Worked shell from the Northern Moluccas

The Northern Moluccas occupy a pivotal geographical zone at the interface of the Island Southeast Asian and Melanesian spheres. Whether one looks at genes, languages, Holocene animal translocations, or the archaeological record, it is clear that the cultures through time on these islands have both been shaped by, and have contributed to shaping, the complex fusion of influences that characterises the Asia/Pacific margin. The project reported on in this monograph intensively investigated this area for the first time, and uncovered a rich range of sites spanning c. 35,000 years of the islands’ history. There are few constants in the archaeological record that can be tracked through time. The vertebrate record of the Northern Moluccas shows dramatic shifts at different points in the past, and the ceramic record is necessarily restricted to the last few thousand years. The pre‑eminence of lithic technology in the study of human cultural change through time is due to its global presence as a robust archaeological constant, but in Island Southeast Asia, and the Northern Moluccas in particular, another constant has emerged: shell technology. From the earliest archaeological deposits at the oldest excavated site, Golo Cave, a range of shell technologies were in use ranging from the formal to the expedient (Szabó et al. 2007; Szabó and Koppel 2015). In contrast, associated lithic technologies were found to be non-standardised and uncomplicated in their manufacture (Szabó et al. 2007). While, to some extent, the early diversification of shell technologies at Golo Cave can be seen as a response to the low-quality lithic materials that were locally available, this in itself does not provide an adequate explanation. The diversity of shell-working from the lowest levels at Golo, both in terms of materials used and reduction techniques employed, clearly implies that a broad tradition of shell-working was well established by the time the site was initially occupied. Additionally, the techniques applied to various types of shell diverge from those applied to lithic material, confirming that shell was no simple technological substitute for stone. The range of stratified sites excavated as part of this archaeological project provides snapshots through time of the rise and decline of a variety of shell-working traditions. Some have clear links beyond the Northern Moluccas whilst others are seemingly idiosyncratic. The shell artefacts will be reported upon site by site, with temporal patterning and extra-Moluccan associations being considered in the discussion section

Looking for activity cycles in late-type Kepler stars using time-frequency analysis

We analyse light curves covering four years of 39 fast-rotating ($P_\mathrm{rot}< 1d$) late-type active stars from the Kepler database. Using time-frequency analysis (Short-Term Fourier-Transform), we find hints for activity cycles of 300-900 days at 9 targets from the changing typical latitude of the starspots, which, with the differential rotation of the stellar surface change the observed rotation period over the activity cycle. We also give a lowest estimation for the shear parameter of the differential rotation, which is ~0.001 for the cycling targets. These results populate the less studied, short period end of the rotation-cycle length relation.Comment: 12 pages, 7 figures, accepted for publication in MNRA

Winning strategies in congested traffic

One-directional traffic on two-lanes is modeled in the framework of a spring-block type model. A fraction $q$ of the cars are allowed to change lanes, following simple dynamical rules, while the other cars keep their initial lane. The advance of cars, starting from equivalent positions and following the two driving strategies is studied and compared. As a function of the parameter $q$ the winning probability and the average gain in the advancement for the lane-changing strategy is computed. An interesting phase-transition like behavior is revealed and conclusions are drawn regarding the conditions when the lane changing strategy is the better option for the drivers.Comment: 5 pages, 5 figure

Pushing the limits: K2 observations of the trans-Neptunian objects 2002 GV31 and (278361) 2007 JJ43

We present the first photometric observations of trans-Neptunian objects (TNOs) taken with the Kepler space telescope, obtained in the course of the K2 ecliptic survey. Two faint objects have been monitored in specifically designed pixel masks that were centered on the stationary points of the objects, when their daily motion was the slowest. In the design of the experiment, only the apparent path of these objects were retrieved from the detectors, i.e. the costs in terms of Kepler pixels were minimized. Because of the faintness of the targets we employ specific reduction techniques and co-added images. We measure rotational periods and amplitudes in the unfiltered Kepler band as follows: for (278361) 2007 JJ43 and 2002 GV31 we get P_rot=12.097 h and P_rot=29.2 h while 0.10 and 0.35 mag for the total amplitudes, respectively. Future space missions, like TESS and PLATO are not well suited to this kind of observations. Therefore, we encourage to include the brightest TNOs around their stationary points in each observing campaign to exploit this unique capability of the K2 Mission -- and therefore to provide unbiased rotational, shape and albedo characteristics of many objects.Comment: Accepted for publication in ApJ Letters, 5.2 pages in emulateapj style, misspelled 2007 JJ43 designation correcte

Frozen to death? -- Detection of comet Hale-Bopp at 30.7 AU

Comet Hale--Bopp (C/1995 O1) has been the single most significant comet encountered by modern astronomy, still having displayed significant activity at 25.7 AU solar distance in late 2007. It is a puzzling question when and where this activity will finally cease. Here we present new observations with the ESO 2.2m telescope at La Silla to check the activity of Hale--Bopp at 30.7 AU solar distance. On 2010-12-04, 26 CCD images were taken with 180 s exposure times for photometry and morphology. The comet was detected in R and had a total brightness of 23.3+-0.2 mag, referring to an absolute brightness of R(1,1,0)=8.3. The profile of the coma was star-like at a seeing of 1.9", without any evidence of a coma or tail extending farther than 2.5" (=55,000 km in projection) and exceeding 26.5 mag/arcs^2 surface brightness. The measured total brightness corresponds to a relative total reflecting surface, a_RC, of 485 km^2, nine times less than three years before. The calculated a_RC value would imply a nucleus with 60--65 km radius assuming 4% albedo. This size estimate is in significant contradiction with the previous results scattering around 35 km. Therefore we suggest that the comet may still be in a low-level activity, despite the lack of a prominent coma. Alternatively, if the nucleus is already dormant, the albedo should be as high as 13%, assuming a radius of 35 km. With this observation, Hale--Bopp has been the most distant comet ever observed, far beyond the orbit of Neptune.Comment: 4 pages, accepted by A&

Generalized mean-field study of a driven lattice gas

Generalized mean-field analysis has been performed to study the ordering process in a half-filled square lattice-gas model with repulsive nearest neighbor interaction under the influence of a uniform electric field. We have determined the configuration probabilities on 2-, 4-, 5-, and 6-point clusters excluding the possibility of sublattice ordering. The agreement between the results of 6-point approximations and Monte Carlo simulations confirms the absence of phase transition for sufficiently strong fields.Comment: 4 pages (REVTEX) with 4 PS figures (uuencoded

The curvature of the QCD phase transition line

We determine the curvature of the phase transition line in the mu-T plane through an analysis of various observables, including the Polyakov loop, the quark number susceptibilities and the susceptibility of the chiral condensate. The second derivative of these quantities with respect to mu was calculated. The measurements were carried out on N_T = 4,6,8 and 10 lattices generated with a Symanzik improved gauge and stout-link improved 2+1 flavour staggered fermion action using physical quark masses.Comment: Talk presented at the XXVI International Symposium on Lattice Field Theory, July 14 - 19, 2008, Williamsburg, Virginia, USA. 7 pages, 6 figure

Target selection of classical pulsating variables for space-based photometry

In a few years the Kepler and TESS missions will provide ultra-precise photometry for thousands of RR Lyrae and hundreds of Cepheid stars. In the extended Kepler mission all targets are proposed in the Guest Observer (GO) Program, while the TESS space telescope will work with full frame images and a ~15-16th mag brightness limit with the possibility of short cadence measurements for a limited number of pre-selected objects. This paper highlights some details of the enormous and important work of the target selection process made by the members of Working Group 7 (WG#7) of the Kepler and TESS Asteroseismic Science Consortium.Comment: 4 pages, 1 figure, proceedings of the RRL2015 - High-Precision Studies of RR Lyrae Stars conference, to appear in the Communications from the Konkoly Observator