Master of Science

thesisOrganic ligands are important components in molecule-based magnets, as they allow for control over the physical and magnetic properties. Spin-carrying radical organic ligands, specifically, have been seen to enhance magnetic properties. Investigating reactions of 1,4-dicyanotetrazine, DCNT, an organic ligand capable of being reduced to a radical anion (-0.033 V vs. SCE), with spin carrier and paramagnetic building-blocks such as decamethylferrocene, vanadium hexacarbonyl, and tetrakis(dimethylamino)-ethylene have led to mixed results. While the reaction of Fe(Cp*)2 with DCNT was expected to form 0-D chains of alternating [DCNT]•- and [FeCp*2]•+ that magnetically ordered, this was not the case as the room-temperature χT value of 0.222 emu K/mol was significantly lower than the calculated spin-only value of 0.75 emu K/mol for a system of two S = 1/2 ions. However, as the infrared spectrum indicates reduced DCNT, another bonding motif may be occurring that could include the dimerization or trimerization of DCNT. The structure of [FeCp*2][DCNT] has not been elucidated and further investigation is needed. Reaction of DCNT and V(CO)6 forms a black amorphous precipitate, similar to V[TCNE]x. Infrared spectra indicate reduced DCNT; however, the magnet data are inconclusive. TDAE and DCNT forms an electron transfer salt, in which DCNT is reduced and TDAE is oxidized to the 2+ charge. The magnetic data are also inconclusive

Impact of inventory inaccuracy on service-level quality: A simulation analysis

This article discusses the impact of inventory inaccuracy on service-level quality in (Q,R) continuous review, lost-sales inventory models. A simulation model is built to study the behaviour of this kind of model exposed to an inaccuracy in inventory records as well as demand variability. We have observed an unusual result which goes against certain empirical practices in the SMEs that consist in hiking the inventory level proportionally to the data inaccuracy rate. A nonmonotone function shows that at the outset, the service-level quality is lowered as the inaccuracy rate increases but when the inaccuracy rate becomes much higher this quality is conversely enhanced. This relation can equally be observed given that stocktaking commences as soon as the threshold of decline in the service-level rate has been reached and when demand consequently dwindles. Finally, another noteworthy result also shows the same phenomenon between the function involving a level of safety stock defined by the simulation and the function between the service-level quality and the inventory inaccuracy. These different observed results are discussed in terms of both contribution to the (Q,R) inventory management policies in SMEs and of the limitations to this study.Continuous review inventory system, inventory inaccuracy, continuous model, discrete-time simulation

Adaptive polynomial predistorters and low-PAR circular APK signaling schemes for systems using non-linear power amplifiers

In this thesis, adaptive polynomial predistortion techniques suitable for DSP implementation at the baseband signals are introduced to counter-balance the AM/AM and AM/PM nonlinear effects of the transmit power amplifier. The proposed polynomial predistortion scheme is based on polar coordinate representation. Both LMS and RLS concepts are used to derive the adaptive algorithms. An enhanced LMS-based algorithm with fast convergence is proposed. For very fast convergence, a cascaded RLS-based adaptive polynomial predistorter structure is introduced. The obtained results show that the polynomial predistortion schemes can be used in M-QAM transmitters with power amplifiers operating near saturation to achieve a highest power efficiency. The thesis also presents a class of circular M-ary Amplitude-Phase Shift Keying (APK) signaling techniques with high bandwidth efficiency and low peak-to-average power ratio (PAR) suitable for systems using non-linear power amplifiers to achieve high power efficiency. Based on bandlimited two-dimensional M-ary signals using circular constellations, a search algorithm for optimum schemes for non-linear amplification in terms of minimum PAR and maximum DPR is introduced. Optimum circular constellations for 8-, 16-, 32-, 64- and 128-APK signalling schemes are proposed. The analytical and simulation results show that this class of circular M-ary APK signals outperforms the square and cross M-ary QAM schemes

The Effects of Caffeine on Premenstrual Syndrome

This study extends current understanding of caffeine intake on the menstrual and premenstrual syndrome; in particular, the association between PMS and caffeine consumption in 83 undergraduate female students--34 PMS and 49 controls. Participants between the ages of 18 and 26 were recruited from psychology courses at the University of Maryland. Diagnoses of PMS were assigned based on a 30% increase across two consecutive cycles of prospective symptom ratings online. Participants were screened using the PHQ for the following exclusion criteria: pregnancy, caffeine sensitivity, and any diagnosis of psychiatric disorder within the past 6 months. It was hypothesized that PMS sufferers would consume more caffeine across the entire menstrual cycle. The result of the present study showed that caffeine intake was higher during the follicular phase than during the luteal phase for both diagnostic groups. However, there was no significant difference between the two groups in caffeine intake

Drosophila RecQ4 Is Directly Involved in Both DNA Replication and the Response to UV Damage in S2 Cells.

The RecQ4 protein shows homology to both the S.cerevisiae DNA replication protein Sld2 and the DNA repair related RecQ helicases. Experimental data also suggest replication and repair functions for RecQ4, but the precise details of its involvement remain to be clarified.Here we show that depletion of DmRecQ4 by dsRNA interference in S2 cells causes defects consistent with a replication function for the protein. The cells show reduced proliferation associated with an S phase block, reduced BrdU incorporation, and an increase in cells with a subG1 DNA content. At the molecular level we observe reduced chromatin association of DNA polymerase-alpha and PCNA. We also observe increased chromatin association of phosphorylated H2AvD--consistent with the presence of DNA damage and increased apoptosis.Analysis of DmRecQ4 repair function suggests a direct role in NER, as the protein shows rapid but transient nuclear localisation after UV treatment. Re-localisation is not observed after etoposide or H₂O₂ treatment, indicating that the involvement of DmRecQ4 in repair is likely to be pathway specific.Deletion analysis of DmRecQ4 suggests that the SLD2 domain was essential, but not sufficient, for replication function. In addition a DmRecQ4 N-terminal deletion could efficiently re-localise on UV treatment, suggesting that the determinants for this response are contained in the C terminus of the protein. Finally several deletions show differential rescue of dsRNA generated replication and proliferation phenotypes. These will be useful for a molecular analysis of the specific role of DmRecQ4 in different cellular pathways

Tren Penggunaan Antikoagulan Oral Direk dan Warfarin pada Pasien Fibrilasi Atrium

Treatments used in atrial fibrillation therapy, such as those of anticoagulants, consist of vitamin K antagonists (warfarin) and direct oral anticoagulants (dabigatran, apixaban, rivaroxaban, and edoxaban). The use of warfarin requires regular monitoring of prothrombin time (PT) and international normalised ratio (INR). The therapeutic dose range is narrow, but the price is cheaper. Oral anticoagulants are directed, the incidence of major bleeding is lower, ease of use, food and drug interactions are minor, the half-life is shorter, and there is a lack of laboratory monitoring needs. Based on this problem, researchers conducted a study to determine the trend of using warfarin and oral anticoagulants in patients with atrial fibrillation at a public hospital in Jakarta. This study uses a qualitative approach, with longitudinal methods and retrospective data using outpatient medical records for the period 2014 to 2018. The trend of using warfarin anticoagulants decreased from 82.3% in 2014 to 62% in 2016, while oral anticoagulants were reduced. Direct oral anticoagulants are rivaroxaban and dabigatran, which are more widely used than apixaban, and edoxaban; no data on their use has been obtained. The opposite was true from 2017 to 2018, when the use of warfarin increased and caused a decrease in the use of direct oral anticoagulants. This research is expected to contribute to various parties, both health practitioners and academics, in terms of selecting therapies for atrial fibrillation.Pengobatan yang digunakan dalam terapi fibrilasi atrium, seperti yaitu antikoagulan, yang terdiri dari antagonis vitamin K (warfarin) dan antikoagulan oral direk (dabigatran, apiksaban, rivaroksaban, dan edoksaban). Penggunaan warfarin membutuhkan pemantauan rutin protrombin time (PT) dan international normalised ratio (INR), rentang dosis terapi sempit, namun harganya lebih murah. Antikoagulan oral direk, insiden perdarahan mayor lebih rendah, kemudahan penggunaan, interaksi makanan dan obat minor, waktu paruh lebih pendek, dan kurangnya kebutuhan pemantauan laboratorium. Berdasarkan masalah tersebut, peneliti melakukan kajian untuk mengetahui tren penggunaan warfarin dan antikoagulan oral direk pada pasien fibrilasi atrium pada salah satu rumah sakit di Jakarta. Penelitian ini menggunakan pendekatan kualitatif, dengan metode longitudinal dan data bersifat retrospektif menggunakan rekam medis pasien rawat jalan periode tahun 2014 sampai tahun 2018. Tren penggunaan antikoagulan warfarin mengalamipenurunan dari 82,3% tahun 2014 menjadi 62% tahun 2016, sedangkan antikoagulan oral direk mengalamipeningkatan. Antikoagulan oral direk rivaroksaban dan dabigatran lebih banyak digunakan dibandingkanapiksaban, dan edoksaban tidak diperoleh data penggunaannya. Hal sebaliknya pada tahun 2017 sampai2018, dimana penggunaan warfarin mengalami peningkatan dan menyebabkan penurunan penggunaanantikoagulan oral direk. Penelitian ini diharapkan dapat memberikan kontribusi kepada berbagai pihakbaik praktisi kesehatan maupun akademisi dalam hal pemilihan terapi untuk fibrilasi atrium

Virtual Reality and Creativity: Lessons Learned from a Luminaire Design Project

Current research in design education showed that experiencing virtual reality (VR) in learning led to higher creativity in students. However, some studies showed only a partial impact of VR on student creativity. Using video data analysis (VDA), the authors examined a half-an-hour excerpt of the recorded VR learning experience from a previous study on interior design students (n=13). The authors sought an explanation for the partial impacts of VR on students’ creativity via observing and interpreting one participant’s (a) interaction with VR and (b) the context of the virtual environment. VDA analysis results indicated that the implemented VR technology was intuitive for a fundamental learner yet required time and practice to gain advanced skills. Exploration time was also necessary for students to fully demonstrate the novel, resolution, and style aspects of creativity in their works. The implication is that the partial impact of VR on creativity found in the previous study might be due to the constraints of time and expertise of students (i.e., learn and explore), not VR technology per se. Educators and institutions wishing to include VR in their curricula should allow students ample time and access to VR applications and headsets to practice and sharpen their expertise

Multi-Objective Multi-Agent Planning for Jointly Discovering and Tracking Mobile Object

We consider the challenging problem of online planning for a team of agents to autonomously search and track a time-varying number of mobile objects under the practical constraint of detection range limited onboard sensors. A standard POMDP with a value function that either encourages discovery or accurate tracking of mobile objects is inadequate to simultaneously meet the conflicting goals of searching for undiscovered mobile objects whilst keeping track of discovered objects. The planning problem is further complicated by misdetections or false detections of objects caused by range limited sensors and noise inherent to sensor measurements. We formulate a novel multi-objective POMDP based on information theoretic criteria, and an online multi-object tracking filter for the problem. Since controlling multi-agent is a well known combinatorial optimization problem, assigning control actions to agents necessitates a greedy algorithm. We prove that our proposed multi-objective value function is a monotone submodular set function; consequently, the greedy algorithm can achieve a (1-1/e) approximation for maximizing the submodular multi-objective function.Comment: Accepted for publication to the Thirty-Fourth AAAI Conference on Artificial Intelligence (AAAI-20). Added algorithm 1, background on MPOMDP and OSP