cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.15468/dl.tqpcr9
title: Occurrence Download

description: A dataset containing 2 species occurrences available in GBIF matching the query:
{
 "and" : [
 "HasGeospatialIssue is false",
 "HasCoordinate is true",
 "OccurrenceStatus is Present",
 {
 "not" : {
 "BasisOfRecord" : [
 "is one of (Fossil, Living Specimen)"
 ]
 }
 },
 "TaxonKey is one of (Crawfurdia poilanei Hul)"
 ]
}

 The dataset includes 2 records from 2 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0032141-241107131044228/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.3s2uqx
title: Occurrence Download

description: A dataset containing 3 species occurrences available in GBIF matching the query:
{
 "and" : [
 "HasGeospatialIssue is false",
 "HasCoordinate is true",
 "OccurrenceStatus is Present",
 {
 "not" : {
 "BasisOfRecord" : [
 "is one of (Fossil, Living Specimen)"
 ]
 }
 },
 "TaxonKey is one of (Oreocharis cotinifolia (W.T.Wang) Mich.Möller & A.Weber)"
 ]
}

 The dataset includes 3 records from 1 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0032142-241107131044228/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.ytqd9a
title: Occurrence Download

description: A dataset containing 80 species occurrences available in GBIF matching the query:
{
 "and" : [
 "HasGeospatialIssue is false",
 "HasCoordinate is true",
 "OccurrenceStatus is Present",
 {
 "not" : {
 "BasisOfRecord" : [
 "is one of (Fossil, Living Specimen)"
 ]
 }
 },
 "TaxonKey is one of (Crawfurdia pricei (C.Marquand) Harry Sm.)"
 ]
}

 The dataset includes 80 records from 7 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0032145-241107131044228/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.wquz3n
title: Occurrence Download

description: A dataset containing 5 species occurrences available in GBIF matching the query:
{
 "and" : [
 "Continent is Oceania",
 "Country is Australia",
 "DatasetKey is NHMO DNA Bank Fish and Herptile collection",
 "Year 1891-1895"
 ]
}

 The dataset includes 5 records from 1 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0032147-241107131044228/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.838gqd
title: Occurrence Download

description: A dataset containing 46 species occurrences available in GBIF matching the query:
{
 "and" : [
 "HasGeospatialIssue is false",
 "HasCoordinate is true",
 "OccurrenceStatus is Present",
 {
 "not" : {
 "BasisOfRecord" : [
 "is one of (Fossil, Living Specimen)"
 ]
 }
 },
 "TaxonKey is one of (Oreocharis craibii Mich.Möller & A.Weber)"
 ]
}

 The dataset includes 46 records from 8 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0032146-241107131044228/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.25574/17422
title: Chandra X-ray Observatory ObsId 17422

description: DEEP STUDY OF THE 20PC-LONG PRECESSING JET IN IGR J11014-6103
DOI: 10.25574/18852
title: Chandra X-ray Observatory ObsId 18852

description: Characterizing past outbursts from Sagittarius A*
DOI: 10.25574/19165
title: Chandra X-ray Observatory ObsId 19165

description: Measuring the proper motion of the radio-quiet gamma-ray pulsar J0633+0632
DOI: 10.25574/20118
title: Chandra X-ray Observatory ObsId 20118

description: Characterizing past outbursts from Sagittarius A*
DOI: 10.25574/20298
title: Chandra X-ray Observatory ObsId 20298

description: PSR J2030+4415: A Breakthrough Target for Bowshock Studies
DOI: 10.25574/20807
title: Chandra X-ray Observatory ObsId 20807

description: Characterizing past outbursts from Sagittarius A*
DOI: 10.25574/20808
title: Chandra X-ray Observatory ObsId 20808

description: Characterizing past outbursts from Sagittarius A*
DOI: 10.25574/20876
title: Chandra X-ray Observatory ObsId 20876

description: Measuring the proper motion of the radio-quiet gamma-ray pulsar J0633+0632
DOI: 10.25574/22171
title: Chandra X-ray Observatory ObsId 22171

description: PSR J2030+4415: A Breakthrough Target for Bowshock Studies
DOI: 10.25574/22172
title: Chandra X-ray Observatory ObsId 22172

description: PSR J2030+4415: A Breakthrough Target for Bowshock Studies
DOI: 10.5281/zenodo.18097126
title: Deconstructing ecosystem disturbance: Driving mechanisms across frequency, intensity, and cumulative dimensions

description: Addressing the challenge that ecosystem vulnerability assessments often rely on static assessments and fail to distinguish between pulse and press disturbances, a multi-dimensional disturbance analysis framework based on Frequency-Intensity-Cumulative (FIC) effects was developed. By integrating XGBoost ensemble learning with SHAP interpretability models, we decouple the non-linear drivers of ecosystem disturbances in the Hohhot-Baotou-Ordos-Yulin (HBOY) urban agglomeration. Results indicate that human activities manifest as persistent spatial expansion and high-frequency chronic stress, contrasting with the pulse-like fluctuations of climatic factors and the cumulative recovery driven by ecological factors. Key quantitative thresholds define the boundaries of ecosystem stability: NDVI below 0.1 marks a critical survival baseline where vulnerability sharply increases, while cumulative grassland cover above 96.0% indicates enhanced structural stability. Crucially, when the frequency of nighttime light exceeds 6.1, the system reaches a fatigue limit, compressing recovery windows and exacerbating the risk of persistent degradation. Climate regulation exhibits a bistable pattern, where synergistic buffering effects emerge when cumulative temperature exceeds 3.4°C and precipitation intensity surpasses 34.4 mm. Furthermore, zonal attribution distinguishes differentiated control logics: vulnerable zones, driven by the coupling of high-frequency anthropogenic disturbance and intense climatic stress, require frequency controls and hard constraints. Conversely, improving zones, dominated by cumulative vegetation recovery, necessitate protective management. Overall, the FIC framework bridges statistical patterns with ecological mechanisms and planning rules, providing threshold-based scientific evidence for sustainable human-land governance.
DOI: 10.25574/22173
title: Chandra X-ray Observatory ObsId 22173

description: PSR J2030+4415: A Breakthrough Target for Bowshock Studies
DOI: 10.5281/zenodo.18097125
title: Deconstructing ecosystem disturbance: Driving mechanisms across frequency, intensity, and cumulative dimensions

description: Addressing the challenge that ecosystem vulnerability assessments often rely on static assessments and fail to distinguish between pulse and press disturbances, a multi-dimensional disturbance analysis framework based on Frequency-Intensity-Cumulative (FIC) effects was developed. By integrating XGBoost ensemble learning with SHAP interpretability models, we decouple the non-linear drivers of ecosystem disturbances in the Hohhot-Baotou-Ordos-Yulin (HBOY) urban agglomeration. Results indicate that human activities manifest as persistent spatial expansion and high-frequency chronic stress, contrasting with the pulse-like fluctuations of climatic factors and the cumulative recovery driven by ecological factors. Key quantitative thresholds define the boundaries of ecosystem stability: NDVI below 0.1 marks a critical survival baseline where vulnerability sharply increases, while cumulative grassland cover above 96.0% indicates enhanced structural stability. Crucially, when the frequency of nighttime light exceeds 6.1, the system reaches a fatigue limit, compressing recovery windows and exacerbating the risk of persistent degradation. Climate regulation exhibits a bistable pattern, where synergistic buffering effects emerge when cumulative temperature exceeds 3.4°C and precipitation intensity surpasses 34.4 mm. Furthermore, zonal attribution distinguishes differentiated control logics: vulnerable zones, driven by the coupling of high-frequency anthropogenic disturbance and intense climatic stress, require frequency controls and hard constraints. Conversely, improving zones, dominated by cumulative vegetation recovery, necessitate protective management. Overall, the FIC framework bridges statistical patterns with ecological mechanisms and planning rules, providing threshold-based scientific evidence for sustainable human-land governance.
DOI: 10.25574/23536
title: Chandra X-ray Observatory ObsId 23536

description: A Remarkable Pulsar-powered Filament
DOI: 10.25574/23537
title: Chandra X-ray Observatory ObsId 23537

description: The Moving Filament of the Guitar Nebula
DOI: 10.60593/ur.d.30166660
title: Original data to accompany Evans et al: "<b>QuickDraw: Detecting HIV in Whole Blood using an Integrated Paper-based Consumable that Enables Direct Amplification of Purified RNA from Paper</b>", 2025

description: This folder contains all original data to accompany the manuscript "<b>QuickDraw: Detecting HIV in WHole Blood using an Integrated Paper-based Consumable that Enables Direct Amplification of Purified RNA from Paper</b>" Evans, A. L.; Sogn, A. K.; Mora, A. C.; Arthur, M. N.; Leach, J.; Bosch, S.; Araselvan, S.; Beard, J. W.; Dewhurst, S.; Mace, C. R.; Miller, B. L.Abstract:A definitive diagnosis of HIV typically requires a positive nucleic acid test. Limited access to these tests means that initiation of anti-HIV therapy is delayed or does not occur in a significant part of the world. While rapid antigen tests are more broadly available, these are insufficient for diagnosis on their own. To address the challenge of improving access to HIV testing, we have developed a passive, paper-based microfluidic sample preparation device we term the QuickDraw. We demonstrate that QuickDraw efficiently processes HIV-containing finger stick-quantities of whole blood to yield purified viral RNA. The output of the QuickDraw is then used as input for a colorimetric reverse transcriptase - loop-mediated isothermal amplification (RT-LAMP) assay. Coupled with sample preparation conducted with the QuickDraw, the assay demonstrated a limit of detection of 1,000 copies/mL, with a PPV of 93% and an NPV of 87%. QuickDraw simplifies viral nucleic acid sample preparation and detection by dramatically reducing the amount of equipment needed, suggesting it could be suitable for deployment in clinical and low-resource settings. By decentralizing nucleic acid testing, the QuickDraw platform has the potential to expand access to nucleic acid diagnostics in low-middle income countries (LMICs), while also supporting the UNAIDS goals for HIV detection, leading to wider access to treatment and reduced community transmission. It is also a significant step towards the goal of a simple-to-use nucleic acid-based HIV self test.
DOI: 10.60593/ur.d.30166660.v2
title: Original data to accompany Evans et al: "<b>QuickDraw: Detecting HIV in Whole Blood using an Integrated Paper-based Consumable that Enables Direct Amplification of Purified RNA from Paper</b>", 2025

description: This folder contains all original data to accompany the manuscript "<b>QuickDraw: Detecting HIV in WHole Blood using an Integrated Paper-based Consumable that Enables Direct Amplification of Purified RNA from Paper</b>" Evans, A. L.; Sogn, A. K.; Mora, A. C.; Arthur, M. N.; Leach, J.; Bosch, S.; Araselvan, S.; Beard, J. W.; Dewhurst, S.; Mace, C. R.; Miller, B. L.Abstract:A definitive diagnosis of HIV typically requires a positive nucleic acid test. Limited access to these tests means that initiation of anti-HIV therapy is delayed or does not occur in a significant part of the world. While rapid antigen tests are more broadly available, these are insufficient for diagnosis on their own. To address the challenge of improving access to HIV testing, we have developed a passive, paper-based microfluidic sample preparation device we term the QuickDraw. We demonstrate that QuickDraw efficiently processes HIV-containing finger stick-quantities of whole blood to yield purified viral RNA. The output of the QuickDraw is then used as input for a colorimetric reverse transcriptase - loop-mediated isothermal amplification (RT-LAMP) assay. Coupled with sample preparation conducted with the QuickDraw, the assay demonstrated a limit of detection of 1,000 copies/mL, with a PPV of 93% and an NPV of 87%. QuickDraw simplifies viral nucleic acid sample preparation and detection by dramatically reducing the amount of equipment needed, suggesting it could be suitable for deployment in clinical and low-resource settings. By decentralizing nucleic acid testing, the QuickDraw platform has the potential to expand access to nucleic acid diagnostics in low-middle income countries (LMICs), while also supporting the UNAIDS goals for HIV detection, leading to wider access to treatment and reduced community transmission. It is also a significant step towards the goal of a simple-to-use nucleic acid-based HIV self test.
DOI: 10.60593/ur.d.30166660.v1
title: Original data to accompany Evans et al: "QuickDraw: A Rapid, Point of Care Blood Based HIV Diagnostic Assay with Plasma Separation, Viral Lysis, RNA Capture, and RNA Amplification on Paper", 2025

description: This folder contains all original data to accompany the manuscript "<b>QuickDraw: A Rapid, Point of Care Blood Based HIV Diagnostic Assay with Plasma Separation, Viral Lysis, RNA Capture, and RNA Amplification on Paper</b>" Evans, A. L.; Sogn, A. K.; Mora, A. C.; Arthur, M. N.; Leach, J.; Bosch, S.; Araselvan, S.; Beard, J. W.; Dewhurst, S.; Mace, C. R.; Miller, B. L.
DOI: 10.25574/23641
title: Chandra X-ray Observatory ObsId 23641

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24236
title: Chandra X-ray Observatory ObsId 24236

description: A Remarkable Pulsar-powered Filament
DOI: 10.25574/24358
title: Chandra X-ray Observatory ObsId 24358

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24359
title: Chandra X-ray Observatory ObsId 24359

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24360
title: Chandra X-ray Observatory ObsId 24360

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24361
title: Chandra X-ray Observatory ObsId 24361

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24362
title: Chandra X-ray Observatory ObsId 24362

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24363
title: Chandra X-ray Observatory ObsId 24363

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24364
title: Chandra X-ray Observatory ObsId 24364

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24365
title: Chandra X-ray Observatory ObsId 24365

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24366
title: Chandra X-ray Observatory ObsId 24366

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24367
title: Chandra X-ray Observatory ObsId 24367

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24368
title: Chandra X-ray Observatory ObsId 24368

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24369
title: Chandra X-ray Observatory ObsId 24369

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24370
title: Chandra X-ray Observatory ObsId 24370

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24371
title: Chandra X-ray Observatory ObsId 24371

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24372
title: Chandra X-ray Observatory ObsId 24372

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24373
title: Chandra X-ray Observatory ObsId 24373

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24374
title: Chandra X-ray Observatory ObsId 24374

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24375
title: Chandra X-ray Observatory ObsId 24375

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/24426
title: Chandra X-ray Observatory ObsId 24426

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24427
title: Chandra X-ray Observatory ObsId 24427

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24428
title: Chandra X-ray Observatory ObsId 24428

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24429
title: Chandra X-ray Observatory ObsId 24429

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24430
title: Chandra X-ray Observatory ObsId 24430

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24431
title: Chandra X-ray Observatory ObsId 24431

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24432
title: Chandra X-ray Observatory ObsId 24432

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24433
title: Chandra X-ray Observatory ObsId 24433

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24434
title: Chandra X-ray Observatory ObsId 24434

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24435
title: Chandra X-ray Observatory ObsId 24435

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24436
title: Chandra X-ray Observatory ObsId 24436

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24437
title: Chandra X-ray Observatory ObsId 24437

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/24954
title: Chandra X-ray Observatory ObsId 24954

description: A Remarkable Pulsar-powered Filament
DOI: 10.25574/24992
title: Chandra X-ray Observatory ObsId 24992

description: The Moving Filament of the Guitar Nebula
DOI: 10.25574/26294
title: Chandra X-ray Observatory ObsId 26294

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/26295
title: Chandra X-ray Observatory ObsId 26295

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/26302
title: Chandra X-ray Observatory ObsId 26302

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/26336
title: Chandra X-ray Observatory ObsId 26336

description: The Moving Filament of the Guitar Nebula
DOI: 10.5281/zenodo.18097696
title: Replication material for paper "Bernauer, Bakaki (2017): Citizens show strong support for climate policy, but are they also willing to pay? Climatic Change. DOI: 10.1007/s10584-017-2078-x"

description: Replication material for paper "Bernauer, Bakaki (2017): Citizens show strong support for climate policy, but are they also willing to pay? Climatic Change. DOI: 10.1007/s10584-017-2078-x"
DOI: 10.5281/zenodo.18097697
title: Replication material for paper "Bernauer, Bakaki (2017): Citizens show strong support for climate policy, but are they also willing to pay? Climatic Change. DOI: 10.1007/s10584-017-2078-x"

description: Replication material for paper "Bernauer, Bakaki (2017): Citizens show strong support for climate policy, but are they also willing to pay? Climatic Change. DOI: 10.1007/s10584-017-2078-x"
DOI: 10.25574/26353
title: Chandra X-ray Observatory ObsId 26353

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/26438
title: Chandra X-ray Observatory ObsId 26438

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/26448
title: Chandra X-ray Observatory ObsId 26448

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/27256
title: Chandra X-ray Observatory ObsId 27256

description: X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/27463
title: Chandra X-ray Observatory ObsId 27463

description: Unique X-ray Window into Internal Structure of the Cold Gas in Dense Molecular Clouds
DOI: 10.25574/28519
title: Chandra X-ray Observatory ObsId 28519

description: The Lighthouse PWN as a probe of ISM structure and a unique relativistic plasma physics laboratory
DOI: 10.25574/28520
title: Chandra X-ray Observatory ObsId 28520

description: The Lighthouse PWN as a probe of ISM structure and a unique relativistic plasma physics laboratory
DOI: 10.15468/dl.hyhzvy
title: Occurrence Download

description: A dataset containing 7066 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Crotalus molossus"
 ]
}

 The dataset includes 7066 records from 110 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0069321-251120083545085/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.25574/29835
title: Chandra X-ray Observatory ObsId 29835

description: Proper Motions for Gamma-Ray Pulsars
DOI: 10.25574/29836
title: Chandra X-ray Observatory ObsId 29836

description: Proper Motions for Gamma-Ray Pulsars
DOI: 10.25574/29838
title: Chandra X-ray Observatory ObsId 29838

description: Proper Motions for Gamma-Ray Pulsars
DOI: 10.15472/ohlqdy
title: Fauna presente en los monitoreos de las fincas de Agropecuaria Aliar S.A.

description: Este recurso contiene los registros de animales que han sido observados esporádicamente en los predios de Agropecuaria Aliar S.A. en tres municipios del departamento del Meta. Contiene 1.406 registros de fauna encontrados a lo largo de los recorridos de monitoreo en las fincas, realizados desde 2021 a 2025.
DOI: 10.25574/29840
title: Chandra X-ray Observatory ObsId 29840

description: Proper Motions for Gamma-Ray Pulsars
DOI: 10.15468/dl.n255ym
title: Occurrence Download

description: A dataset containing 41 species occurrences available in GBIF matching the query:
{
 "and" : [
 {
 "or" : [
 "PublishingCountry is one of (Argentina, Falkland Islands (Malvinas), South Georgia and the South Sandwich Islands)",
 {
 "and" : [
 "Country is one of (Argentina, Falkland Islands (Malvinas), South Georgia and the South Sandwich Islands)",
 "HasGeospatialIssue is false"
 ]
 },
 "Geometry POLYGON((-74 -60, -25 -60, -25 -90, -74 -90, -74 -60))"
 ]
 },
 {
 "and" : [
 "TaxonKey is one of (Polystictus pectoralis [GBIF Backbone Taxonomy])",
 "Geometry POLYGON((-63.1466958694606 -38.453052731949526,-63.1466958694606 -38.82000646707999,-61.8773496535851 -38.82000646707999,-61.8773496535851 -38.453052731949526,-63.1466958694606 -38.453052731949526))"
 ]
 }
 ]
}

 The dataset includes 41 records from 2 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0069320-251120083545085/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.25574/29842
title: Chandra X-ray Observatory ObsId 29842

description: Proper Motions for Gamma-Ray Pulsars
DOI: 10.25574/29843
title: Chandra X-ray Observatory ObsId 29843

description: Proper Motions for Gamma-Ray Pulsars