cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.7910/dvn/jguf4u
title: One Step at a Time: Does Gradualism Build Cooperation in Public Good Provision?

description: Substantial literature in public economics examines coordination in public goods games. We conduct an experiment to explore how varying patterns of thresholds affect the willingness of subjects to contribute to a public good. We exploit experimental variation in threshold patterns (decreasing, constant and increasing) across time to show that for nearly every threshold, it is more profitable to be in an increasing than in a decreasing threshold group type. Each period is identical, except for the possibility of having a different threshold, which is always stated before the players make their contributions. We find that while contributions are similar for the increasing and decreasing threshold group types when thresholds were low, a sizeable gap opens up around the average threshold size. Our findings shed light on the role of past cooperative success and threshold patterns on subsequent willingness to cooperate.
DOI: 10.7910/dvn/kiwwpo
title: Wright Files I-Z Edited; Docketed Case: 22804
DOI: 10.7910/dvn/8c4c3e
title: Madagascar (2008): TRaC Study Evaluating the Use of Insecticide Treated Nets among Pregnant Women and Mothers/Caregivers of Children Younger than Five Years in Endemic Area. Third Round.

description: PSI/Madagascar a conduit la troisieme enquete TRaC qui permet de suivre dans le temps les indicateurs et les comportement des groupes cibles en matiere de prevention de paludisme. L'enquete TRaC permet de determiner les facteurs de changement de comportement sur l'utilisation de moustiquaire impregnee d'insecticide, de mesurer les indicateurs du cadre logique lies a la prevention du paludisme et d'evaluer les efficacites des acitivites de communication de PSI. Cette etude a ete menee en novembre/decembre 2008 sur un echantillon de 1761 femmes de 15 a 49 ans meres ou responsables d'enfant de moins de cinq ans our femmes enceintes. Les participants ont ete selectionnees de maniere aleatoire pour determiner la representativite aussi bien au niveau national qu'au niveau des strates urbain/rural.
DOI: 10.5281/zenodo.15529375
title: Dataset of Synthesis of 4-Furan- and 4-Pyrrol-3-yl-2H-chromenes from Naturally-occurring Compounds by Gold(I)-Catalyed Domino Reactions

description: Dataset for the results shown in the publications "Synthesis of 4-Furan- and 4-Pyrrol-3-yl-2H-chromenes from Naturally-occurring Compounds by Gold(I)-Catalyed Domino Reactions". Citation for and links to publications that cite or use the data: DOI:10.1002/adsc.202300300. (http://doi.org/10.1002/adsc.202300300)
DOI: 10.5281/zenodo.15529376
title: Dataset of Synthesis of 4-Furan- and 4-Pyrrol-3-yl-2H-chromenes from Naturally-occurring Compounds by Gold(I)-Catalyed Domino Reactions

description: Dataset for the results shown in the publications "Synthesis of 4-Furan- and 4-Pyrrol-3-yl-2H-chromenes from Naturally-occurring Compounds by Gold(I)-Catalyed Domino Reactions". Citation for and links to publications that cite or use the data: DOI:10.1002/adsc.202300300. (http://doi.org/10.1002/adsc.202300300)
DOI: 10.5281/zenodo.15575266
title: Women's depression, Self-silencing and endorsement of traditional feminine norms: a 21st century update.
DOI: 10.5281/zenodo.15575267
title: Women's depression, Self-silencing and endorsement of traditional feminine norms: a 21st century update.
DOI: 10.7910/dvn/3oqbba
title: Replication Data for: The finance research network in Brazil: a small world

description: The study of the role of collaboration networks in the production of knowledge is important and has attracted the attention of a substantial number of researchers and policy makers around the world. This paper aims to analyze the structural properties of relationship networks among Finance researchers in Brazil. By applying Social Network Analysis to data from 532 articles produced by 806 researchers between 2003 and 2012, this article's results suggest that: (a) the Brazilian environment has structural features that indicate the existence of Small Worlds; (b) a small fraction (~3%) of researchers has regular production; (c) the higher the centrality of researchers in the network, the greater the number of articles published by them.
DOI: 10.7910/dvn/a4quhh
title: Wright Files I-Z Edited; Docketed Case: 24772
DOI: 10.7910/dvn/pbgcox
title: Replication Data for: Teaching Voters New Tricks: The Effect of Partisan Absentee Vote-By-Mail GOTV Efforts

description: Replication Data for: Teaching Voters New Tricks: The Effect of Partisan Absentee Vote-By-Mail GOTV Efforts
DOI: 10.7910/dvn/jrpbiw
title: Replication Data for: "Migrant Care Workers in the Middle-Class Families: Immigration and Redistribution Preferences"

description: Existing studies have argued that immigrants reduce locals’ support for redistribution by undermining the perceived ethnic homogeneity of the country. In this paper, we suggest an alternative account for the relationship between immigration and redistribution by focusing on the often neglected role of migrants as care service providers. We argue that an increasing supply of migrant domestic care workers diminishes support for redistribution and public services among the middle and upper-middle class by enabling them to opt for private care services. Our argument provides an alternative mechanism that can explain Rueda (2018)’s empirical findings that immigration reduces support for redistribution primarily among the rich. In our replication analysis, we first show that the expected pattern of support for redistribution occurs only in countries with large migrant care markets. Furthermore, by subcategorizing social policies into unemployment benefits and child-care policy and analyzing individuals' preferences towards them, we find evidence that supports our alternative mechanism, alongside that proposed by Rueda(2018).
DOI: 10.7910/dvn/oiykme
title: Evaluation of quality, readability, suitability, and usefulness of online resources available to cancer survivors

description: Supplementary material for: Evaluation of quality, readability, suitability, and usefulness of online resources available to cancer survivors

Authors: 
Lydia Rosa Bourdache, Lydia Ould Brahim, Sydney Wasserman, Marrah Nicolas-Joseph, Francesca Y. E. Frati, Eric Belzile, and Sylvie D. Lambert
DOI: 10.7910/dvn/66dhx4
title: Wright Files I-Z Edited; Docketed Case: 79-1783
DOI: 10.7910/dvn/byqsux
title: Replication Data for: WE HAVE NO TIME TO LOSE: AN INTRODUCTION TO SURVIVAL ANALYSIS

description: Replication dataset for the paper "WE HAVE NO TIME TO LOSE:
AN INTRODUCTION TO SURVIVAL ANALYSIS"
DOI: 10.7910/dvn/jpolzb
title: Replication Data for: Signaling Resolve Through Credit-Claiming

description: What explains when militant groups claim attacks? In this study, I argue that militant groups are more likely to claim attacks early in the organization’s lifespan and after major blows to reputation like loss of a leader due to leadership decapitation. This is because credit-claiming helps militants signal resolve to a wider audience, thereby burnishing the organization’s reputation. Specifically, I argue that claims of militant attacks are costly for organizations because they may be met with government retaliation. However, groups that are younger or have recently suffered the loss of a leader seek to use government retaliation to signal resolve. I find support for this proposition using two sets of empirical analyses. First, I show that claims increase the risk of government retaliation. Then, using a comprehensive dataset of 592 groups, I show that militant groups are more likely to claim attacks in the earliest phases of their lifespans and after their leaders are killed/captured. Although civilian victimization and emerging due to splintering are found to be depressing credit claiming, the findings also suggest that (i) groups that only target security forces, (ii) groups that victimize civilians, (iii) groups that emerged independently without known affiliations with existing groups, and (iv) splinter groups all issue fewer claims as they age. These findings help elucidate a largely overlooked dimension of strategic militant behavior.
DOI: 10.7910/dvn/2fxht
title: Passed Resolves; Resolves 1837, c.75, SC1/series 228, Petition of Samuel Williston

description: &lt;p&gt;Petition subject: Arguing for the right to petition and protesting the existence of slavery in Washington D.C. &lt;/p&gt; &lt;p&gt;Original: &lt;a href="http://nrs.harvard.edu/urn-3:FHCL:10456150"&gt;http://nrs.harvard.edu/urn-3:FHCL:10456150&lt;/a&gt; &lt;/p&gt; &lt;p&gt;Date of creation: (unknown) &lt;/p&gt; &lt;p&gt;Petition location: Easthampton &lt;/p&gt; &lt;p&gt;Legislator, committee, or address that the petition was sent to: Luther Clark Jr., Easthampton &lt;/p&gt; &lt;p&gt;Selected signatures:&lt;ol&gt;&lt;li&gt;Samuel Williston&lt;/li&gt;&lt;li&gt;Isaac Clapp&lt;/li&gt;&lt;li&gt;Alfred E. Lyman&lt;/li&gt;&lt;/ol&gt; &lt;/p&gt; &lt;p&gt;Total signatures: 57 &lt;/p&gt; &lt;p&gt;Legal voter signatures (males not identified as non-legal): 57 &lt;/p&gt; &lt;p&gt;Female only signatures: No &lt;/p&gt; &lt;p&gt;Identifications of signatories: citizens, ["others"] &lt;/p&gt; &lt;p&gt;Prayer format was &lt;a href="http://en.wikipedia.org/wiki/Printing"&gt;printed&lt;/a&gt; vs. &lt;a href="http://en.wikipedia.org/wiki/Manuscript"&gt;manuscript&lt;/a&gt;: Printed &lt;/p&gt; &lt;p&gt;Additional non-petition or unrelated documents available at archive: additional documents available &lt;/p&gt; &lt;p&gt;Location of the petition at the Massachusetts Archives of the Commonwealth: Resolves 1837, c.75, passed April 12, 1837 &lt;/p&gt; &lt;p&gt;Acknowledgements: Supported by the National Endowment for the Humanities (PW-5105612), Massachusetts Archives of the Commonwealth, Radcliffe Institute for Advanced Study at Harvard University, Center for American Political Studies at Harvard University, Institutional Development Initiative at Harvard University, and Harvard University Library.&lt;/p&gt;
DOI: 10.7910/dvn/bxmdt4
title: Wright Files I-Z Edited; Docketed Case: 24825
DOI: 10.7910/dvn/owd7to
title: Wright Casebook Edited; Docketed Case: 20,885
DOI: 10.7910/dvn/etfcfq
title: Wright Files I-Z Edited; Docketed Case: 80-2404
DOI: 10.7910/dvn/bl22lv
title: Matriz de campaña permanente: Corpus cualitativo complementario

description: Corpus cualitativo complementario a la matriz de campaña permanente, compuesto por 72 ejemplos que ilustran las categorías de la matriz.
DOI: 10.7910/dvn/ocmj4r
title: Wright Casebook Edited; Docketed Case: 21,991
DOI: 10.3535/5np-h8s-vj6
title: Animalia

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/p8p-fzb-gn6
title: Cervus Linnaeus, 1758

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/af1-ytg-4w6
title: Pongo pygmaeus (Linnaeus, 1760)

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/2ek-cy1-0zw
title: Rhinoceros Linnaeus, 1758

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/c9q-rr9-sbd
title: Bovidae Gray, 1821

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/lc8-fdk-gy1
title: Elephas Linnaeus, 1758

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/919-nmw-xj7
title: Pongo pygmaeus (Linnaeus, 1760)

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/s46-4xk-fdk
title: Macaca Lacépède, 1799

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/be8-e7x-r84
title: Bovidae Gray, 1821

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/y6a-bc8-x5f
title: Homo sapiens Linnaeus, 1758

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/0ve-3ty-m4y
title: Animalia

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/rcc-etc-h1l
title: Pongo pygmaeus (Linnaeus, 1760)

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/a9a-vh6-grj
title: Animalia

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/ea2-3ev-qbz
title: Muntiacus muntjak (Zimmermann, 1780)

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/vyq-zsq-y2j
title: Foraminifera d'Orbigny, 1826

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/a8l-b8k-6yx
title: Animalia

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/xyk-k1t-229
title: Rodentia Bowdich, 1821

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/4xg-pjw-2qb
title: Animalia

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/6vn-7hg-l56
title: Elephas Linnaeus, 1758

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/fnw-kv9-4rx
title: Bovidae Gray, 1821

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/leg-6al-2mx
title: Pongo pygmaeus (Linnaeus, 1760)

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/b5j-plk-sf4
title: Pongo pygmaeus (Linnaeus, 1760)

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/lb3-ss4-nka
title: Bovidae Gray, 1821

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/5qt-y46-6a1
title: Tapirus Brisson, 1762

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/731-bv5-dze
title: Animalia

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/8np-y2t-fs8
title: Pongo pygmaeus (Linnaeus, 1760)

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/4r8-c8c-ysn
title: Homo sapiens Linnaeus, 1758

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/rls-h9r-fpz
title: Animalia

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/7c5-yyr-7d3
title: Pongo pygmaeus (Linnaeus, 1760)

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/xtm-m01-9gw
title: Bovidae Gray, 1821

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/f05-rx2-5km
title: Bovidae Gray, 1821

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/p60-v47-yz1
title: Cervus Linnaeus, 1758

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/cr4-7sf-87l
title: Bovidae Gray, 1821

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/ewn-anc-qdf
title: Elephas Linnaeus, 1758

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/59s-719-n5g
title: Symphalangus syndactylus (Raffles, 1821)

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/x6s-84k-84r
title: Animalia

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/bcf-0g0-s76
title: Animalia

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/x74-2ca-7q7
title: Animalia

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/hfm-9ak-mx3
title: Cervidae Goldfuss, 1820

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.3535/jtf-228-t0k
title: Bovidae Gray, 1821

description: Digital Specimen for the physical specimen hosted at Naturalis Biodiversity Center.
DOI: 10.25549/inscriptifact-ouc110821918
title: Persepolis Fortification Elamite Tablet 2277.101, Fort 2277.101

description: [Text Description:] Administrative text ❧ [Text or Publication Number Note:] Fort 2277.101 ❧ [Excavation Description:] Found during Oriental Institute's excavations in Spring, 1933, near the northeastern corner of the stone platform of Persepolis, in two small rooms of a bastion in the fortification wall ❧ [Medium:] Clay ❧ [Script Note:] Non-Alphabetic Cuneiform ❧ [Physical Object Description:] Clay tablet with cuneiform text. ❧ [Physical Object Note:] Upper edge, left edge broken.
DOI: 10.25549/inscriptifact-ouc110821867
title: Persepolis Fortification Elamite Tablet 2273.103, Fort 2273.103

description: [Text Description:] Administrative text ❧ [Text or Publication Number Note:] Fort 2273.103 ❧ [Excavation Description:] Found during Oriental Institute's excavations in Spring, 1933, near the northeastern corner of the stone platform of Persepolis, in two small rooms of a bastion in the fortification wall ❧ [Medium:] Clay ❧ [Script Note:] Non-Alphabetic Cuneiform ❧ [Physical Object Description:] Clay tablet with cuneiform text. ❧ [Physical Object Note:] All edges broken, except for small part of bottom edge.
DOI: 10.25549/inscriptifact-ouc110821884
title: Persepolis Fortification Elamite Tablet 2273.103, Fort 2273.103

description: [Text Description:] Administrative text ❧ [Text or Publication Number Note:] Fort 2273.103 ❧ [Excavation Description:] Found during Oriental Institute's excavations in Spring, 1933, near the northeastern corner of the stone platform of Persepolis, in two small rooms of a bastion in the fortification wall ❧ [Medium:] Clay ❧ [Script Note:] Non-Alphabetic Cuneiform ❧ [Physical Object Description:] Clay tablet with cuneiform text. ❧ [Physical Object Note:] All edges broken, except for small part of bottom edge.
DOI: 10.25549/inscriptifact-ouc110821772
title: Persepolis Fortification Elamite Tablet 2273.103, Fort 2273.103

description: [Text Description:] Administrative text ❧ [Text or Publication Number Note:] Fort 2273.103 ❧ [Excavation Description:] Found during Oriental Institute's excavations in Spring, 1933, near the northeastern corner of the stone platform of Persepolis, in two small rooms of a bastion in the fortification wall ❧ [Medium:] Clay ❧ [Script Note:] Non-Alphabetic Cuneiform ❧ [Physical Object Description:] Clay tablet with cuneiform text. ❧ [Physical Object Note:] All edges broken, except for small part of bottom edge.
DOI: 10.25549/inscriptifact-ouc110821803
title: Persepolis Fortification Elamite Tablet 2273.103, Fort 2273.103

description: [Text Description:] Administrative text ❧ [Text or Publication Number Note:] Fort 2273.103 ❧ [Excavation Description:] Found during Oriental Institute's excavations in Spring, 1933, near the northeastern corner of the stone platform of Persepolis, in two small rooms of a bastion in the fortification wall ❧ [Medium:] Clay ❧ [Script Note:] Non-Alphabetic Cuneiform ❧ [Physical Object Description:] Clay tablet with cuneiform text. ❧ [Physical Object Note:] All edges broken, except for small part of bottom edge.
DOI: 10.3886/e229701v2
title: USDA HPAI Detections in Mammals

description: There are many species that are potentially susceptible to highly pathogenic avian influenza (HPAI). In addition to birds and poultry, H5N1 viruses have been detected in some mammals. Infection may cause illness, including severe disease and death in some cases. This dataset includes detections of HPAI in Wild and Captive Wild Mammals in the United States from May 2022 to May 2025.<br>
DOI: 10.25549/inscriptifact-ouc110821265
title: Persepolis Fortification Elamite Tablet 2273.103, Fort 2273.103

description: [Text Description:] Administrative text ❧ [Text or Publication Number Note:] Fort 2273.103 ❧ [Excavation Description:] Found during Oriental Institute's excavations in Spring, 1933, near the northeastern corner of the stone platform of Persepolis, in two small rooms of a bastion in the fortification wall ❧ [Medium:] Clay ❧ [Script Note:] Non-Alphabetic Cuneiform ❧ [Physical Object Description:] Clay tablet with cuneiform text. ❧ [Physical Object Note:] All edges broken, except for small part of bottom edge.
DOI: 10.25549/inscriptifact-ouc110821154
title: Persepolis Fortification Elamite Tablet 2272.102, Fort 2272.102

description: [Text Description:] Administrative text ❧ [Text or Publication Number Note:] Fort 2272.102 ❧ [Excavation Description:] Found during Oriental Institute's excavations in Spring, 1933, near the northeastern corner of the stone platform of Persepolis, in two small rooms of a bastion in the fortification wall ❧ [Medium:] Clay ❧ [Script Note:] Non-Alphabetic Cuneiform ❧ [Physical Object Description:] Clay tablet with cuneiform text. ❧ [Physical Object Note:] Borken right edge, upper edge, most of left edge.
DOI: 10.15468/py53mf
title: Autumn-winter Seasonal Mammal Monitoring Survey in Aguada Pichana Este,Añelo, Neuquén, Argentina – 2024 – TotalEnergies E&P Austral B.V.

description: This dataset collects information from a seasonal campaign run by personal from the environmental consultant, Geólogos Asociados S.A, in the context of the implementation of a Biodiversity Action Plan (BAP) from the oil and gas company Total Energies. A BAP is a document the company prepares for each site they have activities on. This document includes actions regarding conservation, restoration and protection of biodiversity on-site. In this case, the monitoring campaign was aimed to check the biodiversity status of the mammal ensemble on the surroundings of the Aguada Pichana Este deposit.
DOI: 10.15468/dl.wm2d7q
title: Occurrence Download

description: A dataset containing 742 species occurrences available in GBIF matching the query:
{
 "and" : [
 "Country is one of (India, China, Myanmar, Viet Nam, Cambodia, Indonesia, Nepal, Philippines, Malaysia, Chinese Taipei, Bangladesh, Lao People’s Democratic Republic, Thailand, Bhutan)",
 "Geometry POLYGON((82.49485 18.89340,135.50515 18.89340,135.50515 40.10660,82.49485 40.10660,82.49485 18.89340))",
 "HasCoordinate is true",
 "HasGeospatialIssue is false",
 "OccurrenceStatus is Present",
 "TaxonKey is Vaccinium duclouxii (H.Lév.) Hand.-Mazz."
 ]
}

 The dataset includes 742 records from 20 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0009163-250515123054153/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.5281/zenodo.18289938
title: Dataset for T. Latychevskaia, P. Formanek, C. T. Koch, and A. Lubk, "Off-axis and inline electron holography: Experimental comparison",  Ultramicroscopy 110(5), pp. 472–482, 2010, http://dx.doi.org/10.1016/j.ultramic.2009.12.007

description: Dataset for T. Latychevskaia, P. Formanek, C. T. Koch, and A. Lubk, "Off-axis and inline electron holography: Experimental comparison",  Ultramicroscopy 110(5), pp. 472–482, 2010, http://dx.doi.org/10.1016/j.ultramic.2009.12.007

experimental transmission electron microscopy off-axis and in-line (inline) holograms