Extreme eigenvalues of principal minors of random matrices with moment conditions

Hu Jianwei,Keita Seydou,Fu Kang 한국통계학회 2023 Journal of the Korean Statistical Society Vol.52 No.3

Let x_1 ,..., x_n be a random sample of size n from a p-dimensional population distribution, where p = p(n) → ∞. Consider a symmetric matrix W = X^(⊤)X with parameters n and p, where X = (x_1 ,..., x_n )^⊤. In this paper, motivated by model selection theory in high-dimensional statistics, we mainly investigate the asymptotic behavior of the eigenvalues of the principal minors of the random matrix W. For the Gaussian case, under a simple condition that m = o(n∕ log p), we obtain the asymptotic results on maxima and minima of the eigenvalues of all m × m principal minors of W. We also extend our results to general distributions with some moment conditions. Moreover, we gain the asymptotic results of the extreme eigenvalues of the principal minors in the case of the real Wigner matrix. Finally, similar results for the maxima and minima of the eigenvalues of all the principal minors with a size smaller than or equal to m are also given.

Proton Transfer from the Inactive Gas-Phase Nicotine Structure to the Bioactive Aqueous-Phase Structure

Gaigeot, Marie-Pierre,Cimas, Alvaro,Seydou, Mahamadou,Kim, Ju-Young,Lee, Sungyul,Schermann, Jean-Pierre American Chemical Society 2010 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.132 No.51

<P>The role of water in the structural change of nicotine from its inactive form in the gas phase to its bioactive form in aqueous solution has been investigated by two complementary theoretical approaches, i.e., geometry optimizations and molecular dynamics. Structures of the lowest-energy nicotineH(+)-(H(2)O)(n) complexes protonated either on the pyridine (inactive form) or pyrrolidine (active form) ring have been calculated, as well as the free-energy barriers for the proton-transfer tautomerization between the two cycles. These structures show chains of 2-4 water molecules bridging the two protonation sites. The room-temperature free-energy barrier to tautomerization along the minimum-energy path from the pyridine to the pyrrolidine cycle drops rapidly when the number of water molecules increases from 0 to 4, but still remains rather high (16 kJ/mol with four water molecules), indicating that the proton transfer is a rather difficult and rare event. We compare results obtained through this explicit water molecule approach to those obtained by means of continuum methods. Car-Parrinello molecular dynamics (CPMD) simulations of the proton-transfer process in bulk with explicit water molecules have been conducted at room temperature. No spontaneous proton transfers have been observed during the dynamics, and biased CPMD simulations have therefore been performed in order to measure the free-energy profile of the proton transfer in the aqueous phase and to reveal the proton-transfer mechanism through water bridges. The MD bias involves pulling the proton from the pyridine ring to the surrounding bulk. Dynamics show that this triggers the tautomerization toward the pyrrolidine ring, proceeding without energy barrier. The proton transfer is extremely fast, and protonation of the pyrrolidine ring was achieved within 0.5 ps. CPMD simulations confirmed the pivotal role played by the water molecules that bridge the two protonation sites of nicotine within the bulk of the surrounding water.</P>

RNA Interference Targeting Nucleocapsid Protein Inhibits Porcine Reproductive and Respiratory Syndrome Virus Replication in Marc-145 Cells

Minnan Yang,Zhuang Ding,Qun Xiang,Xiaodong Zhang,Xiang Li,Seydou Sylla 한국미생물학회 2014 The journal of microbiology Vol.52 No.4

Porcine reproductive and respiratory syndrome (PRRS) is animportant disease, which leads to severe economic losses inswine-producing areas of the world. However, current antiviralstrategies cannot provide highly effective protection. In this study, three theoretically effective interference targetsites (71-91, 144-164, 218-238) targeting the nucleocapsid (N)gene of PRRSV were designed and selected, and then threesiRNA-expressing plasmids were constructed, respectivelynamed p2.1-N71, p2.1-N144, and p2.1-N218. The recombinantsiRNA-expressing plasmids were transfected into Marc-145 cells; then the cells were infected with PRRSV (JL07SWstrain); finally, after incubation for 48 h, the antiviral activityof those siRNA-expressing plasmids in Marc-145 cells wasassessed by cytopathic effects, virus titers, indirect immunofluorescence,and quantitative real-time PCR. Experimentalresults demonstrated that these three siRNA-expressing plasmidscould effectively and significantly inhibit the replicationof PRRSV by 93.2%, 83.6%, and 89.2% in Marc-145 cells,respectively. Among these three siRNA-expressing plasmids,p2.1-N71 was found to be most effective, while p2.1-N144and p2.1-N218 displayed relatively weak inhibition of virusreplication. The results indicated that siRNA-expressing plasmidstargeting the N gene of PRRSV could significantly inhibitPRRSV replication in Marc-145 cells. Based on our experimentalresults and previous reports, the 71-91, 179-197,and 234-252 sites of the N gene are good choices to effectivelyinhibit the replication of PRRSV, and this RNA interferencetechnique can be a potential anti-PRRSV strategy.

A multi-country study of the economic burden of dengue fever based on patient-specific field surveys in Burkina Faso, Kenya, and Cambodia

Lee, Jung-Seok,Mogasale, Vittal,Lim, Jacqueline K.,Ly, Sowath,Lee, Kang Sung,Sorn, Sopheak,Andia, Esther,Carabali, Mabel,Namkung, Suk,Lim, Sl-Ki,Ridde, Valé,ry,Njenga, Sammy M.,Yaro, Seydou,Yoon Public Library of Science 2019 PLoS neglected tropical diseases Vol.13 No.2

<▼1><P><B>Background</B></P><P>Dengue fever is a rapidly growing public health problem in many parts of the tropics and sub-tropics in the world. While there are existing studies on the economic burden of dengue fever in some of dengue-endemic countries, cost components are often not standardized, making cross-country comparisons challenging. Furthermore, no such studies have been available in Africa.</P><P><B>Methods/Principal findings</B></P><P>A patient-specific survey questionnaire was developed and applied in Burkina Faso, Kenya, and Cambodia in a standardized format. Multiple interviews were carried out in order to capture the entire cost incurred during the period of dengue illness. Both private (patient’s out-of-pocket) and public (non-private) expenditure were accessed to understand how the economic burden of dengue is distributed between private and non-private payers.</P><P>A substantial number of dengue-confirmed patients were identified in all three countries: 414 in Burkina Faso, 149 in Kenya, and 254 in Cambodia. The average cost of illness for dengue fever was $26 (95% CI $23-$29) and $134 (95% CI $119-$152) per inpatient in Burkina Faso and Cambodia, respectively. In the case of outpatients, the average economic burden per episode was $13 (95% CI $23-$29) in Burkina Faso and $23 (95% CI $19-$28) in Kenya. Compared to Cambodia, public contributions were trivial in Burkina Faso and Kenya, reflecting that a majority of medical costs had to be directly borne by patients in the two countries.</P><P><B>Conclusions/Significance</B></P><P>The cost of illness for dengue fever is significant in the three countries. In particular, the current study sheds light on the potential economic burden of the disease in Burkina Faso and Kenya where existing evidence is sparse in the context of dengue fever, and underscores the need to achieve Universal Health Coverage. Given the availability of the current (CYD-TDV) and second-generation dengue vaccines in the near future, our study outcomes can be used to guide decision makers in setting health policy priorities.</P></▼1><▼2><P><B>Author summary</B></P><P>Dengue fever is a major public health concern in many parts of South-East Asia and South America. In addition to countries where dengue has been highly prevalent for many years, there is a growing concern on the undocumented burden of dengue in Africa. Following the successful execution of the first-round economic burden study in Vietnam, Thailand, and Colombia by the Dengue Vaccine Initiative, the second-round economic burden study was implemented in Burkina Faso, Kenya and Cambodia using the same standardized methodology. In particular, the second-round study targeted GAVI eligible countries for future vaccine introductions and included two African countries where the burden of dengue was relatively unknown. Our study outcomes show that the economic burden of dengue fever is significant in all three countries. The dengue vaccination era began in 2016 with the first dengue vaccine (CYD-TDV) although its public use should be carefully determined due to the safety concerns related to the vaccine. Considering that there are other second-generation dengue vaccines in development, the current study outcomes provide an important step to estimate the economic benefits of vaccination in the three countries.</P></▼2>