Buffer Overflow and SQL Injection in C++

Buffer overflows and SQL Injection have plagued programmers for many years. A successful buffer overflow, innocuous or not, damages a computer’s permanent memory. Safer buffer overflow programs are presented in this thesis for the C programs characterizing string concatenation, string copy, and format get string, a C program which takes input and output from a keyboard, in most cases. Safer string concatenation and string copy programs presented in this thesis require the programmer to specify the amount of storage space necessary for the program’s execution. This safety mechanism is designed to help programmers avoid over specifying the amount of storage space in a computer in the event in which the actual storage space is smaller. SQL injection into a computer database can alter or delete some or all of the computer database. To make matters more complicated, not all SQL databases use the same SQL statements and programming syntax. SQLite version 3 is a database which is vulnerable to SQL Injection. Computer Science I (CS I) and Computer Science II (CS II) classes will benefit from a computer program designed to illustrate various defective queries and how SQL injection might occur in a practical, real-world setting. The C++ command-line program designed in this thesis is a contribution to this project

Photocathode Quantum Efficiency of Ultra-Thin Cs2Te Layers On Nb Substrates

The quantum efficiencies (QE) of photocathodes consisting of bulk Nb substrates coated with thin films of Cs2Te are reported. Using the standard recipe for Cs2Te deposition developed for Mo substrates (220 {\AA} Te thickness), a QE ~11% - 13% at light wavelength of 248 nm is achieved for the Nb substrates, consistent with that found on Mo. Systematic reduction of the Te thickness for both Mo and Nb substrates reveals a surprisingly high residual QE ~ 6% for a Te layer as thin as 15 {\AA}. A phenomenological model based on the Spicer 3-Step model along with a solution of the Fresnel equations for reflectance, R, leads to a reasonable fit of the thickness dependence of QE and suggests that layers thinner than 15 {\AA} may still have a relatively high QE. Preliminary investigation suggests an increased operational lifetime as well. Such an ultra-thin, semiconducting Cs2Te layer may be expected to produce minimal ohmic losses for RF frequencies ~ 1 GHz. The result thus opens the door to the potential development of a Nb (or Nb3Sn) superconducting photocathode with relatively high QE and minimal RF impedance to be used in a superconducting radiofrequency (SRF) photoinjector.Comment: 12 pages, 3 figure

Testing for Volatility and Market Efficiency of Uganda Securities Exchange

This study presents empirical evidence of volatility and market efficiency of Uganda Securities Exchange. Results indicate that the Uganda Securities Exchange exhibits a weak-form efficiency based on Generalized Autoregressive Conditional Heteroscedasticity (GARCH), Augmented Dickey Fuller (ADF) and the serial correlation tests. This may be attributed to few listed companies and less liquidity hence the need to implement the over the counter facility, two tier market, more listing and promotion of collective investment schemes. Firms and individuals should be encouraged to buy or sell securities outside their face values, as a means of encouraging financial activities in the economy

Critical Functions Specified by the MLL CXXC Domain Determine Leukemogenic Capacity

TheMixed Lineage Leukemia(MLL) gene can participate in chromosomal translocations which generate a fusion protein leading to acute leukemia. A better understanding of how MLL fusion proteins contribute to leukemia is necessary in order to develop more effective treatments. In my dissertation project, I investigated the functional role of amino acids within the MLL CXXC domain to determine how specific residues contribute to leukemogenic capacity. MLL fusion proteins retain the amino-terminal portion of MLL including the CXXC DNA-binding domain while the carboxy-terminal portion is comprised of a fusion partner. The closest homolog of MLL, MLL2 (alternatively named MLL4), also contains a similar CXXC domain, yet an artificial MLL2 fusion protein is unable to transform cellsin vitro. I hypothesized that specific amino acid differences between the MLL and MLL2 CXXC domains account for differences in leukemogenic capacity. To test this hypothesis, the MLL2 CXXC domain was cloned into the context of the well-studied MLL-AF9 fusion protein to generate an artificial MLL/MLL2-AF9 chimera. Amino acid substitutions were then introduced within the MLL2 CXXC domain of this synthetic chimera to restore residues to the MLL sequence. By comparing residues of the MLL and MLL2 CXXC domains in colony formation and protein binding assays, critical amino acids were identified on both the DNA-binding surface and on the opposite, non-DNA-contact surface of the CXXC. Cysteine 1188 of the MLL CXXC domain is the only non-zinc-coordinating cysteine residue within the CXXC domain. This residue is critically positioned on the DNA-binding surface with susceptibility to post-translational modification. I hypothesized that the Cys1188 may be physiologically altered to regulate DNA-binding affinity. Transformed MLL-AF9 progenitor cells were treated with modifying agents or grown under conditions of varying oxygen concentration. The MLL-AF9 cells showed a modest susceptibility to parthenolide treatmentin vitrobut showed no significant differences in proliferation when grown under conditions of varying oxygen. The results from these studies build on the initial work conducted in our laboratory on the MLL CXXC domain and Cys1188 providing valuable direction for future investigations which may eventually allow for therapeutic targeting of the CXXC domain in MLL-associated leukemia

Editorial: Ecological Development and Functioning of Biological Soil Crusts After Natural and Human Disturbances

[no abstract available

Ekiden: A Platform for Confidentiality-Preserving, Trustworthy, and Performant Smart Contract Execution

Smart contracts are applications that execute on blockchains. Today they manage billions of dollars in value and motivate visionary plans for pervasive blockchain deployment. While smart contracts inherit the availability and other security assurances of blockchains, however, they are impeded by blockchains' lack of confidentiality and poor performance. We present Ekiden, a system that addresses these critical gaps by combining blockchains with Trusted Execution Environments (TEEs). Ekiden leverages a novel architecture that separates consensus from execution, enabling efficient TEE-backed confidentiality-preserving smart-contracts and high scalability. Our prototype (with Tendermint as the consensus layer) achieves example performance of 600x more throughput and 400x less latency at 1000x less cost than the Ethereum mainnet. Another contribution of this paper is that we systematically identify and treat the pitfalls arising from harmonizing TEEs and blockchains. Treated separately, both TEEs and blockchains provide powerful guarantees, but hybridized, though, they engender new attacks. For example, in naive designs, privacy in TEE-backed contracts can be jeopardized by forgery of blocks, a seemingly unrelated attack vector. We believe the insights learned from Ekiden will prove to be of broad importance in hybridized TEE-blockchain systems

In vivo hypothalamic regional volumetry across the frontotemporal dementia spectrum

BACKGROUND: Frontotemporal dementia (FTD) is a spectrum of diseases characterised by language, behavioural and motor symptoms. Among the different subcortical regions implicated in the FTD symptomatology, the hypothalamus regulates various bodily functions, including eating behaviours which are commonly present across the FTD spectrum. The pattern of specific hypothalamic involvement across the clinical, pathological, and genetic forms of FTD has yet to be fully investigated, and its possible associations with abnormal eating behaviours have yet to be fully explored. METHODS: Using an automated segmentation tool for volumetric T1-weighted MR images, we measured hypothalamic regional volumes in a cohort of 439 patients with FTD (197 behavioural variant FTD [bvFTD]; 7 FTD with associated motor neurone disease [FTD-MND]; 99 semantic variant primary progressive aphasia [svPPA]; 117 non-fluent variant PPA [nfvPPA]; 19 PPA not otherwise specified [PPA-NOS]) and 118 age-matched controls. We compared volumes across the clinical, genetic (29 MAPT, 32 C9orf72, 23 GRN), and pathological diagnoses (61 tauopathy, 40 TDP-43opathy, 4 FUSopathy). We correlated the volumes with presence of abnormal eating behaviours assessed with the revised version of the Cambridge Behavioural Inventory (CBI-R). RESULTS: On average, FTD patients showed 14% smaller hypothalamic volumes than controls. The groups with the smallest hypothalamic regions were FTD-MND (20%), MAPT (25%) and FUS (33%), with differences mainly localised in the anterior and posterior regions. The inferior tuberal region was only significantly smaller in tauopathies (MAPT and Pick’s disease) and in TDP-43 type C compared to controls and was the only regions that did not correlate with eating symptoms. PPA-NOS and nfvPPA were the groups with the least frequent eating behaviours and the least hypothalamic involvement. CONCLUSIONS: Abnormal hypothalamic volumes are present in all the FTD forms, but different hypothalamic regions might play a different role in the development of abnormal eating behavioural and metabolic symptoms. These findings might therefore help in the identification of different underlying pathological mechanisms, suggesting the potential use of hypothalamic imaging biomarkers and the research of potential therapeutic targets within the hypothalamic neuropeptides

Improving localization accuracy for non-invasive automated early left ventricular origin localization approach

Background: We previously developed a non-invasive approach to localize the site of early left ventricular activation origin in real time using 12-lead ECG, and to project the predicted site onto a generic LV endocardial surface using the smallest angle between two vectors algorithm (SA).Objectives: To improve the localization accuracy of the non-invasive approach by utilizing the K-nearest neighbors algorithm (KNN) to reduce projection errors.Methods: Two datasets were used. Dataset #1 had 1012 LV endocardial pacing sites with known coordinates on the generic LV surface and corresponding ECGs, while dataset #2 included 25 clinically-identified VT exit sites and corresponding ECGs. The non-invasive approach used “population” regression coefficients to predict the target coordinates of a pacing site or VT exit site from the initial 120-m QRS integrals of the pacing site/VT ECG. The predicted site coordinates were then projected onto the generic LV surface using either the KNN or SA projection algorithm.Results: The non-invasive approach using the KNN had a significantly lower mean localization error than the SA in both dataset #1 (9.4 vs. 12.5 mm, p < 0.05) and dataset #2 (7.2 vs. 9.5 mm, p < 0.05). The bootstrap method with 1,000 trials confirmed that using KNN had significantly higher predictive accuracy than using the SA in the bootstrap assessment with the left-out sample (p < 0.05).Conclusion: The KNN significantly reduces the projection error and improves the localization accuracy of the non-invasive approach, which shows promise as a tool to identify the site of origin of ventricular arrhythmia in non-invasive clinical modalities