Geospatial analysis of household spread of Ebola virus in a quarantined village - Sierra Leone, 2014.

We performed a spatial-temporal analysis to assess household risk factors for Ebola virus disease (Ebola) in a remote, severely-affected village. We defined a household as a family's shared living space and a case-household as a household with at least one resident who became a suspect, probable, or confirmed Ebola case from 1 August 2014 to 10 October 2014. We used Geographic Information System (GIS) software to calculate inter-household distances, performed space-time cluster analyses, and developed Generalized Estimating Equations (GEE). Village X consisted of 64 households; 42% of households became case-households over the observation period. Two significant space-time clusters occurred among households in the village; temporal effects outweighed spatial effects. GEE demonstrated that the odds of becoming a case-household increased by 4·0% for each additional person per household (P < 0·02) and 2·6% per day (P < 0·07). An increasing number of persons per household, and to a lesser extent, the passage of time after onset of the outbreak were risk factors for household Ebola acquisition, emphasizing the importance of prompt public health interventions that prioritize the most populated households. Using GIS with GEE can reveal complex spatial-temporal risk factors, which can inform prioritization of response activities in future outbreaks.

Characterizing electroosmotic flow in microfluidic devices.

The current-monitoring method was used to measure the electroosmotic flow (EOF) in borosilicate glass capillaries and zeonor plastic microfluidic devices. The surface of the zeonor devices must be oxidized to support EOF and this treatment shows signs of aging within 6 days. Oxidized zeonor devices showed the same response to changes in applied field, pH, and ionic concentration as the capillaries. The effects of several common dynamic surfactant coatings on the walls were also studied (0.1%, v/v solutions of POP-6, POP4, Pluronics L81, and NP-40). These generally significantly suppressed the EOF but required several days to stabilize.

Single-molecule vibrations, conformational changes, and electronic conductivity of five-membered heterocycles.

Using an ultrahigh vacuum scanning tunneling microscope (STM), we have explored the interactions of isolated five-membered heterocycles, pyrrole, thiophene, pyrrolidine, and tetrahydrothiophene, with the Cu(001) surface at 9 K. Pyrrolidine was also studied on the Ag(001) surface. Important distinctions in bonding, vibrational spectra, and vibrationally mediated negative differential resistance were observed with the aid of single-molecule inelastic electron tunneling spectroscopy (STM-IETS).

Vibrationally mediated negative differential resistance in a single molecule

A new mechanism for negative differential resistance (NDR) has been discovered and involves a single molecule in the junction of a scanning tunneling microscope. The NDR was observed at voltages corresponding to the vibrational energies of single pyrrolidine molecules on the (001) surface of copper at 9 K. This vibrationally mediated NDR contrasts with the previously known mechanisms which all involve the electronic states of the conducting media.