8 research outputs found
Joined optical and thermal characterization of a III-nitride semiconductor membrane by micro-photoluminescence spectroscopy and Raman thermometry
We present the simultaneous optical and thermal analysis of a freestanding
photonic semiconductor membrane made from wurtzite III-nitride material. By
linking micro-photoluminescence (PL) spectroscopy with Raman thermometry,
we demonstrate how a robust value for the thermal conductivity can be
obtained using only optical, non-invasive means. For this, we consider the
balance of different contributions to thermal transport given by, e.g.,
excitons, charge carriers, and heat carrying phonons. Further complication is
given by the fact that this membrane is made from direct bandgap
semiconductors, designed to emit light based on an InGaN
() quantum well embedded in GaN. To meet these challenges, we designed
a novel experimental setup that enables the necessary optical and thermal
characterizations in parallel. We perform micro-Raman thermometry, either based
on a heating laser that acts as a probe laser (1-laser Raman thermometry), or
based on two lasers, providing the heating and the temperature probe separately
(2-laser Raman thermometry). For the latter technique, we obtain temperature
maps over tens of micrometers with a spatial resolution less than
, yielding
for the
-plane of our -thick membrane at around
room temperature, which compares well to our calculations
applied to a simplified structure. Based on these calculations, we explain the
particular relevance of the temperature probe volume, as quasi-ballistic
transport of heat-carrying phonons occurs on length scales beyond the
penetration depths of the heating laser and even its focus spot radius. The
present work represents a significant step towards non-invasive, highly
spatially resolved, and still quantitative thermometry performed on a photonic
membrane.Comment: 28 pages, 14 figures, and Supplemental Materia
Phase II, open-label, randomized, multicenter trial (HERBY) of Bevacizumab in pediatric patients with newly diagnosed high-grade glioma
Purpose
Bevacizumab (BEV) is approved in more than 60 countries for use in adults with recurrent glioblastoma. We evaluated the addition of BEV to radiotherapy plus temozolomide (RT+TMZ) in pediatric patients with newly diagnosed high-grade glioma (HGG).
Methods
The randomized, parallel group, multicenter, open-label HERBY trial (ClinicalTrials.gov identifier: NCT01390948) enrolled patients age ≥ 3 years to ≤ 18 years with localized, centrally neuropathology-confirmed, nonbrainstem HGG. Eligible patients were randomly assigned to receive RT + TMZ (RT: 1.8 Gy, 5 days per week, and TMZ: 75 mg/m² per day for 6 weeks; 4-week treatment break; then up to 12 3 28-day cycles of TMZ [cycle 1: 150 mg/m² per day, days 1 to 5; cycles 2 to 12: 200 mg/m² per day, days 1 to 5]) with or without BEV (10 mg/kg every 2 weeks). The primary end point was event-free survival (EFS) as assessed by a central radiology review committee that was blinded to treatment. We report findings of EFS at 12 months after the enrollment of the last patient.
Results
One hundred twenty-one patients were enrolled (RT+TMZ [n = 59]; BEV plus RT+TMZ [n = 62]). Central radiology review committee–assessed median EFS did not differ significantly between treatment groups (RT+TMZ, 11.8 months; 95% CI, 7.9 to 16.4 months; BEV plus RT+TMZ, 8.2 months; 95% CI, 7.8 to 12.7 months; hazard ratio, 1.44; P = .13 [stratified log-rank test]). In the overall survival analysis, the addition of BEV did not reduce the risk of death (hazard ratio, 1.23; 95% CI, 0.72 to 2.09). More patients in the BEV plus RT+TMZ group versus the RT+TMZ group experienced one or more serious adverse events (n = 35 [58%] v n = 27 [48%]), and more patients who received BEV discontinued study treatment as a result of adverse events (n = 13 [22%] v n = 3 [5%]).
Conclusion
Adding BEV to RT+TMZ did not improve EFS in pediatric patients with newly diagnosed HGG. Our findings were not comparable to those of previous adult trials, which highlights the importance of performing pediatric-specific studies
Immunotherapy of high-risk acute leukemia with a recipient (autologous) vaccine expressing transgenic human CD40L and IL-2 after chemotherapy and allogeneic stem cell transplantation
CD40L generates immune responses in leukemia-bearing mice, an effect that is potentiated by IL-2. We studied the feasibility, safety, and immunologic efficacy of an IL-2– and CD40L-expressing recipient-derived tumor vaccine consisting of leukemic blasts admixed with skin fibroblasts transduced with adenoviral vectors encoding human IL-2 (hIL-2) and hCD40L. Ten patients (including 7 children) with high-risk acute myeloid (n = 4) or lymphoblastic (n = 6) leukemia in cytologic remission (after allogeneic stem cell transplantation [n = 9] or chemotherapy alone [n = 1]) received up to 6 subcutaneous injections of the IL-2/CD40L vaccine. None of the patients were receiving immunosuppressive drugs. No severe adverse reactions were noted. Immunization produced a 10- to 890-fold increase in the frequencies of major histocompatibility complex (MHC)–restricted T cells reactive against recipient-derived blasts. These leukemia-reactive T cells included both T-cytotoxic/T-helper 1 (Th1) and Th2 subclasses, as determined from their production of granzyme B, interferon-γ, and interleukin-5. Two patients produced systemic IgG antibodies that bound to their blasts. Eight patients remained disease free for 27 to 62 months after treatment (5-year overall survival, 90%). Thus, even in heavily treated patients, including recipients of allogeneic stem cell transplants, recipient-derived antileukemia vaccines can induce immune responses reactive against leukemic blasts. This approach may be worthy of further study, particularly in patients with a high risk of relapse
Upgrading the high contrast imaging facility SPHERE: science drivers and instrument choices
International audienceSPHERE+ is a proposed upgrade of the SPHERE instrument at the VLT, which is intended to boost the current performances of detection and characterization for exoplanets and disks. SPHERE+ will also serve as a demonstrator for the future planet finder (PCS) of the European ELT. The main science drivers for SPHERE+ are 1/ to access the bulk of the young giant planet population down to the snow line (3 − 10 au), to bridge the gap with complementary techniques (radial
The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity