THz Time-Domain Spectroscopy of Ionic Liquids and THz-Pump/Second-Harmonic-Probe Experiment in Solids

THz indicates an electromagnetic wave whose spectrum locates between the microwave and infrared range. In the last two decades the advent of benchtop THz sources filled the so-called ‘THz gap’. The properties of THz radiation such as low photon energy, transparence to it of packaging materials and so on make it suitable for many applications in industrial and scientific fields. In this work we generated intensive broadband THz pulses radiated from femtosecond laser induced plasma via four-wave-mixing process coupling fundamental laser light and its second harmonic. In chapter 1 we generally introduce the principles of THz generation and detection. We also introduce the application of our THz source in static THz time-domain spectroscopy and time-resolved THz spectroscopy. In chapter 2 we present THz generation based on air plasma and THz detection through different methods and sensors, including ZnTe, GaSe, LAPC single crystals and air-based methods. The results show that the detected upper frequency edge with 500 µm ZnTe is limited by the phase mismatch between THz and probe beam. 250 µm ZnTe expands the detected frequency range but the detection efficiency is restricted by phonon absorption at 5.3 THz. GaSe can detect THz up to 30 THz with a deep gap due to phonon mode around 6.5 THz. Another dip around 19.1 THz due to silicon absorption is also found. LAPC is capable of measuring THz up to around 17 THz without gap. The air-based method results in ultra-broadband detection of short unipolar pulses. In chapter 3 we develop a precise contactless micro-distance measurement method based on THz pulses. The resolution of the measurement can achieve 1.5 µm with scanning step equal to 0.01 ps. A comparison between ZnTe detection sensor and air-based sensor indicates that the air-based detection technique has advantages that include the ability to measure smaller distance and the immunity to distortion introduced by vapor absorption in air. We also compare distance measurement with ZnTe in air and in nitrogen. We find that the measurement in nitrogen leads to a more straightforward extraction of the distance as compared to the measurement in air where additional analysis is needed to take into account the coherent oscillations produced by air absorption. In chapter 4 we investigate the mixing behavior of the dielectric function of mixtures of ionic liquids (ILs). In the investigation we measure the cell thickness with the method developed in chapter 3 and detect the THz radiation with electro-optic sampling in a 250 µm ZnTe crystal. The results show that the complex permittivity of ionic mixtures obeys linear mixing law. We also find that all the complex permittivity spectra of mixtures can be simulated with a combination of three oscillators which are assigned to different vibrational modes of the ionic liquids. In chapter 5 we discuss broadband THz time-domain spectroscopy applied to pure imidazolium-based ionic liquids. The broadband THz detection was realized thanks to the use of a LAPC crystal. We find in the absorption spectra of a series of pure ionic liquids clear signatures of both inter- and intra-molecular vibrational modes. This is the first time that inter- and intra-molecular modes of ionic liquids are measured in one shot without combining different techniques. We have assigned these vibrational modes to different processes in ionic liquids. We find an interesting correlation between the specific anion of IL and the peak frequency shift and bandwidth variation observed for the intermolecular absorption band. We discuss these correlations in terms of the ability of the specific anion in forming hydrogen bonds. In chapter 6 we discuss our experiments of THz-pump/second-harmonic-generation in single crystals of quartz. The experiments on quartz show that the second harmonic signal oscillates coherently at several frequencies in the THz frequency range and these oscillations depend on the specific combination of the probe and THz linear polarization, and orientation of quartz axis. We also find that the intensity and bandwidth of the spectrum of second harmonic are enhanced in presence of the THz, i. e., side-bands appears in the second harmonic spectrum

Selection rules for the orbital angular momentum of optically-produced THz radiation

In this work we theoretically study the transduction ofthe Orbital Angular Momentum (OAM)lfor infraredpump lasers into the THz domain. In the case of opti-cal rectification, the transduction of OAM occurs onlythrough a spin-orbit interaction, with the selection ruleon the OAMl=0valid for any kind of polarizationof the pump, which means that there is no transfer ofOAM along the propagation axis. In the difference fre-quency generation the selection rule for the difference∆lbetween the OAM of the pump fields with linear orcircular polarization isl=∆l, whereaslranges from∆l−2to∆l+2in both the cases of radial and azimuthalpolarization. Moreover, for THz generation in the lat-ter case, high diffraction obtained with tightly focusedpumps yieldsltending to∆l±2, whileltends to zeroin the opposite case of large pump beam

Thyroid Carcinoma with Bone Metastases: A Prognostic Factor Study

Objective Occult clinical presentations usually hinder the early detection and management of patients with bone metastases from thyroid carcinoma. We retrospectively investigated the clinical outcomes of such patients from 1993 to 2004 and analyzed the prognostic parameters. Design The basic demographic data and manifestations of 44 patients who had thyroid carcinoma with bone metastases were reviewed. We studied the gender, age, locations of metastases, histological types, treatment methods, hypercalcemic episodes and results of treatments. We used Kaplan-Meier survival analysis and log-rank tests to access the statistical significance. Main Outcome The incidence of bone metastasis from thyroid carcinomas in this series was 5.0%. Twenty patients (45.4%) had follicular, 16 (36.3%) had papillary, 3 (6.8%) had anaplastic, 3 (6.8%) had medullary, and 2 (4.5%) had Hurthel cell carcinomas. Twelve patients had hypercalcemic episodes, ranging from 2.6 to 2.9 mmolL −1 (mean ± SD: 2.68 ± 0.15 mmolL −1 ). Survival time after bone metastases ranged from 2 months to 8 years (mean ± SD: 5.3 ± 1.3 years). The 5-year survival rate was 79.4% and the 10-year survival rate was 52.9%. Regarding the histological cancer type, patients with papillary and follicular cancers survived significantly longer than those with anaplastic and medullary cancers (p < 0.05). In addition, the patients presenting with hypercalcemia had the worst survival (p < 0.05). Conclusions Thyroid carcinoma can present with bone metastases in its early stage. We found that both tumor type and hypercalcemia were significant prognostic factors for survival time

The Metastasectomy and Timing of Pulmonary Metastases on the Outcome of Osteosarcoma Patients

Background The author intended to clarify the therapeutic effect and prognostic factors of metastasectomy and timing of pulmonary metastases in osteosarcoma patents. Methods Data was obtained retrospectively on all consecutive osteosarcoma patients from 1985 to 2005 in author's institute. Fifty-two patients with pulmonary nodules were identified, including 24 patients undergoing pulmonary metastasectomy treatment. These patients were categorized into four groups: group 1, patients with lung metastases at the initial presentation; group 2, lung metastases identified during the period of pre-operative chemotherapy; group 3, lung metastases identified during period of the post-operative chemotherapy; group 4, lung metastases identified after therapy for the primary osteosarcoma completed. Results In our study, the 2-, 3-, and 5-year overall survival rates for 52 patients were 49%, 39% and 20%. The 2-year overall survival rates were 18% for group 1, 32% for group 3, and 70% for group 4 (p < 0.001). The 5-year overall survival rate was 34% for group 4. Patients who underwent metastesectomy showed a better survival outcome as compared with the patients not undergoing metastasectomy (p = 0.003). The 2-year and 5-year overall survival rates of only one lung metastatic nodule were 62% and 50%, and for initially multiple lung metastatic nodules, 45% and 5%, respectively. In addition, the patients presented with lung metastases had a worse prognosis as compared with those without initial lung metastases (p = 0.0001). Conclusions The patients having single metastatic nodule showed a better prognosis than those with multiple lung nodules. Furthermore, those patients who underwent metastasectomy survived longer than those not undergoing metastasectomy. Patients who had late metastases after complete chemotherapy had a better prognosis; whereas those who had metastases identified at the initial presentation predicted a poor prognosis

Performance Evaluation of a THz Pulsed Imaging System: Point Spread Function, Broadband THz Beam Visualization and Image Reconstruction

Terahertz (THz) technology is a promising research field for various applications in basic science and technology. In particular, THz imaging is a new field in imaging science, where theories, mathematical models and techniques for describing and assessing THz images have not completely matured yet. In this work, we investigate the performances of a broadband pulsed THz imaging system (0.2–2.5 THz). We characterize our broadband THz beam, emitted from a photoconductive antenna (PCA), and estimate its point spread function (PSF) and the corresponding spatial resolution. We provide the first, to our knowledge, 3D beam profile of THz radiation emitted from a PCA, along its propagation axis, without the using of THz cameras or profilers, showing the beam spatial intensity distribution. Finally, we evaluate the THz image formation on a test-sample composed by a regular linen natural pattern

A simplified guide ruler from numeric table method in doing rotational osteotomy

<p>Abstract</p> <p>Background</p> <p>Čobeljić et al. recently reported a numeric table method to provide precise rotational osteotomy which is a well established orthopaedic procedure. The numeric table requires four pages in length that is rather inconvenient during performing an osteotomy operation. </p> <p>Methods</p> <p>We thus develop our own method by summarizing the data of the four-page table into a small ruler, which is easy to carry and use in operation room. An electrical version of this ruler is also available. We also build a computer model to verify Čobeljić et al. method.</p> <p>Results</p> <p>The error of Čobeljić et al. is between -37% to 16% (mean ± SD = -6% ± 9%). We verify our ruler by calculating the absolute difference between our method and that of Čobeljić et al. The difference is less than 0.1 mm.</p> <p>Conclusion</p> <p>Our ruler is convenient for practical use for the rotational osteotomy procedure with equal precision. Further clinical verification is needed to justify its real significance.</p

The twilight of the Liberal Social Contract? On the Reception of Rawlsian Political Liberalism

This chapter discusses the Rawlsian project of public reason, or public justification-based 'political' liberalism, and its reception. After a brief philosophical rather than philological reconstruction of the project, the chapter revolves around a distinction between idealist and realist responses to it. Focusing on political liberalism’s critical reception illuminates an overarching question: was Rawls’s revival of a contractualist approach to liberal legitimacy a fruitful move for liberalism and/or the social contract tradition? The last section contains a largely negative answer to that question. Nonetheless the chapter's conclusion shows that the research programme of political liberalism provided and continues to provide illuminating insights into the limitations of liberal contractualism, especially under conditions of persistent and radical diversity. The programme is, however, less receptive to challenges to do with the relative decline of the power of modern states

Constitutivism

A brief explanation and overview of constitutivism

Female Sex Worker Social Networks and STI/HIV Prevention in South China

Reducing harm associated with selling and purchasing sex is an important public health priority in China, yet there are few examples of sustainable, successful programs to promote sexual health among female sex workers. The limited civil society and scope of nongovernmental organizations circumscribe the local capacity of female sex workers to collectively organize, advocate for their rights, and implement STI/HIV prevention programs. The purpose of this study was to examine social networks among low-income female sex workers in South China to determine their potential for sexual health promotion.Semi-structured interviews with 34 low-income female sex workers and 28 health outreach members were used to examine how social relationships affected condom use and negotiation, STI/HIV testing and health-seeking behaviors, and dealing with violent clients. These data suggested that sex worker's laoxiang (hometown social connections) were more powerful than relationships between women selling sex at the same venue in establishing the terms and risk of commercial sex. Female sex workers from the same hometown often migrated to the city with their laoxiang and these social connections fulfilled many of the functions of nongovernmental organizations, including collective mobilization, condom promotion, violence mitigation, and promotion of health-seeking behaviors. Outreach members observed that sex workers accompanied by their laoxiang were often more willing to accept STI/HIV testing and trust local sexual health services.Organizing STI/HIV prevention services around an explicitly defined laoxiang social network may provide a strong foundation for sex worker health programs. Further research on dyadic interpersonal relationships between female sex workers, group dynamics and norm establishment, and the social network characteristics are needed