Have restaurant firms been using right recession turnaround strategies?: Evaluating with propensity score measure

Among the diverse strategies that restaurants use in recessions, some studies have shown that strategies that increase advertising, profit margins, or asset turnover have yielded promising results in terms of firm performance. However, the success of these turnaround strategies might be due to the health or size of a firm rather than the implementation of these strategies. Therefore, this study empirically tested this question utilizing the propensity score measure (PSM) due to concerns with selection bias across restaurant segments. The results showed significant improvements in revenue for limited-service and franchise restaurants when aggressive advertising was used but no improvements in profitability. The profit margin strategy had no impact on revenue but affected profitability and stock returns positively for all segments. Finally, the asset turnover strategy had adverse effects on revenue the year after a recession for all segments. These mixed results suggest that managers need to be cautious when implementing recession turnaround strategies.Accepted manuscrip

Option 2: Why lower priced restaurant segments are better to predict in smaller sub spaces comparing to higher priced restaurants?: A geographical approach using machine learning?

While most causal studies try to find the relationship between market size and the number of restaurants, this study focuses on the difference in predicting the number of restaurants by segments, using machine learning classifiers, which are decision tree, support vector regression, and neural network. The study attempts to provide practical implications in predicting the optimal number of restaurants under the assumption that a market bound exist for restaurants. Results show predictability of the number of restaurants to improve greater for lower priced restaurants than higher priced restaurants when franchise and food retail information was included in the model, which imply uneven market power among lower priced to be greater than higher priced restaurants.Accepted manuscrip

Failure Tolerant Training with Persistent Memory Disaggregation over CXL

This paper proposes TRAININGCXL that can efficiently process large-scale recommendation datasets in the pool of disaggregated memory while making training fault tolerant with low overhead. To this end, i) we integrate persistent memory (PMEM) and GPU into a cache-coherent domain as Type-2. Enabling CXL allows PMEM to be directly placed in GPU's memory hierarchy, such that GPU can access PMEM without software intervention. TRAININGCXL introduces computing and checkpointing logic near the CXL controller, thereby training data and managing persistency in an active manner. Considering PMEM's vulnerability, ii) we utilize the unique characteristics of recommendation models and take the checkpointing overhead off the critical path of their training. Lastly, iii) TRAININGCXL employs an advanced checkpointing technique that relaxes the updating sequence of model parameters and embeddings across training batches. The evaluation shows that TRAININGCXL achieves 5.2x training performance improvement and 76% energy savings, compared to the modern PMEM-based recommendation systems

Deep Learning-based Limited Feedback Designs for MIMO Systems

We study a deep learning (DL) based limited feedback methods for multi-antenna systems. Deep neural networks (DNNs) are introduced to replace an end-to-end limited feedback procedure including pilot-aided channel training process, channel codebook design, and beamforming vector selection. The DNNs are trained to yield binary feedback information as well as an efficient beamforming vector which maximizes the effective channel gain. Compared to conventional limited feedback schemes, the proposed DL method shows an 1 dB symbol error rate (SER) gain with reduced computational complexity.Comment: to appear in IEEE Wireless Commun. Let

Gut Microbial Metabolites Induce Changes in Circadian Oscillation of Clock Gene Expression in the Mouse Embryonic Fibroblasts

Circadian rhythm is an endogenous oscillation of about 24-h period in many physiological processes and behaviors. This daily oscillation is maintained by the molecular clock machinery with transcriptional-translational feedback loops mediated by clock genes including Period2 (Per2) and Bmal1. Recently, it was revealed that gut microbiome exerts a significant impact on the circadian physiology and behavior of its host; however, the mechanism through which it regulates the molecular clock has remained elusive. 3-(4-hydroxyphenyl)propionic acid (4-OH-PPA) and 3-phenylpropionic acid (PPA) are major metabolites exclusively produced by Clostridium sporogenes and may function as unique chemical messengers communicating with its host. In the present study, we examined if two C. sporogenes-derived metabolites can modulate the oscillation of mammalian molecular clock. Interestingly, 4-OH-PPA and PPA increased the amplitude of both PER2 and Bmal1 oscillation in a dosedependent manner following their administration immediately after the nadir or the peak of their rhythm. The phase of PER2 oscillation responded differently depending on the mode of administration of the metabolites. In addition, using an organotypic slice culture ex vivo, treatment with 4-OH-PPA increased the amplitude and lengthened the period of PER2 oscillation in the suprachiasmatic nucleus and other tissues. In summary, two C. sporogenes-derived metabolites are involved in the regulation of circadian oscillation of Per2 and Bmal1 clock genes in the host's peripheral and central clock machineries.1

Estimating the number of severe COVID-19 cases and COVID-19-related deaths averted by a nationwide vaccination campaign in Republic of Korea

Objectives The Korea Disease Control and Prevention Agency promotes vaccination by regularly providing information on its benefits for reducing the severity of coronavirus disease 2019 (COVID-19). This study aimed to analyze the number of averted severe COVID-19 cases and COVID-19-related deaths by age group and quantify the impact of Republic of Korea’s nationwide vaccination campaign. Methods We analyzed an integrated database from the beginning of the vaccination campaign on February 26, 2021 to October 15, 2022. We estimated the cumulative number of severe cases and COVID-19-related deaths over time by comparing observed and estimated cases among unvaccinated and vaccinated groups using statistical modeling. We compared daily age-adjusted rates of severe cases and deaths in the unvaccinated group to those in the vaccinated group and calculated the susceptible population and proportion of vaccinated people by age. Results There were 23,793 severe cases and 25,441 deaths related to COVID-19. We estimated that 119,579 (95% confidence interval [CI], 118,901–120,257) severe COVID-19 cases and 137,636 (95% CI, 136,909–138,363) COVID-19-related deaths would have occurred if vaccination had not been performed. Therefore, 95,786 (95% CI, 94,659–96,913) severe cases and 112,195 (95% CI, 110,870–113,520) deaths were prevented as a result of the vaccination campaign. Conclusion We found that, if the nationwide COVID-19 vaccination campaign had not been implemented, the number of severe cases and deaths would have been at least 4 times higher. These findings suggest that Republic of Korea’s nationwide vaccination campaign reduced the number of severe cases and COVID-19 deaths

Studies of Circadian Nuclear Receptor REV-ERBα in the Dorsal Raphe 5-HT Neurons on Social Interaction Behavior

serotonin; social interaction; social preference; dorsal raphe; Tph2; REV-ERBα; circadian rhythm; fiber-photometry; optogeneticsSocial interaction among conspecifics is essential for maintaining adaptive, cooper-ative, and social behaviors, along with survival among mammals. The 5-hydroxytryptamine (5-HT) neuronal system is an important neurotransmitter for regulat-ing social behaviors, however, the circadian role of 5-HT in social interaction behaviors is unclear. To investigate whether the circadian nuclear receptor, REV-ERBα, a transcrip-tional repressor of the rate-limiting enzyme tryptophan hydroxylase 2 (Tph2) gene in 5-HT biosynthesis, may affect social interaction behaviors, I generated a conditional knock-out (cKO) mouse by targeting Rev-Erbα in the dorsal raphe (DR) 5-HT neurons (5-HTDR-specific REV-ERBα cKO) using the CRISPR/Cas9 gene editing system, and assayed social behaviors, including social preference and social recognition with a three-chamber social interaction test at two circadian time (CT) points, i.e., at dawn (CT00) and dusk (CT12). The genetic ablation of Rev-Erbα in DR 5-HTergic neurons caused impaired social inter-action behaviors, particularly social preference but not social recognition, regardless of two CT points. This deficit of social preference was induced by Rev-Erbα in 5-HTDR-specific mice is functionally associated with real-time elevated neuron activity and 5-HT levels at dusk as determined by fiber-photometry imaging sensors. Moreover, optogenetic inhibition of DR to nucleus accumbens (NAc) 5-HTergic circuit restored the impairment of social preference in 5-HTDR-specific REV-ERB α cKO mouse. These results suggest the significance of the circadian regulation of 5-HT levels by REV-ERBα in regulating social interaction behaviors.|포유류에서 동족 간의 사회적 상호작용은 적응, 협동 및 사회성 (sociability) 행동을 유지하고 종족의 생존에 필수적이다. 세로토닌 (5-hydroxytryptamine, 5-HT)은 사회적 행동을 조절하는 중요한 신경전달물질로서 일주기성을 나타내지만, 사회성 행동에서 세로토닌 뉴런에서 일주기 생체시계 유전자와의 연관성에 대해서는 많은 연구가 이루어지지 않았다. 본 연구에서는 생체 시계 유전자 중 하나인 일주기 핵 수용체 REV-ERBα가 사회성 상호작용 행동에 어떤 영향을 미치는지 연구하고자 유전자 가위 (CRISPR/Cas9) 시스템을 사용하여 세로토닌 뉴런-특이적으로 세로토닌 합성효소 유전자인Tryptophan hydroxylase2 (Tph2)의 전사 억제 인자인 REV-ERBα가 결손된 생쥐 모델을 제작하였고, 낮 (CT00)과 밤 (CT12)의 두 시간대에서 3개의 구획으로 이루어진 사회적 상호작용 행동실험 기법 (three-chamber social interaction test)을 통해 social preference (새로운 생쥐로의 접근, 선호도)와 social recognition (사회성 인지, 기억 정도)를 분석하였다. Dorsal raphe nucleus (DR, 등쪽솔기핵)에 위치한 세로토닌 뉴런에서 Rev-Erbα 유전자 제거는 사회성 행동 중 social preference를 손상시켰지만, social recognition에는 별다른 영향을 주기 않았다. 이는 fiber-photometry (광섬유 광도측정) 기법으로 실시간 세로토닌 뉴런의 활성 및 등쪽솔기핵 세로토닌 양이 증가와 깊은 연관이 있었으며, 이를 등쪽솔기핵에서 nucleus accumbens, (NAc, 측좌핵)을 잇는 신경 회로에서 광유전학적 (optogenetic) 억제로 세로토닌 뉴런 특이적 Rev-Erbα결손 생쥐에서 유도되었던 사회성 손상을 회복시키는 것을 확인하였다. 이러한 결과들은 REV-ERBα에 의한 세로토닌의 정교한 일주기적 조절이 사회성 행동을 조절하는 데 중요하며, REV-ERBα의 조절이 세로토닌 관련 질환의 치료 타겟이 될 수 있음을 시사한다.Ⅰ. INTRODUCTION 1 1.1 Circadian rhythm 1 1.1.1 Master and local or peripheral clock in mammals 5 1.1.2 Molecular clockwork in mammals 6 1.1.3 Circadian regulation of physiology and behaviors 10 1.2 Serotonin (5-hydroxytryptamine, 5-HT) 11 1.2.1 Biosynthesis of serotonin 13 1.2.2 Serotonin transduction and serotonin receptors 17 1.2.3 Functions of central serotonin 18 1.3 Social behavior 19 1.3.1 Social preference and recognition in mammals 20 1.3.2 Serotonin system in social preference and recognition in mammals 21 1.4 Purpose 22 ⅠⅠ. MATERIALS AND METHODS 23 2.1 Animals 23 2.2 Molecular cloning adeno-associated virus (AAV) vectors and virus production 23 2.2.1 Single-guide RNA (sgRNA) 23 2.2.2 AAV production 24 2.2.3 Surgical procedures 24 2.3 Drug preparation and application 25 2.3.1 Local microinjection of SR8278 or GSK4112 25 2.4 RNA isolation and real-time qPCR 25 2.5 High-performance liquid chromatography-coupled electrochemical detector (HPLC-ECD) 26 2.5.1 Sample preparation 26 2.5.2 Measurements of 5-HT and its metabolites 26 2.6 Three chamber social interaction test 27 2.7 Fiber-photometry 28 2.8 Optogenetic manipulation 29 2.9 Immunohistochemistry 29 2.10 Statistical analysis 30 ⅠⅠⅠ. Results 31 3.1 5-HTDR-specific REV-ERBα cKO mouse altered the circadian rhythm of Tph2 and 5-HT levels 31 3.2 Ablation of 5-HTDR-specific REV-ERBα induced impairment of so-cial behavior, especially in social preference, not social recognition 33 3.3 Pharmacological manipulation of REV-ERBα through agonist and/or antagonist affects social behaviors 34 3.4 Changes in the real-time circadian 5-HT neuron activity together with increased 5-HT levels by fiber photometry during the social preference test 36 3.5 DR-NAc circuit-specific ablation of REV-ERBα in 5-HT neurons ex-hibited a deficit in social preference 38 3.6 Optogenetic inhibition of DR 5-HTergic projection to NAc rescued impaired social preference in REV-ERBα cKO mouse 39 ⅠV. Discussion 79 4.1 Circadian regulation of DR 5-HT 79 4.2 DR-NAc 5-HTergic innervation in social interaction 82 4.3 Conclusion 85 V. References 86 VI. Abstract in Korean 96DoctordCollectio

A SIMPLE METHOD FOR MEASURING SYSTEMIC RISK USING CREDIT DEFAULT SWAP MARKET DATA

This paper proposes a simple method that employs credit default swap (CDS) data for analyzing systemic risk. The proposed method overcomes inconsistency problems in existing methods and can produce various indicators of systemic risk in a consistent manner. In addition, this method can measure systemic risk contributions. In particular, the method measures systemic risk contributions in both directions, that is, the overall effect of systemic risk on individual credit risks and vice versa. Using CDS data, we employ the proposed method to measure systemic risk for a group of large financial institutions in the U.S. In addition, we provide empirical results for systemic risk contributions as well as various measures of the overall level of systemic risk and verify the applicability of the proposed method

Mechanical frequency selectivity of an artificial basilar membrane using a beam array with narrow supports

The study presented in this paper assessed the frequency selectivity of an artificial basilar membrane (ABM) constructed using a piezoelectric beam array with narrow supports. Three ABM samples were constructed. Each ABM contained 16 beams with various lengths in a one-dimensional array. To experimentally assess the frequency selectivity of the ABM, mechanical vibration induced either by an electrical or an acoustic stimulus was measured with a scanning laser-Doppler vibrometer. The electro-mechanical and acousto-mechanical transfer functions were defined for the same purpose. The tonotopy of each beam array was visualized by post-processing the experimental results. Finite element analyses were conducted to numerically compute the resonance frequencies, identify the associated vibrational modes, and evaluate the harmonic responses of the beams. The influence of the residual stresses existing in the beams was reflected in the geometric models by introducing three different levels of arc-shaped lateral deformations in the beams. The harmonic analyses revealed that each beam of the ABM samples presented independent band-pass characteristics. The experiments and simulations commonly showed a frequency selectivity of the fabricated ABMs in the range of 2-20 kHz. Therefore, the device is suitable for development of a totally implantable artificial cochlea, implementing a mechanical frequency analyzer. This work is part of research to develop a prototype of a totally implantable artificial cochlea. © 2013 IOP Publishing Ltd.1