Fiber-Optic Technologies for Wireline and Wireless In-building Networks

This doctoral dissertation aims to establish fiber-optic technologies overcoming the limiting issues of data communications in indoor environments. Specific applications are broadband mobile distribution in different in-building scenarios and high-speed digital transmission over short-range wired optical systems. Two key enabling technologies are considered: Radio over Fiber (RoF) techniques over standard silica fibers for distributed antenna systems (DAS) and plastic optical fibers (POFs) for short-range communications. Hence, the objectives and achievements of this thesis are related to the application of RoF and POF technologies in different in-building scenarios. On one hand, a theoretical and experimental analysis combined with demonstration activities has been performed on cost-effective RoF systems. An extensive modeling on modal noise impact both on linear and non-linear characteristics of RoF link over silica multimode fiber has been performed to achieve link design rules for an optimum choice of the transmitter, receiver and launching technique. A successful transmission of Long Term Evolution (LTE) mobile signals on the resulting optimized RoF system over silica multimode fiber employing a Fabry-Perot LD, central launch technique and a photodiode with a built-in ball lens was demonstrated up to 525m with performances well compliant with standard requirements. On the other hand, digital signal processing techniques to overcome the bandwidth limitation of POF have been investigated. An uncoded net bit-rate of 5.15Gbit/s was obtained on a 50m long POF link employing an eye-safe transmitter, a silicon photodiode, and DMT modulation with bit and power loading algorithm. With the insertion of 3x2N quadrature amplitude modulation constellation formats, an uncoded net-bit-rate of 5.4Gbit/s was obtained on a 50 m long POF link employing an eye-safe transmitter and a silicon avalanche photodiode. Moreover, simultaneous transmission of baseband 2Gbit/s with DMT and 200Mbit/s with an ultra-wideband radio signal has been validated over a 50m long POF link.

Ultra-low power WSNs: distributed signal processing and dynamic resource management

This thesis presents several data processing and compression techniques capable of addressing the strict requirements of wireless sensor networks. After introducing a general overview of sensor networks, the energy problem is introduced, dividing the different energy reduction approaches according to the different subsystem they try to optimize. To manage the complexity brought by these techniques, a quick overview of the most common middlewares for WSNs is given, describing in detail SPINE2, a framework for data processing in the node environment. The focus is then shifted on the in-network aggregation techniques, used to reduce data sent by the network nodes trying to prolong the network lifetime as long as possible. Among the several techniques, the most promising approach is the Compressive Sensing (CS). To investigate this technique, a practical implementation of the algorithm is compared against a simpler aggregation scheme, deriving a mixed algorithm able to successfully reduce the power consumption. The analysis moves from compression implemented on single nodes to CS for signal ensembles, trying to exploit the correlations among sensors and nodes to improve compression and reconstruction quality. The two main techniques for signal ensembles, Distributed CS (DCS) and Kronecker CS (KCS), are introduced and compared against a common set of data gathered by real deployments. The best trade-off between reconstruction quality and power consumption is then investigated. The usage of CS is also addressed when the signal of interest is sampled at a Sub-Nyquist rate, evaluating the reconstruction performance. Finally the group sparsity CS (GS-CS) is compared to another well-known technique for reconstruction of signals from an highly sub-sampled version. These two frameworks are compared again against a real data-set and an insightful analysis of the trade-off between reconstruction quality and lifetime is given.

THERMAL CHARACTERIZATION OF A GASOLINE TURBOCHARGED DIRECT INJECTION (GTDI) ENGINE UTILIZING LEAN OPERATION AND EXHAUST GAS RECIRCULATION (EGR)

The push for improved fuel economy and reduced emissions has led to great achievements in engine performance and control. These achievements have increased the efficiency and power density of gasoline engines dramatically in the last two decades. With the added power density, thermal management of the engine has become increasingly important. Therefore it is critical to have accurate temperature and heat transfer models as well as data to validate them. With the recent adoption of the 2025 Corporate Average Fuel Economy(CAFE) standard, there has been a push to improve the thermal efficiency of internal combustion engines even further. Lean and dilute combustion regimes along with waste heat recovery systems are being explored as options for improving efficiency. In order to understand how these technologies will impact engine performance and each other, this research sought to analyze the engine from both a 1st law energy balance perspective, as well as from a 2nd law exergy analysis. This research also provided insights into the effects of various parameters on in-cylinder temperatures and heat transfer as well as provides data for validation of other models. It was found that the engine load was the dominant factor for the energy distribution, with higher loads resulting in lower coolant heat transfer and higher brake work and exhaust energy. From an exergy perspective, the exhaust system provided the best waste heat recovery potential due to its significantly higher temperatures compared to the cooling circuit. EGR and lean combustion both resulted in lower combustion chamber and exhaust temperatures; however, in most cases the increased flow rates resulted in a net increase in the energy in the exhaust. The exhaust exergy, on the other hand, was either increased or decreased depending on the location in the exhaust system and the other operating conditions. The effects of dilution from lean operation and EGR were compared using a dilution ratio, and the results showed that lean operation resulted in a larger increase in efficiency than the same amount of dilution with EGR. Finally, a method for identifying fuel spray impingement from piston surface temperature measurements was found. Note: The material contained in this section is planned for submission as part of a journal article and/or conference paper in the future.

Combined ultrasmall superparamagnetic particles of iron oxide-enhanced and diffusion-weighted magnetic resonance imaging reliably detect pelvic lymph node metastases in normal-sized nodes of bladder and prostate cancer patients

BACKGROUND: Lymph node staging of bladder or prostate cancer using conventional imaging is limited. Newer approaches such as ultrasmall superparamagnetic particles of iron oxide (USPIO) and diffusion-weighted magnetic resonance imaging (DW-MRI) have inconsistent diagnostic accuracy and are difficult to interpret. OBJECTIVE: To assess whether combined USPIO and DW-MRI (USPIO-DW-MRI) improves staging of normal-sized lymph nodes in bladder and/or prostate cancer patients. DESIGN, SETTING, AND PARTICIPANTS: Twenty-one consecutive patients with bladder and/or prostate cancer were enrolled between May and October 2008. One patient was excluded secondary to bone metastases detected on DW-MRI with subsequent abstention from surgery. INTERVENTION: Patients preoperatively underwent 3-T MRI before and after administration of lymphotropic USPIO using conventional MRI sequences combined with DW-MRI. Surgery consisted of extended pelvic lymphadenectomy and resection of primary tumors. MEASUREMENTS: Diagnostic accuracies of the new combined USPIO-DW-MRI approach compared with the "classic" reading method evaluating USPIO images without and with DW-MRI versus histopathology were evaluated. Duration of the two reading methods was noted for each patient. RESULTS AND LIMITATIONS: Diagnostic accuracy (90% per patient or per pelvic side) was comparable for the classic and the USPIO-DW-MRI reading method, while time of analysis with 80 min (range 45-180 min) for the classic and 13 min (range 5-90 min) for the USPIO-DW-MRI method was significantly shorter (p<0.0001). Interobserver agreement (three blinded readers) was high with a kappa value of 0.75 and 0.84, respectively. Histopathological analysis showed metastases in 26 of 802 analyzed lymph nodes (3.2%). Of these, 24 nodes (92%) were correctly diagnosed as positive on USPIO-DW-MRI. In two patients, one micrometastasis each (1.0x0.2 mm; 0.7x0.4 mm) was missed in all imaging studies. CONCLUSIONS: USPIO-DW-MRI is a fast and accurate method for detecting pelvic lymph node metastases, even in normal-sized nodes of bladder or prostate cancer patients.

Prothrombotic changes with acute psychological stress: combined effect of hemoconcentration and genuine coagulation activation

INTRODUCTION: Acute psychosocial stress accelerates blood coagulation and elicits hemoconcentration which mechanisms are implicated in acute coronary thrombotic events. We investigated the extent to which the change in prothrombotic measures with acute stress reflects hemoconcentration and genuine activation of coagulation. MATERIAL AND METHODS: Twenty-one middle-aged healthy men underwent three sessions of a combined speech and mental arithmetic task with one-week intervals. Coagulation and plasma volume were assessed at baseline, immediately post-stress, and 45 min post-stress at sessions one and three. Measures of both visits were aggregated to enhance robustness of individual biological stress responses. Changes in eight coagulation measures with and without adjustment for simultaneous plasma volume shift were compared. RESULTS: From baseline to immediately post-stress, unadjusted levels of fibrinogen (p=0.028), clotting factor VII activity (FVII:C) (p=0.001), FVIII:C (p<0.001), FXII:C (p<0.001), and von Willebrand factor (VWF) (p=0.008) all increased. Taking into account hemoconcentration, fibrinogen (p=0.020) and FVII:C levels (p=0.001) decreased, activated partial prothrombin time (APPT) shortened (p<0.001) and prothrombin time (PT) was prolonged (p<0.001). Between baseline and 45 min post-stress, unadjusted (p=0.050) and adjusted (p=0.001) FVIII:C levels increased, adjusted APTT was prolonged (p=0.017), and adjusted PT was shortened (p=0.033). D-dimer levels did not significantly change over time. CONCLUSIONS: Adjustment for stress-hemoconcentration altered the course of unadjusted levels of several prothrombotic factors. After adjustment for hemoconcentration, APPT was shortened immediately post-stress, whereas 45 min post-stress, FVIII:C was increased and PT was shortened. Procoagulant changes to acute stress may reflect both hemoconcentration and genuine activation of coagulation molecules and pathways.

The Magnetism of Power in Helping Relationships. Professional Attitude and Asymmetry

What makes helping relationships - or social interventions in general - so sensitive to abuse? These problems are directly related to the nature of the helping relationship. The core of this relationship is the inequality, the asymmetry, between the helper and the person being helped, and the dependence of the latter. Asymmetry is the driving force behind every social intervention and at the same time its weakest point. Handling asymmetry in an appropriate manner constitutes a major part of the work of the intervening party. This asymmetry makes heavy demands on the professional attitude of the intervening party i.e. the helper. Is s/he capable of dealing with dependence in an acceptable way? Is s/he well-versed in her/his profession? This article contains a comprehensive sketch of many of the possible dangers and pitfalls which beset asymmetric intervention relations. At the end it will be argued that, for a better understanding, the proximity of helping and power has to be taken into account.

The Interplay of Power and Trust in Platform Ecosystems of the Enterprise Application Software Industry

In recent years, the formerly oligopolistic Enterprise Application Software (EAS) industry began to disintegrate into focal inter-firm networks with one huge, powerful, and multi-national plat-form vendor as the center, surrounded by hundreds or even thousands of small, niche players that act as complementors. From a theoretical point of view, these platform ecosystems may be governed by two organizing principles - trust and power. However, it is neither from a practical nor from a theoretical perspective clear, how trust and power relate to each other, i.e. whether they act as complements or substitutes. This study tries to elaborate our understanding of the relationship of trust and power by exploring their interplay using multi-dimensional conceptual-izations of trust and power, and by investigating potential dynamics in this interplay over the course of a partnership. Based on an exploratory multiple-case study of seven dyadic partner-ships between four platform vendors, and seven complementors, we find six different patterns of how trust and power interact over time. These patterns bear important implications for the suc-cessful management of partnerships between platform vendors and complementors, and clarify the theoretical debate surrounding the relationship of trust and power.

Fatal combined infection with canine distemper virus and orthopoxvirus in a group of Asian marmots (Marmota caudata)

A fatal combined infection with canine distemper virus (CDV) and orthopoxvirus (OPXV) in Asian marmots (Marmota caudata) is reported in this article. A total of 7 Asian marmots from a small zoological garden in Switzerland were found dead in hibernation during a routine check in the winter of 2011. The marmots died in February 2011. No clinical signs of disease were observed at any time. The viruses were detected in all individuals for which the tissues were available (n = 3). Detection of the viruses was performed by reverse transcription polymerase chain reaction. The most consistent gross lesion was a neck and thorax edema. A necrotizing pharyngitis and a multifocal necrotizing pneumonia were observed histologically. Numerous large intracytoplasmic eosinophilic inclusions were seen in the epithelial cells of the pharynx, of the airways, and in the skin keratinocytes. Brain lesions were limited to mild multifocal gliosis. Phylogenetic analysis revealed that the marmot CDV strain was closely related to the clusters of CDVs detected in Switzerland in wild carnivores during a local outbreak in 2002 and the 2009-2010 nationwide epidemic, suggesting a spillover of this virus from wildlife. The OPXV was most closely related to a strain of cowpoxvirus, a poxvirus species considered endemic in Europe. This is the first reported instance of CDV infection in a rodent species and of a combined CDV and OPXV infection.

Fractures in Children and Adolescents

Fractures of the growing bone require fixation techniques, which preclude any injury to the growth plate regions. This requirement is met by Elastic Stable Intramedullary Nails (ESIN) which are positioned between both metaphyseal regions. Pronounced malposition and/or shortening, open fractures and fractures with impending skin perforation are indications for clavicle nailing in adolescents. Retrograde nailing with two elastic nails, inserted from lateral, is the method of choice for stabilization of humerus fractures. In radial neck fractures with severe tilting of the radial head, a retrograde nail may reduce and fix the head. In Monteggia lesions, the ulna fracture is reduced and fixed with an antegrade nail. Forearm fractures with unacceptable axial deviation are reduced and fixed with one antegrade nail in the ulna and a retrograde nail in the radius. Ascending elastic nailing is done for femur shaft and proximal femur fractures. The medial and lateral entry sites are located above the distal physis. End caps are used to prevent shortening in spiral and multiple segment fractures. Fractures of the distal third of the femur are nailed in a descending technique. The entry sites of two nails are located on the lateral cortex below the greater trochanter. Combined tibia and fibula fractures, open fractures and unstable fracture types such as spiral and multifragmental tibia fractures are good indications for ESIN. Descending nailing is the method of choice. The nail entry points are medially and laterally distal to the apophysis of the proximal tibia. Thorough knowledge of each fracture type, fracture location and age specific healing pattern is necessary for safe and effective treatment of pediatric fractures

Symptoms Have Modest Accuracy in Detecting Endoscopic and Histologic Remission in Adults With Eosinophilic Esophagitis.

BACKGROUND & AIMS It is not clear whether symptoms alone can be used to estimate the biologic activity of eosinophilic esophagitis (EoE). We aimed to evaluate whether symptoms can be used to identify patients with endoscopic and histologic features of remission. METHODS Between April 2011 and June 2014, we performed a prospective, observational study and recruited 269 consecutive adults with EoE (67% male; median age, 39 years old) in Switzerland and the United States. Patients first completed the validated symptom-based EoE activity index patient-reported outcome instrument and then underwent esophagogastroduodenoscopy with esophageal biopsy collection. Endoscopic and histologic findings were evaluated with a validated grading system and standardized instrument, respectively. Clinical remission was defined as symptom score <20 (range, 0-100); histologic remission was defined as a peak count of <20 eosinophils/mm(2) in a high-power field (corresponds to approximately <5 eosinophils/median high-power field); and endoscopic remission as absence of white exudates, moderate or severe rings, strictures, or combination of furrows and edema. We used receiver operating characteristic analysis to determine the best symptom score cutoff values for detection of remission. RESULTS Of the study subjects, 111 were in clinical remission (41.3%), 79 were in endoscopic remission (29.7%), and 75 were in histologic remission (27.9%). When the symptom score was used as a continuous variable, patients in endoscopic, histologic, and combined (endoscopic and histologic remission) remission were detected with area under the curve values of 0.67, 0.60, and 0.67, respectively. A symptom score of 20 identified patients in endoscopic remission with 65.1% accuracy and histologic remission with 62.1% accuracy; a symptom score of 15 identified patients with both types of remission with 67.7% accuracy. CONCLUSIONS In patients with EoE, endoscopic or histologic remission can be identified with only modest accuracy based on symptoms alone. At any given time, physicians cannot rely on lack of symptoms to make assumptions about lack of biologic disease activity in adults with EoE. ClinicalTrials.gov, Number: NCT00939263.

Holocene vegetation and fire history of the mountains of Northern Sicily (Italy)

Knowledge about vegetation and fire history of the mountains of Northern Sicily is scanty. We analysed five sites to fill this gap and used terrestrial plant macrofossils to establish robust radiocarbon chronologies. Palynological records from Gorgo Tondo, Gorgo Lungo, Marcato Cixé, Urgo Pietra Giordano and Gorgo Pollicino show that under natural or near natural conditions, deciduous forests (Quercus pubescens, Q. cerris, Fraxinus ornus, Ulmus), that included a substantial portion of evergreen broadleaved species (Q. suber, Q. ilex, Hedera helix), prevailed in the upper meso-mediterranean belt. Mesophilous deciduous and evergreen broadleaved trees (Fagus sylvatica, Ilex aquifolium) dominated in the natural or quasi-natural forests of the oro-mediterranean belt. Forests were repeatedly opened for agricultural purposes. Fire activity was closely associated with farming, providing evidence that burning was a primary land use tool since Neolithic times. Land use and fire activity intensified during the Early Neolithic at 5000 bc, at the onset of the Bronze Age at 2500 bc and at the onset of the Iron Age at 800 bc. Our data and previous studies suggest that the large majority of open land communities in Sicily, from the coastal lowlands to the mountain areas below the thorny-cushion Astragalus belt (ca. 1,800 m a.s.l.), would rapidly develop into forests if land use ceased. Mesophilous Fagus-Ilex forests developed under warm mid Holocene conditions and were resilient to the combined impacts of humans and climate. The past ecology suggests a resilience of these summer-drought adapted communities to climate warming of about 2 °C. Hence, they may be particularly suited to provide heat and drought-adapted Fagus sylvatica ecotypes for maintaining drought-sensitive Central European beech forests under global warming conditions.

Undergraduate Engineering Students' Understanding of Heat, Temperature, and Radiation

Difficulty understanding heat and temperature concepts has been recognized in engineering education. Confusion has been shown to persist after instruction. The purpose of this study was to determine whether undergraduate engineering students’ knowledge of four heat transfer concept areas significantly changed with instruction and whether this varied by major and GPA. Two hundred twenty-eight undergraduate engineering students from six institutions were assessed prior to and after instruction. Results showed significant improvement in most concept areas but mean scores were below mastery. Previously documented misconceptions persisted after instruction. Significant differences were found by major and GPA. Suggestions for future research provided.

Effect of patient accrual patterns on power and size of log-rank test for time-to-event outcome in clinical trials

The determination of size as well as power of a test is a vital part of a Clinical Trial Design. This research focuses on the simulation of clinical trial data with time-to-event as the primary outcome. It investigates the impact of different recruitment patterns, and time dependent hazard structures on size and power of the log-rank test. A non-homogeneous Poisson process is used to simulate entry times according to the different accrual patterns. A Weibull distribution is employed to simulate survival times according to the different hazard structures. The current study utilizes simulation methods to evaluate the effect of different recruitment patterns on size and power estimates of the log-rank test. The size of the log-rank test is estimated by simulating survival times with identical hazard rates between the treatment and the control arm of the study resulting in a hazard ratio of one. Powers of the log-rank test at specific values of hazard ratio (≠1) are estimated by simulating survival times with different, but proportional hazard rates for the two arms of the study. Different shapes (constant, decreasing, or increasing) of the hazard function of the Weibull distribution are also considered to assess the effect of hazard structure on the size and power of the log-rank test. ^

A hybrid method in combining treatment effects from matched and unmatched studies

In the biomedical studies, the general data structures have been the matched (paired) and unmatched designs. Recently, many researchers are interested in Meta-Analysis to obtain a better understanding from several clinical data of a medical treatment. The hybrid design, which is combined two data structures, may create the fundamental question for statistical methods and the challenges for statistical inferences. The applied methods are depending on the underlying distribution. If the outcomes are normally distributed, we would use the classic paired and two independent sample T-tests on the matched and unmatched cases. If not, we can apply Wilcoxon signed rank and rank sum test on each case. ^ To assess an overall treatment effect on a hybrid design, we can apply the inverse variance weight method used in Meta-Analysis. On the nonparametric case, we can use a test statistic which is combined on two Wilcoxon test statistics. However, these two test statistics are not in same scale. We propose the Hybrid Test Statistic based on the Hodges-Lehmann estimates of the treatment effects, which are medians in the same scale.^ To compare the proposed method, we use the classic meta-analysis T-test statistic on the combined the estimates of the treatment effects from two T-test statistics. Theoretically, the efficiency of two unbiased estimators of a parameter is the ratio of their variances. With the concept of Asymptotic Relative Efficiency (ARE) developed by Pitman, we show ARE of the hybrid test statistic relative to classic meta-analysis T-test statistic using the Hodges-Lemann estimators associated with two test statistics.^ From several simulation studies, we calculate the empirical type I error rate and power of the test statistics. The proposed statistic would provide effective tool to evaluate and understand the treatment effect in various public health studies as well as clinical trials.^