Fiber Switch Research Articles

Spatial and mode selective switch for orbital angular momentum mode division multiplexing.

In analogy to a wavelength selective switch in wavelength-division multiplexing (WDM) optical fiber communication systems, a spatial and optical mode selective switch (SMSS) would be an important component in future ultrahigh capacity optical fiber communication systems based on space and mode division multiplexing. In this work, a free-space SMSS for orbital angular momentum (OAM) mode-division multiplexing (MDM) is proposed and experimentally demonstrated. The SMSS consists of a separating part for transforming OAM modes to spatial modes and a recombining part for selecting and recombining the modes to any spatial channel. The SMSS is able to implement strictly non-blocking switching between a total of 36 SDM/MDM channels configured as four spatial channels each supporting nine OAM mode channels.

Automated fiber switch with path verification enabled by an AI-powered multi-task mobile robot

As the capacity of optical transport networks undergoes significant growth, there is an ongoing discussion on how to effectively leverage both spectral and spatial degrees of freedom to scale future network capacity. This paper presents an artificial intelligence (AI)-powered multi-task robot comprising a collaborative robotic arm and a mobile robotic base designed for optical network automation. The robot demonstrates the capability of direct fiber switching, establishing static fiber links that consume zero power and have minimal insertion loss from fiber connectors. As a precautionary measure before physically switching fiber cables, the robot performs path verification by detecting robot-driven events using real-time coherent receivers, aiming to avoid accidental unplugging. Additionally, the robot showcases its mobility by efficiently navigating between different network racks and rooms while executing various tasks. Implementing the automation of network operations using robots has the potential to reduce both capital and operational expenditures.

Switching in quantum networks: an optimization investigation

Quantum key distribution (QKD) promises information theoretic security. However, the distances over which complete security can be achieved are fundamentally limited in the absence of quantum repeaters. Thus, a key question is how to build a quantum network (QN) given this restriction. One paradigm that has been considered is trusted node (TN) quantum networks where intermediate trusted nodes are used as relays of quantum keys. Another paradigm is to route key channels through intermediate nodes optically, either through wavelength or fiber switching, thus avoiding the use of TNs. In both of these paradigms, a QKD receiver or transmitter at a specific node can be shared between multiple QKD transmitters or receivers at different nodes in order to reduce the overall costs; this sharing can be enabled via an optical switch. In this paper, we investigate the two paradigms for designing QNs. In the TN model we assume the Decoy BB84 protocol, whereas in the non-TN model, we employ twin-field QKD (TF-QKD) due to the increased single hop distances. We present mixed integer linear program models to optimize network design in both of these paradigms and use these to investigate the viability of switching in the network models as a method of sharing devices. We show that sharing of devices can provide cost reduction in QNs up to a certain transmission requirement rate between users in the TN model, while also providing benefits even at significantly higher transmission requirements in the TF-QKD model. The specific value of this rate is dependent on the network graph; however, for mesh topology TN networks this is expected to occur at average key transmission requirements of ∼1000−5000bits/s. We further use the models to investigate the effects of different network parameters, such as cooling costs, switch frequency, and device costs. We show that cooled detectors are useful in large TF-QKD networks, despite higher costs, but are only useful in TN networks when transmission requirements are very high or cooling is cheap. We also investigate how network costs vary with switching frequency and switch loss, showing that compromising for slightly faster switching times and higher loss switches does not significantly increase network costs; thus a significant effort in improving switch loss may not be necessary. Finally, we look at how the benefits of sharing devices change as the cost of devices changes, showing that for any non-negligible device cost, device sharing is always beneficial at low transmission requirements.

Mitochondrial Quantity and Quality in Age-Related Sarcopenia.

Sarcopenia, the age-associated decline in skeletal muscle mass and strength, is a condition with a complex pathophysiology. Among the factors underlying the development of sarcopenia are the progressive demise of motor neurons, the transition from fast to slow myosin isoform (type II to type I fiber switch), and the decrease in satellite cell number and function. Mitochondrial dysfunction has been indicated as a key contributor to skeletal myocyte decline and loss of physical performance with aging. Several systems have been implicated in the regulation of muscle plasticity and trophism such as the fine-tuned and complex regulation between the stimulator of protein synthesis, mechanistic target of rapamycin (mTOR), and the inhibitor of mTOR, AMP-activated protein kinase (AMPK), that promotes muscle catabolism. Here, we provide an overview of the molecular mechanisms linking mitochondrial signaling and quality with muscle homeostasis and performance and discuss the main pathways elicited by their imbalance during age-related muscle wasting. We also discuss lifestyle interventions (i.e., physical exercise and nutrition) that may be exploited to preserve mitochondrial function in the aged muscle. Finally, we illustrate the emerging possibility of rescuing muscle tissue homeostasis through mitochondrial transplantation.

Loss of lysosomal acid lipase results in mitochondrial dysfunction and fiber switch in skeletal muscles of mice

ObjectiveLysosomal acid lipase (LAL) is the only enzyme known to hydrolyze cholesteryl esters (CE) and triacylglycerols in lysosomes at an acidic pH. Despite the importance of lysosomal hydrolysis in skeletal muscle (SM), research in this area is limited. We hypothesized that LAL may play an important role in SM development, function, and metabolism as a result of lipid and/or carbohydrate metabolism disruptions. ResultsMice with systemic LAL deficiency (Lal−/−) had markedly lower SM mass, cross-sectional area, and Feret diameter despite unchanged proteolysis or protein synthesis markers in all SM examined. In addition, Lal−/− SM showed increased total cholesterol and CE concentrations, especially during fasting and maturation. Regardless of increased glucose uptake, expression of the slow oxidative fiber marker MYH7 was markedly increased in Lal−/−SM, indicating a fiber switch from glycolytic, fast-twitch fibers to oxidative, slow-twitch fibers. Proteomic analysis of the oxidative and glycolytic parts of the SM confirmed the transition between fast- and slow-twitch fibers, consistent with the decreased Lal−/− muscle size due to the “fiber paradox”. Decreased oxidative capacity and ATP concentration were associated with reduced mitochondrial function of Lal−/− SM, particularly affecting oxidative phosphorylation, despite unchanged structure and number of mitochondria. Impairment in muscle function was reflected by increased exhaustion in the treadmill peak effort test in vivo. ConclusionWe conclude that whole-body loss of LAL is associated with a profound remodeling of the muscular phenotype, manifested by fiber type switch and a decline in muscle mass, most likely due to dysfunctional mitochondria and impaired energy metabolism, at least in mice.

Automated fiber switch with path verification enabled by an AI-powered multi-task mobile robot

Automated fiber switch with path verification enabled by an AI-powered multi-task mobile robot

Multi-core fiber rotated optical switch

We propose an optical switch technique that enables unused optical fiber to be activated without on-site work for the purpose of efficiently supporting future optical communication services. The proposed technique performs fiber switching by rotating a multi-core fiber (MCF) by a single motor. The MCF is inserted into a cylindrical ferrule to avoid fiber damage, when rotated against another fiber. The two ferrules are inserted into a sleeve so that their endfaces oppose each other, and the cores are linked across the gap. We optimize the sleeve size not only to reduce the friction between the ferrule and the sleeve, which can create excessive motor power consumption, but also to reduce the loss. We fabricate a 2.5-mm diameter cylindrical ferrule attached a homogeneous MCF with a hexagonal seven-core structure and experimentally evaluate the loss characteristics during rotation of the MCF for core switching. We clarify the potential of the resulting optical switch.

Nitrosative and Oxidative Stress, Reduced Antioxidant Capacity, and Fiber Type Switch in Iron-Deficient COPD Patients: Analysis of Muscle and Systemic Compartments

We hypothesized that a rise in the levels of oxidative/nitrosative stress markers and a decline in antioxidants might take place in systemic and muscle compartments of chronic obstructive pulmonary disease (COPD) patients with non-anemic iron deficiency. In COPD patients with/without iron depletion (n = 20/group), markers of oxidative/nitrosative stress and antioxidants were determined in blood and vastus lateralis (biopsies, muscle fiber phenotype). Iron metabolism, exercise, and limb muscle strength were assessed in all patients. In iron-deficient COPD compared to non-iron deficient patients, oxidative (lipofuscin) and nitrosative stress levels were greater in muscle and blood compartments and proportions of fast-twitch fibers, whereas levels of mitochondrial superoxide dismutase (SOD) and Trolox equivalent antioxidant capacity (TEAC) decreased. In severe COPD, nitrosative stress and reduced antioxidant capacity were demonstrated in vastus lateralis and systemic compartments of iron-deficient patients. The slow- to fast-twitch muscle fiber switch towards a less resistant phenotype was significantly more prominent in muscles of these patients. Iron deficiency is associated with a specific pattern of nitrosative and oxidative stress and reduced antioxidant capacity in severe COPD irrespective of quadriceps muscle function. In clinical settings, parameters of iron metabolism and content should be routinely quantify given its implications in redox balance and exercise tolerance.

Microstructure and high temperature properties of tungsten processed via electron beam melting additive manufacturing

There is considerable interest in the adoption of additive manufacturing for processing refractory metals. The layer-wise fabrication approach enables opportunities for producing complex geometries which cannot be otherwise be achieved via powder metallurgy. However, the processing science is still in its nascent stages and structure–property relations are relatively unexplored. Fundamental research is needed to further develop the technology and enable the fabrication of refractory metals for high temperature applications. Here we focus on the processing of pure tungsten using electron beam melting additive manufacturing. Experimentally we develop a suitable processing window for achieving high density crack free material. Microstructural analysis reveals that the microstructure generally consists of a columnar structure with a 111 build direction fiber preference, although, fiber switching was observed. Process induced deformation is believed to drive the formation of subgrains whose boundaries exhibit a high dislocation density. High temperature tensile testing reveals that the material exhibits excellent properties closer to that of annealed tungsten. Significant mechanical anisotropy was observed to be present which is likely driven by strong crystallographic texture.

Adenovirus vector system: construction, history and therapeutic applications.

Since the isolation of adenovirus (AdV) in 1953, AdVs have been used as vectors for various therapeutic purposes, such as gene therapy in cancers and other malignancies, vaccine development and delivery of CRISPR-Cas9 machinery. Over the years, several AdV vector modifications have been introduced, including fiber switching, incorporation of ligands in the viral capsid and hexon modification of the fiber, to improve the efficiency of AdV as a vector. CRISPR-Cas9 has recently been used for these modifications and is also used in other adeno-associated viruses. These modifications further allow the production of AdV libraries that display random peptides for the production of cancer-targeting AdV vectors. This review focuses on the common methods of AdV construction, changes in AdV tropism for the improvement of therapeutic efficiency and the role of AdV vectors in gene therapy, vaccine development and CRISPR-Cas9 delivery.

Gomisin G improves muscle strength by enhancing mitochondrial biogenesis and function in disuse muscle atrophic mice

Disuse muscle atrophy is characterized by a decrease in muscle mass and strength and an increase in glycolytic muscle fiber type. Although Schisandra chinensis extract has beneficial effects on muscle atrophy induced by various conditions (e.g., dexamethasone and aging), the effect of gomisin G, a lignan component of S. chinensis, on disuse muscle atrophy is unclear. Here, we induced disuse muscle atrophy through wire immobilization of the hind legs in mice followed by the oral administration of gomisin G. The cross-sectional area and muscle strength in disuse muscle atrophic mice were increased by gomisin G; however, the total muscle mass did not increase. Gomisin G decreased the expression of muscle atrophic factors (myostatin, atrogin-1, and MuRF1) but increased the expression of protein synthesis factors (mTOR and 4E-BP1). In H2O2-treated C2C12 myotubes, the level of puromycin incorporation (as a marker of protein synthesis) gradually increased in a dose-dependent manner by gomisin G. Furthermore, gomisin G induced a muscle fiber switch from fast-type glycolytic fibers (type 2B) to slow-type oxidative fibers (type I, 2A) in the gastrocnemius (GA) muscle as proved a decrease in the expression of TnI-FS and an increase in the expression of TnI-SS. Gomisin G increased mitochondrial DNA content and ATP levels in the GA muscle and COX activity in H2O2-treated C2C12 myotubes, improving mitochondrial function. Mechanistically, mitochondrial biogenesis is regulated by gomisin G via the Sirt 1/PGC-1α signaling pathway, targeting NRF1 and TFAM. These data suggest that gomisin G has a potential therapeutic effect on disuse muscle atrophy.

Real-time measurement system for overlapping reflection signals of fiber Bragg gratings using high-speed wavelength-swept laser

We propose a real-time measurement system that prevents overlapping reflection signals in fiber Bragg gratings (FBGs). The system combines a wavelength-swept laser using Fourier domain mode-locking (FDML) and a buffer stage with three optical paths to obtain a high-speed measurement rate of 304.2 kHz. Systems using high-speed wavelength-swept lasers are affected by the propagation time (delay) of the optical fiber. The delay causes problems such as inaccurate measurements, difficulty in distinguishing FBG reflection signals, and overlapping FBG reflection signals. To prevent these problems, we introduce a method for pulse modulation of a wavelength-swept laser by a fiber switch. This method allows for correction of delays by extracting and identifying only the reflection signal of the FBG at a specific wavelength. By identifying the reflection signals of all FBGs, the overlapping signals can be determined. Accordingly, we devise a measurement method that uses a fiber switch to shade light in the wavelength region of one FBG with overlapping signals from the wavelength-swept light of the laser. This method suppresses overlapping and allows only the reflection signal of the other FBGs to be extracted and demodulated. The proposed system uses bidirectional forward and backward scans with the wavelength-swept laser, such that the shaded FBG signals can be demodulated with either scanning direction. We demonstrate that the system using a three-buffered FDML laser can simultaneously measure the strain or vibration of FBGs installed at arbitrary distances.

Skeletal Muscle Dysfunction in Experimental Pulmonary Hypertension Kosmas Kosmas1,2, Zoe Michael2,3, Fotios Spyropoulos1,2, Jeffrey Widrick2,4, Ravi Jasuja2, Aimilia Papathanasiou1,2, Helen Christou 1,21Department of Pediatric Newborn Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA 2Harvard Medical School, Boston, MA 02215, USA 3Department of Pediatrics, Boston Children’s Hospital, Boston, MA 02215, USA 4Department of Genetics, Boston Children’s Hospital, Boston, MA 02215,

BackgroundPulmonary arterial hypertension (PAH), is a progressive disease that seriously compromises quality of life due to dyspnea and fatigue on exertion that worsens over time such that patients are ultimately immobile. Although hemodynamic compromise is the main contributor to exercise intolerance in PAH, accumulating evidence supports that intrinsic skeletal muscle dysfunction also occurs and may contribute to this symptomatology. We previously showed that treatment with the carbonic anhydrase inhibitor Acetazolamide (ACTZ) ameliorates the hemodynamic components of experimental PAH but its effects on skeletal muscle function and exercise tolerance are unknown. Our objective is to characterize the mechanisms of skeletal muscle dysfunction in a preclinical model of severe PAH and evaluate the effect of ACTZ treatment.HypothesesWe hypothesized that reduced exercise endurance in experimental PAH is associated with increased proportion of fast glycolytic (Type II) fibers to slow oxidative (Type I) fibers, and sarcomeric dysfunction in skeletal muscles and that treatment with ACTZ, alters muscle fiber specificity, improves skeletal muscle contractile properties and exercise tolerance.MethodsWe used the adult rat Sprague Dawley sugen/hypoxia (Su/Hx) model of severe pulmonary hypertension and performed hemodynamic and exercise tolerance studies (treadmill). We evaluated the abundance of Type I and Type II fiber specific markers and sarcomeric organization in muscles from Su/Hx and ACTZ treated rats and measured twitch and tetanic forces, contraction and relaxation times in diaphragm, soleus and extensor digitorum longus (EDL). We used the rat myoblast cell line (L6) to evaluate the molecular mechanisms of muscle fiber switch using immunofluorescence, RNA and protein expression studies.ResultsWe found that diaphragm and soleus muscle from the adult rat sugen/hypoxia (Su/Hx) model of severe PAH have increased abundance of type II fiber markers and thick sarcomeric aggregates and these changes are accompanied by decreased twitch and tetanic forces, contraction and half‐relaxation time and exercise endurance despite absence of muscle atrophy. Acetazolamide (ACTZ), treatment restored the above derangements. In vitro rat myotube differentiation was associated with a predominance of type II fiber markers in conjunction with increased abundance of the transcription factor FoxO1. This pattern of increased abundance of FoxO1 and increased type II markers was also seen in Su/Hx soleus muscles and was reversed in response to ACTZ treatment.ConclusionsWe conclude that a shift in skeletal muscle fiber type specification may underlie skeletal muscle dysfunction in experimental PAH and that treatment with ACTZ may ameliorate skeletal muscle dysfunction through an inhibitory effect on FoxO1‐mediated fiber type specification.

Enhancement of a silicon waveguide single photon source by temporal multiplexing

Efficient generation of single photons is one of the key challenges of building photonic quantum technology, such as quantum computers and long-distance quantum networks. Photon source multiplexing—where successful pair generation is heralded by the detection of one of the photons, and its partner is routed to a single mode output—has long been known to offer a concrete solution, with output probability tending toward unity as loss is reduced. Here, we present a temporally multiplexed integrated single photon source based on a silicon waveguide and a low-loss fibre switch and loop architecture, which achieves enhancement of the single photon output probability of 4.5 ± 0.5, while retaining g (2)(0) = 0.01.

Design of a temperature-control optical switch based on conjoined-tubular anti-resonance fiber with toluene core

In this paper, a temperature-control optical switch is designed based on a conjoined-tubular anti-resonance optical fiber (CTF). The CTF adopts eight pairs of conjoined tubes and four vertical-layout holes were coated with Au to increase the fiber confinement loss (Loss). Toluene was used as transmission medium to injected into the CTF core. The proposed switch produces a Loss difference over 100 dB and ER more than 30 dB. Influence of switch material refractive index and structural parameters on optical switch performance was further discussed. The proposed optical fiber switch has the features of simple structure, small size, broad working wavebands and adjustable operation temperature, which promises broad application prospects in industry, chemistry, biology and other fields.

Two-photon-polymerization enabled and enhanced multi-channel fibre switch

This article discusses the fabrication and performance of a multi-channel fibre switch, consisting of 19 single-mode fibres, with enhanced coupling efficiency due to micro-optics, directly printed via two-photon-polymerization on the end-face of each fibre. The use of high-resolution two-photon-polymerization not only allows the enhancement of the coupling efficiency with respect to the coupling device in use but likewise offers great freedom in the arrangement of the used fibres. This letter gives a thorough explanation of the fabrication method as well as the optical simulations for the lenses on the fibre assembly.

Naringin Promotes Skeletal Muscle Fiber Remodeling by the AdipoR1-APPL1-AMPK Signaling Pathway.

Naringin, a natural flavonoid mainly found in citrus fruit, has been reported to exert a positive effect on improving skeletal muscle health. However, the effects and potential mechanisms of naringin on skeletal muscle fiber switching is still unclear. Here, we discovered that oral administration of naringin increased the low-speed running time, four-limb hanging time, body oxygen consumption in mice, enhanced aerobic enzyme activity, MyHC I expression, and slow-twitch fiber percentage in mice skeletal muscle. By contrast, naringin decreased α-GPDH enzyme activity, MyHC IIb expression, and fast-twitch fiber percentage. Moreover, naringin increased the concentration of serum adiponectin and activated the expression of AdipoR1, APPL1, AMPK, and PGC-1α. Furthermore, by the in vitro experiment and AdipoR1 knockdown, we found that inhibition of the AdipoR1 signaling pathway significantly reduced the effect of naringin on slow-twitch fiber-/fast-twitch fiber-related gene and protein expression. In conclusion, our results indicated that naringin could induce skeletal muscle fiber transition from fast twitch to slow twitch via the AdipoR1 signaling pathway. This study may provide new strategy for improving exercise endurance and slow muscle fiber deficiency-related diseases.

Protective effects of Enterococcus faecium strain R30 supplementation on decreased muscle endurance under disuse in rats.

What is the central question of this study? Does Enterococcus faecium strain R30 (R30), a new lactic acid bacterial strain for supplementation, attenuate shifts in the typology of whole muscle fibres from slow- to fast-twitch by altering the autonomic nervous system in atrophied skeletal muscles? What is the main finding and its importance? R30 supplementation may attenuate the shifts in the typology of whole muscle fibres from slow- to fast-twitch fibres by upregulating peroxisome proliferator-activated receptor-γ coactivator-1α and activating the calcineurin-nuclear factor of activated T-cells signalling pathway, thus ameliorating the decrease in muscle endurance associated with disuse. Enterococcus faecium strain R30 (R30), a new lactic acid bacterial strain for supplementation, was hypothesized to attenuate shifts in the typology of whole muscle fibres from slow- to fast-twitch fibres in atrophied skeletal muscles. We further postulated that the prevention of slow-to-fast fibre shifts would suppress the decreased muscle endurance associated with atrophy. To evaluate the protective effects of R30, we analysed slow-to-fast fibre shifts and disuse-associated reduced muscle endurance. R30 was administered to rats with an acclimation period of 7days before hindlimb unloading (HU) for 2weeks. The composition ratio of the fibre type and the expression levels of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), calcineurin and nuclear factor of activated T-cells (NFAT) were measured. Muscle endurance was evaluated at the end of the 2-week HU period in an in situ environment. R30 supplementation suppressed the slow-to-fast fibre switch and decreased the HU-induced expression of PGC-1α proteins and the deactivation of the calcineurin-NFAT pathway. Furthermore, R30 prevented a decrease in HU-associated muscle endurance in calf muscles. These results indicate that R30 supplementation may attenuate the shifts in the typology of whole muscle fibres from slow- to fast-twitch fibres via the upregulation of PGC-1α and the activation of the calcineurin-NFAT signalling pathway, thereby ameliorating the decrease in muscle endurance associated with disuse.

Performance of Dynamic Optical Path Networks with Large-scale WBSS-based Optical Cross-connects

In this paper, we have proposed a generalized large-scale optical cross-connect (OXC) architecture utilizing waveband selective switches (WBSS) for realizing future cost-effective, bandwidth-abundant and flexible optical networks. The developed architecture implements multiple WBSSs for each incoming fiber and small size wavelength selective switches (WSSs) for dropping optical paths while simply deploying 1´2 WSSs or 1´2 optical couplers for realizing the adding function. Thanks to the use of WBSSs, which are more cost-effective and simpler devices, the developed architecture enables a significant hardware scale reduction. The WBSS-based OXC, however, suffers from a limited routing capability, which relies on the inner node parameter (i.e., the WBSS number per input fiber) and the waveband granularity of WBSSs. We, therefore, evaluate the hardware scale requirement of our developed architecture in comparison with that of conventional WSS-based OXC. It is verified that a substantial hardware scale reduction can be achieved by using the proposed architecture, especially for high port count OXCs or when applying coarser granular WBSSs. Moreover, we also assess the performance of dynamic optical networks based on the proposed OXC. Numerical simulations show that the network offers a substantial necessary hardware scale reduction at the cost of a small performance offset comparing to that of the network using conventional WSS-based OXC.

Highly compact and cost-effective 2-beam super-resolution structured illumination microscope based on all-fiber optic components.

Current super-resolution structured illumination microscopes (SR-SIM) utilize relatively expensive electro-optic components and free-space optics, resulting in large setups. Moreover, high power laser sources are required to compensate for the losses associated with generating the illumination pattern by diffractive optics. Here, we present a highly compact and flexible 2D SR-SIM microscope based on all-fiber optic components (fiberSIM). Fiber-splitters deliver the laser light to the sample resulting in the interference illumination pattern. A microelectromechanical systems (MEMS) based fiber switch performs rapid pattern rotation. The pattern phase shift is achieved by the spatial displacement of one arm of the fiber interferometer using a piezoelectric crystal. Compared with existing methods, fiberSIM is highly compact and significantly reduces the SR-SIM component cost while achieving comparable results, thus providing a route to making SR-SIM technology accessible to even more laboratories in the life sciences.