A promising approach investigated here is to utilize thin film multilayer structures where the thickness of a catalyst layer at an exposed edge of photolithographically defined pattern determines the diameter of the nanotubes/nanowires grown from it. This can in turn be incorporated into photolithographically defined post structures resulting in an array of suspended nanowires for line-of-site shadow lithography. Success of the diameter control approach has been shown by selectively growing carbon nanotubes (CNTs) from narrow lines (12-60 nm) of SiO2, Fe, Ni, Co on micron-scale patterned substrates in a ferrocene or nonferrocene catalyzed CVD process. In addition, the concept has been extended to VS growth of CuO nanowires and VLS growth of ZnO nanowires from an exposed edge in a Al2O3/Cu(40-100 nm)/Al2O3 and Al2O3/Au(10 nm)/Al2O3 thin film multilayer structures. The exposed middle layer of patterned thin-film multilayer acts as a nm-scale wide selective growth area. The resultant CNT/nanowire diameter is directly related to the catalyst/catalyst support size. Growth kinetic studies of CuO nanowires from a thin film multilayer structure indicate diffusion controlled process. Dispersion of CNTs between lithographically defined trenches of width of 200 nm and depth of 500 nm when coupled with line-of-site deposition resulted in nm-scale line underneath the suspended CNT. The width of the resulting shadow is nearly a simple function of CNT/nanowire diameter, incident evaporation angle, and height of CNT above the substrate in a line-of-site evaporation geometry. Another promising approach to control the placement of nanotubes/nanowires is the selective functionalization of only their tips followed by selfassembly onto chemically patterned substrates. Towards this goal, arrays of aligned CNTs were impregnated with polystyrene to form aligned CNT membranes. These CNT membranes were also studied for gas and ionic transport studies. Different functionalization chemistry was performed on each side of the membrane. After dissolution of polymer matrix, a suspension of CNTs with different functionality at each tip was formed, allowing for sophisticated selfassembled architectures.

The current project examined the ability of a novel series of guandine and amidine-containing nicotine analogs to interact with several native and recombinantlyexpressed mammalian neuronal nicotinic-acetylcholine receptor (nAChR) subtypes. Rational drug design methods and parallel organic synthesis was used to generate a library of guanidine-containing nicotine (NIC) analogs (AH compounds). A smaller series of amidine-containing nicotine analogs (JC compounds) were also synthesized. In total, >150 compounds were examined. Compounds were first assayed for affinity in a high-throughput [3H]epibatidine radioligand-binding screen. Lead compounds were evaluated in subtype-selective binding experiments to probe for affinity at the α4β2* and α7* neuronal nAChRs. Several compounds were identified which possess affinity and selectivity for the α4β2* subtype [AH-132 (Ki=27nm) and JC-3-9 (Ki=11nM)]. Schild analysis of binding suggests a complex one-site binding interaction at the desensitized high-affinity nAChR. Whole-cell functional fluorescence (FLIPR) assays revealed mixed subtype pharmacology. AH-compounds were identified which act as activators and inhibitors at nAChR subtypes, while lead JC-compounds were found which possess full agonist activity at α4β2* and α3β4* subtypes. Compounds were identified as partial agonists, full agonists and inhibitors of multiple nAChR subtypes. Several SAR-based, ligand-receptor pharmacophore models were developed to guide future ligand design. Second-generation lead compounds were identified.

Nitrogen oxides (NOx) are atmospheric pollutants that pose a serious threat to both the environment and human health. Although catalytic deNOx technologies for engines working under stoichiometric air-to-fuel ratios (i.e., most gasoline engines) are already available, their performance is unsatisfactory under excess air conditions like those under which diesel engines operate. The selective catalytic reduction of NOx with hydrocarbon reductants (HC-SCR) is a potential deNOxsolution for diesel engines, whose operating temperatures are 150-500 ºC. Given that is unlikely for a single catalyst to show acceptable activity throughout this entire temperature span, the use of two catalysts is proposed in this dissertation. Whereas several catalysts active at high temperatures (>300 ºC) are already available, a catalyst showing an acceptable performance at low temperatures (<300 ºC) is yet to be found. Platinum group metals (PGMs) supported on activated carbon have been identified as promising low temperature HC-SCR catalysts. However, these materials show three main drawbacks: 1) the propensity of the carbon support to undergo combustion in an oxidizing environment, 2) a narrow temperature window of operation; and 3) a high selectivity towards N2O (as opposed to N2). To address the first limitation, the use of multi-walled carbon nanotubes (MWCNTs) as the support has been investigated and found to yield catalysts displaying a higher resistance to oxidation. Further, the acid activation of MWCNTs prior to their use as catalyst support has been explored, following reports than link carrier acidity with improved catalyst performance. In turn, the use of PGM alloys as the active phase has been examined as a means to improve catalyst activity and selectivity. Additionally, kinetic, spectroscopic and mechanistic studies have been performed in an attempt to probe structure-activity relationships in the MWCNTs-based formulations showing the best deNOx performance. The fundamental insights gained through these studies may inform further improvements to HC-SCR catalysts. Finally, the synthesis of the most promising formulations has been scaled-up using commercial metal monoliths as the catalyst substrate and the resulting monolithic catalysts have been tested in a diesel engine for activity in the HC-SCR reaction.

One means by which inhibitory control in selective attention may be studied is with the negative priming (NP) procedure. It is widely assumed that children are characterised by reduced capacity for inhibition (Diamond, 2002) and that inhibitory dysfunction is a key characteristic of children and adolescents with ADHD (Barkley, 1997). This should translate into reduced NP effects for these populations. In this dissertation, four studies using the NP procedure find no evidence for reduced inhibitory function in typical children or in adolescents with ADHD. Study 1 examined the magnitude of NP in children compared with adults. An important line of support for the idea that children suffer an inhibitory decrement has been based an empirical report suggesting that conceptual (identity or semantic) NP effects, assumed to reflect the by-product of distractor inhibition, while consistently found in adults are lacking in children (Tipper, Bourque, Anderson, & Brehaut, 1989). In Study 1, the opposite result was found. Study 2 compared NP effects between 7-year-old children and adults while replicating the respective methodologies of the only two studies to explore conceptual NP effects in developmental populations to date (Pritchard & Neumann, 2004, vs. Tipper et al., 1989) to determine the nature of the divergent results between these studies. In Study 2, it was found that distractor inhibition effects are comparable between children and adults when a NP task contains trials in which the distractor stimulus is consistently incongruent with the target stimulus, but that children may be more susceptible than adults to divide attention between target and distractor when a NP task contains a number of trials in which target selection difficulty is reduced. These are critical new findings, highlighting that reduced NP may often relate to methodological artifacts, and when considered in the light of current theories of NP, are also problematic for anti-inhibitory accounts of NP. Having distinguished more definitively the role of inhibition in developmental NP effects, Studies 3 and 4 explored whether the inhibitory process underpinning NP was implicated in young persons with ADHD. To date, evidence for NP in ADHD populations is equivocal. Study 3 found no evidence for a reduced NP effect in ADHD devoid of a corresponding diagnosis. Study 4 found that conduct and oppositional defiant disorders had the potential to confound the evaluation of NP in ADHD. Taken together, results in Studies 1 - 4 parallel very recent results in the literature on NP in older adults and adult psychopathology where presumed reductions of NP in these populations may also be accounted for by methodological artifacts (Buchner & Mayr, in press). It is concluded that NP may reflect a primitive and robust form of inhibitory processing, one that develops early and one that is often the last to deteriorate.

The purpose of this study is to review the lives of three immigrant women from the town of Doctor Mora, Guanajuato, Mexico. The following questions were used to gather and analyze the data: 1) How were their lives prior to migrating to the U.S.? 2) What was their experience crossing the border? 3) What are their life experiences in the U.S.? This study is intended to analyze the history and path of acculturation of these three immigrant women. This study analyzes Alejandro Portes's theory of selective acculturation, concept of funds of knowledge, Gordon's classical theory of assimilation, and the concepts of cultural and social capital. Selective acculturation theory is applied as a basis for analysis of the case studies. These studies were conducted using observational, audio-taped and open ended interviews. This study took place in Tucson, Arizona. Interviews took place in Spanish, the interviews were transcribed, translated, verified and analyzed. Findings show the persistence of these participants to become part of American society through education and involvement in the host society, utilizing their inherent cultural and social capital and supporting the theory of selective acculturation path. The next section gives a more detailed introduction of this study.

Three areas related to Polymer Membrane Ion-Selective Electrodes were investigated. The first two concered (1) their application to analysis of organic cations and pharmaceuticals, and (2) the use of electrochemically polymerized films for potentiometric sensors. The third area focused on the development of a computer controlled data acquisition system for studying Ion Transport at the Interface of Two Immiscible Electrolyte Solutions (ITTIES). Coated wire Polymer Membrane Ion-Selective Electrodes (PMISEs) based on dinonylnapthalenesulfonic acid (DNNS) were prepared for several alkylammonium ions and pharmaceuticals. Selectivity coefficients and other operational characteristics were predictable from calculated distribution constants. Specifically, Log k ᵖᵒᵗ(i)(j) values increased linearly with carbon number in a homologous series of alkylammonium ions. Among cations of the same carbon number, interference increased tenfold with each additional substitution in going from quaternary, tertiary, secondary and primary alkylammonium ions. Addition of hydrophilic subtituent groups to cyclohexylammonium interferents further diminished electrode response. Electrodes for several important pharmaceuticals, namely cocaine, methamphetamine, methadone, protriptyline, cimetidine, lidoflazine, verapamil, acebutalol, diltiazem, and nicardipine, displayed nearly theoretical response down to micromolar concentrations. Their selectivity was consistent with calculated distribution constants. Selectivity was independent of sensitivity, suggesting that the magnitude of each was determined by the distribution of both the free cation and the association complex of this cation with DNNS. The polymerization of phenol derivatives onto copper rendered the resulting films responsive to counter-ions of the electroactive species present in the polymerization medium. Those incorporating Aliquat 336 (tricaprylmethylammonium chloride) showed response to various anions, while others prepared using a sulfonated phenol derivative (m-hydroxybenzenesulfonic acid) responded to tributylammonium. The films had short lifetimes due to poor adhesion to the copper substrate. Construction of a computer controlled data acquisition system provided a rapid method for obtaining electrocapillary data simultaneously with the current-scan polarogram. The system was evaluated by observation of ion-transfer of a variety of alkylammonium ions.

隨著網路的進步與發展，許多新興的資訊服務，如影音資訊，在網路上傳輸時並未要求封包都送達，不同的封包有不同的重要性，例如 MPEG的關鍵畫面(I -Frame)就比其他畫面重要。常用的傳輸層通訊協定中，UDP與TCP都對所有的封包一視同仁，前者不做任何保證，而後者雖可保證所有封包的送達，但效率較差。 本研究提出一個新的TCP，”Partial-Reliable TCP”，使用選擇性重傳機制，配合應用程式的需求，對指定的封包提供遞送保護。當封包遺失時，只重傳保護的封包，可減少額外的網路資源消耗，並提升服務的品質。 此外，我們提出Single-Side的版本，接收端可以使用一般的 TCP，在封包傳送時，讓接收端以為封包都是無誤傳達的，在server-client架構的網路服務中，只有伺服器端必須使用我們的Partial-Reliable TCP，大幅提高本通訊協定的可行性。 最後我們利用網路模擬工具NS-2來模擬實際網路環境，將我們的方法與現行的通訊協定在可解畫面封包數、PSNR值及額外耗用的網路資源三個參數做比較。我們使用兩個 Video 影像作為傳輸標的，在高遺失率的有線與無線網路的環境中進行實驗。當傳輸時間限制很短時，（例如影像會議的應用），在有線的環境中， Basic PR-TCP比TCP Reno、TFRC最少增加約18%的可解畫面封包數，比UDP、TFRC及TCP Reno的PSNR值最少高出約15%，比TCP Reno及TFRC最少節省了12%的頻寬資源，Single-Side PR-TCP比Basic PR-TCP的PSNR值約低了11%，額外耗用的頻寬約多出10%。在無線的環境中，Basic PR-TCP比TCP Reno、TFRC最少增加約19%的可解畫面封包數，比UDP、TFRC及TCP Reno的PSNR值最少高出約20%，比Single-Side PR-TCP、TCP Reno及TFRC最少節省了15%的頻寬資源，Single-Side PR-TCP比Basic PR-TCP的PSNR值約低了14%。當傳輸時間限制較充裕時 (例如VoD應用)，Basic PR-TCP雖然比TCP Reno及TFRC降低了約3%的PSNR值，但是最少能節省8%的頻寬耗費，Single-Side PR-TCP的PSNR值跟Basic PR-TCP相近，但是額外耗用約5%的頻寬資源。 / With the advance of computer and communication networks, many new information services over IP-based networks such as video streaming and VoIP (Voice over IP) are growing rapidly. These services can tolerate some packets lost in transmission without too much damage to their quality. The content carried in the packets of these services is not equally important in their replay processes. For example, key frames (e.g. I-Frames) of a video encoded in MPEG format are more important than others. The loss of I-frames may have a large impact to the quality of the transmitted video, while the loss of other types of frames may only have nominal damage. Unfortunately, the two most popular transport protocols, UDP and TCP, treat all packets equally without any discrimination. TCP guarantees the delivery of all packets, while UDP doesn't. TCP may waste too much resource to guarantee the delivery of unimportant packets, while UDP may fail to deliver too many important packets. This thesis proposes a new TCP protocol, named Partial-Reliable TCP (PR-TCP), which applies selective retransmission strategy to provide delivery guarantee to the selected packets designated by the application programs. In this way, we can save bandwidth consumption and reduce the average delivery time without significant quality degradation. In fact, if the delivery of an object requires a stringent delivery time, the reduction of average delivery time may also lead to the reduction of abandoned packets at the receiver end. We propose two different versions of PR-TCP, Basic PR-TCP and Single-Side PR-TCP. Basic PR-TCP requires both ends of a connection to adopt PR-TCP while Single-Side PR-TCP only requires the sender end to adopt it. It is much easier to deploy Single-Side PR-TCP on the client-server systems where only servers need to use PR-TCP. Finally, we use NS-2 network simulator to evaluate our PR-TCP against TCP Reno, TFRC and UDP. Two video stream samples are used for video sources. Three quality parameters are evaluated: wasted bandwidth consumption, PSNR, and the number of packets in decodable frames. Under heavy loaded wired network and short delay bound (<0.8 sec.), the simulation shows that Basic PR-TCP can outperform TCP Reno and TFRC in the number of packets in decodable frames by at least 18%. It can outperform TCP Reno, TFRC, and UDP in PSNR by at least 12%. The performance of Single-Side PR-TCP is less then Basic PR-TCP in terms of PSNR by 10%, and it consumes larger bandwidth by 8%. Under wireless environments where error rate is high, the simulation shows that Basic PR-TCP can outperform TCP Reno and TFRC in the number of packets in decodable frames by at least 19% as well as wasted transmission overhead by at least 15%. It can also outperform TCP Reno, TFRC, and UDP in PSNR by at least 20%. The performance of Single-Side PR-TCP is less then Basic PR-TCP in terms of PSNR by 14%, and it consumes larger bandwidth by 10%. Under large delay bound (>8 sec.), the quality (PSNR) of the video transmitted using Basic PR-TCP is downgraded by only 3%, while it can save network bandwidth by 8%. The performance of Single-Side PR-TCP is about the same as Basic PR-TCP in terms of PSNR, but it consumes slightly larger bandwidth by 5%.

No description available.

Catalytic ethylene oligomerization is a well understood industrially viable process. The large majority of scientific literature and patents concerning this process has been developed with the use of chromium catalysts. Commercial systems producing selective tri/tetramerization, non-selective oligomerization and polymerization are all based on this metal with the exception of a few systems based on other transition metals (Zr, Ti, Ni etc.). This versatility raises interesting questions about chromium’s unique behaviour. Essentially, selective or non-selective oligomerization and polymerization processes could be regarded as belonging to the same category of C-C bond forming reactions, though different mechanisms are involved. The first part of this thesis explores a variety of chromium complexes for ethylene oligomerization purposes. In order to gather further information about the unique behaviour of chromium, we have explored a variety of nitrogen and phosphorus containing ligands. We started with a simple bi-dentate anionic amidophosphine (NP) ligand and assessed the role of the ligand’s negative charge and number of donor atoms in determining the type of catalytic behaviour in relation to the metal oxidation state. This ligand proved capable of generating a series of chromium dimeric, tetrameric or polymeric and even heterobimetallic chromium-aluminate complexes in different valence states. This allowed us to isolate a “single component” self activating Cr(II) complex as well as a rare example of mixed valence Cr(I)/Cr(II) species. Additionally, each of these species acted as switchable catalyst depending on the type of co-catalyst

Magistro darbe tiriama žėlimo ypatumai grynuose pušynuose po neplynųjų atvejinių kirtimų Liepynės, Meros, Nemenčinės, Purviniškių girininkijose. Darbo objektas – V.Į. Nemenčinės miškų urėdijos Liepynės, Meros, Nemenčinės, Purviniškių girininkijų 2006–2012 metais neplynaisiais (atvejiniais) kirtimais iškirstos brandžių pušynų kirtavietės. Darbo metodai – Tyrimai vykdyti 1–7 metų minėtų girininkijų neplynųjų atvejinių kirtimų pušynų kirtavietėse 2012–2013 metais. Siekiant įvertinti žėlinių kokybę ir atlikti jų apskaitą tiriamų kirtaviečių apskaitos aikštelės buvo tolygiai išdėstytos sąlyginai – vienodais atstumais sklypų įstrižainių kryptimis. Nuo žėlinių tankumo priklausėšių stačiakampių apskaitos aikštelių plotas.Kai žėliniai buvo vidutinio tankumo (2–8 tūkst. vnt./ha) – 10 m2, kai reti (< 2 tūkst. vnt./ha) – 20 m2. Apskaitos aikštelių kiekis priklausė nuo kirtavietės ploto. Mažesniuose kaip 1 ha sklypuose buvo išdėstytos penkios aikštelės, 1–3 ha – išdėstytos aštuonios ir didesniuose kaip 3 ha – dešimt ir daugiau apskaitos aikštelių.Kiekvienoje apskaitos aikštelėje atlikti tokie vertinimai: savaiminukų gausa ir rūšis, savaiminukų gyvybingumas, žolinės dangos agresyvumo laipsnis, pažeidimai ir galimos priežastys. Darbo rezultatai – tirtose 20 neplynųjų kirtimų kirtaviečių vidutinis žėlinių tankis – 2270 vnt./ha, vidutinė žėlinių rūšinė sudėtis – 6P4B. Liepynės girininkijos – 3750 vnt./ha, 8P2B. Meros – 1210 vnt./ha,7B3P. Nemenčinės – 2070 vnt./ha,6P4B. Purviniškių – 1500 vnt... [toliau žr. visą tekstą] / The present Master’s thesis examines the growth peculiarities of pure pine forests after selective shelterwood cutting in Liepynė, Mera, Nemenčinė, Purviniškės forestries. Object of the thesis – cutting areas of mature pine forests, cut by selective (shelterwood) cutting, in Liepynė, Mera, Nemenčinė, Purviniškių forestries of Nemenčinė Forest Enterprise during the period of 2006–2012. Methods of the research – research was carried out in selective cutting areas of pine forests of aforementioned forestries in 1-7 years, during the period of 2012-2013. Seeking to assess the quality of sprouts and make the inventory, inventory sites of researched cutting areas were divided into relatively equal distances between areas at diagonal direction. The area of rectangular inventory sites depended on density of sprouts. In case of average density (2–8 thousandunits/ha) – 10 m2, and in case of low density (< 2 thousand units/ha) – 20 m2. The number of inventory sites depended on area of cutting zone. There were five sites in smaller than 1 ha plots, while there were eight sites in plots of 1–3 ha, and there were ten and more inventory sites in 3 ha plots. The following assessments were made in each inventory site: abundance and species of wildings, viability of wildings, aggressiveness degree of grass cover, its damage and possible causes. Results of the thesis– average density of sprouts in 20 researched selective cutting areas is2270 units/ha, average species composition of sprouts –... [to full text]