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Background Hospital-acquired (HA) Clostridioides difficile infection (CDI) is among the most common hospital-acquired infections and is a leading cause of morbidity and mortality among hospitalized older adults. Oral vancomycin prophylaxis (OVP) has been demonstrated in recent studies to reduce the incidence of HA CDI. This study aims to evaluate the effectiveness of OVP in the prevention of HA CDI in a community hospital setting. Methods We developed a protocol to administer prophylactic oral vancomycin based on patients’ risk factors and implemented it at our community hospital in Evanston, Illinois, in September 2020. The intervention group consists of patients admitted to our hospital between October 1, 2020, to March 31, 2021, who received OVP. Patients admitted between October 1, 2019, to March 31, 2020, who had at least one risk factor of CDI and met the inclusion criteria of OVP protocol were selected as the control group. Electronic medical records were retrospectively collected and analyzed. Propensity score matching was performed for a one-to-one match between two groups. Logistic regression models were used to study the relationship between HA CDI and independent variables, including OVP, risk factors of CDI, and demographic characteristics. Table 1.Sample characteristics of the control and intervention groups A Student t-test was performed for continuous parameters. A Chi-square test was performed for categorical parameters. Non PPx = control group; OVP PPx = oral vancomycin prophylaxis group; SNF = skilled nursing facility; LOS = length of stay; PPI = proton pump inhibitor; H2RA = histamine 2 receptor antagonist. Results A total of 446 patients (267 in the intervention group and 179 in the control group) were included. The sample characteristics are summarized in Table 1. 4/175 (2.2%) patients in the control group developed HA CDI, compared with 12/255 (4.5%) in the intervention group. Before matching, patients who received OVP (OR=7.62, p=0.010) and had a longer length of stay (LOS, OR=1.11, p=0.002) were found to have increased odds ratios (OR) of development of HA CDI (Table 2). After propensity score matching, 4/176 (2.3%) patients in the control group developed HA CDI, compared with 5/176 (2.8%) (Figure 1). Patients from skilled nursing facilities (SNF, OR=15.41, p=0.021) and with longer LOS (OR 1.15, p=0.005) were found to be associated with higher OR of HA CDI (Table 3). Table 2.The odds ratio of development of hospital-acquired C.diff infection among control and intervention groups. A binary logistic regression model was used for this study. CI = 95% confidence interval. R2 Tujur = coefficients of determination (D); AIC = Akaike’s Information Criteria. OVP PPx = oral vancomycin prophylaxis group; SNF = skilled nursing facility; LOS = length of stay; PPI = proton pump inhibitor; H2RA = histamine 2 receptor antagonist. Figure 1.Propensity score matching of control and intervention groups. (A) Distribution of propensity scores between unmatched and matched control and intervention groups. (B) Distribution balance of propensity score before and after matching. Treatment o = control group; Treatment 1 = OVP intervention group. (C) The distribution balance of covariates used for propensity score calculation before and after matching. (D) Summary of propensity score matching results. HA CDI = hospital-acquired C.diff infection (after propensity score matching). Table 3.The odds ratio of development of hospital-acquired C.diff infection among control and intervention groups after propensity score matching. A binary logistic regression model was used for this study. CI = 95% confidence interval. R2 Tujur = coefficients of determination (D); AIC = Akaike’s Information Criteria. OVP PPx = oral vancomycin prophylaxis group; SNF = skilled nursing facility; LOS = length of stay; PPI = proton pump inhibitor; H2RA = histamine 2 receptor antagonist. Conclusion Prophylactic administration of oral vancomycin to patients with selected risk factors has no statistical significance in reducing or preventing HA CDI. A longer length of hospital stay may be associated with higher risk for developing HA CDI. Disclosures All Authors: No reported disclosures.

Objective To describe the clinical characteristics and outcomes of two waves of the COVID-19 pandemic. Methods We retrospectively reviewed a de-identified dataset of patients with COVID-19 admitted to our community hospital in Evanston, Illinois, from March 1, 2020, to February 28, 2021. We then identified patients from the first wave as those admitted during the initial peak of admissions observed at our hospital between March 1, 2020, and September 3, 2020. The second wave was defined as those admitted during the second peak of admissions observed between October 1, 2020, and February 28, 2021. Results A total of 671 patients were included. Of those, 399 (59.46%) were identified as patients from the first wave, and 272 (40.54%) were identified as patients from the second wave. Significantly more patients received steroids (86.4% vs. 47.9%, p

Senescence is an irreversible mitotic arrest of the cell that can result from replicative aging or stressors. It can be beneficial by conferring resistance to apoptosis, or detrimental by inducing pro-inflammatory signaling in the microenvironment. Senescent cells have been observed in both aged and diseased tissue, including the brain. The aging brain undergoes changes such as cortical atrophy and increases in inflammatory and oxidative factors, with decreases in synaptic plasticity and mitochondrial function. Significant neuronal loss is observed and thought to drive the atrophy in the corresponding areas of the brain in neurodegenerative diseases (ND). Despite being terminally differentiated, a senescence-like phenotype is observed in neurons upon stress in vitro and also in neurocognitive disorders like HIV-associated dementia and Alzheimer’s disease in vivo. Aging is also associated with lower regenerative capacity of neural stem and progenitor cells (NSPC). In vivo, their neurogenerative capacity is modulated by a variety of external factors, including growth factors, diet, and inflammation. NSPC have been observed to undergo stress-induced senescence in vitro. Deregulation of other CNS cell types, including oligodendrocytes and microglia occur in aging and ND. Microglia, which are not post-mitotic, senesce in culture in response to replicative or inflammatory stress. Astrocytes, which make up half of all cells in the CNS, maintain and protect neurons. In response to insult or injury however, astrocytes undergo phenotypic changes collectively termed reactive astrogliosis. This response can be both detrimental and beneficial to the neurons, and its downregulation improves disease parameters in a mouse model of AD. We have observed astrocyte senescence in vitro in response to replicative and oxidative stress and Aβ peptides, along with accumulation of senescent astrocytes in aged and AD brain. Given that astrocytes perform a myriad of complex functions in the CNS in order to maintain homeostasis, the loss of astrocyte function or the gain of neuroinflammatory function as a result of senescence could have profound implications for aging brain and neurodegenerative disorders.

This paper is the second part of a two-part series presenting the results from an experimental demonstration of frequency regulation in a commercial building test facility. In Part I, we developed relevant building models and designed a hierarchical controller for reserve scheduling, building climate control and frequency regulation. In Part II, we introduce the communication architecture and experiment settings, and present extensive experimental results under frequency regulation. More specifically, we compute the day-ahead reserve capacity of the test facility under different assumptions and conditions. Furthermore, we demonstrate the ability of model predictive control to satisfy comfort constraints under frequency regulation, and show that fan speed control can track the fast-moving RegD signal of the Pennsylvania, Jersey, and Maryland Power Market (PJM) very accurately. In addition, we report the observed effects of frequency regulation on building control and provide suggestions for realworld implementation projects. Our results show that hierarchical control is appropriate for frequency regulation from commercial buildings., Comment: 22 pages

Co-simulation platforms are necessary to study the interactions of complex systems integrated in future smart grids. The Virtual Grid Integration Laboratory (VirGIL) is a modular co-simulation platform designed to study interactions between demand response strategies, building comfort, communication networks, and power system operation. This paper presents the coupling of power systems, buildings, communications and control under a master algorithm. There are two objectives. First, to use a modular architecture for VirGIL, based on the Functional Mock-up Interface (FMI), where several different modules can be added, exchanged, and tested. Second, to use a commercial power system simulation platform, familiar to power system operators, such as DIgSILENT Powerfactory. This will help reduce the barriers to the industry for adopting such platforms, investigate and subsequently deploy demand response strategies in their daily operation. VirGIL further introduces the integration of the Quantized State System (QSS) methods for simulation in this co-simulation platform. Results on how these systems interact using a real network and consumption data are also presented.

Integrity measurement is a key issue in building trust in distributed systems. A good solution to integrity measurement has to provide both strong isolation between the measurement agent and the measurement target and Time of Check to Time of Use (TOCTTOU) consistency (i.e., the consistency between measured version and executed version throughout the lifetime of the target). Unfortunately, none of the previous approaches provide (or can be easily modified to provide) both capabilities. This paper presents HIMA, a hypervisor-based agent that measures the integrity of Virtual Machines (VMs) running on top of the hypervisor, which provides both capabilities identified above. HIMA performs two complementary tasks: (1) active monitoring of critical guest events and (2) guest memory protection. The former guarantees that the integrity measures are refreshed whenever the guest VM memory layout changes (e.g., upon creation of processes), while the latter ensures that integrity measurement of user programs cannot be bypassed without HIMA's knowledge. This paper also reports the experimental evaluation of a HIMA prototype using both micro-benchmark and application benchmark; the experimental results indicate that HIMA is a practical solution for real world applications.

Despite decades of research, software continues to have vulnerabilities. Successful exploitations of these vulnerabilities by attackers cost millions of dollars to businesses and individuals. Unfortunately, most effective defensive measures, such as patching and intrusion prevention systems, require an intimate knowledge of the vulnerabilities. Many systems for detecting attacks have been proposed. However, the analysis of the exploited vulnerabilities is left to security experts and programmers. Both the human effortinvolved and the slow analysis process are unfavorable for timely defensive measure to be deployed. The problem is exacerbated by zero-day attacks.

Remote attestation of system integrity is an essential part of trusted computing. However, current remote attestation techniques only provide integrity proofs of static properties of the system. To address this problem we present a novel remote dynamic attestation system named ReDAS (Remote Dynamic Attestation System) that provides integrity evidence for dynamic system properties. Such dynamic system properties represent the runtime behavior of the attested system, and enable an attester to prove its runtime integrity to a remote party. ReDAS currently provides two types of dynamic system properties for running applications: structural integrity and global data integrity. In this work, we present the challenges of remote dynamic attestation, provide an in-depth security analysis and introduce a first step towards providing a complete runtime dynamic attestation framework. Our prototype implementation and evaluation with real-world applications show that we can improve on current static attestation techniques with an average performance overhead of 8%.

Understanding security bugs in a vulnerable program is a non-trivial task, even if the target program is known to be vulnerable. Though there exist debugging tools that facilitate the vulnerability analysis and debugging process, human developers still need to manually trace the program execution most of the times. This makes security debugging a difficult and tiresome task even for experienced programmers. In this paper, we present the development of a novel security debugging tool called CBones (SeeBones, where bones is an analogy of program structures). CBones is intended to fully automate the analysis of a class of security vulnerabilities in C programs, the exploits of which would compromise the integrity of program structures satisfied by all legitimate binaries compiled from C source code. In other words, CBones automatically discovers how unknown vulnerabilities in C programs are exploited based on program structural constraints. Unlike the previous approaches, CBones can automatically identify exploit points of unknown security bugs without requiring a training phase, source code access (analysis or instrumentation), or additional hardware supports. To validate the effectiveness of this approach, we evaluate CBones with 12 real-world applications that contain a wide range of vulnerabilities. Our results show that CBones can discover all security bugs with no false alarms, pinpoint the corrupting instructions, and provide information to facilitate the understanding of how an attack exploits a security bug.

Software vulnerabilities have been the main contributing factor to the Internet security problems such as fast spreading worms. Among these software vulnerabilities, memory corruption vulnerabilities such as buffer overflow and format string bugs have been the most common ones exploited by network-based attacks. Many security countermeasures (e.g., patching, automatic signature generation for intrusion detection systems) require vulnerability information to function correctly. However, despite many years of research, automatically identifying unknown software vulnerabilities still remains an open problem.In this paper, we present the development of a security debugging tool named MemSherlock, which can automatically identify unknown memory corruption vulnerabilities upon the detection of malicious payloads that exploit such vulnerabilities. MemSherlock provides critical information for unknown memory corruption vulnerabilities, including (1) the corruption point in the source code (i.e., the statement that allows the exploitation of memory corruption vulnerability), (2) the slice of source code that helps the malicious input to reach the corruption point, and (3) the description of how the malicious input exploits the unknown vulnerability. We evaluate MemSherlock with a set of 11 real-world applications that have buffer overflow, heap overflow, and format string vulnerabilities. The evaluation results indicate that MemSherlock is a useful tool to facilitate the automatic vulnerability analysis process.

Self-propagating computer worms have been terrorizing the Internet for the last several years. With the increasing density, inter-connectivity and bandwidth of the Internet combined with security measures that inadequately scale, worms will continue to plague the Internet community. Existing anti-virus and intrusion detection systems are clearly inadequate to defend against many recent fast-spreading worms. In this paper we explore an active counter-attack method - anti-worms. We propose a method that transforms a malicious worm into an anti-worm which disinfects its original. The method is evaluated using the CodeRed, Blaster and Slammer worms. We show through simulation the effectiveness of an anti-worm with several propagation schemes and its impact on the overall network. We also discuss important limitations of the proposed method.

Dear Editor: We have read the article by Waldinger et al 1. First of all, once again we do apologise for the mistake in our article regarding a possible asssociation of the 5-HTTLPR gene polymorphism and lifelong premature ejaculation (PE) in Turkish men. Previously, the total number of patients and controls had been mistakenly written as '70' instead of '69'. The percentage of L/S and S/S had also been written mistakenly 53 % and 28 % instead of 54 % and 29 %, respectively. In addition , the number of 'S' allele '74' was corrected as '77' in Table 1. All these mistakes have been corrected in the 'Abstract', 'Results' and 'Table 1' sections of the study. 'The S allele of the 5-HTTLPR gene was significantly more frequent in PE patients than in controls (P < 0.025)' expression was added to the 'Results' section of the study. Main revisions have been carried out in the Abstract, Results and Table 1, no change has been applied on the other sections (introduction, material and methods, and discussion) of the study. The other criticised issue is the statistical method used in our study. Statistical analyses were performed by an expert statistician in our study. All the statistical analyses of the groups were carried out again and the results of statistical analyses were found to be similar to previous values. Nevertheless, in our study results were statistically significant when genotype groups were compared according to χ2–test. Also, Hardy-Weinberg equilibrium test is pivotal for this kind of laboratory DNA testing and it can be used to generalize results of a study population to all population. There is a homogen distrubition in the control group of our study but not in the study group. When to consider if our study is the first real DNA study showing an association between the intravaginal ejaculation latency time (IELT) in men with lifelong PE and 5-HTTLPR polymorphism, we have to point out that our study was received in 23 April 2008 and was accepted in 20 July 2008 by your journal. A similar study regarding the issue, performed by Janssen et al., was published in October 2008 (e-pub), latter than our study. Of course some authors also reported that high prevelance of PE in family members of men with lifelong PE, but these are only clinical observations which are not DNA-based molecular genetic studies.