remains underused. The overall purpose of this review is to provide an understanding of what occupational therapy is and its relevance to patients with cancer, highlight the reasons to refer, and, last, provide general advice on how to access services