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1.
PLoS Genet ; 18(6): e1010230, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35709096

RESUMO

Central nervous system-expressed long non-coding RNAs (lncRNAs) are often located in the genome close to protein coding genes involved in transcriptional control. Such lncRNA-protein coding gene pairs are frequently temporally and spatially co-expressed in the nervous system and are predicted to act together to regulate neuronal development and function. Although some of these lncRNAs also bind and modulate the activity of the encoded transcription factors, the regulatory mechanisms controlling co-expression of neighbouring lncRNA-protein coding genes remain unclear. Here, we used high resolution NG Capture-C to map the cis-regulatory interaction landscape of the key neuro-developmental Paupar-Pax6 lncRNA-mRNA locus. The results define chromatin architecture changes associated with high Paupar-Pax6 expression in neurons and identify both promoter selective as well as shared cis-regulatory-promoter interactions involved in regulating Paupar-Pax6 co-expression. We discovered that the TCF7L2 transcription factor, a regulator of chromatin architecture and major effector of the Wnt signalling pathway, binds to a subset of these candidate cis-regulatory elements to coordinate Paupar and Pax6 co-expression. We describe distinct roles for Paupar in Pax6 expression control and show that the Paupar DNA locus contains a TCF7L2 bound transcriptional silencer whilst the Paupar transcript can act as an activator of Pax6. Our work provides important insights into the chromatin interactions, signalling pathways and transcription factors controlling co-expression of adjacent lncRNAs and protein coding genes in the brain.


Assuntos
RNA Longo não Codificante , Cromatina/genética , Neurônios/metabolismo , Fator de Transcrição PAX6/genética , Fator de Transcrição PAX6/metabolismo , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Fatores de Transcrição/genética
2.
Environ Res ; 258: 119454, 2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38906450

RESUMO

Urbanization of estuaries drastically changed existing shorelines and bathymetric contours, in turn modifying habitat for marine foundational species that host critical biodiversity. And yet we lack approaches to characterize a significant fraction of the biota that inhabit these ecosystems on time scales that align with rates of urbanization. Environmental DNA (or eDNA) metabarcoding that combines multiple assays targeting a broad range of taxonomic groups can provide a solution, but we need to determine whether the biological communities it detects ally with different habitats in these changing aquatic environments. In this study, we tested whether tree of life metabarcoding (ToL-metabarcoding) data extracted from filtered seawater samples correlated with four known geomorphic habitat zones across a heavily urbanized estuary (Sydney Harbour, Australia). Using this method, we substantially expanded our knowledge on the composition and spatial distribution of marine biodiversity across the tree of life in Sydney Harbour, particularly for organisms where existing records are sparse. Excluding terrestrial DNA inputs, we identified significant effects of both distance from the mouth of Sydney Harbour and geomorphic zone on biological community structure in the ToL-metabarcoding dataset (entire community), as well as in each of the taxonomic subgroups that we considered (fish, macroinvertebrates, algae and aquatic plants, bacteria). This effect appeared to be driven by taxa as a collective versus a few individual taxa, with each taxon explaining no more than 0.62% of the variation between geomorphic zones. Similarly, taxonomic richness was significantly higher within geomorphic zones with large sample sizes, but also decreased by 1% with each additional kilometer from the estuary mouth, a result consistent with a reduction in tidal inputs and available habitat in upper catchments. Based on these results, we suggest that ToL-metabarcoding can be used to benchmark biological monitoring in other urbanized estuaries globally, and in Sydney Harbour at future time points based on detection of bioindicators across the tree of life. We also suggest that robust biotic snapshots can be archived following extensive curation of taxonomic assignments that incorporates ecological affinities, supported by records from relevant and regional biodiversity repositories.

3.
J Biol Chem ; 298(12): 102565, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36208776

RESUMO

α-synuclein (αS) is the key component of synucleinopathies such as Parkinson's disease (PD), dementia with Lewy bodies, and multiple system atrophy. αS was first linked to PD through the identification of point mutations in the SNCA gene, causing single amino acid substitutions within αS and familial autosomal dominant forms of PD that profoundly accelerated disease onset by up to several decades. At least eight single-point mutations linked to familial PD (A30G/P, E46K, H50Q, G51D, and A53T/E/V) are located in proximity of the region preceding the non-ß amyloid component (preNAC) region, strongly implicating its pathogenic role in αS-mediated cytotoxicity. Furthermore, lipids are known to be important for native αS function, where they play a key role in the regulation of synaptic vesicle docking to presynaptic membranes and dopamine transmission. However, the role of lipids in the function of mutant αS is unclear. Here, we studied αS aggregation properties of WT αS and five of the most predominant single-point missense mutants associated with early onset PD in the presence of anionic 1,2-dimyristoyl-sn-glycero-3-phospho-l-serine lipid vesicles. Our results highlight significant differences between aggregation rates, the number of aggregates produced, and overall fibril morphologies of WT αS and the A30P, E46K, H50Q, G51D, and A53T missense mutants in the presence of lipid vesicles. These findings have important implications regarding the interplay between the lipids required for αS function and the individual point mutations known to accelerate PD and related diseases.


Assuntos
Doença de Parkinson , alfa-Sinucleína , Humanos , alfa-Sinucleína/metabolismo , Expressão Gênica , Lipídeos , Doença de Parkinson/metabolismo , Mutação Puntual , Mutação de Sentido Incorreto
4.
J Gambl Stud ; 2023 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-37355524

RESUMO

Gambling-related harm is a public health issue requiring market regulation and efforts aimed at prevention and treatment. An important consideration for the regulation of gambling is whether certain types of gambling are intrinsically more harmful than others. The present study was a comprehensive investigation of this issue in a nationwide sample of 10,199 Canadian adult gamblers that included 1346 individuals with problem gambling. We investigated (a) the univariate cross-sectional association between individual types of gambling and problem gambling; (b) the cross-sectional association between individual gambling types and problem gambling when controlling for breadth of gambling involvement; (c) the prospective/lagged relationship between participation in different gambling types and future problem gambling; and (d) the self-reports of people with gambling problems concerning the types and modalities they consider to be most problematic. Our collective results indicate that breadth of gambling involvement is a stronger predictor of gambling problems than involvement in any particular type, but that involvement in certain types (electronic gambling machines in particular, and casino table games and online gambling to a lesser extent) does confer additional risk.

5.
J Gambl Stud ; 39(2): 843-855, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36565358

RESUMO

Gambling fallacies are a collection of error-stricken beliefs about gambling and how gambling works. Gambling fallacies, while common in the general public, appear to increase as a function of gambling severity. This being the case, many interventions have focused on reducing gambling fallacies as a means of treating problem-gambling. Less research, however, has investigated what factors contributes to gambling fallacy susceptibility in the first place. Available studies have identified associations between gambling fallacy susceptibility and isolated individual differences in, for example, statistical reasoning/understanding, intelligence, or cognitive ability. The current study aimed to assess these cognitive factors in conjunction, and their relative predictive potential for gambling fallacy susceptibility. In an Australian university student sample (n = 90) it was found that there were moderate to strong association between gambling fallacy endorsement and general intelligence, probabilistic reasoning ability, rational cognitive style and the ability to suppress intuitive thought, however, only probabilistic reasoning, rational cognitive style and the ability to suppress intuitive thinking contributed to the prediction of fallacy endorsement. Importantly, each of these factors are malleable. Interventions for the correction of gambling-specific fallacious beliefs should focus on these factors.


Assuntos
Jogo de Azar , Humanos , Jogo de Azar/psicologia , Austrália , Cognição , Pensamento , Individualidade
6.
J Gambl Stud ; 38(1): 67-85, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33733295

RESUMO

The present study provides a profile of Canadian Indigenous gambling and problem gambling using the 2018 Canadian Community Health Survey (CCHS) (n = 23,952 adults; 1,324 Indigenous) and an online panel survey of 10,199 gamblers (n = 589 Indigenous). The relative popularity of different types of gambling was similar between Indigenous and non-Indigenous samples. However, there was higher Indigenous participation in electronic gambling machines (EGMs), bingo, instant lotteries, overall gambling and a higher rate of problem gambling (2.0% versus 0.5%). Variables predictive of Indigenous problem gambling were EGM participation, gambling fallacies, having a mental or substance use disorder, sports betting, and male gender. Compared to non-Indigenous problem gamblers, Indigenous problem gamblers had higher substance use and lower impulsivity. In general, variables predictive of Indigenous problem gambling were the same ones predictive of problem gambling in all populations, with elevated Indigenous problem gambling rates primarily being due to elevated rates of these generic risk factors. Many of these risk factors are modifiable. Particular consideration should be given to reducing the disproportionate concentration of EGMs in geographic areas having the highest concentration of Indigenous people and ameliorating the disadvantageous social conditions in this population that are conducive to mental health and substance use problems.


Assuntos
Comportamento Aditivo , Jogo de Azar , Transtornos Relacionados ao Uso de Substâncias , Adulto , Comportamento Aditivo/epidemiologia , Comportamento Aditivo/psicologia , Canadá/epidemiologia , Jogo de Azar/psicologia , Humanos , Masculino , Inquéritos e Questionários
7.
J Gambl Stud ; 38(2): 371-396, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34545513

RESUMO

The current study investigated the impact of the COVID pandemic lockdown on gambling and problem gambling in Canada. The AGRI National Project's online panel participants (N = 3449) provided baseline gambling data 6 months prior to the pandemic. Re-surveying this sample during the lockdown provided an opportunity to make quantitative comparisons of the changes. Nearly one-third of gamblers reported ceasing gambling altogether during the lockdown. For the continuing gamblers, quantitative data indicated significant decreases in gambling frequency, time spent in gambling sessions, money spent, and the number of game types played. Qualitative perceptions of changes in gambling were examined and the accuracy of these reports were not closely aligned with actual changes in gambling. Gambling platform was the only gambling engagement metric where increases were found with ~ 17% of the gambling sample migrating to online gambling during the lockdown. Although problem gambling within the sample generally declined, consistent with previous literature, it was also found that gambling online-among other biopsychosocial factors-was a significant predictor for classification as a problem gambler during the lockdown. COVID-specific influences on health, employment, leisure time and social isolation were moderately associated with problem gambling scores but were not independent predictors of changes in gambling engagement during lockdown. Future studies are required to assess if the pandemic related changes in gambling evidenced in this study remain stable, or if engagement reverts to pre-pandemic levels when the pandemic response allows for the re-opening of land-based gambling venues.


Assuntos
COVID-19 , Jogo de Azar , COVID-19/prevenção & controle , Canadá , Controle de Doenças Transmissíveis , Jogo de Azar/psicologia , Humanos , Estudos Prospectivos
8.
J Gambl Stud ; 38(3): 905-915, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34420137

RESUMO

This study analyzed the Responsible Gambling Check patron survey data from Canadian casinos and racinos collected from 2011-2019 (18,580 patrons and 75 venues). The results indicated increasing awareness and use over time of harm minimization tools among more frequent patrons. Despite these promising trends, it is concerning that a substantial percentage of gamblers are still unaware of the harm minimization tools available. Further, the actual impact of this awareness on responsible gambling behaviour is largely unknown. We suggest greater efforts are needed nation-wide to promote the awareness, utilization, and evaluation of these harm minimization tools.


Assuntos
Jogo de Azar , Canadá , Jogo de Azar/psicologia , Redução do Dano , Humanos , Inquéritos e Questionários
9.
J Gambl Stud ; 2022 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-36445607

RESUMO

Casino employees regularly interact with problem and at-risk gamblers and thus have considerable potential to both prevent and reduce gambling-related harm. While harm minimization (HM) and responsible gambling (RG) are routinely espoused by the casino industry, the actual level of employee HM/RG training, knowledge, and behaviour is unknown. The present study investigated this issue in the Canadian context by examining employee surveys collected by the RG Check accreditation program (8,262 surveys from 78 Canadian casinos/racinos collected between 2011 and 2020). These surveys revealed that almost all casino employees receive HM/RG training, but the amount of training tends to be quite limited (one hour) except for supervisors, managers, and security personnel. Basic HM/RG knowledge among all employees appears adequate, although their understanding of probability is incomplete. The most important consideration is whether this training and knowledge translates into meaningful HM/RG behaviour towards patrons. The large majority of employees (83.1%) report engaging in at least one HM/RG interaction with a patron at some point during the course of their employment (median length of 4 to 9 years), with security personnel reporting the highest rates. However, the frequency, nature, and impact of these interactions is unknown.

10.
BMC Psychiatry ; 21(1): 15, 2021 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-33413234

RESUMO

BACKGROUND: There is little longitudinal evidence on the cumulative risk of harm from gambling associated with excess spending and frequency of play. The present study sought to assess the risk of gambling problems over a five-year period in adults who exceed previously derived low-risk gambling limits compared to those who remain within the limits after controlling for other modifiable risk factors. METHODS: Participants were adults (N = 4212) drawn from two independent Canadian longitudinal cohort studies who reported gambling in the past year and were free of problem gambling at time 1. Multivariate Cox regression was employed to assess the impact over time of gambling above low-risk gambling thresholds (frequency ≥ 8 times per month; expenditure ≥75CAD per month; percent of household income spent on gambling ≥1.7%) on developing moderate harm and problem gambling. Covariates included presence of a DSM5 addiction or mental health disorder at time 1, irrational gambling beliefs, number of stressful life events in past 12 months, number of game types played each year, and playing electronic gaming machines or casino games. RESULTS: In both samples, exceeding the low-risk gambling limits at time 1 significantly increased the risk of moderate harm (defined as ≥2 consequences on the Problem Gambling Severity Index [PGSI]) within 5 years after controlling for other modifiable risk factors. Other significant predictors of harm were presence of a mental disorder at time 1, cognitive distortions about gambling, stressful life events, and playing electronic gaming machines or casino games. In one sample, the five-year cumulative survival rate for moderate harm among individuals who stayed below all the low-risk limits was 95% compared to 83% among gamblers who exceeded all limits. Each additional low-risk limit exceeded increased the cumulative probability of harm by 30%. Similar results were found in models when the outcome was problem gambling. CONCLUSIONS: Level of gambling involvement represents a highly modifiable risk factor for later harm. Staying below empirically derived safe gambling thresholds reduces the risk of harm over time.


Assuntos
Comportamento Aditivo , Jogo de Azar , Adulto , Canadá , Jogo de Azar/epidemiologia , Humanos , Estudos Longitudinais , Análise de Sobrevida
11.
Can J Psychiatry ; 66(5): 485-494, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33353387

RESUMO

OBJECTIVE: The purpose of this study was to provide an updated profile of gambling and problem gambling in Canada and to examine how the rates and pattern of participation compare to 2002. METHOD: An assessment of gambling and problem gambling was included in the 2018 Canadian Community Health Survey and administered to 24,982 individuals aged 15 and older. The present analyses selected for adults (18+). RESULTS: A total of 66.2% of people reported engaging in some type of gambling in 2018, primarily lottery and/or raffle tickets, the only type in which the majority of Canadians participate. There are some significant interprovincial differences, with perhaps the most important one being the higher rate of electronic gambling machine (EGM) participation in Manitoba and Saskatchewan. The overall pattern of gambling in 2018 is very similar to 2002, although participation is generally much lower in 2018, particularly for EGMs and bingo. Only 0.6% of the population were identified as problem gamblers in 2018, with an additional 2.7% being at-risk gamblers. There is no significant interprovincial variation in problem gambling rates. The interprovincial pattern of problem gambling in 2018 is also very similar to what was found in 2002 with the main difference being a 45% decrease in the overall prevalence of problem gambling. CONCLUSIONS: Gambling and problem gambling have both decreased in Canada from 2002 to 2018 although the provincial patterns are quite similar between the 2 time periods. Several mechanisms have likely collectively contributed to these declines. Decreases have also been reported in several other Western countries in recent years and have occurred despite the expansion of legal gambling opportunities, suggesting a degree of inoculation or adaptation in large parts of the population.


Assuntos
Jogo de Azar , Adulto , Canadá/epidemiologia , Jogo de Azar/epidemiologia , Humanos , Manitoba/epidemiologia , Prevalência , Saskatchewan , Inquéritos e Questionários
12.
Opt Express ; 28(10): 15232-15239, 2020 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-32403554

RESUMO

We report experimental observations of thermal lens effects in a diamond Raman laser operating up to 1.1 kW output power in a quasi- steady-state regime. Measured changes in the output beam parameters as a function of output power, including beam quality factor and beam divergence after a fixed focusing lens, are compared to modelling enabling us to track the development of a thermal lens up to 16 diopters at maximum output power. Analysis shows that good agreement between model and experiment is obtained by considering the power deposition profile and the spatial overlap with the laser mode. The results clarify previous work that raised questions about thermal lens effects in the diamond gain medium and provides increased confidence in thermal models for determining the power limits for the current design.

13.
Opt Lett ; 44(10): 2506-2509, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31090718

RESUMO

An external cavity diamond Raman laser with 1.2 kW output power is demonstrated for durations 7 times longer than the thermal lens time constant. An 83% slope efficiency and a 53% optical-to-optical efficiency were obtained for conversion from a 1.06 µm pump to the 1.24 µm first Stokes. The pump had an M2 of 15, demonstrating that efficiency is maintained at the highest levels even when using exceptionally poor quality pumps. We show that a measured decrease in the output beam quality factor from M2=2.95 to M2=1.25 as power increased is evidence for thermal lens development in the diamond. The results foreshadow development of continuous-wave kilowatt-class lasers or amplifiers based on single diamond elements and pumped efficiently by lasers having poor spatial coherence such as line-narrowed diode laser arrays.

14.
Opt Lett ; 44(4): 839-842, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30768000

RESUMO

Single longitudinal mode (SLM) operation of a 620 nm diamond Raman laser is demonstrated in a standing-wave cavity that includes a second-harmonic generation element. Mode competition provided by the harmonic mixing is shown to greatly increase mode stability, in addition to the benefits of the spatial-hole-burning-free gain medium. Using a multi-longitudinal mode 1064 nm Nd:YAG pump laser of power 321 W and linewidth 3.3 GHz, SLM powers of 38 W at 620 nm and 11.8 W at 1240 nm were obtained. The results indicate that simple standing-wave oscillators pumped by multimode Yb or Nd pumps compose a promising practical route towards the generation of high-power SLM beams in the yellow-red part of the spectrum.

15.
J Gambl Stud ; 35(4): 1397-1406, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31062285

RESUMO

Associations that people report in response to words or phrases ('implicit associations') may provide information about their interest and engagement in certain activities that might not have been reported if they had been directed asked. The present study investigated the word and behavioural associations reported by 494 university undergraduates to words and phrases that could be construed as having gambling-related connotations. These reported associations were then related to each student's level of gambling involvement and his or her problem gambling status. Results showed there to be a significant positive relationship between the number of gambling-related memory associations and reported level of gambling involvement as well as problem gambling status. Behaviour associations tended to be stronger than word associations, suggesting that each type of association may tap into a different facet of associative memory. Associations with problem gambling status were also stronger than associations with level of gambling involvement. The results suggest that implicit associations may have utility in both the assessment of problem gambling as well as predicting future gambling involvement.


Assuntos
Jogo de Azar/psicologia , Memória , Rememoração Mental , Recompensa , Feminino , Humanos , Masculino , Defesa Perceptiva , Adulto Jovem
16.
J Gambl Stud ; 35(4): 1079-1108, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30793249

RESUMO

To examine the underlying dimensionality and structure of problem gambling using a comprehensive range of problem gambling assessments from an international online survey of gamblers. A total of 12,521 gamblers from 105 countries were recruited through banner advertising placed on a popular online gambling portal to take an online survey. Although participants were recruited online, the majority of the sample (71.6%) gambled only at land-based venues in the past 12 months. A total of 5081 individuals completed all items from the four problem gambling assessments. Participants were allocated to answer one of the four problem gambling assessments and the remaining unique items from the three other problem gambling assessments. The order of assessments were counterbalanced. Two optimal scaling procedures were independently employed to estimate the number of dimensions within the data: exploratory categorical principal component bootstrap analysis and multidimensional scaling. Nonlinear canonical correlation was then used to establish how well each of the four assessment instruments captured the identified dimensions. A final confirmatory principal component analysis was run to understand and characterise the nature of the dimensions that were identified. Both the categorical principal component bootstrap analysis and multidimensional scaling indicated the data was multidimensional, with four dimensions (including a single dominant dimension) providing the best characterisation of the data. The nonlinear canonical correlation analysis found that the Problem and Pathological Gambling Measure and the National Opinion Research Center DSM-IV Screen for Gambling Problems operationalization of the Diagnostic and Statistical Manual of Mental Disorders Four (DSM-IV) criteria best captured these multiple dimensions. Confirmatory principal component analysis suggest a core experience of generic problem gambling symptomology and three other components: "financial problems", "health and relationship issues", and "difficulty controlling gambling". Problem gambling symptomology appears to be multi-dimensional. Certain assessments capture this heterogeneity better than others and thereby provide a more complete and accurate assessment of this construct.


Assuntos
Jogo de Azar/epidemiologia , Jogo de Azar/psicologia , Internet , Adulto , Comportamento Aditivo/epidemiologia , Manual Diagnóstico e Estatístico de Transtornos Mentais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
17.
J Neurovirol ; 24(1): 52-61, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29063515

RESUMO

Zika virus (ZIKV) is a rapidly emerging flavivirus that has been associated with a number of congenital neurological manifestations. Here, we show that ZIKV replicated efficiently in mouse neural stem cells (mNSCs). ZIKV infection caused a cytopathic effect without affecting cell viability, yet led to a significant decrease in the number of proteins secreted into mNSC supernatants. A gene expression array of neural stem cell progenitor and differentiation markers suggested that infection reduced the number of neuronal and oligodendrocyte progenitors while increasing the number of astrocyte progenitors. Infection in astrocytes increased transcription of key genes involved in the antiviral response. These data provide molecular and cellular evidence that ZIKV significantly alters neural development in the vertebrate host and that astrocyte differentiation may be a protective response that limits neuropathogenesis.


Assuntos
Astrócitos/metabolismo , Interações Hospedeiro-Patógeno , Células-Tronco Neurais/metabolismo , Zika virus/fisiologia , Animais , Astrócitos/virologia , Diferenciação Celular , Sobrevivência Celular , Cromatografia Líquida , Embrião de Mamíferos , Espaço Extracelular/química , Regulação da Expressão Gênica , Ontologia Genética , Espectrometria de Massas , Camundongos , Anotação de Sequência Molecular , Células-Tronco Neurais/virologia , Transdução de Sinais , Replicação Viral
18.
Opt Express ; 26(16): 19797-19803, 2018 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-30119299

RESUMO

We report a second Stokes diamond Raman laser at 1.49 µm capable of high power and large-scale-factor brightness enhancement. Using a quasi-continuous 1.06 µm pump of power 823 W (0.85% duty cycle) and M2 up to 6.4, a maximum output power of 302 W was obtained with an M2 = 1.1 providing an overall brightness enhancement factor of 6.0. The pulse length of ~210 µs was selected to ensure operation was representative of steady-state continuous lasing conditions in the diamond bulk. Accompanying theoretical calculations indicate that even more strongly aberrated pumps may be used to efficiently generate high beam quality output and with higher brightness enhancement factors. This diamond-based beam conversion technique addresses needs for high brightness and efficient eye-safe sources using low-brightness 1 µm pumps and reveals a widely-applicable route to practical high brightness lasers of increased wavelength range.

19.
Opt Express ; 26(2): 1930-1941, 2018 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-29401914

RESUMO

We report a high power quasi-continuous-wave (QCW) 620 nm laser from an external cavity diamond Raman laser utilizing intracavity frequency doubling in lithium triborate. Output power of 30 W for durations of 0.25 ms at 15% conversion efficiency was achieved with a beam quality factor M2 = 1.1 from a free-running Nd:YAG pump laser of M2 = 1.5. The critical design parameters that affect conversion efficiency and power were analysed with the aid of an analytical model. By adaptation to other pump technologies, the diamond approach provides a novel pathway towards high brightness CW beam generation in the visible and ultraviolet regions.

20.
Opt Lett ; 43(3): 563-566, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-29400841

RESUMO

High average power lasers with high beam quality are critical for emerging applications in industry and research for defense, materials processing, and space applications. However, overcoming thermal effects in the gain medium remains the key challenge for increasing laser brightness at high powers. Here we report a means for increasing the beam brightness of high-power continuous-wave (CW) beams based on external cavity Raman lasers using diamond, a material with thermal properties far superior to any other laser material. With pump beam quality in the range M2=2.3-7.3, efficient pump-limited conversion to an M2=1.1 Stokes beam is achieved in all cases, with increases in brightness from the pump by factors as high as 12.7. The influence of pump beam quality on laser threshold and slope efficiency is analyzed. This Letter foreshadows an alternative approach for scaling the brightness of CW lasers using high-power, moderate beam quality pumps up to M2=20 or more, such as thin-disk and slab lasers and fiber lasers operating in a mode instability regime.

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