Frequency and correlates of subjective cognitive complaints and objective cognitive screening results in African American adults following COVID-19 infection

Background

Subjective cognitive complaints are frequent following COVID-19 infection, but assessment of whether these complaints map onto objective cognitive findings may not be routine in busy clinical settings. Consequently, opportunities to confirm these complaints and to provide follow-up referrals and appropriate care may be missed, thereby impacting patients' functional independence and quality of life. African Americans are vulnerable to poor outcomes from COVID-19, and thus represent a minority group in whom subjective concerns are especially important to investigate. Towards this end, we examined the frequency and correlates of subjective complaints and objective screening results of African American patients referred to the Post-Acute Sequelae of SARS-CoV-2 (PASC) Clinic at Grady Memorial Hospital, a large county teaching hospital in Atlanta, Georgia.

Methods

Eighty seven African American patients (mean age = 52.5, SD = 10.5, range = 30-73) were evaluated between January 28, 2021-October 14, 2021 in the Grady PASC clinic. They ranged from 1 to 17 months post positive SARS-COV-2 antigen testing. Patients were administered a subjective cognitive complaint questionnaire (PROMIS Cognitive Function Scale Short Form 8a) as well as cognitive screening measures including the Mini-Cog (3 item recall, clock) and the Digit Symbol Substitution Test (timed visuomotor sequencing). Mood was assessed via the Patient Health Questionnaire-9, and anxiety via the Generalized Anxiety Disorders Scale. Published norms were used to identify clinically elevated scores.

Results

Sixty six (76%) patients denied experiencing meaningful cognitive concerns, and of these, 25 (38%) had positive cognitive screens indicating impaired performance on objective testing. Of 21 patients with subjectively elevated cognitive concerns, 17 (81%) also had positive cognitive screens. There were no significant differences in sociodemographic factors (p values = .07-.71), days post-acute positive SARS-COV-2 Antigen Test (p = .99), disease severity (p values = .67-.75), or COVID-19 comorbidity indices (medical conditions (p values = .20-.77), substance abuse (p = .79), psychiatric history (p values = .11-.99) in those with or without subjective complaints and objective cognitive findings. However, patients with subjective complaints and objective cognitive findings reported more post-COVID-19 anxiety (p = .02) and depression (p = .001).

Conclusions

Findings indicate a high concordance between subjective complaints on the PROMIS Cognitive Scale and objectively confirmed cognitive impairments in African Americans. Further, almost 40% who reported no cognitive complaints screened positive for cognitive impairment. Although depression and anxiety are associated with subjective complaints, they do not account for positive cognitive screening results, as those patients without depressive complaints also had similar rates of positive objective screens. The findings suggest that cognitive screening using assessment tools should be routinely performed in African Americans, especially those reporting cognitive symptoms on outcome scales. While future studies are needed to assess long-term outcomes, we highly recommend follow-ups in those with positive screens to characterize the specific domains that are impacted and that could affect activities of daily living and quality of life.

Chronic inflammation, neutrophil activity, and autoreactivity splits long COVID

While immunologic correlates of COVID-19 have been widely reported, their associations with post-acute sequelae of COVID-19 (PASC) remain less clear. Due to the wide array of PASC presentations, understanding if specific disease features associate with discrete immune processes and therapeutic opportunities is important. Here we profile patients in the recovery phase of COVID-19 via proteomics screening and machine learning to find signatures of ongoing antiviral B cell development, immune-mediated fibrosis, and markers of cell death in PASC patients but not in controls with uncomplicated recovery. Plasma and immune cell profiling further allow the stratification of PASC into inflammatory and non-inflammatory types. Inflammatory PASC, identifiable through a refined set of 12 blood markers, displays evidence of ongoing neutrophil activity, B cell memory alterations, and building autoreactivity more than a year post COVID-19. Our work thus helps refine PASC categorization to aid in both therapeutic targeting and epidemiological investigation of PASC.

Mild antecedent COVID-19 associated with symptom-specific post-acute sequelae

BACKGROUND

The impact of COVID-19 severity on development of long-term sequelae remains unclear, and symptom courses are not well defined.

METHODS

This ambidirectional cohort study recruited adults with new or worsening symptoms lasting ≥3 weeks from confirmed SARS-CoV-2 infection between August 2020-December 2021. COVID-19 severity was defined as severe for those requiring hospitalization and mild for those not. Symptoms were collected using standardized questionnaires. Multivariable logistical regression estimated odds ratios (OR) and 95% confidence intervals (CI) for associations between clinical variables and symptoms.

RESULTS

Of 332 participants enrolled, median age was 52 years (IQR 42-62), 233 (70%) were female, and 172 (52%) were African American. Antecedent COVID-19 was mild in 171 (52%) and severe in 161 (48%). In adjusted models relative to severe cases, mild COVID-19 was associated with greater odds of fatigue (OR:1.83, CI:1.01-3.31), subjective cognitive impairment (OR:2.76, CI:1.53-5.00), headaches (OR:2.15, CI:1.05-4.44), and dizziness (OR:2.41, CI:1.18-4.92). Remdesivir treatment was associated with less fatigue (OR:0.47, CI:0.26-0.86) and fewer participants scoring >1.5 SD on PROMIS Cognitive scales (OR:0.43, CI:0.20-0.92). Fatigue and subjective cognitive impairment prevalence was higher 3-6 months after COVID-19 and persisted (fatigue OR:3.29, CI:2.08-5.20; cognitive OR:2.62, CI:1.67-4.11). Headache was highest at 9-12 months (OR:5.80, CI:1.94-17.3).

CONCLUSIONS

Mild antecedent COVID-19 was associated with highly prevalent symptoms, and those treated with remdesivir developed less fatigue and cognitive impairment. Sequelae had a delayed peak, ranging 3-12 months post infection, and many did not improve over time, underscoring the importance of targeted preventative measures.

Researching COVID to Enhance Recovery (RECOVER) adult study protocol: Rationale, objectives, and design

IMPORTANCE

SARS-CoV-2 infection can result in ongoing, relapsing, or new symptoms or other health effects after the acute phase of infection; termed post-acute sequelae of SARS-CoV-2 infection (PASC), or long COVID. The characteristics, prevalence, trajectory and mechanisms of PASC are ill-defined. The objectives of the Researching COVID to Enhance Recovery (RECOVER) Multi-site Observational Study of PASC in Adults (RECOVER-Adult) are to: (1) characterize PASC prevalence; (2) characterize the symptoms, organ dysfunction, natural history, and distinct phenotypes of PASC; (3) identify demographic, social and clinical risk factors for PASC onset and recovery; and (4) define the biological mechanisms underlying PASC pathogenesis.

METHODS

RECOVER-Adult is a combined prospective/retrospective cohort currently planned to enroll 14,880 adults aged ≥18 years. Eligible participants either must meet WHO criteria for suspected, probable, or confirmed infection; or must have evidence of no prior infection. Recruitment occurs at 86 sites in 33 U.S. states, Washington, DC and Puerto Rico, via facility- and community-based outreach. Participants complete quarterly questionnaires about symptoms, social determinants, vaccination status, and interim SARS-CoV-2 infections. In addition, participants contribute biospecimens and undergo physical and laboratory examinations at approximately 0, 90 and 180 days from infection or negative test date, and yearly thereafter. Some participants undergo additional testing based on specific criteria or random sampling. Patient representatives provide input on all study processes. The primary study outcome is onset of PASC, measured by signs and symptoms. A paradigm for identifying PASC cases will be defined and updated using supervised and unsupervised learning approaches with cross-validation. Logistic regression and proportional hazards regression will be conducted to investigate associations between risk factors, onset, and resolution of PASC symptoms.

DISCUSSION

RECOVER-Adult is the first national, prospective, longitudinal cohort of PASC among US adults. Results of this study are intended to inform public health, spur clinical trials, and expand treatment options.

REGISTRATION

NCT05172024.

Wellness and Coping of Physicians Who Worked in ICUs During the Pandemic: A Multicenter Cross-Sectional North American Survey

OBJECTIVES

Few surveys have focused on physician moral distress, burnout, and professional fulfilment. We assessed physician wellness and coping during the COVID-19 pandemic.

DESIGN

Cross-sectional survey using four validated instruments.

SETTING

Sixty-two sites in Canada and the United States.

SUBJECTS

Attending physicians (adult, pediatric; intensivist, nonintensivist) who worked in North American ICUs.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

We analysed 431 questionnaires (43.3% response rate) from 25 states and eight provinces. Respondents were predominantly male (229 [55.6%]) and in practice for 11.8 ± 9.8 years. Compared with prepandemic, respondents reported significant intrapandemic increases in days worked/mo, ICU bed occupancy, and self-reported moral distress (240 [56.9%]) and burnout (259 [63.8%]). Of the 10 top-ranked items that incited moral distress, most pertained to regulatory/organizational ( n = 6) or local/institutional ( n = 2) issues or both ( n = 2). Average moral distress (95.6 ± 66.9), professional fulfilment (6.5 ± 2.1), and burnout scores (3.6 ± 2.0) were moderate with 227 physicians (54.6%) meeting burnout criteria. A significant dose-response existed between COVID-19 patient volume and moral distress scores. Physicians who worked more days/mo and more scheduled in-house nightshifts, especially combined with more unscheduled in-house nightshifts, experienced significantly more moral distress. One in five physicians used at least one maladaptive coping strategy. We identified four coping profiles (active/social, avoidant, mixed/ambivalent, infrequent) that were associated with significant differences across all wellness measures.

CONCLUSIONS

Despite moderate intrapandemic moral distress and burnout, physicians experienced moderate professional fulfilment. However, one in five physicians used at least one maladaptive coping strategy. We highlight potentially modifiable factors at individual, institutional, and regulatory levels to enhance physician wellness.

Giant Zero Bias Anomaly due to Coherent Scattering from Frozen Phonon Disorder in Quantum Point Contacts

We demonstrate an unusual manifestation of coherent scattering for electron waves in mesoscopic quantum point contacts, in which fast electron dynamics allows the phonon system to serve as a quasistatic source of disorder. The low-temperature conductance of these devices exhibits a giant (≫2e^{2}/h) zero bias anomaly (ZBA), the features of which are reproduced in a nonequilibrium model for coherent scattering from the "frozen" phonon disorder. According to this model, the ZBA is understood to result from the in situ electrical manipulation of the phonon disorder, a mechanism that could open up a pathway to the on-demand control of coherent scattering in the solid state.

High-Dose Vitamin D3 Administration Is Associated With Increases in Hemoglobin Concentrations in Mechanically Ventilated Critically Ill Adults: A Pilot Double-Blind, Randomized, Placebo-Controlled Trial

BACKGROUND

Anemia and vitamin D deficiency are highly prevalent in critical illness, and vitamin D status has been associated with hemoglobin concentrations in epidemiologic studies. We examined the effect of high-dose vitamin D therapy on hemoglobin and hepcidin concentrations in critically ill adults.

MATERIALS AND METHODS

Mechanically ventilated critically ill adults (N = 30) enrolled in a pilot double-blind, randomized, placebo-controlled trial of high-dose vitamin D3 (D3 ) were included in this analysis. Participants were randomized to receive placebo, 50,000 IU D3 , or 100,000 IU D3 daily for 5 days (totaling 250,000 IU D3 and 500,000 IU D3 , respectively). Blood was drawn weekly throughout hospitalization for up to 4 weeks. Linear mixed-effects models were used to assess change in hemoglobin and hepcidin concentrations by treatment group over time.

RESULTS

At enrollment, >75% of participants in all groups had plasma 25-hydroxyvitamin D (25(OH)D) concentrations <30 ng/mL, and >85% of participants across groups were anemic. In the 500,000-IU D3 group, hemoglobin concentrations increased significantly over time (Pgroup × time = .01) compared with placebo but did not change in the 250,000-IU D3 group (Pgroup × time = 0.59). Hepcidin concentrations decreased acutely in the 500,000-IU D3 group relative to placebo after 1 week (P = .007). Hepcidin did not change significantly in the 250,000-IU D3 group.

CONCLUSION

In these critically ill adults, treatment with 500,000 IU D3 was associated with increased hemoglobin concentrations over time and acutely reduced serum hepcidin concentrations. These findings suggest that high-dose vitamin D may improve iron metabolism in critical illness and should be confirmed in larger studies.

Oxidative stress in critically ill ventilated adults: effects of vitamin D3 and associations with alveolar macrophage function

Background

Disruptions in redox balance lead to oxidative stress, a promoter of morbidity in critical illness. This study aimed to: 1) characterize the plasma and alveolar thiol/disulfide redox pools, 2) examine their associations with alveolar macrophage phagocytosis, and 3) determine the effect of high dose vitamin D₃ on plasma thiol/disulfide redox.

Methods

Subjects were 30 critically ill, ventilated adults in a double-blind randomized trial of high-dose (250 000 or 500 000 IU) vitamin D₃ or placebo. Baseline bronchoalveolar lavage fluid (BALF) samples were analyzed for determination of alveolar phagocytosis index (PI) and for concentrations of glutathione (GSH), glutathione disulfide (GSSG), cysteine (Cys), cystine (CySS), and their respective redox potentials (EhGSSG and EhCySS). Plasma redox outcomes were assessed at baseline and days 7 and 14.

Results

Baseline plasma Cys was inversely associated with alveolar PI (ρ = −0.69, P=0.003), and E_hCySS was positively associated with PI (ρ = 0.61, P=0.01). Over time, among all subjects there was an increase in plasma GSH levels and a decrease in E_hGSSG (P<0.01 for both), with no difference by treatment group. Vitamin D₃ decreased oxidized plasma GSSG to a more normal state (P for group × time=0.009).

Conclusions

Oxidative stress indicators were positively associated with alveolar macrophage phagocytic function in acutely ill ventilated adults. High-dose vitamin D₃ decreased plasma GSSG concentrations, which suggests that vitamin D can possibly improve the oxidative stress environment.

Impact of high-dose vitamin D3 on plasma free 25-hydroxyvitamin D concentrations and antimicrobial peptides in critically ill mechanically ventilated adults

OBJECTIVES

High-dose vitamin D₃ increases plasma total 25-hydroxyvitamin D [25(OH)D] in critically ill, ventilated patients; however, to our knowledge, the effect on plasma levels of free (nonprotein-bound) 25(OH)D has not been investigated in critical illness. Moreover, the relationship of free 25(OH)D and the regulation of endogenous antimicrobial peptides (AMPs) remains unknown. The aims of this study were to determine in critically ill adults with respiratory failure the effect of previous high-dose regimens of vitamin D₃ on free 25(OH)D concentrations, the relationship of free 25(OH)D with circulating cathelicidin (LL-37) and human beta-defensin-2 (hBD-2), and the associations between plasma levels of free 25(OH)D and these AMPs to alveolar macrophage phagocytosis function.

METHODS

In a double blind, randomized controlled trial, critically ill ventilator-dependent adults (N = 30) received enteral vitamin D₃ (250,000 or 500,000 IU total over 5 d) or placebo. Plasma was obtained serially for concentrations of free 25(OH)D, LL-37, hBD-2, and expression of peripheral blood mononuclear cell human cationic antimicrobial protein (hCAP18) mRNA. Total 25(OH)D and LL-37 concentrations and alveolar macrophage phagocytosis were determined in bronchoalveolar lavage fluid.

RESULTS

Plasma concentrations of free 25(OH)D over time were correlated with total 25(OH)D levels (r= 0.82; P < 0.001). The increase in free 25(OH)D was greater with the 500 000 IU vitamin D₃ dose than with the lower dose. The percent change in mRNA expression of hCAP18 was positively associated with percent change in free 25(OH)D at days 7 and 14 (ρ = 0.48; P = 0.04 and ρ = 0.59; P = 0.03, respectively). Additionally, plasma LL-37 levels correlated with the percentage of alveolar macrophages exhibiting phagocytosis (ρ = 0.51; P = 0.04).

CONCLUSIONS

The present study found a dose-related increase in plasma free-25(OH)D levels, which was associated with increasing circulating mRNA expression of hCAP18 over time. There were no correlations between changes in total and free 25(OH)D against plasma LL-37 and hBD-2 concentrations. Larger studies appear warranted to determine the impact of high-dose vitamin D₃ administration on endogenous AMPs.

Effect of Electronic Health Record Implementation in Critical Care on Survival and Medication Errors

BACKGROUND

Electronic health records (EHR) with computerized physician order entry have become exceedingly common and government incentives have urged implementation. The purpose of this study was to ascertain the effect of EHR implementation on medical intensive care unit (MICU) mortality, length of stay (LOS), hospital LOS and medication errors.

MATERIALS AND METHODS

Prospective, observational study from July 2010-June 2011 in MICU at an urban teaching hospital in Atlanta, Georgia of 797 patients admitted to the MICU; 281 patients before the EHR implementation and 516 patients post-EHR implementation.

RESULTS

Compared with the preimplementation period (N = 43 per 281), the mortality risk at 4 months post-EHR implementation (N = 41 per 247) and at 8 months post-EHR implementation (N = 26 per 269) significantly decreased (P < 0.001). In addition, the mean MICU LOS statistically decreased from 4.03 ± 1.06 days pre-EHR to 3.26 ± 1.06 days 4 months post-EHR and to 3.12 ± 1.05 days 8 months post-EHR (P = 0.002). However, the mean hospital LOS was not statistically decreased. Although medication errors increased after implementation (P = 0.002), this was attributable to less severe errors and there was actually a decrease in the number of severe medication errors (both P < 0.001).

CONCLUSIONS

We report a survival benefit following the implementation of EHR with computerized physician order entry in a critical care setting and a concomitant decrease in the number of severe medication errors. Although overall hospital LOS was not shortened, this study proposes that EHR implementation in a busy urban hospital was associated with improved ICU outcomes.

Evaluating Simulation-Based ACLS Education on Patient Outcomes: A Randomized, Controlled Pilot Study

BACKGROUND

Simulation training is widely accepted as an effective teaching tool, especially for dealing with high-risk situations.

OBJECTIVE

We assessed whether standardized, simulation-based advanced cardiac life support (ACLS) training improved performance in managing simulated and actual cardiac arrests.

METHODS

A total of 103 second- and third-year internal medicine residents were randomized to 2 groups. The first group underwent conventional ACLS training. The second group underwent two 2 1/2-hour sessions of standardized simulation ACLS teaching. The groups were assessed by evaluators blinded to their assignment during in-hospital monthly mock codes and actual inpatient code sheets at 3 large academic hospitals. Primary outcomes were time to initiation of cardiopulmonary resuscitation, time to administration of first epinephrine/vasopressin, time to delivery of first defibrillation, and adherence to American Heart Association guidelines.

RESULTS

There were no differences in primary outcomes among the study arms and hospital sites. During 21 mock codes, the most common error was misidentification of the initial rhythm (67% [6 of 9] and 58% [7 of 12] control and simulation arms, respectively, P  =  .70). There were no differences in primary outcome among groups in 147 actual inpatient codes.

CONCLUSIONS

This blinded, randomized study found no effect on primary outcomes. A notable finding was the percentage of internal medicine residents who misidentified cardiac arrest rhythms.

Formation of a protected sub-band for conduction in quantum point contacts under extreme biasing

Managing energy dissipation is critical to the scaling of current microelectronics and to the development of novel devices that use quantum coherence to achieve enhanced functionality. To this end, strategies are needed to tailor the electron-phonon interaction, which is the dominant mechanism for cooling non-equilibrium ('hot') carriers. In experiments aimed at controlling the quantum state, this interaction causes decoherence that fundamentally disrupts device operation. Here, we show a contrasting behaviour, in which strong electron-phonon scattering can instead be used to generate a robust mode for electrical conduction in GaAs quantum point contacts, driven into extreme non-equilibrium by nanosecond voltage pulses. When the amplitude of these pulses is much larger than all other relevant energy scales, strong electron-phonon scattering induces an attraction between electrons in the quantum-point-contact channel, which leads to the spontaneous formation of a narrow current filament and to a renormalization of the electronic states responsible for transport. The lowest of these states coalesce to form a sub-band separated from all others by an energy gap larger than the source voltage. Evidence for this renormalization is provided by a suppression of heating-related signatures in the transient conductance, which becomes pinned near 2e(2)/h (e, electron charge; h, Planck constant) for a broad range of source and gate voltages. This collective non-equilibrium mode is observed over a wide range of temperature (4.2-300 K) and may provide an effective means to manage electron-phonon scattering in nanoscale devices.

In-plane uniaxial magnetic anisotropy in (Ga, Mn)As due to local lattice distortions around Mn²⁺ ions

We theoretically investigate the interplay between local lattice distortions around the Mn(2+) impurity ion and its magnetization, mediated through spin-orbit coupling of holes. We show that the tetrahedral symmetry around the Mn(2+) ion is spontaneously broken and that local Jahn-Teller distortions coupled with growth strain result in uniaxial magnetic anisotropy. We also account for the experimentally observed in-plane uniaxial magnetic anisotropy rotation due to variation of hole density. According to this model, lack of inversion and top-down symmetries of (Ga, Mn)As layers lead to in-plane biaxial symmetry breaking in the presence of Jahn-Teller distortions.

Vitamin D and sepsis: An emerging relationship

Vitamin D insufficiency and sepsis are both highly prevalent worldwide problems and this article reviews the emerging science that is defining the intersections of these conditions. The importance of vitamin D’s role in skeletal health has long been understood but recent evidence is beginning to highlight its role in the functioning of other physiologic systems of the body. Basic science data reveal its integral role in local immune responses to pathogens and the systemic inflammatory pathways of sepsis. Furthermore, clinical scientists have found associations with respiratory infections, critical illness and sepsis but the causal relationship and its clinical impact have yet to be clearly defined. The article ends with speculations on the connections between racial disparities and seasonal differences in sepsis and vitamin D insufficiency.

Isolation and characterization of a lytic Myoviridae bacteriophage PAS-1 with broad infectivity in Aeromonas salmonicida

To search for candidate control agents against Aeromonas salmonicida subsp. salmonicida infections in aquaculture, one bacteriophage (phage), designated as PAS-1, was isolated from the sediment samples of the rainbow trout (Oncorhynchus mykiss) culture farm in Korea. The PAS-1 was morphologically classified as Myoviridae and possessed approximately 48 kb of double-strand genomic DNA. The phage showed broad host ranges to other subspecies of A. salmonicida as well as A. salmonicida subsp. salmonicida including antibiotic-resistant strains. Its latent period and burst size were estimated to be approximately 40 min and 116.7 PFU/cell, respectively. Furthermore, genomic and structural proteomic analysis of PAS-1 revealed that the phage was closely related to other Myoviridae phages infecting enterobacteria or Aeromonas species. The bacteriolytic activity of phage PAS-1 was evaluated using three subspecies of A. salmonicida strain at different doses of multiplicity of infection, and the results proved to be efficient for the reduction of bacterial growth. Based on these results, PAS-1 could be considered as a novel Aeromonas phage and might have potentiality to reduce the impacts of A. salmonicida infections in aquaculture.

Genomic sequence of infectious hypodermal and hematopoietic necrosis virus (IHHNV) KLV-2010-01 originating from the first Korean outbreak in cultured Litopenaeus vannamei

Due to the need to track and monitor genetic diversity, the genome of the infectious hypodermal and hematopoietic necrosis virus (IHHNV) strain KLV-2010-01 in cultured Litopenaeus vannamei shrimp that originated from the first Korean outbreak in 2010 was sequenced and analyzed. The genome, with a length of 3914 nucleotides, was sequenced from the Korean IHHNV. The genome encoded three large and overlapping open reading frames: ORF1 (NS-1) of 2001 bp, ORF2 (NS-2) of 1092 bp and ORF3 (capsid protein) of 990 bp. The overall organization, size and predicted amino acid sequence of the three ORFs in Korean IHHNV were highly similar to those of members of the infectious IHHNV group, and the most closely related strains were IHHNVs described from Ecuador and Hawaii. Additionally, phylogenetic analysis showed that the Korean IHHNV was clustered with lineage III in the infectious IHHNV group and was most similar to IHHNV isolates from Ecuador, China and Taiwan.

Prevalence and different characteristics of two serotypes of Streptococcus parauberis isolated from the farmed olive flounder, Paralichthys olivaceus (Temminck and Schlegel), in Korea

The prevalence of two serotypes of Streptococcus parauberis isolated from the olive flounder, Paralichthys olivaceus, was evaluated in a total of 29 isolates between 2003 and 2010 in Korea. Streptococcus parauberis isolates were divided into two serologically distinct types (serotype 1 and serotype 2), except for one strain (S1091), using an agglutination assay with rabbit antiserum, and serotype 1 was identified as the dominant type (24 of 29 isolates) in this study. To identify the characteristics of the two serotypes of S. parauberis, we conducted a biochemical test using the API 20 Strep kit, a transmission electron microscopy (TEM) assay, sequence analysis of 16S-23S rRNA intergenic spacer region (ISR) and a pathogenicity test. In TEM, both serotypes possessed polysaccharide capsule layers around the cell surface when bacterial cells were treated with a homologous serotype of rabbit antiserum. However, we were unable to discriminate serotype-specific biochemical characteristics and genetic characteristics of 16S-23S rRNA ISR between the two serotypes. In the pathogenicity test, the serotype 1 strains induced significantly higher mortality than the serotype 2 strains in olive flounder when experimentally inoculated via the intraperitoneal route.

Ferromagnetic spin coupling as the origin of 0.7 anomaly in quantum point contacts

We study one-dimensional itinerant electron models with ferromagnetic coupling to investigate the origin of the 0.7 anomaly in quantum point contacts. Linear conductance calculations from the quantum Monte Carlo technique for spin interactions of different spatial range suggest that 0.7(2e;{2}/h) anomaly results from a strong interaction of low-density conduction electrons to ferromagnetic fluctuations formed across the potential barrier. The conductance plateau appears due to the strong incoherent scattering at high temperature when the electron traversal time matches the time scale of dynamic ferromagnetic excitations.

Imaginary-time formulation of steady-state nonequilibrium: application to strongly correlated transport

We extend the imaginary-time formulation of the equilibrium quantum many-body theory to steady-state nonequilibrium with an application to strongly correlated transport. By introducing the Matsubara voltage, we maintain the finite chemical potential shifts in the Fermi-Dirac function, in agreement with the Keldysh formulation. The formulation is applied to strongly correlated transport in the Kondo regime using the quantum Monte Carlo method.

Strong superconductivity with local Jahn-Teller phonons in C60 solids

We analyze fulleride superconductivity at experimental doping levels, treating the electron-electron and electron-phonon interactions on an equal footing, and demonstrate that the Jahn-Teller phonons create a local (intramolecular) pairing which is surprisingly resistant to the Coulomb repulsion, despite the weakness of retardation in these low-bandwidth systems. The requirement for coherence throughout the solid then yields a very strong doping dependence to T(c), one consistent with experiment and much stronger than expected from standard Eliashberg theory.

Abrupt topological transitions in the hysteresis curves of ferromagnetic metalattices

When a metal is confined to the interstices of an inert colloidal crystal, the intrinsic order parameter(s) of electronic and magnetic phenomena within the metal interact with the structural order parameter of the surrounding (and confining) colloidal crystal. If the magnetic stiffness length is comparable to the colloidal lattice constant, the interplay of competing interactions stabilizes multiple topologically distinct magnetic phases separated by sharp transitions in the hysteresis curves. The colloidal confinement also induces substantial coercivity in metals that are perfectly soft in the bulk.

Tuning Fermi-surface properties through quantum confinement in metallic metalattices: new metals from old atoms

We describe a new class of nanoscale structured metals wherein the effects of quantum confinement are combined with dispersive metallic electronic states to induce modifications to the fundamental low-energy microscopic properties of a three-dimensional metal: the density of states, the distribution of Fermi velocities, and the collective electronic response.

Metal-insulator transitions: influence of lattice structure, jahn-teller effect, and Hund's rule coupling

We study the influence of the lattice structure, the Jahn-Teller effect, and the Hund's rule coupling on a metal-insulator transition in A(n)C60 (A = K,Rb). The difference in the lattice structure favors A3C60 (fcc) being a metal and A4C60 (bct) being an insulator, and the coupling to H(g) Jahn-Teller phonons favors A4C60 being nonmagnetic. The coupling to H(g) ( A(g)) phonons decreases (increases) the value U(c) of the Coulomb integral at which the metal-insulator transition occurs. There is an important partial cancellation between the Jahn-Teller effect and the Hund's rule coupling.