Abstract
The carbon cycle is a key regulator of Earth’s climate. On geological time-scales, our understanding of particulate organic matter (POM), an important upper ocean carbon pool that fuels ...ecosystems and an integrated part of the carbon cycle, is limited. Here we investigate the relationship of planktonic foraminifera-bound organic carbon isotopes (δ
13
C
org-pforam
) with δ
13
C
org
of POM (δ
13
C
org-POM
). We compare δ
13
C
org-pforam
of several planktonic foraminifera species from plankton nets and recent sediment cores with δ
13
C
org-POM
on a N-S Atlantic Ocean transect. Our results indicate that δ
13
C
org-pforam
of planktonic foraminifera are remarkably similar to δ
13
C
org-POM
. Application of our method on a glacial sample furthermore provided a δ
13
C
org-pforam
value similar to glacial δ
13
C
org-POM
predictions. We thus show that δ
13
C
org-pforam
is a promising proxy to reconstruct environmental conditions in the upper ocean, providing a route to isolate past variations in δ
13
C
org-POM
and better understanding of the evolution of the carbon cycle over geological time-scales.
Introduction
Foraminiferal shells are extensively used to reconstruct the marine environment in the geological past. The foraminifera test-bound organic material (FBOM), sheltered by the test from ...potential diagenetic alteration and contamination, has great feasibility to improve our understanding of carbon and nitrogen cycling. The FBOM δ
13
C has been proposed as a proxy for reconstructing past environmental conditions. However, to fully exploit the proxy potential of FBOM, its molecular composition and the influence of the latter on the FBOM δ
13
C need to be assessed.
Method
Here we use a novel combination of gas chromatography-mass spectrometry, flame ionization detection (GC-MS/FID) and liquid chromatography organic carbon and nitrogen detection (LC-OCD/ OND) analyses to study the FBOM chemical composition.
Results
Our results indicate that polysaccharides and proteins dominate FBOM, as proposed by earlier studies, with no evidence of detectable lipids (alkyl lipids, trimethylsilyl ethers of fatty alcohols, trimethylsilyl esters of fatty acids and steranes derivatives were targeted).
Discussion
Previous studies suggested that FBOM δ
13
C may be used to reconstruct past atmospheric CO
2
concentrations. However, our results indicate that the use of FBOM δ
13
C to reconstruct CO
2
carries an approximate uncertainty of ±21 ppm for past atmospheric CO
2
abundance. We suggest that FBOM δ
13
C can be used as a novel proxy to reconstruct particulate organic material (POM) δ
13
C. This is also supported by the recently confirmed minor fractionation between POM and FBOM δ
13
C.
The aim of our study was to classify scoliosis compared to to healthy patients using non-invasive surface acquisition via Video-raster-stereography, without prior knowledge of radiographic data. Data ...acquisitions were made using Rasterstereography; unsupervised learning was adopted for clustering and supervised learning was used for prediction model Support Vector Machine and Deep Network architectures were compared. A M-fold cross validation procedure was performed to evaluate the results. The accuracy and balanced accuracy of the best supervised model were close to 85%. Classification rates by class were measured using the confusion matrix, giving a low percentage of unclassified patients. Rasterstereography has turned out to be a good tool to distinguish subject with scoliosis from healthy patients limiting the exposure to unnecessary radiations.
Photocatalysis has become a prominent tool in the arsenal of organic chemists to develop and (re)imagine transformations. However, only a handful of versatile organic photocatalysts (PCs) are ...available, hampering the discovery of new reactivities. Here, we report the design and complete physicochemical characterization of 9-aryl dihydroacridines (9ADA) and 12-aryl dihydrobenzoacridines (12ADBA) as strong reducing organic PCs. Punctual structural variations modulate their molecular orbital distributions and unlock locally or charge-transfer (CT) excited states. The PCs presenting a locally excited state showed better performances in photoredox defunctionalization processes (yields up to 92%), whereas the PCs featuring a CT excited state produced promising results in atom transfer radical polymerization under visible light (up to 1.21 Đ, and 98% I*). Unlike all the PC classes reported so far, 9ADA and 12ADBA feature a free NH group that enables a catalytic multisite proton-coupled electron transfer (MS-PCET) mechanism. This manifold allows the reduction of redox-inert substrates including aryl, alkyl halides, azides, phosphate and ammonium salts (E red up to −2.83 vs SCE) under single-photon excitation. We anticipate that these new PCs will open new mechanistic manifolds in the field of photocatalysis by allowing access to previously inaccessible radical intermediates under one-photon excitation.
Focal repetitive muscle vibration (fMV) is a safe and well-tolerated non-invasive brain and peripheral stimulation (NIBS) technique, easy to perform at the bedside, and able to promote the ...post-stroke motor recovery through conditioning the stroke-related dysfunctional structures and pathways. Here we describe the concurrent cortical and spinal plasticity induced by fMV in a chronic stroke survivor, as assessed with 99mTc-HMPAO SPECT, peripheral nerve stimulation, and gait analysis. A 72-years-old patient was referred to our stroke clinic for a right leg hemiparesis and spasticity resulting from a previous (4 years before) hemorrhagic stroke. He reported a subjective improvement of his right leg's spasticity and dysesthesia that occurred after a30-min ride on a
Vespa
scooter as a passenger over the Roman Sampietrini (i.e., cubic-shaped cobblestones). Taking into account both the patient's anecdote and the current guidelines that recommend fMV for the treatment of post-stroke spasticity, we then decided to start fMV treatment. 12 fMV sessions (frequency 100 Hz; amplitude range 0.2–0.5 mm, three 10-min daily sessions per week for 4 consecutive weeks) were applied over the quadriceps femoris, triceps surae, and hamstring muscles through a specific commercial device (Cro®System, NEMOCOsrl). A standardized clinical and instrumental evaluation was performed before (T0) the first fMV session and after (T1) the last one. After fMV treatment, we observed a clinically relevant motor and functional improvement, as assessed by comparing the post-treatment changes in the score of the Fugl-Meyer assessment, the Motricity Index score, the gait analysis, and the Ashworth modified scale, with the respective minimal detectable change at the 95% confidence level (MDC
95
). Data from SPECT and peripheral nerve stimulation supported the evidence of a concurrent brain and spinal plasticity promoted by fMV treatment trough activity-dependent changes in cortical perfusion and motoneuron excitability, respectively. In conclusion, the substrate of post-stroke motor recovery induced by fMV involves a concurrently acting multisite plasticity (i.e., cortical and spinal plasticity). In our patient, operant conditioning of both cortical perfusion and motoneuron excitability throughout a month of fMV treatment was related to a clinically relevant improvement in his strength, step symmetry (with reduced limping), and spasticity.
Objective. Classify scoliosis versus healthy patients using rasterstereography non invasive surface acquisition, without prior knowledge from X-ray data.Methods. Data acquisition via ...rasterstereography; unsupervised learning for clustering and supervised learning for predicting models. Comparison among Support Vector Machine and Deep Network architectures. K-fold cross validation procedure for assessing the results.Results. The accuracy and the balanced accuracy of the best supervised model was close to 85%. Classification rates per class were measured using confusion matrix giving low percentage of misclassified patients.Conclusion. Rasterstereography turns out to be a good tool to identify scoliosis vs healthy patients with the advantage of not exposing patient to unhealthy X-Ray. Furthermore, thanks to the portability and the low cost of the rasterstereography, it is possible to use it to promote screening campaign.
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