12 research outputs found

    Turbulent coherent structures in a long cavity semiconductor laser near the lasing threshold

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    We report on the formation of novel turbulent coherent structures in a long cavity semiconductor laser near the lasing threshold. Experimentally, the laser emits a series of power dropouts within a roundtrip and the number of dropouts per series depends on a set of parameters including the bias current. At fixed parameters, the drops remain dynamically stable, repeating over many roundtrips. By reconstructing the laser electric field in the case where the laser emits one dropout per round trip and simulating its dynamics using a time-delayed model, we discuss the reasons for long-term sustainability of these solutions. We suggest that the observed dropouts are closely related to the coherent structures of the cubic complex Ginzburg-Landau equation

    Wavelet (valić) transformacija

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    Valić transformacija daje sofisticiranu vremensko-frekvencijsku analizu i koristi se u brojnim algoritmima u raznim područjima znanosti. Nakon teorijske pozadine i usporedbe sa frekvencijskom analizom, bit će prezentirane neke primjene u području sažimanja slike i uklanjanju šuma iz signala. Pojašnjen je i algoritam za prepoznavanje osoba pomoću očnog uzorka

    Transplant Physicians’ Attitudes on Candidacy for Allogeneic Hematopoietic Cell Transplantation (HCT) in Older Patients: The Need for a Standardized Geriatric Assessment (GA) Tool

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    Background Despite improvements in conditioning regimens and supportive care having expanded the curative potential of HCT, underutilization of HCT in older adults persists (Bhatt VR et al, BMT 2017). Therefore, we conducted a survey of transplant physicians (TP) to determine their perceptions of the impact of older age (≥60 years) on HCT candidacy and utilization of tools to gauge candidacy. Methods We conducted a 23-item, online cross-sectional survey of adult physicians recruited from the Center for International Blood and Marrow Transplant Research between May and July 2019. Results 175/770 (22.7%) TP completed the survey; majority of respondents were 41-60 years old, male, and practicing in a teaching hospital. Over 75% were at centers performing ≥50 HCT per year. When considering regimen intensity, most (96%, n=168) had an upper age limit (UAL) for using a myeloablative regimen (MAC), with only 29 physicians (17%) stating they would consider MAC for patients ≥70 years. In contrast, when considering a reduced intensity/non-myeloablative conditioning (RIC/NMA), 8%, (n=13), 54% (n=93), and 20% (n=35) stated that age 70, 75, and 80 years respectively would be the UAL to use this approach, with 18% (n=31) reporting no UAL. TP agreed that Karnofsky Performance Score (KPS) could exclude older pts for HCT, with 39.1% (n=66), 42.6% (n=72), and 11.4% (n=20) requiring KPS of ≥70, 80, and 90, respectively. The majority (n=92, 52.5%) indicated an HCT-comorbidity index threshold for exclusion, mostly ranging from ≥3 to ≥ 5. Almost all (89.7%) endorsed the need for a better health assessment of pre-HCT vulnerabilities to guide candidacy for pts ≥60 with varied assessments being utilized beyond KPS (Figure 1). However, the majority of centers rarely (33.1%) or never (45.7%) utilize a dedicated geriatrician/geriatric-oncologist to assess alloHCT candidates ≥60 yrs. The largest barriers to performing GA included uncertainty about which tools to use, lack of knowledge and training, and lack of appropriate clinical support staff (Figure 2). Approximately half (n=78, 45%) endorsed GA now routinely influences candidacy. Conclusions The vast majority of TP will consider RIC/NMA alloHCT for patients ≥70 years. However, there is heterogeneity in assessing candidacy. Incorporation of GA into a standardized and easily applied health assessment tool for risk stratification is an unmet need. The recently opened BMT CTN 1704 may aid in addressing this gap

    Turbulent coherent structures in a long cavity semiconductor laser near the lasing threshold

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    We report on the formation of novel turbulent coherent structures in a long cavity semiconductor laser near the lasing threshold. Experimentally, the laser emits a series of power dropouts within a roundtrip, and the number of dropouts per series depends on a set of parameters including the bias current. At fixed parameters, the drops remain dynamically stable, repeating over many roundtrips. By reconstructing the laser electric field in the case where the laser emits one dropout per roundtrip and simulating its dynamics using a time-delayed model, we discuss the reasons for long-term sustainability of these solutions. We suggest that the observed dropouts are closely related to the coherent structures of the cubic complex Ginzburg–Landau equation
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