An increase in the number of cases of hepatocellular carcinoma has occurred in the United States over the past two decades. The age-specific incidence of this cancer has progressively shifted toward younger people.

We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within ∼4 kpc of the Galactic Centre. Characterized by a chemical composition resembling those of low-mass satellites of the Milky Way, this new inner Galaxy structure (IGS) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy. We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way. Comparing the mean elemental abundances of this structure with predictions from cosmological numerical simulations, we estimate that the progenitor system had a stellar mass of ∼5 × 108 M⊙, or approximately twice the mass of the recently discovered Gaia-Enceladus/Sausage system. We find that the accreted:in situ ratio within our metal-poor ([Fe/H] < –0.8) bulge sample is somewhere between 1:3 and 1:2, confirming predictions of cosmological numerical simulations by various groups.

Background: A recent increase in the incidence of hepatocellular carcinoma was reported in the United States. The cause of this witnessed rise remains unknown.

The physics of sound propagation imposes fundamental constraints on sound localization: for a given frequency, the smaller the receiver, the smaller the available cues. Thus, the creation of nanoscale acoustic microphones with directional sensitivity is very difficult. The fly Ormia ochracea possesses an unusual 'ear' that largely overcomes these physical constraints; attempts to exploit principles derived from O. ochracea for improved hearing aids are now in progress. Here we report that O. ochracea can behaviourally localize a salient sound source with a precision equal to that of humans. Despite its small size and minuscule interaural cues, the fly localizes sound sources to within 2 degrees azimuth. As the fly's eardrums are less than 0.5 mm apart, localization cues are around 50 ns. Directional information is represented in the auditory system by the relative timing of receptor responses in the two ears. Low-jitter, phasic receptor responses are pooled to achieve hyperacute timecoding. These results demonstrate that nanoscale/microscale directional microphones patterned after O. ochracea have the potential for highly accurate directional sensitivity, independent of their size. Notably, in the fly itself this performance is dependent on a newly discovered set of specific coding strategies employed by the nervous system.

Myopophyllum speciosum is a pseudophylline katydid (Tettigoniidae) from the neotropics that generates unusually high ultrasonic frequencies as the dominant carrier in its calling song. Male calls average only 148 ms duration and are given at long intervals: 8.7 s. Pairing is completed with vibrational signals, generated at closer range by body oscillation (tremulation). Two distinctive vibrational motor patterns, short and long, are produced by both sexes. Physical parameters of the sound and vibratory signals of this species are described. The relatively high‐Q carrier frequency (mean = 81 kHz) varies between males over a range of 20 kHz but does not predict a singer's body size. Short tremulations are much more intense than long as measured by acceleration. Descriptions of the songs of three other pseudophylline species with unusually high principal carriers (65–105 kHz) are also presented. Eavesdropping by predatory bats offers the most plausible selective explanation for the features of M. speciosum's signal system. This hypothesis is supported by the species' sexually dimorphic defensive spination: males, the sound‐signalling sex, have metafemoral spines of greater size and distinctive orientation. Evidence for eavesdropping and for alternative hypotheses is assessed. Other neotropical tettigoniids in rainforest understorey also employ elaborate vibratory signals (species of Choeroparnops, Schedocentrus, Docidocercus, Copiphora) and some show a trend to reduce or even to eliminate their use of airborne sound. Some rainforest tettigoniids may have replaced acoustic with vibrational signalling as a response to bat eavesdropping.

Buzz-pollination is a plant strategy that promotes gamete transfer by requiring a pollinator, typically bees (Hymenoptera: Apoidea), to vibrate a flower's anthers in order to extract pollen. Although buzz-pollination is widespread in angiosperms with over 20,000 species using it, little is known about the functional connection between natural variation in buzzing vibrations and the amount of pollen that can be extracted from anthers. We characterized variability in the vibrations produced by Bombus terrestris bumblebees while collecting pollen from Solanum rostratum (Solanaceae), a buzz-pollinated plant. We found substantial variation in several buzzing properties both within and among workers from a single colony. As expected, some of this variation was predicted by the physical attributes of individual bumblebees: heavier workers produced buzzes of greater amplitude. We then constructed artificial "pollination buzzes" that varied in three parameters (peak frequency, peak amplitude, and duration), and stimulated S. rostratum flowers with these synthetic buzzes to quantify the relationship between buzz properties and pollen removal. We found that greater amplitude and longer duration buzzes ejected substantially more pollen, while frequency had no directional effect and only a weak quadratic effect on the amount of pollen removed. These findings suggest that foraging bumblebees may improve pollen collection by increasing the duration or amplitude of their buzzes. Moreover, given that amplitude is positively correlated with mass, preferential foraging by heavier workers is likely to result in the largest pollen yields per bee, and this could have significant consequences for the success of a colony foraging on buzz-pollinated flowers.

Assessment strategies are an important component in game theoretical models of contests. Strategies can be either based on one’s own abilities (self assessment) or on the relative abilities of two opponents (mutual assessment). Using statistical methodology that allows discrimination between assessment types, we examined contests in the jumping spider Phiddipus clarus. In this species, aggressive interactions can be divided into ‘pre-contact’ and ‘contact’ phases. Pre-contact phases consist of bouts of visual and vibratory signaling. Contact phases follow where males physically contact each other (leg fencing). Both weight and vibratory signaling differences predicted winners with heavier and more actively signaling males winning more contests. Vibratory behaviour predicted pre-contact phase duration, with higher signaling rates and larger differences between contestants leading to longer pre-contact interaction times. Contact phase duration was predicted most strongly by the weight of losing males relative to that of winning males, suggesting that P. clarus males use self-assessment in determining contest duration. While a self-assessment strategy was supported, our data suggest a secondary role for mutual assessment (“partial mutual assessment”). After initial contest bouts, male competitors changed their behaviour. Pre-contact and contact phase durations were reduced while vibratory signaling behaviour in winners was unchanged. In addition, only vibratory signaling differences predicted winners in subsequent bouts suggesting a role of experience in determining contest outcomes. We suggest that the rules and assessment strategies males use can change depending on experience and that assessment strategies are likely a continuum between self- and mutual assessment.

In the study of animal signals, spiders have emerged as a classic example of signalling using substrate-propagated vibrations (Barth, 1998). The vibrations propagated through the delicate webs of orb-weaving spiders are clear examples of signalling through vibrations (Barth, 1998;Finck, 1981;Frohlich and Buskirk, 1982;Klarner and Barth, 1982;Landolfa and Barth, 1996;Masters, 1984;Masters and Markl, 1981;Vollrath, 1979), but the majority of spiders may also use substrate-propagated vibrations in such varied substrates as water, soil, leaf litter or plants (Barth, 1985(Barth, , 1998(Barth, , 2002Bleckmann and Barth, 1984;Bristowe, 1929;Fernandezmontraveta and Schmitt, 1994;Rovner, 1968;Stratton and Uetz, 1983;Uetz and Stratton, 1982). Three types of substrate-borne vibration-production mechanisms have been described in spiders: percussion, stridulation and vibration (tremulation; Uetz and Stratton, 1982). Percussion is produced by the drumming of body parts against the substrate and has been described in a variety of species (Dierkes and Barth, 1995;Stratton, 1983;Uetz and Stratton, 1982). Stridulation occurs by the rubbing of two rigid body structures relative to each other (Dumortier, 1963) and seems to occur commonly in spiders (Legendre, 1963), particularly in wolf spiders (Family:Lycosidae; Rovner, 1975;Stratton and Uetz, 1983;Uetz and Stratton, 1982). Tremulation (Morris, 1980) is the third method of substrate-borne vibration production found in spiders (Barth, 2002;Dierkes and Barth, 1995;Rovner, 1980;Uetz and Stratton, 1982) and occurs by the oscillation of body parts, without a frequency multiplier (i.e. stridulation), coupled to the substratum, usually by adhesive hairs on the tips of one or more of the legs. All of these mechanisms can be used to produce substrate-borne (seismic) signals (Aicher et al., 1983;Aicher and Tautz, 1990;Narins, 1990).Jumping spiders (Family: Salticidae) are unique among spiders in that they are visual 'specialists', having two large, prominent frontal eyes that are specialized for high spatial resolution, as befits their predatory habits as stalker-hunters (Forster, 1982a;Land, 1985). Not surprisingly, vision also plays a prominent role in their signalling behaviour. Males, unlike females, have evolved conspicuously ornamented and coloured appendages that they wave like semaphores during courtship, producing stereotyped, species-specific visual displays that unfold over periods of seconds to minutes (Crane, 1949;Forster, 1982b;Jackson, 1982). These displays function in species isolation, species recognition and female