Search

Oil frequently plays a crucial role in modern industrial economies. It is a very costly natural resource for those countries that do not have it, but very profitable for those that do. Yet, developing oil resources and transporting them to market has its own costs, not only in terms of production but also in terms of impacts on other valuable natural resources such as clean water. Not surprisingly, governments can have strict environmental regulations concerning oil transport. However, such regulations can be complicated, especially in countries like the United States where many different government agencies claim jurisdiction, especially at differing spatial scales. Consequently, conflict can result from competing interests, pitting those developing oil resources against those already using resources such as clean water. This paper explores the complicated geographies of environmental regulations and how competing entities pursue and protect their interests through environmental ligation. In doing so, this study uses the example of the Dakota Access Pipeline (the DAPL) because the conflict surrounding it garnered considerable national and international attention.

We present the results of a new study of the K-band galaxy luminosity function (KLF) at redshifts z0.25 is relatively steep (-1.30.25 the evolution of the KLF is remarkably smooth, with little or no evolution evident at faint (M_K>-20.5) or bright magnitudes (M_K, Comment: 18 pages, 10 figures, accepted for publication in MNRAS

We present a direct method for isolating the component of the starlight blocked by a planet as it transits its host star, and apply it to spectra of the bright transiting planet HD 189733b. We model the global shape of the stellar cross-correlation function as the convolution of a limb-darkened rotation profile and a gaussian representing the Doppler core of the average photospheric line profile. The light blocked by the planet during the transit is a gaussian of the same intrinsic width, whose trajectory across the line profile yields a precise measure of the misalignment angle and an independent measure of v sin I. We show that even when v sin I is less than the width of the intrinsic line profile, the travelling Doppler "shadow" cast by the planet creates an identifiable distortion in the line profiles which is amenable to direct modelling. Direct measurement of the trajectory of the missing starlight yields self-consistent measures of the projected stellar rotation rate, the intrinsic width of the mean local photospheric line profile, the projected spin-orbit misalignment angle, and the system's centre-of-mass velocity. Combined with the photometric rotation period, the results give a geometrical measure of the stellar radius which agrees closely with values obtained from high-precision transit photometry if a small amount of differential rotation is present in the stellar photosphere., 8 pages, 5 figures, 2 tables; accepted by MNRAS

We present a new method to search for candidate z~>2 Herschel 500{\mu}m sources in the GOODS-North field, using a S500{\mu}m/S24{\mu}m "color deconfusion" technique. Potential high-z sources are selected against low-redshift ones from their large 500{\mu}m to 24{\mu}m flux density ratios. By effectively reducing the contribution from low-redshift populations to the observed 500{\mu}m emission, we are able to identify counterparts to high-z 500{\mu}m sources whose 24{\mu}m fluxes are relatively faint. The recovery of known z~4 starbursts confirms the efficiency of this approach in selecting high-z Herschel sources. The resulting sample consists of 34 dusty star-forming galaxies at z~>2. The inferred infrared luminosities are in the range 1.5x10^12-1.8x10^13 Lsun, corresponding to dust-obscured star formation rates (SFRs) of ~260-3100 Msun/yr for a Salpeter IMF. Comparison with previous SCUBA 850{\mu}m-selected galaxy samples shows that our method is more efficient at selecting high-z dusty galaxies with a median redshift of z=3.07+/-0.83 and 10 of the sources at z~>4. We find that at a fixed luminosity, the dust temperature is ~5K cooler than that expected from the Td-LIR relation at z, Comment: 33 pages in emulateapj format, 24 figures, 2 tables, accepted for publication in the ApJS

The European Southern Observatory's (ESO) Visible and Infrared Survey Telescope for Astronomy (VISTA) is a 4-m class survey telescope for wide-field near-infrared imaging. VISTA is currently running a suite of six public surveys, which will shortly deliver their first Europe wide public data releases to ESO. The VISTA Kilo-degree Infrared Galaxy Survey (VIKING) forms a natural intermediate between current wide shallow, and deeper more concentrated surveys, by targeting two patches totalling 1500 sq.deg in the northern and southern hemispheres with measured 5-sigma limiting depths of Z ~ 22.4, Y ~ 21.4, J ~ 20.9, H ~ 19.9 and Ks ~19.3 (Vega). This architecture forms an ideal working parameter space for the discovery of a significant sample of 6.5

We present the results from a study of the morphologies of moderate luminosity X-ray selected AGN host galaxies in comparison to a carefully mass-matched control sample at 0.5 < z < 3 in the CANDELS GOODS-S field. We apply a multi-wavelength morphological decomposition analysis to these two samples and report on the differences between the morphologies as fitted from single Sersic and multiple Sersic models, and models which include an additional nuclear point-source component. Thus, we are able to compare the widely adopted single Sersic fits from previous studies to the results from a full morphological decomposition, and address the issue of how biased the inferred properties of AGN hosts are by a potential nuclear contribution from the AGN itself. We find that the AGN hosts are mixed systems which have higher bulge fractions than the control sample in our highest redshift bins at the >99.7% confidence level, according to all model fits even those which adopt a point-source component. This serves to alleviate concerns that previous, purely single Sersic, analyses of AGN hosts could have been spuriously biased towards higher bulge fractions. This dataset allows us to further probe the physical nature of these point-source components; we find no strong correlation between the point-source component and AGN activity, and that these point-source components are best modelled physically by nuclear starbursts. Our analysis of the bulge and disk fractions of these AGN hosts in comparison to a mass-matched control sample reveals a similar morphological evolutionary track for both the active and non-active populations, providing further evidence in favour of a model where AGN activity is triggered by secular processes., 14 pages, 16 figures, submitted to MNRAS

Submillimetre (submm) galaxies are among the most rapidly star-forming and most massive high-redshift galaxies; thus, their properties provide important constraints on galaxy evolution models. However, there is still a debate about their stellar masses and their nature in the context of the general galaxy population. To test the reliability of their stellar mass determinations, we used a sample of simulated submm galaxies for which we derived stellar masses via spectral energy distribution (SED) modelling (with Grasil, Magphys, Hyperz and LePhare) adopting various star formation histories (SFHs). We found that the assumption of SFHs with two independent components leads to the most accurate stellar masses. Exponentially declining SFHs (tau) lead to lower masses (albeit still consistent with the true values), while the assumption of single-burst SFHs results in a significant mass underestimation. Thus, we conclude that studies based on the higher masses inferred from fitting the SEDs of real submm galaxies with double SFHs are most likely to be correct, implying that submm galaxies lie on the high-mass end of the main sequence of star-forming galaxies. This conclusion appears robust to assumptions of whether or not submm galaxies are driven by major mergers, since the suite of simulated galaxies modelled here contains examples of both merging and isolated galaxies. We identified discrepancies between the true and inferred stellar ages (rather than the dust attenuation) as the primary determinant of the success/failure of the mass recovery. Regardless of the choice of SFH, the SED-derived stellar masses exhibit a factor of ~2 scatter around the true value; this scatter is an inherent limitation of the SED modelling due to simplified assumptions. Finally, we found that the contribution of active galactic nuclei does not have any significant impact on the derived stellar masses., Comment: Accepted to A&A. 11 pages, 9 figures, 1 table. V2 main changes: 1) discussion of the stellar age as the main parameter influencing the success of an SED model (Fig. 4, 5, 7); 2) discussion of the age-dust degeneracy (Fig 9); 3) the comparison of real and simulated submm galaxies (Fig 1)

We have constructed a mass-selected sample of M* > 1011舁M⊙ galaxies at 1 < z < 3 in the CANDELS UKIDSS UDS and COSMOS fields and have decomposed these systems into their separate bulge and disc components according to their H160-band morphologies. By extending this analysis to multiple bands, we have been able to conduct individual bulge and disc component SED fitting which has provided us with stellar-mass and star formation rate estimates for the separate bulge and disc components. Having utilized the new decomposed stellar-mass estimates, we confirm that the bulge components display a stronger size evolution than the discs. The median sizes of the bulge components is 3.09 ± 0.20 times smaller than similarly massive local galaxies over the full 1 < z < 3 redshift range; for the discs, the corresponding factor is 1.77 ± 0.10. Moreover, by splitting our sample into the passive and star-forming bulge and disc sub-populations and examining their sizes as a fraction of their present-day counter-parts, we find that the star-forming and passive bulges are equally compact, star-forming discs are larger, while the passive discs have intermediate sizes. This trend is not evident when classifying galaxy morphology on the basis of single-Sérsic fits and adopting the overall star formation rates. Finally, by evolving the star formation histories of the passive discs back to the redshifts when the passive discs were last active, we show that the passive and star-forming discs have consistent sizes at the relevant epoch. These trends need to be reproduced by any mechanisms which attempt to explain the morphological evolution of galaxies., Monthly Notices of the Royal Astronomical Society, 444 (2), ISSN:0035-8711, ISSN:1365-2966, ISSN:1365-8711

We report the results of a comprehensive study of the relationship between galaxy size, stellar mass and specific star-formation rate (sSFR) at redshifts 1.3= 6x10^10 Msun), spectroscopic sample from the UKIDSS Ultra-deep Survey (UDS), with accurate stellar-mass measurements derived from spectro photometric fitting, we find that at z~1.4 the location of massive galaxies on the size-mass plane is determined primarily by their sSFR. At this epoch we find that massive galaxies which are passive (sSFR, Comment: 21 pages, 11 figures, accepted for publication in MNRAS. Replaced to match accepted version

We have exploited the HST CANDELS WFC3/IR imaging to study the properties of (sub-)mm galaxies in GOODS-South. After using the deep radio and Spitzer imaging to identify galaxy counterparts for the (sub-)mm sources, we have used the new CANDELS data in two ways. First, we have derived improved photometric redshifts and stellar masses, confirming that the (sub-)mm galaxies are massive (=2.2x10^11 M_solar) galaxies at z=1-3. Second, we have exploited the depth and resolution of the WFC3/IR imaging to determine the sizes and morphologies of the galaxies at rest-frame optical wavelengths, fitting two-dimensional axi-symmetric Sersic models. Crucially, the WFC3/IR H-band imaging enables modelling of the mass-dominant galaxy, rather than the blue high-surface brightness features which often dominate optical (rest-frame UV) images of (sub-)mm galaxies, and can confuse visual morphological classification. As a result of this analysis we find that >95% of the rest-frame optical light in almost all of the (sub-)mm galaxies is well-described by either a single exponential disk, or a multiple-component system in which the dominant constituent is disk-like. We demonstrate that this conclusion is consistent with the results of high-quality ground-based K-band imaging, and explain why. The massive disk galaxies which host luminous (sub-)mm emission are reasonably extended (r_e=4 kpc), consistent with the sizes of other massive star-forming disks at z~2. In many cases we find evidence of blue clumps within the sources, with the mass-dominant disk becoming more significant at longer wavelengths. Finally, only a minority of the sources show evidence for a major galaxy-galaxy interaction. Taken together, these results support the view that most (sub-)mm galaxies at z~2 are simply the most extreme examples of normal star-forming galaxies at that era., Comment: 30 pages, 9 figures

We present the results of a search for the most luminous star-forming galaxies at redshifts z~6 based on CFHT Legacy Survey data. We identify a sample of 40 Lyman break galaxies brighter than magnitude z'=25.3 across an area of almost 4 square degrees. Sensitive spectroscopic observations of seven galaxies provide redshifts for four, of which only two have moderate to strong Lyman alpha emission lines. All four have clear continuum breaks in their spectra. Approximately half of the Lyman break galaxies are spatially resolved in 0.7 arcsec seeing images, indicating larger sizes than lower luminosity galaxies discovered with the Hubble Space Telescope, possibly due to on-going mergers. The stacked optical and infrared photometry is consistent with a galaxy model with stellar mass ~ 10^{10} solar masses. There is strong evidence for substantial dust reddening with a best-fit A_V=0.7 and A_V>0.48 at 2 sigma confidence, in contrast to the typical dust-free galaxies of lower luminosity at this epoch. The spatial extent and spectral energy distribution suggest that the most luminous z~6 galaxies are undergoing merger-induced starbursts. The luminosity function of z=5.9 star-forming galaxies is derived. This agrees well with previous work and shows strong evidence for an exponential decline at the bright end, indicating that the feedback processes which govern the shape of the bright end are occurring effectively at this epoch., 14 pages, 11 figures, AJ in press, revised to address referee comments

In this paper we describe the first data release of the the Visible and Infrared Survey Telescope for Astronomy (VISTA) Deep Extragalactic Observations (VIDEO) survey. VIDEO is a ~12degree^2 survey in the near-infrared Z,Y,J,H and K_s bands, specifically designed to enable the evolution of galaxies and large structures to be traced as a function of both epoch and environment from the present day out to z=4, and active galactic nuclei (AGN) and the most massive galaxies up to and into the epoch of reionization. With its depth and area, VIDEO will be able to fully explore the period in the Universe where AGN and starburst activity were at their peak and the first galaxy clusters were beginning to virialize. VIDEO therefore offers a unique data set with which to investigate the interplay between AGN, starbursts and environment, and the role of feedback at a time when it was potentially most crucial. We provide data over the VIDEO-XMM3 tile, which also covers the Canada-France-Hawaii-Telescope Legacy Survey Deep-1 field (CFHTLS-D1). The released VIDEO data reach a 5-sigma AB-magnitude depth of Z=25.7, Y=24.5, J=24.4, H=24.1 and K_s=23.8 in 2 arcsec diameter apertures (the full depth of Y=24.6 will be reached within the full integration time in future releases). The data are compared to previous surveys over this field and we find good astrometric agreement with the Two-Micron All Sky Survey, and source counts in agreement with the recently released UltraVISTA survey data. The addition of the VIDEO data to the CFHTLS-D1 optical data increases the accuracy of photometric redshifts and significantly reduces the fraction of catastrophic outliers over the redshift range 0, Comment: 16 Pages, 12 figure and 5 tables, MNRAS in press. Figures have been degraded due to size constraints, Figure 10 also updated

We report the discovery of WASP-3b, the third transiting exoplanet to be discovered by the WASP and SOPHIE collaboration. WASP-3b transits its host star USNO-B1.0 1256-0285133 every 1.846834+-0.000002 days. Our high precision radial-velocity measurements present a variation with amplitude characteristic of a planetary-mass companion and in-phase with the light-curve. Adaptive optics imaging shows no evidence for nearby stellar companions, and line-bisector analysis excludes faint, unresolved binarity and stellar activity as the cause of the radial-velocity variations. We make a preliminary spectroscopic analysis of the host star finding it to have Teff = 6400+-100 K and log g = 4.25+-0.05 which suggests it is most likely an unevolved main sequence star of spectral type F7-8V. Our simultaneous modelling of the transit photometry and reflex motion of the host leads us to derive a mass of 1.76 +0.08 -0.14 M_J and radius 1.31 +0.07-0.14 R_J for WASP-3b. The proximity and relative temperature of the host star suggests that WASP-3b is one of the hottest exoplanets known, and thus has the potential to place stringent constraints on exoplanet atmospheric models., 10 pages, 7 figures, 4 tables, submitted for publication in MNRAS

Volunteers consumed a mixed-fat diet for 6 d (Pre-exp) and then either a canola-oil-based diet (CAN) containing linolenic acid (18:3n-3) or a sunflower-oil-based diet (SUN) rich in linoleic acid (18:2n-6) for 18 d, followed by the alternative diet in a crossover design. Platelet phospholipids were analyzed for changes in fatty acid composition. Eicosapentaenoic acid (EPA) (20:5n-3) was significantly higher in alkenylacyl ethanolamine phosphoglyceride (PPE) and in total phosphatidylcholine (PC) after CAN compared with SUN and Pre-exp. The 22:5n-3 was increased in PPE after CAN above concentrations found after both SUN and Pre-exp. Lower concentrations of 20:4n-6 and 22:4n-6 were observed with CAN in PC and lower concentrations of 22:4n-6 in PPE. These results indicate that the consumption of canola oil moderately increases EPA concentrations and alters the concentrations of other n-6 and n-3 fatty acids in human platelet phospholipids.

For more than forty years, the Atlantic Alliance found itself locked in a critical confrontation with the Soviet Union. The alliance won the Cold War, and the Soviet bloc remained saddled with a crippled and uncompetitive economic and social system, a discredited political structure, a bankrupt ideology, and unresolved internal conflicts that had been suppressed for decades. During the Cold War years, Western Europe, under the defense umbrella of the alliance and with the earlier massive support of the Marshall Plan, not only recovered but became through the European Community and its economic partner, the European Free Trade Association, one of the strongest economic regions in the world. Even Western European countries that were not members of the alliance and, indeed, many Third World states were beneficiaries of the security and stability that the North Atlantic Treaty Organization (NATO) provided.

On a compare l'apport et la concentration fonctionnelle des vitamines B 6 , C et B 1 chez 15 sujets atteints de la maladie d'Alzheimer et chez 15 sujets bien portants. Les resultats sont similaires pour les deux groupes, excepte pour la vitamine B 1 dont la concentration fonctionelle est plus faible chez les sujets atteints de la maladie d'Alzheimer. Il semble donc peu probable qu'on puisse recourir aux vitamines B 6 ou C pour traiter cette maladie. Le role de la vitamine B 1 , quant a lui, reste a preciser

A survey was conducted to compare the total viable fungal content and the number of different mold species encountered in 10 types of health foods labeled organically grown and in the same foods without such a label. The foods were wheat flour, corn meal, brown rice, figs, split peas, pinto beans, soybeans, walnuts, pecans, and peanuts. Results showed no consistent difference in either the total viable fungal content or the number of different mold species encountered between the labeled and unlabeled foods. Two genera of yeasts (Rhodotorula and Saccharomyces) and 22 gener of molds, including more than 65 species, were encountered. The mold flora was dominated by Aspergillus glaucus, Aspergillus niger, Aspergillus flavus, Aspergillus candidus, Penicillium cyclopium, and Penicillium viridicatum. Isolates of the genera Alternaria, Cladosporium, Fusarium, and Helminthosporium also occurred in certain foods. At least 10 toxicogenic species of Aspergillus and Penicillium were encountered. A total of 87 cultures of these species, all isolated from health foods, were screened for laboratory production of their respective toxins. Toxin production potential of these 87 cultures did not differ from that of cultures of the same species isolated from conventional foods.

Ninety-five isolates of Aspergillus and Penicillium species from selected dried foods were examined for their ability to produce cyclopiazonic acid (CPA). The isolates were grown in sterile synthetic liquid medium at 28 degrees C for 8 days in the dark. The medium and mold mycelia were then extracted with chloroform. CPA was semiquantitatively determined by thin layer chromatography through visual comparison with standards. The cultures of A. flavus were also examined for their ability to produce aflatoxin. One A. tamarii and all 13 P. urticae isolates produced CPA, whereas only 19 of the 31 (61%) A. flavus isolates produced CPA, and 6 (19%) A. flavus produced aflatoxin. All 13 P. urticae isolates also produced patulin and griseofulvin. CPA-producing A. flavus was found in all food types but not in all samples. CPA-producing P. urticae was found only in dried beans and macaroni.

Two methods presently used for examining whole foods and feeds for viable molds were evaluated for their relative effectiveness in the qualitative determination of the total number of mold species present in soybeans and dried beans: the direct plating method and the serial dilution method. Sixty-nine soybean samples and 40 dried bean samples were examined. Although the quantitative results of this study were inconclusive, the qualitative results show that the direct plating method was substantially more effective in detecting individual mold species. An average of 12.9 and 10.9 species was detected by the direct plating method in whole soybean and dried bean samples, respectively. An average of 4.4 and 2.8 species was detected by the dilution method in ground soybean and dried bean samples, respectively. A total of at least 37 mold species were found in the study, including 10 toxicogenic species. With few exceptions, detection rates of the 37 individual species were substantially greater among the samples examined by direct plating than those examined by serial dilution.

The behaviour of microorganisms was studied in mung beans and alfalfa seeds before and after germination in modified, commercially available bean-sprouting kits. The microorganism were enumerated by the aerobic plate count (APC) and by total yeast and mold count procedures. Salmonella species were artificially inoculated into selected samples and were enumerated by the most probable number (MPN) method. After germination of the beans or seeds into mature sprouts, significant increases were noted in APCs and in MPN values of Salmonella species. Although counts of yeasts and molds did not increase significantly after germination, these samples show an increase in toxic Aspergillus flavus and potentially toxic Alternaria species. The presence of toxic Penicillium cyclopium molds also increase substantially in 5 samples of a single brand of mung beans. Analysis of selected sprout samples, however, showed no presence of aflatoxin.

To evaluate the potential for mycotoxin production by molds in dried beans, the mold flora of 114 samples was determined both before and after surface disinfection of the beans with 5% NaOCl. Surface disinfection substantially reduced mold incidence, indicating that contamination was mainly on the surface. The flora, both before and after disinfection, was dominated by species of the Aspergillus glaucus group, the toxicogenic species A. ochraceus, Penicillium cyclopium , and P. viridicatum , and species of Alternaria, Cladosporium , and Fusarium . The toxicogenic species Aspergillus flavis, A. versicolor, Penicillium citrinum, P. expansum, P. islandicum , and P. urticae were encountered less frequently. Of 209 species of Aspergillus and Penicillium screened for mycotoxin production on sterile rice substrate, 114 produced one or more of the following mycotoxins: A. flavus , aflatoxins; A. ochraceus , ochratoxins; A. nidulans, A. unguis , and A. versicolor , sterigmatocystin; P. cyclopium , penicillic acid; P. citrinum and P. viridicatum , citrinin; P. urticae , patulin and griseofulvin. Sterigmatocystin production by A. unguis is reported for the first time.

This paper will deal with the studies which we have made to determine the extent to which the circadian clock in Chlamydomonas might be involved in controlling or influencing various cell cycle and developmental events.

A microbiological survey was performed on 4 selected imported spices: black peppercorns, white peppercorns, coriander, and fennel seed. Aerobic plate count values ranged from 10(4) to 10(7) colony-forming units (CFU)/g for black and white peppercorns and from 10(3) to 10(5) CFU/g for coriander and fennel seed. Combined results of the 3-tube most probable number procedure and the API 20E kit indicated the presence of Escherichia coli in 4 test samples of black peppercorns, 1 test sample of white peppercorns, and 1 test sample of coriander. Two test samples of black peppercorns were positive for Salmonella contamination. Among the various Enterobacteriaceae isolated from the spices, Enterobacter cloacae and Klebsiella pneumoniae were found most frequently in all spice types. Of 18 mammalian and avian fecal pellets removed from the spices and analyzed microbiologically, E. coli was found in only 2 pellet specimens. There was no apparent relationship between the enteric microflora found in spices and those found in the fecal pellets.

Fifteen fungal species, all isolated from food, were compared for their growth abilities on potato dextrose agar acidified to pH 3.5, and on nonacidified potato dextrose agar amended with 40 ppm chlortetracycline hydrochloride. Comparisons were made at 16, 21, 26, 32, and 37 degrees C. Of the 15 species, only Penicillium expansum exhibited better growth on the acidified medium than on the nonacidified antibiotic medium, while 9 species grew better on the nonacidified antibiotic medium. Five species grew equally well on either medium.

A short review of the general properties and ideas concerning the possible mechanism of biological clocks in unicellular microorganisms is given. Phototactic rhythms are reviewed briefly, and a preliminary report describing mutant phototactic behavioral mutants in Chlamydomonas reinhardi is included.

We present the results of the first, deep ALMA imaging covering the full 4.5 sq arcmin of the Hubble Ultra Deep Field (HUDF) as previously imaged with WFC3/IR on HST. Using a mosaic of 45 pointings, we have obtained a homogeneous 1.3mm image of the HUDF, achieving an rms sensitivity of 35 microJy, at a resolution of 0.7 arcsec. From an initial list of ~50 >3.5sigma peaks, a rigorous analysis confirms 16 sources with flux densities S(1.3) > 120 microJy. All of these have secure galaxy counterparts with robust redshifts ( = 2.15), and 12 are also detected at 6GHz in new deep JVLA imaging. Due to the wealth of supporting data in this unique field, the physical properties of the ALMA sources are well constrained, including their stellar masses (M*) and UV+FIR star-formation rates (SFR). Our results show that stellar mass is the best predictor of SFR in the high-z Universe; indeed at z > 2 our ALMA sample contains 7 of the 9 galaxies in the HUDF with M* > 2 x 10^10 Msun and we detect only one galaxy at z > 3.5, reflecting the rapid drop-off of high-mass galaxies with increasing redshift. The detections, coupled with stacking, allow us to probe the redshift/mass distribution of the 1.3-mm background down to S(1.3) ~ 10 micro-Jy. We find strong evidence for a steep `main sequence' for star-forming galaxies at z ~ 2, with SFR \propto M* and a mean specific SFR = 2.2 /Gyr. Moreover, we find that ~85% of total star formation at z ~ 2 is enshrouded in dust, with ~65% of all star formation at this epoch occurring in high-mass galaxies (M* > 2 x 10^10 Msun), for which the average obscured:unobscured SF ratio is ~200. Finally, we combine our new ALMA results with the existing HST data to revisit the cosmic evolution of star-formation rate density; we find that this peaks at z ~ 2.5, and that the star-forming Universe transits from primarily unobscured to primarily obscured thereafter at z ~ 4., 26 pages, 15 figures, updated to match version accepted for publication in MNRAS

SYNCHRONIZATION of cellular and nuclear division in Salmonella typhimurium populations at densities of 1–4 × 107 cell/ml. has been reported previously1,2. Two systems for obtaining such synchronization were described, both systems employing temperature shifts between 25° and 37°. In the first system the temperature of a culture which had been growing for ten generations at 25° was raised to 37°. In the period between 5 and 10 min. following the rise in temperature, 80–90 per cent of the population underwent nuclear division as observed cytologically3, and as inferred from the interaction of the cells with a temperate bacteriophage. On the other hand, cellular division, as measured by colony counts, was delayed for 20–25 min., at which time it took place at an increased rate, finally re-establishing the exponential growth of the culture at the normal 37° rate (see Fig. 1).