Incidence and trends of low back pain hospitalisation during military service – An analysis of 387,070 Finnish young males

<p>Abstract</p> <p>Background</p> <p>There is evidence that low back pain (LBP) during young adulthood and military service predicts LBP later in life. The purpose of this study was to investigate the incidence and trends of LBP hospitalisation among Finnish military conscripts.</p> <p>Methods</p> <p>All male conscripts performing their compulsory military service during 1990–2002 were included in the study population. Altogether 387,070 military conscripts were followed throughout their six-to-twelve-month service period. Data on LBP hospitalisations were obtained from the National Hospital Discharge Register.</p> <p>Results</p> <p>Altogether 7,240 LBP hospitalisations were identified among 5,061 (1.3%) male conscripts during the study period. The event-based incidence of LBP hospitalisation was 27.0 (95% confidence interval (CI): 25.7–28.2). In most cases, the diagnosis was unspecified LBP (<it>n </it>= 5,141, 71%) followed by lumbar disc disorders (<it>n </it>= 2,069, 29%). Hospitalisation incidence due to unspecified LBP was 19.1 per 1,000 person-years (95% CI: 18.3 to 20.4), and 7.8 per 1,000 person-years (95% CI: 6.7 to 8.3) due to lumbar disc disorders. The incidence of unspecified LBP remained unaltered, while hospitalisation due to lumbar disc disorders declined from 1993 onwards.</p> <p>Conclusion</p> <p>Although conscripts accepted into military training pass physician-performed examinations as healthy, young adults, LBP hospitalisation causes significant morbidity during military service.</p

Fast plastic detection with a time-resolved Raman spectrometer

Abstract The performance of a time-resolved Raman spectrometer equipped with a new CMOS SPAD (single-photon avalanche diode) sensor was studied in fast detection of common plastic types. Sixteen samples, including transparent, white, and colored pieces of polyethylene, polypropylene, polyethylene terephthalate, and polystyrene were measured with different acquisition times and all measurements were repeated 200 times for detection probability calculations. When a time gate width of 450 ps was applied to reject the fluorescence emission, a 99% detection probability was achieved for transparent and white samples with the acquisition time of 250 μs. With colored samples, a 10-ms acquisition time was required to get at least a 99% detection probability for all the samples. For most of the samples, the acquisition time could be reduced when 450 ps time gate width was used instead of 3-ns time gate. For highly fluorescent samples, the reduction in required acquisition time was more than 90%

Timing skew compensation methods for CMOS SPAD line sensors used for Raman spectroscopy

Abstract Two methods were developed to compensate for the timing skew of CMOS SPAD line sensors used for time-resolving Raman spectroscopy. Both methods were tested using a time-resolving Raman spectrometer built around a 256-channel CMOS SPAD line sensor. As an example, Raman spectrum of highly fluorescent sesame seed oil was measured. Most of the distortion in the measured spectrum was caused by the timing skew and about 75 % of it could be removed by using either of the methods presented

On the spectral quality of time-resolved CMOS SPAD-based Raman spectroscopy with high fluorescence backgrounds

Abstract The fluorescence background in Raman spectroscopy can be effectively suppressed by using pulsed lasers and time-gated detectors. A recent solution to reduce the high complexity and bulkiness of the time-gated systems is to implement the detector by utilizing time-resolved single-photon avalanche diodes (SPADs) fabricated in complementary-metal-oxide-semiconductor (CMOS) technology. In this study, we investigate the effects of fluorescence-to-Raman ratio, recording time and excitation intensity on the quality of Raman spectra measured by using one of the furthest developed fluorescence-suppressed Raman spectrometers based on a time-resolved CMOS SPAD line sensor. The objectives were to provide information on the significance of the different causes behind the distortion of the measured Raman spectra with various measurement conditions and to provide general information on the possibilities to exploit the high-intensity non-stationary pulsed laser excitation to gain additional improvement on the spectral quality due to laser-induced fluorescence saturation. It was shown that the distortion of the spectra with samples having short fluorescence lifetimes (~2 ns) and high fluorescence-to-Raman ratios, i.e. with challenging samples, is dominated by the timing skew of the sensor instead of the shot noise caused by the detected events. In addition, the actual reason for the observed improvement in the spectral quality as a function of excitation intensity was discovered not to be the conventionally thought increased number of detected photons but rather the laser-induced fluorescence saturation. At best, 26% improvement to the signal-to-noise ratio was observed due to fluorescence saturation

Time- and spectrally-resolved mesoscopic Raman and fluorescence imaging of carious enamel by a CMOS SPAD-based spectrometer

Abstract Dental caries is the most widespread non-communicable disease affecting 2.5 billion people worldwide. Recently various optical spectroscopy methods have gained a lot of interest in dental research and caries detection due to their noninvasive and nonionizing nature. We demonstrate here, to the best of our knowledge, for the first time simultaneous Raman, fluorescence intensity and fluorescence lifetime imaging of carious human enamel with a single device based on a time-resolved single-photon avalanche diode (SPAD) sensor fabricated in 110-nm CMOS technology. The sensor has identical 256 spectral channels each of them containing an integrated tunable 7-bit time-to-digital converter (TDC) enabling time- and spectrally-resolved photon counting. We were able to show with the spectrometer built around the CMOS SPAD sensor and by utilizing a simple unsupervised machine learning algorithm (K-means) that a more comprehensive and reliable images of the enamel and caries-affected regions can be obtained by combining the information from the three different optical spectroscopy methods. We believe that the technology presented here could pave the way for novel multimodal optical devices not only in dental research and clinical dentistry but also in other biomedical applications in which molecular and chemical changes are studied

CMOS SPAD line sensor with fine-tunable parallel connected time-to-digital converters for Raman spectroscopy

Abstract A 256-channel single-photon avalanche diode (SPAD) line sensor was designed for time-resolved Raman spectroscopy in 110-nm CMOS technology. The line sensor consists of an 8 X 256 SPAD array and 256 parallel connected time-to-digital converters (TDCs). The adjustable temporal resolution and dynamic range of TDCs are 25.6–65 ps and 3.2–8.2 ns, respectively. The median timing skew along 256 channels is 43.7 ps, and TDC bin boundaries can be fine-tuned at the ps-level to enable precise timing skew compensation. The sensor is capable of real-time dark count measurement (two dark measurements for each excitation pulse) that gives accurate data for dark count compensation without any increment in measurement time. The maximum excitation pulse rate with real-time dark count measurement is 680 kHz. Raman spectra of six different samples were measured to prove the performance of the sensor in time-resolved Raman spectroscopy

3-D Raman imaging using time-resolving CMOS SPAD line sensor and 2-D mapping

Abstract The capability of Raman imaging to produce 2-D and 3-D chemical presentations of samples has gained a lot of interest in different application fields. In this article, we present a 3-D chemical image reconstruction based on 2-D scanning of a sample utilizing a time-resolved Raman spectrometer based on a complementary metal–oxide–semiconductor (CMOS) single-photon avalanche diode (SPAD) line sensor. The 2-D scanning data contain the lateral information (XY plane), whereas the time-of-arrival data of the Raman photons measured by the sensor carry the axial information (i.e., depth information, Z -axis). The sensor is fabricated in 110-nm CMOS technology. It has 256-spectral channels, and each channel has its own 7-bit ON-chip time-to-digital converter (TDC) with an adjustable resolution from 25 to 65 ps. In addition to the 3-D chemical reconstruction of the scanned sample, we have shown the ability to retrieve depth profiling information of each scanned pixel, such as the boundaries and middle points of any selected layer over the depth range of the scanned object by means of a single measurement for each scanned pixel. In addition, we have discussed the system components and the postprocessing parameters that affect the depth profiling accuracy and the 3-D reconstruction operation the most. Results showed that the instrument response function (IRF) of the system and the time gate window width in a postprocessing phase are playing the most important role in determining the axial (depth) accuracy. We believe that our system will enable a whole new class of Raman applications that will allow simultaneous 3-D chemical geometric representation at the centimeter level during Raman operations

Multipoint Raman spectrometer based on a time-resolved CMOS SPAD sensor

Abstract The potential of in-line Raman spectrometers for process monitoring applications has been shown for many industrial processes, but in most cases, only one measurement point has been monitored by one spectrometer. In this letter, we describe and demonstrate a novel, time-resolved method for measuring Raman spectra and fluorescence lifetimes from multiple points using a single excitation source and a single spectrometer. This technique is based on a combination of a time-resolved CMOS SPAD (single-photon avalanche diode) line sensor and a fitting optical light guiding system. The line sensor is designed to make multiple individual measurements at intervals of tens of nanoseconds and the optical light guiding system, in turn, produces matching temporal differences for optical signals from different measurement points. Thereby, signals from different points are distinguished in the time domain. A combined Raman and fluorescence lifetime monitoring of two measurement points was demonstrated with an oil-ethanol emulsion sample

Designed inorganic porous nanovector with controlled release and MRI features for safe administration of doxorubicin

Embargo 12 kkThe inability of traditional chemotherapeutics to reach cancer tissue reduces the treatment efficacy and leads to adverse effects. A multifunctional nanovector was developed consisting of porous silicon, superparamagnetic iron oxide, calcium carbonate, doxorubicin and polyethylene glycol. The particles integrate magnetic properties with the capacity to retain drug molecules inside the pore matrix at neutral pH to facilitate drug delivery to tumor tissues. The MRI applicability and pH controlled drug release were examined in vitro together with in-depth material characterization. The in vivo biodistribution and compound safety were verified using A549 lung cancer bearing mice before proceeding to therapeutic experiments using CT26 cancer implanted mice. Loading doxorubicin into the porous nanoparticle negated the adverse side effects encountered after intravenous administration highlighting the particles’ excellent biocompatibility. Furthermore, the multifunctional nanovector induced 77% tumor reduction after intratumoral injection. The anti-tumor effect was comparable with that of free doxorubicin but with significantly alleviated unwanted effects. These results demonstrate that the developed porous silicon-based nanoparticles represent promising multifunctional drug delivery vectors for cancer monitoring and therapy.Peer reviewe

Inorganic mesoporous particles for controlled α-linolenic acid delivery to stimulate GLP-1 secretion in vitro

Novel treatment methods for obesity are urgently needed due to the increasing global severity of the problem. Gastrointestinal hormones, such as GLP-1 and PYY, are secreted by the enteroendocrine cells, playing a critical role in regulating food intake. Digested nutrients trigger the secretion of these hormones, which have a very short half-life. α-Linolenic acid (αLA) has been shown to stimulate GLP-1 secretion, however, chemical instability and fast uptake in the small intestine hinder its use in body weight management. We developed a novel delivery system based on inorganic mesoporous particles for αLA to increase secretion of gastrointestinal peptides. αLA was loaded to thermally hydrocarbonized porous silicon particles (THCPSi). 47.9 ± 3.84% and 30.7 ± 2.86% of αLA was released during 6 h from 3.0% and 9.2% loading degree (w/w) samples in vitro, respectively. Native αLA (50 µM) significantly increased GLP-1 secretion from enteroendocrine STC-1 and GLUTag cell lines. αLA loaded THCPSi significantly and dose dependently stimulated GLP-1 secretion from STC-1 cells, whereas empty particles did not. We demonstrated in vitro that THCPSi particles have the potential to be used as a controlled delivery system for nutrients such as αLA, increasing GLP-1 secretion. Our results justify further in vivo investigations