Static and reconfigurable devices for near-field and far-field terahertz applications

The terahertz frequency electromagnetic radiation has gathered a growing interest from the scientific and technological communities in the last 30 years, due to its capability to penetrate common materials, such as paper, fabrics, or some plastics and offer information on a length scale between 100 µm and 1 mm. Moreover, terahertz radiation can be employed for wireless communications, because it is able to sustain terabit-per-second wireless links, opening to the possibility of a new generation of data networks. However, the terahertz band is a challenging range of the electromagnetic spectrum in terms of technological development and it falls amidst the microwave and optical techniques. Even though this so-called “terahertz gap” is progressively narrowing, the demand of efficient terahertz sources and detectors, as well as passive components for the management of terahertz radiation, is still high. In fact, novel strategies are currently under investigation, aiming at improving the performance of terahertz devices and, at the same time, at reducing their structure complexity and fabrication costs. In this PhD work, two classes of devices are studied, one for near-field focusing and one for far-field radiation with high directivity. Some solutions for their practical implementation are presented. The first class encompasses several configurations of diffractive lenses for focusing terahertz radiation. A configuration for a terahertz diffractive lens is proposed, numerically optimized, and experimentally evaluated. It shows a better resolution than a standard configuration. Moreover, this lens is investigated with regard to the possibility to develop terahertz diffractive lenses with a tunable focal length by means of an electro-optical control. Preliminary numerical data present a dual-focus capability at terahertz frequencies. The second class encompasses advanced radiating systems for controlling the far-field radiating features at terahertz frequencies. These are designed by means of the formalism of leaky-wave theory. Specifically, the use of an electro-optical material is considered for the design of a leaky-wave antenna operating in the terahertz range, achieving very promising results in terms of reconfigurability, efficiency, and radiating capabilities. Furthermore, different metasurface topologies are studied. Their analytical and numerical investigation reveals a high directivity in radiating performance. Directions for the fabrication and experimental test at terahertz frequencies of the proposed radiating structures are addressed

Disability among refugees and asylum seekers in Italy. Results from a global health perspective

Limited evidence exists on the proportion ofrefugees and asylum seekers with disabilities, and knowledges about this target population are lacking. The objectives of the present investigation were a) mapping reception centers for hosting refugees and asylum seekers with disabilities; b) estimating the percentage of people with disabilities and examining the risks for specific migration routes; and c) highlighting the needs of refugees and asylum seekers using a global health perspective. We used the Washington Group Short Set Enhanced for estimating prevalence of disability, while Community-Based Rehabilitation Indicators were used to investigate their global needs. A total of 483 refugees and asylum seekers were interviewed on the whole national territory. The percentage of people with disabilities was 23.81, with a high prevalence of mental health problems, namely anxiety (18.22%) and depression (9.94%). Migrants who travel across the central Mediterranean route showed a high risk for disability condition (OR 2.08), with higher prevalence of anxiety (OR 2.19), while people who travelled the Balkan route seem to be a higher risk for mobility limitations (OR 3.03). The availability for hosting migrants with disabilities in reception centers is limited: 2.03% of the total national availability, with different distribution among regions. Disparities for each component of community-based rehabilitation indicators were also found, namely in health, education, social, livelihood and empowerment. Differences in access to healthcare services among migrants were also observed, in particular Ukrainian group seems to be more likely to get medical assistance, probably due to specific norms and communication strategies adopted by EU and Italy. The “Ukrainian Model” for refugees could be used for the general migrant population, in order to guarantee protection and adequate reception in host countries

PENGARUH VARIASI WAKTU PENCELUPAN PLAT BAJA A36 TERHADAP KETEBALAN dan KEKERASAN PELAPISAN ZN pada PROSES ELEKTROPLATING

Banyak sektor industri yang menggunakan lapisan logam krom dan hampir semua manusia menggunakan alat yang terbuat dari logam karena baja A36 banyak digunakan diberbagai komponen sepeda motor, mobil, furniture, dan kontruksi bangunan/jembatan tetapi mudah terkorosi juga berwarna abu-abu, tidak menarik, untuk menghambat korosi serta mempercantik tampilan dilakukan pelapisan. Metode ini menggunakan proses electroplating  dengan pelapisan anoda ZN dan material yang dilapisi adalah baja A36, dan memvariasikan lama waktu pencelupan pada proses electroplating yaitu antara 60, 90, dan 120 menit setelah dilapisi di uji ketebalan dan kekerasan lapisan. Dari hasil penelitian ini menghasilkan nilai ketebalan terkecil pada pelapisan anoda zn pada variasi lama waktu pencelupan 60 menit sebesar 9,7 μm, sedangkan nilai ketebalan tertinggi pada variasi lama waktu pencelupan 120 menit sebesar 17,25 μm. Dan nilai kekerasan terkecil terdapat pada variasi lama waktu pencelupan 60 menit sebesar 265,7 μm, sedangkan nilai kekerasan tertinggi pada variasi lama waktu pencelupan 120 menit sebesar 498,1 μm. Kata Kunci : Ketebalan & kekerasan lapisan, electroplating, Zinc, Baja A36

Thermal-AFM under aqueous environment

The aim of this thesis is to describe the work developing and demonstrating the use of Scanning Thermal Microscopy (SThM) in an aqueous electrically conductive environment for the first time. This has been achieved by using new instrumentation to allow conventional SThM probes to measure and manipulate the temperature of non-biological and biological samples. For the latter, the aqueous environment is crucial to allow in-vitro experimentation, which is important for the future use of SThM in the life sciences. SThM is known to be a powerful technique able to acquire simultaneous topographic and thermal images of samples. It is able to measure the microscopic thermal properties of a surface with nanoscale spatial resolution. However, SThM has traditionally been limited to use in vacuum, air and electrically inert liquids. The aqueous Scanning Thermal Microscopy (a-SThM) described in this thesis is an entirely novel technique that opens up a new field for thermal-AFM. The first challenge addressed in this work was the adaptation of a commercial Multimode Nanoscope IIIa AFM to permit electrical access to a SThM probe completely immersed in aqueous solutions. By employing a newly designed probe holder and electronic instrumentation, the probe could then be electrically biased without inducing electrochemical reactions. This approach permitted conventional microfabricated thermal probes to be operated whilst fully immersed in water. This innovation allowed SThM measurements under deionized (DI) water to be performed on a simple solid sample (Pt on Si3N4) and the results compared with in-air scans and accurate 3D Finite Element (FE) simulations. Once the validity of the technique was proven, its performance was investigated, including crucially the limit of its thermal-spatial resolution; this was investigated using nanofabricated solid samples (Au on Si3N4) with well-defined features. These results were compared to the FE model, allowing an understanding of the mechanisms limiting resolution to be developed. In order to demonstrate the advantages granted by the water’s superior thermal conductivity compared to air or other liquids, non-contact thermal images were also acquired using the same samples. The final part of this thesis was focused on extending SThM into the biological area; a completely new field for this technique. New results are presented for soft 4 samples: I-collagen gel and collagen fibrils, which were thermally manipulated using a self-heated SThM probe. This successfully demonstrated the possibility of using heat to alter a biological sample within a very well localised area while being operated for long time in an aqueous environment. The difference in force response originated from the AFM scans with different levels of self-heating further proved the robustness of the technique. Finally, the technique was employed to study MG-63 living cells: The SThM probe was left in contact with each cell for a pre-determined period of time, with and without self heating. The results demonstrated that only the heated cells, directly beneath the probe tip died, tallying with the highly localised temperature gradient predicted by FE analysis

Role of an Atomic-Level-Based Approach for Improving Cancer Therapy

Looking at the atomic level of biological activity, the electron spin may be considered a key parameter, governing fundamental biological processes. Spin states have a major role in defining the structure, reactivity, magnetic and spectroscopic properties of a molecule. In the last decades, there has been a growing interest in the use of magnetic fields (MF) to study their influence on different biological systems, considering their effect on electron spin energy levels and consequently on redox-related cellular changes. Different authors have studied the use of magnetic fields as potential antitumor agent as well as an adjuvant agent to chemotherapy and radiotherapy with promising results. Overall, the published data support the presence, in laboratory animals, of antitumor efficacy in many types of cancer including adenocarcinoma, breast cancer, melanoma and neuroblastoma. Those antitumor effects seem to be associated with no observable side effects or toxicity in animals or in humans. More studies are necessary, mainly at the clinical level, to understand the real potential of this atomic approach in improving availability of cancer therapy. In addition, this approach may contribute to fulfill a knowledge gap facing biomedical science today, the one between the atomic level and the cellular level

Illustrando i Balcani: immagini tra cronaca e esotismo nelle pagine di "Illustrazione Italiana" dal 1873 al 1914

Questa tesi ha come oggetto di studio l’immagine dei popoli e dei paesi balcanici mostrata attraverso le pagine della rivista “Illustrazione Italiana” in un arco di tempo che va dai primi anni Settanta del XIX secolo al periodo precedente lo scoppio della Prima guerra mondiale. Lo scopo è quello di analizzare, attraverso le rappresentazioni grafiche e le testimonianze pubblicate dalla rivista, come la complessa realtà balcanica veniva contemporaneamente immaginata, scoperta e riprodotta alla luce di eventi politici e sociali e di influenze culturali fondamentali per la storia europea. Come fonte principale d’indagine di questo multiforme “Oriente europeo”, è stata scelta “Illustrazione Italiana”, una delle più note riviste italiane dell’epoca per alcune caratteristiche che la rendono idonea allo scopo: periodico al tempo stesso politico, culturale, scientifico e di diletto, che raggiungeva un pubblico relativamente ampio, e che fin dagli esordi (nel dicembre del 1873) mostra la volontà di essere una pubblicazione di stampo marcatamente italiano, in un’Italia unita costituitasi solo da poco come tale. Il lavoro è stato quindi articolato in due parti: la prima offre uno sguardo d’insieme sulla fonte utilizzata, sul periodo storico e sui rapporti tra Italia e paesi balcanici, letti attraverso le pagine della rivista, mentre la seconda parte si concentra essenzialmente sulle immagini pubblicate dalla rivista. Nel corso dei quaranta anni esaminati i Balcani vengono presentati come un luogo incognito e mostrati al pubblico come una realtà fatta di miseria e violenza, carente di quei parametri considerati espressione di civiltà, ma che comincia a manifestare una certa spinta verso la modernizzazione. L’immagine generale che la rivista propone è quella di un affascinante e al contempo sconcertante mondo orientale, prossimo solo geograficamente alla “civiltà” europea, filtrato attraverso l’esperienza dei cronisti, che per la volontà politica e l’ideologia del momento permane nell’immaginario italiano come una terra arcaica, ostica, abitata da popolazioni semicivilizzate le cui vicende poco interessano se non alla luce degli avvenimenti internazionali

WEVERSE SEBAGAI SARANA KOMUNIKASI FANS DENGAN IDOL (STUDI PADA INTERAKSI SEVENTEEN DAN CARAT)

This paper discusses the interaction between idols and fans through the Weverse fandom application, with the aim of knowing how the interaction and communication occurs. This research uses the concept of verbal communication with the theory of Computer Mediated Communication (CMC) asynchronous communication type. The method used in this research is qualitative with a netnographic approach. The data collection technique used in this research is observation and documentation conducted on online interactions that occur between Seventeen and their fans, namely Carat through the Weverse fandom application. The results of this research indicate that through Weverse idols and fans interact and communicate about their idol activities and their personal lives which makes them feel more connected to each other

ANALISIS PERBEDAAN RATA-RATA RETURN SAHAM SEBELUM DAN SESUDAH HARI LIBUR NASIONAL (Studi Pada Saham Jakarta Islamic Index Tahun 2016)

ABSTRAK Peran pasar modal di era globalisasi saat ini sangat dirasakan oleh para pelaku ekonomi di Indonesia. Pasar modal adalah kegiatan yang bersangkutan dengan penawaran umum dan perdagangan efek, perusahaan publik yang berkaitan dengan efek yang diterbitkannya, serta lembaga dan potensi yang berkaitan dengan efek. Berbagai penelitian menyatakan bahwa terjadi penyimpangan atau anomali terhadap pasar modal efisien. Anomali pasar dapat menyebabkan kenaikan dan penurunan harga saham yang berdampak pada return atau keuntungan investasi. Salah satu anomali yang ada pasar modal yaitu efek hari libur nasional atau Holiday Effect. Penelitian ini bertujuan untuk mengetahui apakah ada perbedaan yang signifikan antara return saham sebelum dan sesudah hari libur nasional pada perusahaan yang terdaftar di Jakarta Islamic Index Tahun 2016. Penelitian ini menggunakan data harga saham harian Jakarta Islamic Index tahun 2016 sebagai sampel. Pengambilan sampel dilakukan dengan cara purposive sampling. Penelitian ini menggunakan data return saham sebelum dan sesudah hari libur nasional tahun 2016. Tes statistik yang digunakan untuk uji hipotesis dalam penelitian ini adalah Paired sampel T-Test. Kesimpulan dari hasil penelitian ini adalah tidak ada perbedaan yang signifikan antara rata-rata return saham sebelum dan sesudah hari libur nasional pada saham Jakarta Islamic Index tahun 2016. Kata Kunci : Return Saham, Anomali Pasar, Hari Libur Nasional, Holiday Effec

Fabry-Perot cavity leaky wave antennas with tunable features for terahertz applications

Terahertz (THz) radiation is a very appealing band of the electromagnetic spectrum due to its practical applications. In this context, the THz generation and manipulation is an essential part of the technological development. The demand of THz antennas is still high because it is already difficult to obtain directive, efficient, planar, low-cost, and easy-to-fabricate THz radiating systems. In this regard, Fabry-Perot cavity leaky-wave antennas are gaining increasing attention at THz, due to their very interesting radiating features: the combination of planar designs with metamaterials and metasurfaces could offer a promising platform for future THz manipulation technologies. In this short review, we focus on different classes of leaky-wave antennas, based on materials with tunable quasi-optical parameters. The possibility of producing directive patterns with particularly good efficiencies, as well as the capability of dynamically reconfiguring their radiating features, are discussed by taking into account the risk of increasing costs and fabrication complexity