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2.
J Dent Res ; : 22034519875443, 2019 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-31537151

RESUMO

Periodontitis has low-prevalence, highly severe disease manifestations with an early onset and rapid progression. The diagnosis is based on severe destruction of the alveolar bone in adolescents and young adults. Genetic susceptibility variants and smoking are well-established risk factors, but their interactions in modifying disease susceptibility have not been studied. We aimed to identify genetic risk variants of early-onset periodontitis that unmask their effects on tobacco smoke exposure. To this end, we analyzed 79,780,573 common variants in 741 northwest Europeans diagnosed to have >30% bone loss at >2 teeth before 35 y of age, using imputed genotypes of the OmniExpress BeadChip. Never versus ever smokers were compared in a logistic regression analysis via a case-only approach. To explore the effect of tobacco smoke on the expression of the G×S-associated genes, cultures of primary gingival fibroblasts (n = 9) were exposed to cigarette smoke extract, and transcripts were quantified by reverse transcription polymerase chain reaction. We identified 16 loci for which our analysis suggested an association with G×S increased disease risk (P < 5 × 10-5). Nine loci had previously been reported to be associated with spirometric measures of pulmonary function by an earlier G×S genome-wide association study. Genome-wide significant cis expression quantitative trait loci were reported for G×S-associated single-nucleotide polymorphisms at ST8SIA1 and SOST, indicating a causal role of these genes in tobacco-related etiopathology. Notably, SOST is a negative regulator of bone growth, and ST8SIA1 has a role in tissue remodeling. Cigarette smoke extract significantly altered the expression of 2 associated genes: SSH1 (P = 5 × 10-07), which is required for NF-κB activation and innate immune responses to bacterial invasion, and ST8SIA1 (P = 0.0048). We conclude that the genetic predisposition to early-onset periodontitis is in part triggered by smoking and that tobacco smoke directly affects the expression of genes involved in bone homeostasis, tissue repair, and immune response.

3.
Orthopade ; 2019 Aug 30.
Artigo em Alemão | MEDLINE | ID: mdl-31471643

RESUMO

BACKGROUND: Osteoarthritis is the most common joint disease worldwide and mostly affects the knee joint (gonarthrosis). In treatment algorithms, technical aids in the form of laterally wedged insoles, valgizing knee braces and ankle-foot orthoses have an importance in the treatment of medial unicompartmental knee joint disease. However, national and international guidelines differ in their recommendations. INSOLES: Taking into account a great amount of scientific work, the measurable effect of laterally wedged insoles appears to be low, so that a justifying indication only exists at low gonarthrosis levels. KNEE BRACES: Valgizing knee braces have shown stronger biomechanical and clinical effects, but with a slightly increased complication potential and low compliance. Low to medium-grade arthrosis can be treated. ANKLE-FOOT ORTHOSES: Ankle-foot arthroses have not yet been conclusively examined. Initial work indicates biomechanical and clinical efficacy. The overall effects and indications appear comparable to knee braces, probably with less complication potential.

4.
J Burn Care Res ; 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31294797

RESUMO

Obesity and the related medical, social and economic impacts are relevant multifactorial and chronic conditions that also have a meaningful impact on outcomes following severe injury, including burns. In addition to burn-specific difficulties such as adequate hypermetabolic response, fluid resuscitation and early wound coverage, obese patients also present with common comorbidities such as arterial hypertension, diabetes mellitus or non-alcoholic fatty liver disease. In addition, the pathophysiologic response to severe burns can be enhanced. Besides the increased morbidity and mortality compared to burn patients with normal weight, obese patients present a challenge in fluid resuscitation, perioperative management, and difficulties in wound healing. The present work is an in-depth review of the current understanding of the influence of obesity on the management and outcome of severe burns.

5.
Gait Posture ; 73: 1-7, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31299498

RESUMO

BACKGROUND: In subjects with Chopart amputation the foot lever is clearly diminished. Usually high or low profile prostheses are routinely utilized to re-establish the lost forefoot lever. RESEARCH QUESTION: The aim of this study was to investigate to what extent the proposed prostheses were able to replace the forefoot lever in chopart-amputees. METHODS: An instrumented 3D gait analysis, including plantar and socket pressure measurements, was performed in thirteen subjects with Chopart amputation using a clamshell and/or a Bellmann prosthesis including an ankle foot orthosis during level ground walking. RESULTS: The largest range of motion (p < 0.05) in the ankle joint was seen for the Bellmann prosthesis (32 ±â€¯3°) followed by the Bellmann prosthesis with ankle-foot orthosis (22 ±â€¯6°) whereas in the clamshell prosthesis (10 ±â€¯4°) almost no ankle motion was seen. Conversely, the highest ankle joint moment (p < 0.05) was seen for the clamshell prosthesis (1.04 ±â€¯0.24Nm/kg) followed by the Bellmann prosthesis with ankle-foot orthosis (0.66 ±â€¯0.14Nm/kg) and, finally, the Bellmann (0.37 ±â€¯0.11Nm/kg) alone offering the lowest joint moment. CONCLUSION: High-profile prostheses with ventral shell are more suitable to reacquire the lost forefoot lever after Chopart amputation. However, the issue of restricted range of motion in the ankle joint with the clamshell prosthesis needs to be addressed.

6.
Am J Physiol Regul Integr Comp Physiol ; 317(3): R491-R501, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31314544

RESUMO

The vitamin D-folate hypothesis has been proposed as an explanation for the evolution of human skin pigmentation. According to this hypothesis, a darkened skin pigment was adapted by early human populations living in equatorial Africa to protect against photodegradation of bioavailable folate by ultraviolet radiation (UVR). As humans moved away from the equator to more northern latitudes and occupied regions of lower UVR exposure and greater seasonal variation, however, depigmentation occurred to allow for adequate biosynthesis of vitamin D. Vitamin D and folate are both recognized for their evolutionary importance in healthy pregnancy and early childhood development. More recently, evidence has emerged demonstrating the importance of both vitamin D and folate in vascular health via their effects in reducing oxidative stress and improving nitric oxide (NO) bioavailability. Thus, populations with darkened skin pigmentation may be at elevated risk of vascular dysfunction and cardiovascular disease in low UVR environments due to hypovitaminosis D; particularly important as darkly-pigmented African-Americans represent an at-risk population for cardiovascular disease. Conversely, lightly pigmented populations in high UVR environments may be at risk of deleterious vascular effects of UVR-induced folate degradation. The focus of this review is to explore the currently available literature regarding the potential role of UVR in vascular health via its differential effects on vitamin D and folate metabolism, as well as the interaction between skin pigmentation, genetics, and environment in modulating the vascular influence of UVR exposure.

7.
Am J Clin Nutr ; 109(6): 1640-1647, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31051498

RESUMO

BACKGROUND: The beverage hydration index (BHI) is a composite measure of fluid balance after consuming a test beverage relative to water. BHI is a relatively new measure that has been explored in young, but not yet older, adults. OBJECTIVE: The aim of this study was to investigate potential differences in BHI between euhydrated younger and older adults after drinking 4 different commercial beverages. We hypothesized that 1) older subjects would remain in positive fluid balance longer than young subjects after ingestion of each test beverage due to decreased urinary excretion rates, 2) glucose (glu)- and amino acid (AA)-based hydration beverages with sodium would have a BHI greater than water in both groups, and 3) the traditional 2-h postingestion BHI may be inappropriate for older adults. METHODS: On 5 separate visits, 12 young (23 ± 3 yr, 7 M/5F) and 12 older (67 ± 6 yr, 5 M/7F) subjects consumed 1 L of distilled water, G-20 (6% CHO, 20 mmol/L Na+), G-45 (2.5% CHO, 45 mmol/L Na+), AA-30 (5 AAs, 30 mmol/L Na+), or AA-60 (8 AAs, 60 mmol/L Na+) over 30 min. Blood and urine samples were collected before ingestion and at 0, 60, 120, 180, and 240 min postingestion with additional venous blood sampling at 5, 10, 15, and 30 min postingestion. RESULTS: In young subjects, BHI increased with increasing beverage Na+ concentration, and AA-60 had the highest BHI (AA-60 = 1.24 ± 0.10 compared with water = 1.00, P = 0.01). For older subjects, BHI was highest in AA-30 (AA-30; 1.20 ± 0.13 compared with water, P < 0.01) and was still in flux beyond 2 h in AA-60 (P < 0.05). CONCLUSIONS: Beverage Na+ content progressively increased BHI in young adults independent of glucose or AA content. For older adults, the AA-30 beverage had the highest BHI. A 4-h BHI may be more appropriate for older adults due to attenuated urine excretion rates. This trial was registered at clinicaltrials.gov as NCT03559101.

8.
Orthopade ; 2019 May 14.
Artigo em Alemão | MEDLINE | ID: mdl-31089773

RESUMO

Although the number of major amputations is declining throughout Germany, more than 57,000 surgical procedures for amputation still take place. As a consequence of high prosthetic care costs, these often lead to disputes before the social court in which expert medical opinions are required. With knowledge of the legal norms, the remit of the expert opinion can be fulfilled. The expert begins with evaluation of the patient's file and a search of the contested parts. The investigation includes a medical history, in addition to a physical examination, in order to be able to comment on the disputed beneficial use of the therapeutic appliance and respond to questions of proof. Questionnaires may be helpful.

9.
Exp Physiol ; 104(7): 1136-1146, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31004462

RESUMO

NEW FINDINGS: What is the central question of this study? Are ultraviolet radiation (UVR)-induced increases in skin blood flow independent of skin erythema? Does broad-spectrum UVR exposure attenuate NO-mediated cutaneous vasodilatation, and does sunscreen or sweat modulate this response? What are the main findings and their importance? Erythema and vascular responses to UVR are temporally distinct, and sunscreen prevents both responses. Exposure to UVR attenuates NO-mediated vasodilatation in the cutaneous microvasculature; sunscreen or simulated sweat on the skin attenuates this response. Sun over-exposure may elicit deleterious effects on human skin that are separate from sunburn, and sunscreen or sweat on the skin may provide protection. ABSTRACT: Exposure to ultraviolet radiation (UVR) may result in cutaneous vascular dysfunction independent of erythema (skin reddening). Two studies were designed to differentiate changes in erythema from skin vasodilatation throughout the 8 h after acute broad-spectrum UVR exposure with (+SS) or without SPF-50 sunscreen (study 1) and to examine NO-mediated cutaneous vasodilatation after acute broad-spectrum UVR exposure with or without +SS or simulated sweat (+SW) on the skin (study 2). In both studies, laser-Doppler flowmetry was used to measure red cell flux, and cutaneous vascular conductance (CVC) was calculated (CVC = flux/mean arterial pressure). In study 1, in 14 healthy adults (24 ± 4 years old; seven men and seven women), the skin erythema index and CVC were measured over two forearm sites (UVR only and UVR+SS) before, immediately after and every 2 h for 8 h post-exposure (750 mJ cm-2 ). The erythema index began to increase immediately post-UVR (P < 0.05 at 4, 6 and 8 h), but CVC did not increase above baseline for the first 4-6 h (P ≤ 0.01 at 6 and 8 h); +SS prevented both responses. In study 2, in 13 healthy adults (24 ± 4 years old; six men and seven women), three intradermal microdialysis fibres were placed in the ventral skin of the forearm [randomly assigned to UVR (450 mJ cm-2 ), UVR+SS or UVR+SW], and one fibre (non-exposed control; CON) was placed in the contralateral forearm. After UVR, a standardized local heating (42°C) protocol quantified the percentage of NO-mediated vasodilatation (%NO). The UVR attenuated %NO compared with CON (P = 0.01). The diminished %NO was prevented by +SS (P < 0.01) and +SW (P < 0.01). Acute broad-spectrum UVR attenuates NO-dependent dilatation in the cutaneous microvasculature, independent of erythema. Sunscreen protects against both inflammatory and heating-induced endothelial dysfunction, and sweat might prevent UVR-induced reductions in NO-dependent dilatation.

10.
J Appl Physiol (1985) ; 126(4): 1042-1048, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30763158

RESUMO

Aging is associated with altered water, electrolyte, and glucose handling. Alternative beverages to those containing carbohydrate (CHO) should be considered for older adults. We hypothesized that reduced sodium (CNa+) and/or water (CH2O) clearance would underlie greater beverage retention in older compared with young adults, secondary to reduced glomerular filtration rate (GFR). We further hypothesized that amino acid (AA)- and CHO-based beverages would promote retention better than water. Over five visits, 12 young (23 ± 3 yr; 7 men, 5 women) and 12 older (67 ± 6 yr; 5 men, 7 women) subjects consumed 1 liter of distilled water or beverages with 6% CHO, 0.46 g/l Na+ [Gatorade (GAT)]; 2.5% CHO, 0.74 g/l Na+ [Pedialyte (PED)]; 5 AA, 1.04 g/l Na+ [enterade (ENT)-5]; or 8 AA, 1.38 g/l Na+ (ENT-8) over 30 min. Blood and urine were collected every hour for 4 h after ingestion; retention, CH2O, and CNa+ were calculated at 2 and 4 h. Additional calculations adjusted CH2O and CNa+ for estimated GFR (eGFR). Water yielded the lowest retention in both groups ( P ≤ 0.02). Retention was higher in older vs. young adults except for ENT-8 at 4 h ( P = 0.73). CH2O was higher for older vs. young adults for GAT at 2 h ( P < 0.01) and GAT and PED at 4 h ( P < 0.01) after ingestion but was otherwise similar between groups. CNa+ was lower in older vs. young adults except for ENT-8 ( P ≥ 0.19). Adjusting for eGFR resulted in higher CH2O for all beverages in older vs. young adults ( P < 0.05) but did not influence CNa+. Older adults may better retain beverages with less Na+ than young adults because of reduced CNa+. AA- and CHO-based electrolyte-rich beverages may similarly promote beverage retention. NEW & NOTEWORTHY Commercially available amino acid (AA)-containing beverages may provide an alternative to traditional carbohydrate (CHO)-containing beverages, particularly for older adults with attenuated water, electrolyte, and glucose handling. We compared beverage retention and free water and sodium clearance between young and older adults after ingestion of water, two CHO-based beverages, and two AA-based beverages. Our data suggest that older adults better retain beverages with less sodium compared with young adults and that AA-based and CHO-based electrolyte-containing beverages similarly promote retention.

11.
Gait Posture ; 68: 525-530, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30623847

RESUMO

BACKGROUND: Treatment of cerebral palsy includes an interdisciplinary concept and in more severe cases the well-established multi-level surgery (MLS). Different kinds of orthoses are typically part of postoperative treatment but there is a lack of knowledge about their additional benefit. RESEARCH QUESTION: Do ankle foot orthoses lead to an additional, measurable improvement of gait after MLS? METHODS: 20 children with bilateral spastic cerebral palsy (9 retrospective, 11 in a postoperative clinical routine) were included. All had a preoperative gait analysis before MLS. Postoperatively, they were fitted with different ankle foot orthoses (AFO), depending on their individual needs. Dynamic ankle foot orthoses (DAFO), combined DAFO with additional dynamic, elastic shank adaptation (DESA) and ground reaction force AFOs (GRAFO) were used. Patients underwent a second gait analysis 1.5 (± 0.6) years postoperatively barefoot and with orthoses. Data analysis included testing for normal distribution (Shapiro-Wilk-Test) and further nonparametric statistical testing on basis of a Wilcoxon Single-Rank Test. RESULTS: The operation produced changes in the hip, knee and ankle joint, and the pelvis. Spatiotemporal parameters showed significant changes due to additional use of the orthoses. Further, additional kinematic changes occurred at the hip, knee and ankle joint as well as the foot. The Gillette Gait Index (GGI) improved significantly by supplementary orthoses, but not by surgery alone. The Gait Profile Score (GPS) and Gait Deviation Index (GDI) rather showed changes due to the surgery. SIGNIFICANCE: MLS significantly improves GPS and GDI more than a year after surgery, which can be interpreted as an improvement in gait pattern. In contrast, the GGI is improved by additional postoperative orthotic treatment, which implies that walking ability itself has improved, rather than the gait pattern. Orthoses show a positive additional effect on surgical results at different anatomical levels. Spatiotemporal parameters are positively influenced solely by additional orthotic support.


Assuntos
Articulação do Tornozelo/fisiopatologia , Paralisia Cerebral/cirurgia , Órtoses do Pé , Transtornos Neurológicos da Marcha/reabilitação , Marcha/fisiologia , Articulação do Joelho/fisiopatologia , Procedimentos Neurocirúrgicos/métodos , Adolescente , Fenômenos Biomecânicos , Paralisia Cerebral/complicações , Paralisia Cerebral/fisiopatologia , Criança , Feminino , Transtornos Neurológicos da Marcha/etiologia , Humanos , Masculino , Período Pós-Operatório , Estudos Retrospectivos
12.
Eur J Neurol ; 26(6): 887-892, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30624008

RESUMO

BACKGROUND AND PURPOSE: Here, we studied the safety of apnea testing (AT) for the determination of brain death with regard to intracranial pressure (ICP), cerebral perfusion and arterial blood gas parameters. We hypothesized that ICP only increases when cerebral perfusion pressure (CPP) remains positive during AT. METHODS: A total of 34 patients who fulfilled brain death criteria were identified by chart review (2009-2017). We analysed ICP, CPP and mean arterial pressure (MAP) prior to AT, during AT and after AT, as well as arterial pH, paCO2 , paO2 and arterial O2 saturation at the start and end of AT. RESULTS: Intracranial pressure was 87.9 ± 17.7 mmHg (mean ± SD) prior to AT, 89.9 ± 17.2 mmHg during AT and 86.4 ± 15.2 mmHg after AT (P = 0.9). CPP was -6.9 ± 12.8 mmHg prior to AT, -7.1 ± 13.7 mmHg during AT and -8.6 ± 13.0 mmHg after AT (P = 0.98), respectively. MAP was 82.9 ± 14.6 mmHg prior to AT, 84.7 ± 13.9 mmHg during AT and 79.7 ± 9.6 mmHg after AT (P = 0.57), respectively. A total of 10 patients had positive CPP (8.6 ± 4.3 mmHg), but ICP did not increase during AT. Arterial pH decreased from 7.43 ± 0.06 to 7.22 ± 0.06 (P < 0.05), paCO2 increased from 38.6 ± 4.2 to 69.6 ± 8.0 mmHg (P < 0.05), paO2 decreased from 416.3 ± 113.4 to 289.2 ± 146.5 mmHg (P < 0.05), and O2 saturation was stable at 99.8 ± 0.4% and 98.2 ± 3.2% (P = 0.39). CONCLUSIONS: Apnea testing had no detrimental effect on ICP, CPP, MAP or oxygenation, regardless of the presence of an initially positive CPP. The lack of further ICP elevations is presumably explained by critical closing pressures above individual CPP levels during AT.

14.
Rev Sci Instrum ; 89(10): 10H115, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30399932

RESUMO

A passive phased array Doppler reflectometry system has recently been installed in the Wendelstein-7X stellarator. In contrast to conventional Doppler reflectometry systems, the microwave beam can be steered on short time scales in the measurement plane perpendicular to the magnetic field in the range of ±25° without mechanical steering components. This paper characterizes the design and properties of the phased array antenna system and presents the first measurement results from the latest OP1.2a campaign.

15.
Nutr Metab Cardiovasc Dis ; 28(11): 1100-1105, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30143407

RESUMO

BACKGROUND AND AIMS: Chronic inflammatory diseases (CID) are associated with a profound increase in cardiovascular (CV) risk resulting in reduced life expectancy. However, LDL-cholesterol is reported to be low in CID patients which is referred to as the "LDL paradoxon". The aim of the present study was to investigate whether LDL-particles in CID exhibit an increased content of the highly atherogenic small-dense LDL subfraction (sdLDL). METHODS AND RESULTS: In this prospective, single center, observational study we enrolled 141 patients with CID (RA n = 59, inflammatory bowel disease (IBD) n = 35, ankylosing spondylitis (SpA) n = 25, Psoriasis n = 22) in 2011 through 2013 to evaluate sdLDL levels before as well as 6 and 26 weeks after initiation of different anti-cytokine therapies (anti-TNFα, anti-IL-6R antibodies). sdLDL levels were compared to 141 healthy individuals in a case control design. Compared to healthy controls, all CID patients displayed a significantly higher sdLDL content within the LDL cholesterol fraction: RA 35.0 ± 9.2% (p < 0.001), SpA 42.5 ± 10.5% (p < 0.001), IBD 37.5 ± 7.1% (p < 0.001), Psoriasis 33.6 ± 4.6% (p < 0.01). Furthermore, the sdLDL/LDL ratio was significantly higher in male compared to female RA subjects (p < 0.05). Neither anti-TNFα nor anti-IL6R medication altered sdLDL levels despite a significant improvement of disease activity. CONCLUSION: In several different chronic inflammatory disease entities, LDL-cholesterol is shifted toward a pro-atherogenic phenotype due to an increased sdLDL content which might in part explain the LDL paradoxon. Since premature CV disease is a major burden of affected patients, specifically targeting lipid metabolism should be considered routinely in clinical patient care. CLINICAL TRIALS: Registration at German Clinical Trial Register (DRKS): DRKS00005285.

16.
Artigo em Inglês | MEDLINE | ID: mdl-30138076

RESUMO

5-methyltetrahydrofolate (5-MTHF) is important for nitric oxide (NO)-mediated cutaneous microvascular vasodilation. Ultraviolet B (UVB) radiation may deplete 5-MTHF, either directly or via production of reactive oxygen species (ROS), decreasing NO-mediated vasodilation. We hypothesized that 1) acute UVB exposure would attenuate NO-dependent cutaneous vasodilation, 2) local perfusion of 5-MTHF or ascorbate (ASC; anti-oxidant) would augment NO-dependent vasodilation after UVB, and 3) darker skin pigmentation would be UVB-protective. Three intradermal microdialysis fibers placed in each forearm of 21 healthy young adults (23±1 yr; 8M/13F) locally delivered lactated Ringer's (control), 5mM 5-MTHF, or 10mM ASC. One arm was UVB-exposed (300mJ/cm2), the other served as non-exposed control (CON). Following UVB exposure, a standardized local heating (42˚C) protocol induced cutaneous vasodilation. After attaining a plateau blood flow, 15mM NG-nitro-L-arginine methyl ester (L-NAME; nitric oxide synthase inhibiter) was infused at all sites to quantify the NO contribution. Red cell flux was measured at each site by laser-Doppler flowmetry (LDF) and cutaneous vascular conductance (CVC=LDF/MAP) was expressed as a percentage of maximum (%CVCmax; 28mM sodium nitroprusside+43°C). UVB attenuated NO-mediated vasodilation compared to CON (23.1±3.6 vs 33.9±3.4 %; p=0.001). Delivery of 5-MTHF or ASC improved NO-mediated vasodilation versus lactated Ringer's in the UVB-exposed arm (MTHF: 30.1±4.8 vs 23.1±3.8 %; p=0.03; ASC: 30.9±4.3 vs 23.1±3.8 %; p=0.02). Neither treatment affected the response in the non-exposed arm (p≥0.09). Skin pigmentation (M-index) was not predictive of the UVB response (p≥0.34). These data suggest that acute UVB exposure attenuates NO-mediated vasodilation via direct and/or ROS-induced reductions in 5-MTHF, independent of skin pigmentation.

18.
Science ; 359(6378): 887-891, 2018 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-29472477

RESUMO

Light detection and ranging is widely used in science and industry. Over the past decade, optical frequency combs were shown to offer advantages in optical ranging, enabling fast distance acquisition with high accuracy. Driven by emerging high-volume applications such as industrial sensing, drone navigation, or autonomous driving, there is now a growing demand for compact ranging systems. Here, we show that soliton Kerr comb generation in integrated silicon nitride microresonators provides a route to high-performance chip-scale ranging systems. We demonstrate dual-comb distance measurements with Allan deviations down to 12 nanometers at averaging times of 13 microseconds along with ultrafast ranging at acquisition rates of 100 megahertz, allowing for in-flight sampling of gun projectiles moving at 150 meters per second. Combining integrated soliton-comb ranging systems with chip-scale nanophotonic phased arrays could enable compact ultrafast ranging systems for emerging mass applications.

19.
Opt Express ; 26(1): 220-232, 2018 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-29328299

RESUMO

We demonstrate the generation of higher-order modulation formats using silicon-based inphase/quadrature (IQ) modulators at symbol rates of up to 100 GBd. Our devices exploit the advantages of silicon-organic hybrid (SOH) integration, which combines silicon-on-insulator waveguides with highly efficient organic electro-optic (EO) cladding materials to enable small drive voltages and sub-millimeter device lengths. In our experiments, we use an SOH IQ modulator with a π-voltage of 1.6 V to generate 100 GBd 16QAM signals. This is the first time that the 100 GBd mark is reached with an IQ modulator realized on a semiconductor substrate, leading to a single-polarization line rate of 400 Gbit/s. The peak-to-peak drive voltages amount to 1.5 Vpp, corresponding to an electrical energy dissipation in the modulator of only 25 fJ/bit.

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