Biological Microscopy with Undetected Photons

Novel imaging techniques utilizing nondegenerate, correlated photon pairs sparked intense interest during the last couple of years among scientists of the quantum optics community and beyond. It is a key property of such "ghost imaging" or "quantum interference" methods that they use those photons of the correlated pairs for imaging that never interacted with the sample, allowing detection in a spectral range different from that of the illumination of the object. Extensive applications of these techniques in spectroscopy and microscopy are envisioned, however, their limited spatial resolution to date has not yet supported real-life microscopic investigations of tiny biological objects. Here we report a modification of the method based on quantum interference by using a seeding laser and confocal scanning, that allows the improvement of the resolution of imaging with undetected photons by more than an order of magnitude, and we also present examples of application in the microscopy of biological samples.Comment: This article has been accepted for publication in IEEE Access, but has not been fully edite

Protein-based integrated optical switching and modulation

The static and dynamic response of optical waveguides coated with a thin protein film of bacteriorhodopsin was investigated. The size and kinetics of the light-induced refractive index changes of the adlayer were determined under different conditions of illumination. The results demonstrate the applicability of this protein as an active, programmable nonlinear optical material in all-optical integrated circuits. (C) 2002 American Institute of Physics

Correlação entre teores de nitrogênio e de clorofila na folha com o rendimento de grãos de aveia branca Correlation among nitrogen and chlorophyll contents of leaves and grain yield of oat

Um experimento foi conduzido na Universidade de Passo Fundo (UPF) com o objetivo de avaliar as correlações entre teores de N e de clorofila em folhas de aveia branca e entre estes e o rendimento de grãos (RG), massa de mil grãos (MMG), período de enchimento (PEG) e taxa de enchimento de grãos (TEG). O ensaio foi conduzido no ano agrícola de 2003, utilizando-se 21 cultivares de aveia branca desenvolvidas pela FAMV/UPF, distribuídas em blocos ao acaso, em quatro repetições. Estimou-se o teor de clorofila por meio do índice SPAD (clorofilômetro) e determinou-se o seu teor pelo método químico e também os teores de N, nas folhas bandeia e bandeira-1, no estádio de antese. Na maturação (colheita), determinou-se o RG, o MMG, o TEG e o PEG. Verificou-se que não houve correlações significativas entre teores de clorofila com os teores de N, com RG, MMG, TEG e PEG, porém, houve correlações significativas entre teores de N com o RG, MMG e PEG.<br>An experiment was conducted at the Passo Fundo University, with the aim of evaluate the correlations among nitrogen contents, chlorophyll contents, grain yield (GY), thousand grain weight (TGW), grain filling period (GFP) and grain filling rate (GFR) in oat cultivars. The experiment was conducted during 2003 agriculture year, with oat cultivars developed by Passo Fundo University, with four replications, at random blocks distribution. The chlorophyll contents, estimated by chlorophyll meter (SPAD 502 model) and chemical method, and nitrogen contents were determined at anthesis stage. At maturation stage, the GY, TGW, GFP and GFR variables were determined. It was observed that there were no significant correlations among chlorophyll contents with nitrogen contents, with GY, TGW and GFP, but there were significant correlations among nitrogen contents and GY, TGW and GFP

Intravenous alteplase for stroke with unknown time of onset guided by advanced imaging: systematic review and meta-analysis of individual patient data

Background: Patients who have had a stroke with unknown time of onset have been previously excluded from thrombolysis. We aimed to establish whether intravenous alteplase is safe and effective in such patients when salvageable tissue has been identified with imaging biomarkers. Methods: We did a systematic review and meta-analysis of individual patient data for trials published before Sept 21, 2020. Randomised trials of intravenous alteplase versus standard of care or placebo in adults with stroke with unknown time of onset with perfusion-diffusion MRI, perfusion CT, or MRI with diffusion weighted imaging-fluid attenuated inversion recovery (DWI-FLAIR) mismatch were eligible. The primary outcome was favourable functional outcome (score of 0–1 on the modified Rankin Scale [mRS]) at 90 days indicating no disability using an unconditional mixed-effect logistic-regression model fitted to estimate the treatment effect. Secondary outcomes were mRS shift towards a better functional outcome and independent outcome (mRS 0–2) at 90 days. Safety outcomes included death, severe disability or death (mRS score 4–6), and symptomatic intracranial haemorrhage. This study is registered with PROSPERO, CRD42020166903. Findings: Of 249 identified abstracts, four trials met our eligibility criteria for inclusion: WAKE-UP, EXTEND, THAWS, and ECASS-4. The four trials provided individual patient data for 843 individuals, of whom 429 (51%) were assigned to alteplase and 414 (49%) to placebo or standard care. A favourable outcome occurred in 199 (47%) of 420 patients with alteplase and in 160 (39%) of 409 patients among controls (adjusted odds ratio [OR] 1·49 [95% CI 1·10–2·03]; p=0·011), with low heterogeneity across studies (I 2=27%). Alteplase was associated with a significant shift towards better functional outcome (adjusted common OR 1·38 [95% CI 1·05–1·80]; p=0·019), and a higher odds of independent outcome (adjusted OR 1·50 [1·06–2·12]; p=0·022). In the alteplase group, 90 (21%) patients were severely disabled or died (mRS score 4–6), compared with 102 (25%) patients in the control group (adjusted OR 0·76 [0·52–1·11]; p=0·15). 27 (6%) patients died in the alteplase group and 14 (3%) patients died among controls (adjusted OR 2·06 [1·03–4·09]; p=0·040). The prevalence of symptomatic intracranial haemorrhage was higher in the alteplase group than among controls (11 [3%] vs two [<1%], adjusted OR 5·58 [1·22–25·50]; p=0·024). Interpretation: In patients who have had a stroke with unknown time of onset with a DWI-FLAIR or perfusion mismatch, intravenous alteplase resulted in better functional outcome at 90 days than placebo or standard care. A net benefit was observed for all functional outcomes despite an increased risk of symptomatic intracranial haemorrhage. Although there were more deaths with alteplase than placebo, there were fewer cases of severe disability or death. Funding: None