Ilia State University

Citation: Alam, S., Albareti, F. D., Prieto, C. A., Anders, F., Anderson, S. F., Anderton, T., . . . Zhu, G. T. (2015). THE ELEVENTH AND TWELFTH DATA RELEASES OF THE SLOAN DIGITAL SKY SURVEY: FINAL DATA FROM SDSS-III. Astrophysical Journal Supplement Series, 219(1), 27. doi:10.1088/0067-0049/219/1/12

We present a one per cent measurement of the cosmic distance scale from the detections of the baryon acoustic oscillations (BAO) in the clustering of galaxies from the Baryon Oscillation Spectroscopic Survey, which is part of the Sloan Digital Sky Survey III. Our results come from the Data Release 11 (DR11) sample, containing nearly one million galaxies and covering approximately 8500 square degrees and the redshift range 0.2 < z < 0.7. We also compare these results with those from the publicly released DR9 and DR10 samples. Assuming a concordance cold dark matter ( CDM) cosmological model, the DR11 sample covers a volume of 13 Gpc 3 and is the largest region of the Universe ever surveyed at this density. We measure the correlation function and power spectrum, including density-field reconstruction of the BAO feature. The acoustic features are detected at a significance of over 7 in both the correlation function and power spectrum. Fitting for the position of the acoustic features measures the distance relative to the sound horizon at the drag epoch, r d , which has a value of r d,fid = 149.28 Mpc in our fiducial cosmology. We find D V = (1264 25 Mpc)(r d /r d,fid )

We create a sample of spectroscopically identified galaxies with z < 0.2 from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7), covering 6813 deg 2 . Galaxies are chosen to sample the highest mass haloes, with an effective bias of 1.5, allowing us to construct 1000 mock galaxy catalogues (described in Paper II), which we use to estimate statistical errors and test our methods. We use an estimate of the gravitational potential to 'reconstruct' the linear density fluctuations, enhancing the baryon acoustic oscillation (BAO) signal in the measured correlation function and power spectrum. Fitting to these measurements, we determine D V (z eff = 0.15) = (664 25)(r d /r d, fid ) Mpc; this is a better than 4 per cent distance measurement. This 'fills the gap' in BAO distance ladder between previously measured local and higher redshift measurements, and affords significant improvement in constraining the properties of dark energy. Combining our measurement with other BAO measurements from Baryon Oscillation Spectroscopic Survey and 6-degree Field Galaxy Redshift Survey galaxy samples provides a 15 per cent improvement in the determination of the equation of state of dark energy and the value of the Hubble parameter at z = 0 (H 0 ). Our measurement is fully consistent with the Planck results and the cold dark matter concordance cosmology, but increases the tension between Planck+BAO H 0 determinations and direct H 0 measurements.

BACKGROUND: The Republic of Georgia (Sakartvelo in Georgian language) is part of the Caucasus biodiversity hotspot, and human agricultural plant use dates bat at least 6000 years. However, little ethnobiological research has been published from the region since the 1940s. Given the lack of recent research in the region, the present study we report on plant uses in Skartvelo (Republic of Georgia), Caucasus. We hypothesized that, (1) given the long tradition of plant use, and the isolation under Soviet rule, plant use both based on homegardens and wild harvesting would be more pronounced in Georgia than in the wiser region, (2) the Soviet occupation would have had broad influence on plant use, and (3) there would still be incidence of knowledge loss despite wide plant use. METHODS: Fieldwork was conducted in Khevsureti, Samtskhe-Javakheti, Tusheti, Svaneti, and Racha in July-August 2013, July-August 2014, and September-October 2015. Interviews using semi-structured questionnaires were conducted with 170 participants (80 women and 90 men) after obtaining their oral prior informed consent. All interviews were carried out in the participants' homes and gardens by native speakers of Georgian and its local dialects (Svan, Tush, Khevsur, Psav), or, where participants spoke these as their native language, Armenian, Russian, or Greek. RESULTS: In the present study we encountered 480 plant species belonging to 249 genera of 95 families being used in the research region. The highest number of species and of unique species were reported from the remote Tusheti-Khevsureti region. Informant consensus and number of use reports were highest for each region in the food and medicinal use categories. Of the 480 plants being used in the research region 282 species were exclusively wild-harvested, 103 were grown in homegardens, and 84 were both grown in gardens and sourced in the wild. CONCLUSIONS: Plant species, and uses, found in our study, both for Georgia in general, as well as for its regions, showed clear relations to the wider Caucasus - Asia Minor - Balkans cultural complex. However, plant use in Georgia was much more diverse than reported in other studies from Eurasia.

ABSTRACT The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z ∼ 0.52), 102,100 new quasar spectra (median z ∼ 2.32), and 90,897 new stellar spectra, along with the data presented in previous data releases. These spectra were obtained with the new BOSS spectrograph and were taken between 2009 December and 2011 July. In addition, the stellar parameters pipeline, which determines radial velocities, surface temperatures, surface gravities, and metallicities of stars, has been updated and refined with improvements in temperature estimates for stars with T eff &lt; 5000 K and in metallicity estimates for stars with [Fe/H] &gt; -0.5. DR9 includes new stellar parameters for all stars presented in DR8, including stars from SDSS-I and II, as well as those observed as part of the SEGUE-2. The astrometry error introduced in the DR8 imaging catalogs has been corrected in the DR9 data products. The next data release for SDSS-III will be in Summer 2013, which will present the first data from the APOGEE along with another year of data from BOSS, followed by the final SDSS-III data release in 2014 December.

Research was conducted in July 2013 as part of anethnobotany research-training course in Georgia(საქართველო). After obtaining prior informed consent forinterviews and photographs, semi-structured interviewswere conducted with participants in local villages.Images were taken of the physical environment (soils, waterfeatures, and other geographical context elements), biologicalenvironment (parts of plants used, whole plants,animals, ecosystems, landscapes), and cultural environment(artifacts, villages, crop fields, and other anthropogeniclandscapes, individuals and groups interacting witheach other or the researchers, and people conducting dailytasks of life). Most of the photographs were taken opportunisticallyand only Figures 79-81 were &ldquo;staged.&rdquo;

In mountainous regions, climate warming is expected to shift species' ranges to higher altitudes. Evidence for such shifts is still mostly from revisitations of historical sites. We present recent (2001 to 2008) changes in vascular plant species richness observed in a standardized monitoring network across Europe's major mountain ranges. Species have moved upslope on average. However, these shifts had opposite effects on the summit floras' species richness in boreal-temperate mountain regions (+3.9 species on average) and Mediterranean mountain regions (-1.4 species), probably because recent climatic trends have decreased the availability of water in the European south. Because Mediterranean mountains are particularly rich in endemic species, a continuation of these trends might shrink the European mountain flora, despite an average increase in summit species richness across the region.

Abstract We present cosmological results from the measurement of baryon acoustic oscillations (BAO) in galaxy, quasar and Lyman- α forest tracers from the first year of observations from the Dark Energy Spectroscopic Instrument (DESI), to be released in the DESI Data Release 1. DESI BAO provide robust measurements of the transverse comoving distance and Hubble rate, or their combination, relative to the sound horizon, in seven redshift bins from over 6 million extragalactic objects in the redshift range 0.1 &lt; z &lt; 4.2. To mitigate confirmation bias, a blind analysis was implemented to measure the BAO scales. DESI BAO data alone are consistent with the standard flat ΛCDM cosmological model with a matter density Ω m =0.295±0.015. Paired with a baryon density prior from Big Bang Nucleosynthesis and the robustly measured acoustic angular scale from the cosmic microwave background (CMB), DESI requires H 0 =(68.52±0.62) km s -1 Mpc -1 . In conjunction with CMB anisotropies from Planck and CMB lensing data from Planck and ACT, we find Ω m =0.307± 0.005 and H 0 =(67.97±0.38) km s -1 Mpc -1 . Extending the baseline model with a constant dark energy equation of state parameter w , DESI BAO alone require w =-0.99 +0.15 -0.13 . In models with a time-varying dark energy equation of state parametrised by w 0 and w a , combinations of DESI with CMB or with type Ia supernovae (SN Ia) individually prefer w 0 &gt; -1 and w a &lt; 0. This preference is 2.6 σ for the DESI+CMB combination, and persists or grows when SN Ia are added in, giving results discrepant with the ΛCDM model at the 2.5 σ , 3.5 σ or 3.9 σ levels for the addition of the Pantheon+, Union3, or DES-SN5YR supernova datasets respectively. For the flat ΛCDM model with the sum of neutrino mass ∑ m ν free, combining the DESI and CMB data yields an upper limit ∑ m ν &lt; 0.072 (0.113) eV at 95% confidence for a ∑ m ν &gt; 0 (∑ m ν &gt; 0.059) eV prior. These neutrino-mass constraints are substantially relaxed if the background dynamics are allowed to deviate from flat ΛCDM.

We present measurements of galaxy clustering from the Baryon Oscillation Spectroscopic Survey (BOSS), which is part of the Sloan Digital Sky Survey III (SDSS-III). These use the Data Release 9 (DR9) CMASS sample, which contains 264 283 massive galaxies covering 3275 square degrees with an effective redshift z = 0.57 and redshift range 0.43 < z < 0.7. Assuming a concordance CDM cosmological model, this sample covers an effective volume of 2.2 Gpc 3 , and represents the largest sample of the Universe ever surveyed at this density, n 3 10 -4 h -3 Mpc 3 . We measure the angle-averaged galaxy correlation function and power spectrum, including density-field reconstruction of the baryon acoustic oscillation (BAO) feature. The acoustic features are detected at a significance of 5 in both the correlation function and power spectrum. Combining with the SDSS-II luminous red galaxy sample, the detection significance increases to 6.7 . Fitting for the position of the acoustic features measures the distance to z = 0.57 relative to the sound horizon D V /r s = 13.67 0.22 at z = 0.57. Assuming a fiducial sound horizon of 153.19 Mpc, which matches cosmic microwave background constraints, this corresponds to a distance D V (z = 0.57) = 2094 34 Mpc. At 1.7 per cent, this is the most precise distance constraint ever obtained from a galaxy survey. We place this result alongside previous BAO measurements in a cosmological distance ladder and find excellent agreement with the current supernova measurements. We use these distance measurements to constrain various cosmological models, finding continuing support for a flat Universe with a cosmological constant.

We derive constraints on cosmological parameters and tests of dark energy models from the combination of baryon acoustic oscillation (BAO) measurements with cosmic microwave background (CMB) data and a recent reanalysis of Type Ia supernova (SN) data. In particular, we take advantage of high-precision BAO measurements from galaxy clustering and the Lyman-$\ensuremath{\alpha}$ forest (LyaF) in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). Treating the BAO scale as an uncalibrated standard ruler, BAO data alone yield a high confidence detection of dark energy; in combination with the CMB angular acoustic scale they further imply a nearly flat universe. Adding the CMB-calibrated physical scale of the sound horizon, the combination of BAO and SN data into an ``inverse distance ladder'' yields a measurement of ${H}_{0}=67.3\ifmmode\pm\else\textpm\fi{}1.1\text{ }\text{ }\mathrm{km}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$, with 1.7% precision. This measurement assumes standard prerecombination physics but is insensitive to assumptions about dark energy or space curvature, so agreement with CMB-based estimates that assume a flat $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ cosmology is an important corroboration of this minimal cosmological model. For constant dark energy ($\mathrm{\ensuremath{\Lambda}}$), our $\mathrm{BAO}+\mathrm{SN}+\mathrm{CMB}$ combination yields matter density ${\mathrm{\ensuremath{\Omega}}}_{m}=0.301\ifmmode\pm\else\textpm\fi{}0.008$ and curvature ${\mathrm{\ensuremath{\Omega}}}_{k}=\ensuremath{-}0.003\ifmmode\pm\else\textpm\fi{}0.003$. When we allow more general forms of evolving dark energy, the $\mathrm{BAO}+\mathrm{SN}+\mathrm{CMB}$ parameter constraints are always consistent with flat $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ values at $\ensuremath{\approx}1\ensuremath{\sigma}$. While the overall ${\ensuremath{\chi}}^{2}$ of model fits is satisfactory, the LyaF BAO measurements are in moderate ($2--2.5\ensuremath{\sigma}$) tension with model predictions. Models with early dark energy that tracks the dominant energy component at high redshift remain consistent with our expansion history constraints, and they yield a higher ${H}_{0}$ and lower matter clustering amplitude, improving agreement with some low redshift observations. Expansion history alone yields an upper limit on the summed mass of neutrino species, $\ensuremath{\sum}{m}_{\ensuremath{\nu}}&lt;0.56\text{ }\text{ }\mathrm{eV}$ (95% confidence), improving to $\ensuremath{\sum}{m}_{\ensuremath{\nu}}&lt;0.25\text{ }\text{ }\mathrm{eV}$ if we include the lensing signal in the Planck CMB power spectrum. In a flat $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ model that allows extra relativistic species, our data combination yields ${N}_{\mathrm{eff}}=3.43\ifmmode\pm\else\textpm\fi{}0.26$; while the LyaF BAO data prefer higher ${N}_{\mathrm{eff}}$ when excluding galaxy BAO, the galaxy BAO alone favor ${N}_{\mathrm{eff}}\ensuremath{\approx}3$. When structure growth is extrapolated forward from the CMB to low redshift, standard dark energy models constrained by our data predict a level of matter clustering that is high compared to most, but not all, observational estimates.

In this study, we documented traditional plant use in Tusheti, Khevsureti, and Pshavi and hypothesized that (i) plant use knowledge in general would be higher in isolated high elevation communities, and that (ii) use of home gardens would be much more restricted to lower elevation settings. Fieldwork was conducted in Khevsureti, Pshavi, and Tusheti. Interviews using semi-structured questionnaires were conducted with 74 participants. In the present study, we encountered 317 plant species belonging to 203 genera of 80 families being used in the research region. Of these, 197 species were exclusively wild-harvested, 73 were grown in homegardens, and 47 were both grown in gardens and sourced in the wild. The ordinations in plant-space and in use-space were significantly fit by elevation of informant community, and community itself. Age and gender did not significantly fit the distribution of informants across either plant-space or use-space, respectively. Number of use-reports was highest across all communities in the food and medicinal use-categories, and informant consensus. Species with especially high use-diversity (UD) tended to be woody species although. Species with high use-value (UV) were mostly managed/domesticated species from home orchards, gardens, or farms. Plant species, and uses, found in our study, showed clear relations to the wider Eurasian cultural complex. The species number found was, however, far higher than in any published study from either the region or the wiser Mediterranean and Eurasia. The maintenance of home gardens in Georgia serves as socio-ecological memory. While the great variety of plant species used in the Georgian Caucasus might provide a reservoir for food security climate change is starting to affect both natural floristic diversity and gardens both in the Caucasus as well as continent wide.

The north of Peru represents the "Health Axis" of the Central Andes, with the roots of traditional practices going back to the Cupisnique culture (1000 BC). During a decade of research semi-structured interviews of healers, collectors and sellers of medicinal plants were conducted. Bioassays were carried out to evaluate the effectiveness and toxicity of the plants found. The majority (83%) of the 510 species used were native to Peru. 50% of the plants used in the colonial era disappeared from the pharmacopoeia. In the markets, vendors were grouped: common and exotic plants, plants for common diseases, plants only used by healers, and plants with magical purposes. About 974 preparations with up to 29 ingredients treated 164 conditions. Nearly 65% of the medicinal flora are applied in mixtures. Antibacterial activity was confirmed in most plants used for infections. 24% aqueous extract and 76% ethanol extracts showed toxicity. Traditional methods of preparation take this into account when choosing the appropriate solvent for the preparation of a remedy. The growing demand did not increase the significant cultivation of medicinal plants. The majority represent plants collected in nature, causing doubts about the sustainability of trade.The focus of ethnobotanical studies and the participation of local stakeholders have changed a lot in recent decades. From the scientific point of view, the research has gone from simple inventories for example of mainly medicinal plants to detailed quantitative studies, often focused on all useful plants. However, the most important thing is that the research has finally moved away from colonial style research to modern ethnobotany based on the principles of the Nagoya Protocol. This is of great importance for the ethnobiological community. However, these changes have not been the same in all Latin American countries, and there are large regional differences.The objective of this publication is to provide examples of twenty-five years of global research, describing the change of attitude and methodology during that time, highlighting the increasing role of local actors in ethnobotanical research and contributing ideas for the future development of the discipline.With this special issue of Ethnobotany Research and Applications we try to bring 20 years of research in Northern Peru to a wider audience.

Effective identification of species using short DNA fragments (DNA barcoding and DNA metabarcoding) requires reliable sequence reference libraries of known taxa. Both taxonomically comprehensive coverage and content quality are important for sufficient accuracy. For aquatic ecosystems in Europe, reliable barcode reference libraries are particularly important if molecular identification tools are to be implemented in biomonitoring and reports in the context of the EU Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD). We analysed gaps in the two most important reference databases, Barcode of Life Data Systems (BOLD) and NCBI GenBank, with a focus on the taxa most frequently used in WFD and MSFD. Our analyses show that coverage varies strongly among taxonomic groups, and among geographic regions. In general, groups that were actively targeted in barcode projects (e.g. fish, true bugs, caddisflies and vascular plants) are well represented in the barcode libraries, while others have fewer records (e.g. marine molluscs, ascidians, and freshwater diatoms). We also found that species monitored in several countries often are represented by barcodes in reference libraries, while species monitored in a single country frequently lack sequence records. A large proportion of species (up to 50%) in several taxonomic groups are only represented by private data in BOLD. Our results have implications for the future strategy to fill existing gaps in barcode libraries, especially if DNA metabarcoding is to be used in the monitoring of European aquatic biota under the WFD and MSFD. For example, missing species relevant to monitoring in multiple countries should be prioritized for future collaborative programs. We also discuss why a strategy for quality control and quality assurance of barcode reference libraries is needed and recommend future steps to ensure full utilisation of metabarcoding in aquatic biomonitoring.

The growth in international research on public service motivation (PSM) raises a number of important questions about the degree to which the theory and research developed in one country can contribute to our understanding of PSM in other counties. To help address this issue, this study revisits the conceptual and operational definitions of PSM to address weaknesses previously noted in the literature. Although some important steps have been taken to both improve and internationalize the PSM scale, this work has been done incrementally. In contrast, this study takes a more systematic and comprehensive approach by combining the efforts of international PSM scholars to develop and then test a revised measurement instrument for PSM in 12 countries. Although the resulting four dimensional 16-item measure of PSM reported here provides a better theoretical and empirical foundation for the measurement of PSM, our results suggest that the exact meaning and scaling of PSM dimensions are likely to differ across cultures and languages. These results raise serious concerns regarding the ability to develop a single universal scale of PSM, or making direct comparisons of PSM across countries.

The Baryon Oscillation Spectroscopic Survey (BOSS), part of the Sloan Digital Sky Survey (SDSS) III project, has provided the largest survey of galaxy redshifts available to date, in terms of both the number of galaxy redshifts measured by a single survey, and the effective cosmological volume covered. Key to analysing the clustering of these data to provide cosmological measurements is understanding the detailed properties of this sample. Potential issues include variations in the target catalogue caused by changes either in the targeting algorithm or properties of the data used, the pattern of spectroscopic observations, the spatial distribution of targets for which redshifts were not obtained, and variations in the target sky density due to observational systematics. We document here the target selection algorithms used to create the galaxy samples that comprise BOSS. We also present the algorithms used to create large scale structure catalogues for the final Data Release (DR12) samples and the associated random catalogues that quantify the survey mask. The algorithms are an evolution of those used by the BOSS team to construct catalogues from earlier data, and have been designed to accurately quantify the galaxy sample. The code used, designated MKSAMPLE, is released with this paper.

We analyze the anisotropic clustering of massive galaxies from the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9 (DR9) sample, which consists of 264,283 galaxies in the redshift range 0.43 &lt; z &lt; 0.7 spanning 3,275 square degrees. Both peculiar velocities and errors in the assumed redshift-distance relation ("Alcock-Paczynski effect") generate correlations between clustering amplitude and orientation with respect to the line-of-sight. Together with the sharp baryon acoustic oscillation (BAO) standard ruler, our measurements of the broadband shape of the monopole and quadrupole correlation functions simultaneously constrain the comoving angular diameter distance (2190 +/- 61 Mpc) to z=0.57, the Hubble expansion rate at z=0.57 (92.4 +/- 4.5 km/s/Mpc), and the growth rate of structure at that same redshift (d sigma8/d ln a = 0.43 +/- 0.069). Our analysis provides the best current direct determination of both DA and H in galaxy clustering data using this technique. If we further assume a LCDM expansion history, our growth constraint tightens to d sigma8/d ln a = 0.415 +/- 0.034. In combination with the cosmic microwave background, our measurements of DA, H, and growth all separately require dark energy at z &gt; 0.57, and when combined imply Ω_Λ = 0.74 +/- 0.016, independent of the Universe's evolution at z&lt;0.57. In our companion paper (Samushia et al. prep), we explore further cosmological implications of these observations.

Abstract Background The Republic of Georgia is part of the Caucasus biodiversity hotspot, and human agricultural plant use dates back at least 6000 years. Over the last years, lots of ethnobotanical research on the area has been published. In this paper, we analyze the use of food plants in the 80% of Georgia not occupied by Russian forces. We hypothesized that (1) given the long tradition of plant use, and the isolation under Soviet rule, plant use both based on home gardens and wild harvesting would be more pronounced in Georgia than in the wider region, (2) food plant use knowledge would be widely and equally spread in most of Georgia, (3) there would still be incidence of knowledge loss despite wide plant use, especially in climatically favored agricultural regions in Western and Eastern Georgia. Methods From 2013 to 2019, we interviewed over 380 participants in all regions of Georgia not occupied by Russian forces and recorded over 19,800 mentions of food plants. All interviews were carried out in the participants’ homes and gardens by native speakers of Georgian and its dialects (Imeretian, Rachian, Lechkhumian, Tush, Khevsurian, Psavian, Kakhetian), other Kartvelian languages (Megrelian, Svan) and minority languages (Ossetian, Ude, Azeri, Armenian, Greek). Results The regional division was based primarily on historic provinces of Georgia, which often coincides with the current administrative borders. The total number of taxa, mostly identified to species, including their varieties, was 527. Taxonomically, the difference between two food plant groups—garden versus wild—was strongly pronounced even at family level. The richness of plant families was 65 versus 97 families in garden versus wild plants, respectively, and the difference was highly significant. Other diversity indices also unequivocally pointed to considerably more diverse family composition of wild collected versus garden plants as the differences between all the tested diversity indices appeared to be highly significant. The wide use of leaves for herb pies and lactofermented is of particular interest. Some of the ingredients are toxic in larger quantities, and the participants pointed out that careful preparation was needed. The authors explicitly decided to not give any recipes, given that many of the species are widespread, and compound composition—and with it possible toxic effects—might vary across the distribution range, so that a preparation method that sufficiently reduces toxicity in the Caucasus might not necessary be applicable in other areas. Conclusions Relationships among the regions in the case of wild food plants show a different and clearer pattern. Adjacent regions cluster together (Kvemo Zemo Racha, and Zemo Imereti; Samegrelo, Guria, Adjara, Lechkhumi and Kvemo and Zemo Svaneti; Meskheti, Javakheti, Kvemo Kartli; Mtianeti, Kakheti, Khevsureti, Tusheti. Like in the case of the garden food plants, species diversity of wild food plants mentioned varied strongly. Climate severity and traditions of the use of wild food plants might play role in this variation. Overall food plant knowledge is widely spread all-across Georgia, and broadly maintained.

Abstract The Dark Energy Spectroscopic Instrument (DESI) embarked on an ambitious 5 yr survey in 2021 May to explore the nature of dark energy with spectroscopic measurements of 40 million galaxies and quasars. DESI will determine precise redshifts and employ the baryon acoustic oscillation method to measure distances from the nearby universe to beyond redshift z &gt; 3.5, and employ redshift space distortions to measure the growth of structure and probe potential modifications to general relativity. We describe the significant instrumentation we developed to conduct the DESI survey. This includes: a wide-field, 3.°2 diameter prime-focus corrector; a focal plane system with 5020 fiber positioners on the 0.812 m diameter, aspheric focal surface; 10 continuous, high-efficiency fiber cable bundles that connect the focal plane to the spectrographs; and 10 identical spectrographs. Each spectrograph employs a pair of dichroics to split the light into three channels that together record the light from 360–980 nm with a spectral resolution that ranges from 2000–5000. We describe the science requirements, their connection to the technical requirements, the management of the project, and interfaces between subsystems. DESI was installed at the 4 m Mayall Telescope at Kitt Peak National Observatory and has achieved all of its performance goals. Some performance highlights include an rms positioner accuracy of better than 0.″1 and a median signal-to-noise ratio of 7 of the [O ii ] doublet at 8 × 10 −17 erg s −1 cm −2 in 1000 s for galaxies at z = 1.4–1.6. We conclude with additional highlights from the on-sky validation and commissioning, key successes, and lessons learned.

Light-by-light scattering (γγ → γγ) is a quantum-mechanical process that is forbidden in the classical theory of electrodynamics. This reaction is accessible at the Large Hadron Collider thanks to the large electromagnetic field strengths generated by ultra-relativistic colliding lead ions. Using 480 μb−1 of lead–lead collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, here we report evidence for light-by-light scattering. A total of 13 candidate events were observed with an expected background of 2.6 ± 0.7 events. After background subtraction and analysis corrections, the fiducial cross-section of the process Pb + Pb (γγ) → Pb(∗) + Pb(∗)γγ, for photon transverse energy ET > 3 GeV, photon absolute pseudorapidity |η| < 2.4, diphoton invariant mass greater than 6 GeV, diphoton transverse momentum lower than 2 GeV and diphoton acoplanarity below 0.01, is measured to be 70 ± 24 (stat.) ± 17 (syst.) nb, which is in agreement with the standard model predictions. Quantum electrodynamics predicts a rare process in which light is scattered by light. The ATLAS Collaboration reports signs of this elusive effect in the collisions of ultra-relativistic lead ions.

We present baryon acoustic oscillation (BAO) measurements from more than 14 million galaxies and quasars drawn from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2), based on three years of operation. For cosmology inference, these galaxy measurements are combined with DESI Lyman- <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>α</a:mi> </a:math> forest BAO results presented in a companion paper (M. Abdul-Karim , companion paper, .). The DR2 BAO results are consistent with DESI DR1 and the Sloan Digital Sky Survey, and their distance-redshift relationship matches those from recent compilations of supernovae (SNe) over the same redshift range. The results are well described by a flat <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi mathvariant="normal">Λ</c:mi> </c:math> cold dark matter ( <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"> <f:mi mathvariant="normal">Λ</f:mi> <f:mi>CDM</f:mi> </f:math> ) model, but the parameters preferred by BAO are in mild, <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"> <i:mn>2.3</i:mn> <i:mi>σ</i:mi> </i:math> tension with those determined from the cosmic microwave background (CMB), although the DESI results are consistent with the acoustic angular scale <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"> <k:msub> <k:mi>θ</k:mi> <k:mo>*</k:mo> </k:msub> </k:math> that is well measured by Planck. This tension is alleviated by dark energy with a time-evolving equation of state parametrized by <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:msub> <m:mi>w</m:mi> <m:mn>0</m:mn> </m:msub> </m:math> and <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"> <o:msub> <o:mi>w</o:mi> <o:mi>a</o:mi> </o:msub> </o:math> , which provides a better fit to the data, with a favored solution in the quadrant with <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"> <q:msub> <q:mi>w</q:mi> <q:mn>0</q:mn> </q:msub> <q:mo>&gt;</q:mo> <q:mo>−</q:mo> <q:mn>1</q:mn> </q:math> and <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"> <s:msub> <s:mi>w</s:mi> <s:mi>a</s:mi> </s:msub> <s:mo>&lt;</s:mo> <s:mn>0</s:mn> </s:math> . This solution is preferred over <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" display="inline"> <u:mi mathvariant="normal">Λ</u:mi> <u:mi>CDM</u:mi> </u:math> at <x:math xmlns:x="http://www.w3.org/1998/Math/MathML" display="inline"> <x:mn>3.1</x:mn> <x:mi>σ</x:mi> </x:math> for the combination of DESI BAO and CMB data. When also including SNe, the preference for a dynamical dark energy model over <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"> <z:mi mathvariant="normal">Λ</z:mi> <z:mi>CDM</z:mi> </z:math> ranges from <cb:math xmlns:cb="http://www.w3.org/1998/Math/MathML" display="inline"> <cb:mn>2.8</cb:mn> <cb:mo>−</cb:mo> <cb:mn>4.2</cb:mn> <cb:mi>σ</cb:mi> </cb:math> depending on which SNe sample is used. We present evidence from other data combinations which also favor the same behavior at high significance. From the combination of DESI and CMB we derive 95% upper limits on the sum of neutrino masses, finding <eb:math xmlns:eb="http://www.w3.org/1998/Math/MathML" display="inline"> <eb:mo>∑</eb:mo> <eb:msub> <eb:mi>m</eb:mi> <eb:mi>ν</eb:mi> </eb:msub> <eb:mo>&lt;</eb:mo> <eb:mn>0.064</eb:mn> <eb:mtext> </eb:mtext> <eb:mtext> </eb:mtext> <eb:mi>eV</eb:mi> </eb:math> assuming <gb:math xmlns:gb="http://www.w3.org/1998/Math/MathML" display="inline"> <gb:mi mathvariant="normal">Λ</gb:mi> <gb:mi>CDM</gb:mi> </gb:math> and <jb:math xmlns:jb="http://www.w3.org/1998/Math/MathML" display="inline"> <jb:mo>∑</jb:mo> <jb:msub> <jb:mi>m</jb:mi> <jb:mi>ν</jb:mi> </jb:msub> <jb:mo>&lt;</jb:mo> <jb:mn>0.16</jb:mn> <jb:mtext> </jb:mtext> <jb:mtext> </jb:mtext> <jb:mi>eV</jb:mi> </jb:math> in the <lb:math xmlns:lb="http://www.w3.org/1998/Math/MathML" display="inline"> <lb:msub> <lb:mi>w</lb:mi> <lb:mn>0</lb:mn> </lb:msub> <lb:msub> <lb:mi>w</lb:mi> <lb:mi>a</lb:mi> </lb:msub> </lb:math> model. Unless there is an unknown systematic error associated with one or more datasets, it is clear that <nb:math xmlns:nb="http://www.w3.org/1998/Math/MathML" display="inline"> <nb:mi mathvariant="normal">Λ</nb:mi> <nb:mi>CDM</nb:mi> </nb:math> is being challenged by the combination of DESI BAO with other measurements and that dynamical dark energy offers a possible solution.