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In the search for life in the cosmos, transiting exoplanets are currently our best targets. With thousands already detected, our search is entering a new era of discovery with upcoming large telescopes that will look for signs of 'life' in the atmospheres of transiting worlds. Previous work has explored the zone from which Earth would be visible while transiting the Sun1-4. However, these studies considered only the current position of stars, and did not include their changing vantage point over time. Here we report that 1,715 stars within 100 parsecs from the Sun are in the right position to have spotted life on a transiting Earth since early human civilization (about 5,000 years ago), with an additional 319 stars entering this special vantage point in the next 5,000 years. Among these stars are seven known exoplanet hosts, including Ross-128, which saw Earth transit the Sun in the past, and Teegarden's Star and Trappist-1, which will start to see it in 29 and 1,642 years, respectively. We found that human-made radio waves have already swept over 75 of the closest stars on our list.

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'Cataclysmic variables' are binary star systems in which one star of the pair is a white dwarf, and which often generate bright and energetic stellar outbursts. Classical novae are one type of outburst: when the white dwarf accretes enough matter from its companion, the resulting hydrogen-rich atmospheric envelope can host a runaway thermonuclear reaction that generates a rapid brightening. Achieving peak luminosities of up to one million times that of the Sun, all classical novae are recurrent, on timescales of months to millennia. During the century before and after an eruption, the 'novalike' binary systems that give rise to classical novae exhibit high rates of mass transfer to their white dwarfs. Another type of outburst is the dwarf nova: these occur in binaries that have stellar masses and periods indistinguishable from those of novalikes but much lower mass-transfer rates, when accretion-disk instabilities drop matter onto the white dwarfs. The co-existence at the same orbital period of novalike binaries and dwarf novae-which are identical but for their widely varying accretion rates-has been a longstanding puzzle. Here we report the recovery of the binary star underlying the classical nova eruption of 11 March AD 1437 (refs 12, 13), and independently confirm its age by proper-motion dating. We show that, almost 500 years after a classical-nova event, the system exhibited dwarf-nova eruptions. The three other oldest recovered classical novae display nova shells, but lack firm post-eruption ages, and are also dwarf novae at present. We conclude that many old novae become dwarf novae for part of the millennia between successive nova eruptions.

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Menarche, the first menstrual period, is a significant life event with important cultural, social, and personal implications. After noticing that several girls in a rural pediatric practice reached menarche at young ages, the researchers conducted a qualitative case study to investigate when menarche occurs and factors that may be associated with menarche onset. Four of the total of seven cases reached menarche before the average age of 12.8 years and had mothers who started at later ages. All four also experienced significant stressors just prior to onset. Lack of generalizability and the small sample disallow for any significant findings. However, the findings do indicate that menarche occurs in rural girls as young as age 9, creating implications for nurses in the areas of assessment, client teaching/counseling, and future research.

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The present investigation employed a balanced placebo design to examine the effects of alcohol versus the belief that one has consumed alcohol, i.e. alcohol expectancy, on error production while operating a driving simulator. The male subjects employed were social drinkers, having no history of alcohol abuse. The alcoholic beverage consisted of vodka and tonic in the ratio of 1:5, resulting in a mean blood alcohol level of .064%. The placebo beverage consisted of water and tonic, also in the ration 1:5. Principal findings were that alcohol ingestion had a debilitating effect on certain measures of driving behavior (operation of brakes, steering), whereas the belief that one had consumed alcohol had no discernable effects. The results are discussed in relation to other findings using the balanced placebo design. It was concluded that reckless driving under the influence of alcohol, is at least partly a result of the pharmological effects of ethanol.

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