975 research outputs found
Unlabeled Semen Analysis by Means of the Holographic Imaging
The morphology, the motility, and the biochemical structure of the spermatozoon have often been correlated with the outcome of in vitro fertilization and have been shown to be the sole parameters of the semen analysis in predicting the success of intracytoplasmic sperm injection and intracytoplasmic morphologically selected sperm injection. In this context, digital holography has demonstrated to be an attractive technique to perform a label-free, noninvasive, and high-resolution technique for characterization of live spermatozoa. The aim of this chapter is to summarize the recent achievements of digital holography in order to show its high potentiality as an efficient method for healthy and fertile sperm cell selection, without injuring the specimen and to explore new possible applications of digital holography in this field
State-of-the-art all-silicon sub-bandgap photodetectors at telecom and datacom wavelengths
Silicon-based technologies provide an ideal platform for the monolithic integration of photonics and microelectronics. In this context, a variety of passive and active silicon photonic devices have been developed to operate at telecom and datacom wavelengths, at which silicon has minimal optical absorption - due to its bandgap of 1.12 eV. Although in principle this transparency window limits the use of silicon for optical detection at wavelengths above 1.1Â ÎŒm, in recent years tremendous advances have been made in the field of all-silicon sub-bandgap photodetectors at telecom and datacom wavelengths. By taking advantage of emerging materials and novel structures, these devices are becoming competitive with the more well-established technologies, and are opening new and intriguing perspectives. In this paper, a review of the state-of-the-art is presented. Devices based on defect-mediated absorption, two-photon absorption and the internal photoemission effect are reported, their working principles are elucidated and their performance discussed and compared
Critical limb ischaemia: definition and natural hystory
The term critical limb ischemia refers to a condition characterized by chronic ischemic at-rest pain, ulcers, or gangrene in one or both legs attributable to objectively proven arterial occlusive disease. Critical limb ischemia implies chronicity and is to be distinguished from acute limb ischemia. Its incidence is approximately 500 to 1000 per million year, with the highest rates among older subjects, smokers and diabetics. The rate of primary amputation ranges from 10% to 40%, and was performed only when no graftable distal vessels were present, or in neurologically impaired or hopelessly nonambulatory patients. Contrarily, in some highly specialized and aggressive centres about 90% of patients with CLI had an attempted revascularization. Furthermore, patients with critical limb ischemia have an elevated risk of future myocardial infarction, stroke and vascular death, 3-fold higher than patients with intermittent claudication. Therefore, due to its negative impact on the quality of life and the poor prognosis both in terms of limb salvage and survival, critical limb ischemia is a critical public health issue
Peripheral artery disease: potential role of ACE-inhibitor therapy
Subjects with peripheral arterial disease (PAD) of the lower limbs are at high risk for cardiovascular and cerebrovascular events and the prevalence of coronary artery disease in such patients is elevated. Recent studies have shown that regular use of cardiovascular medications, such as therapeutic and preventive agents for PAD patients, seems to be promising in reducing long-term mortality and morbidity. The angiotensin-converting-enzyme (ACE) system plays an important role in the pathogenesis and progression of atherosclerosis, and ACE-inhibitors (ACE-I) seem to have vasculoprotective and antiproliferative effects as well as a direct anti-atherogenic effect. ACE-I also promote the degradation of bradykinin and the release of nitric oxide, a potent vasodilator; further, thay have shown important implications for vascular oxidative stress. Other studies have suggested that ACE-I may also improve endothelial dysfunction. ACE-I are useful for reducing the risk of cardiovascular events in clinical and subclinical PAD. Particularly, one agent of the class (ie, ramipril) has shown in many studies to able to significantly reduce cardiovascular morbidity and mortality in patients with PAD
Digital holographic microscopy for the evaluation of human sperm structure
The morphology of the sperm head has often been correlated with the outcome
of in vitro fertilization (IVF), and has been shown to be the sole parameter in
semen of value in predicting the success of intracytoplasmic sperm injection
(ICSI) and intracytoplasmic morphologically selected sperm injection (IMSI). In
this paper, we have studied whether Digital Holographic (DH) microscopy may be
useful to obtain quantitative data on human sperm head structure and compared
this technique to high power digitally enhanced Nomarski microscope. The main
advantage of DH is that a high resolution 3-D quantitative sample imaging may
be obtained thorugh numerical refocusing at different object planes without any
mechanical scanning. We show that DH can furnish useful information on the
dimensions and structure of human spermatozoo, that cannot be revealed by
conventional phase contrast microscopy. In fact, in this paper DH has been used
to evaluate volume and indicate precise location of vacuoles, thus suggesting
its use as an additional useful prognostic quantitative tool in assisted
reproduction technology (ART)
Intermediate Alpha-1 Antitrypsin Deficiency Can Play a Role in Pulmonary Exacerbation?
Alpha-1 antitrypsin deficiency is generally suspected in young patients with pulmonary emphysema or chronic obstructive pulmonary disease (COPD). Patients often suffer from diagnostic delays or are misdiagnosed, for example, with COPD, asthma, or airway hyperresponsiveness because of the nonspecific nature of respiratory symptoms recognised with Alpha-1 antitrypsin deficiency (AATD). These pathologies develop in homozygous patients (both compromised alleles) with severely deficient protein; however, they are also frequently observed in heterozygous patients (only one compromised allele) for the gene mutation with a more or less deficient protein and functional anatomical damage of varying severity depending on the type of mutation and the exposure to environmental risk factors and/or professional that can trigger the repeated injurious inflammatory process. Case Description: We describe two cases of late diagnosis of alpha- 1 antitrypsin deficiency, with many exacerbations and intermediate level of alpha-1 antitrypsin. Due to the peculiar clinical history, and the PLowell rare mutation, although intermediate AATD, the patients were subjected to replacement therapy and they obtained clinical improvement. Discussion: Both the cases carried a heterozygous PLowell mutation representing two interesting and rare examples of clinical cases with double heterozygosity. The presence in the other AAT allele of the S- mutation in the first case and a concomitant presence of another mutation in the cystic fibrosis gene in the second case contributed to the protease-antiprotease imbalance and, despite intermediate AATD, was the probable cause of the numerous exacerbations. Conclusion: Alpha-1 antitrypsin deficiency should always be suspected in patients with respiratory disease and an unclear or complex clinical history. It may be useful to recognize and evaluate treatment even outside the established parameters, in selected cases
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Tuning the exponential sensitivity of a bound-state-in-continuum optical sensor.
In this work, we investigate the evanescent field sensing mechanism provided by an all-dielectric metasurface supporting bound states in the continuum (BICs). The metasurface is based on a transparent photonic crystal with subwavelength thickness. The BIC electromagnetic field is localized along the direction normal to the photonic crystal nanoscale-thin slab (PhCS) because of a topology-induced confinement, exponentially decaying in the material to detect. On the other hand, it is totally delocalized in the PhCS plane, which favors versatile and multiplexing sensing schemes. Liquids with different refractive indices, ranging from 1.33 to 1.45, are infiltrated in a microfluidic chamber bonded to the sensing dielectric metasurface. We observe an experimental exponential sensitivity leading to differential values as large as 226 nm/RIU with excellent FOM. This behavior is explained in terms of the physical superposition of the field with the material under investigation and supported by a thorough numerical analysis. The mechanism is then translated to the case of molecular adsorption where a suitable theoretical engineering of the optical structure points out potential sensitivities as large as 4000 nm/RIU
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