Fossils and phylogeny uncover the evolutionary history of a unique antipredator behaviour.

Recently, two squirrel species (Spermophilus spp.) were discovered to anoint their bodies with rattlesnake scent as a means of concealing their odour from these chemosensory predators. In this study, we tested multiple species with predator scents (rattlesnake and weasel) to determine the prevalence of scent application across the squirrel phylogeny.

Donning your enemy's cloak: ground squirrels exploit rattlesnake scent to reduce predation risk.

Ground squirrels (Spermophilus spp.) have evolved a battery of defences against the rattlesnakes (Crotalus spp.) that have preyed on them for millions of years.

Ground squirrels use an infrared signal to deter rattlesnake predation.

The evolution of communicative signals involves a major hurdle; signals need to effectively stimulate the sensory systems of their targets. Therefore, sensory specializations of target animals are important sources of selection on signal structure. Here we report the discovery of an animal signal that uses a previously unknown communicative modality, infrared radiation or "radiant heat," which capitalizes on the infrared sensory capabilities of the signal's target.

The rattling sound of rattlesnakes (Crotalus viridis) as a communicative resource for ground squirrels (Spermophilus beecheyi) and burrowing owls (Athene cunicularia).

Animal communication involves very dynamic processes that can generate new uses and functions for established communicative activities. In this article, the authors describe how an aposematic signal, the rattling sound of rattlesnakes (Crotalus viridis), has been exploited by 2 ecological associates of rattlesnakes: (a) California ground squirrels (Spermophilus beecheyi) use incidental acoustic cues in rattling sounds to assess the danger posed by the rattling snake, and (b) burrowing owls (Athene cunicularia) defend themselves against mammalian predators by mimicking the sound of rattling. The remarkable similarity between the burrowing owl's defensive hiss and the rattlesnake's rattling reflects both exaptation and adaptation.

Do California ground squirrels (Spermophilus beecheyi) use ritualized syntactic cephalocaudal grooming as an agonistic signal?

Animal communication theory holds that many signals have evolved from nonsignal precursors. This field and laboratory study of California ground squirrels (Spermophilus beecheyi) provides evidence for the coexistence of such a precursor with its derived display. The precursor is an ancient, endogenously sequenced (syntactic) pattern of cephalocaudal grooming movements (CCGs) shared by all rodent suborders.

Assessment of rattlesnake dangerousness by California ground squirrels: exploitation of cues from rattling sounds.

We propose that the predator-prey relationship between California ground squirrels, Spermophilus beecheyi beecheyi, and northern Pacific rattlesnakes, Crotalus viridis oreganus, offers a compelling analogy with the well-studied case of intraspecific fighting and assessment. Because ground squirrels frequently place themselves at risk by harassing rattlesnakes, they stand to benefit from assessment strategies which serve to mediate risk. For example, larger and warmer snakes are more dangerous than smaller and cooler ones.

Conflict and assessment in a predator-prey system: ground squirrels versus rattlesnakes.

Adult California ground squirrels, Spermophilus beecheyi beecheyi, actively confront and harass northern Pacific rattlesnakes, Crotalus viridis oreganus, which are the principal predator of ground squirrel pups. In this report we examine the roles of risk (snake size) and context (location of encounter and squirrel reproductive category) in rattlesnake assessment by ground squirrels. In interpreting the results, we borrow heavily from the well-developed conceptual framework applied in the analogous case of intraspecific conflict.

Ranging of male Oropsylla montana fleas via male California ground squirrel (Spermophilus beecheyi) juveniles.

We asked if fleas more frequently remain on those California ground squirrels (Spermophilus beecheyi) that are likely to emigrate from their natal nest. In Camp Ohlone, Alameda County, California, juvenile male squirrels were infested with more fleas (Oropsylla montana) than were juvenile females, and juveniles of both sexes were infested with more fleas (O. montana and Hoplopsyllus anomalus) than adults.

Myocardial fibrin deposition in experimental viral myocarditis that progresses to dilated cardiomyopathy.

Myocardial fibrosis is a characteristic late feature in cases of viral myocarditis that progress to dilated cardiomyopathy. However, the pathogenesis of the myocardial fibrosis in such cases is unknown. Prior studies have shown that in healing wounds and tumor stroma generation, interstitial fibrin deposition precedes the development of fibrosis.

Conceptual design and cost estimate for a modified hemoglobin production plant.

Polymerized, pyridoxalated stroma-free hemoglobin (Poly PSFH), made from outdated human blood, has excellent attributes for use as a blood substitute. A hypothetical larger scale process for the production of Poly PSFH is detailed, and facility design and cost estimates are presented. This paper gives the opportunity to discuss the engineering activities of process scope definition, utilities selection, and aseptic processing techniques, etc.

How thoroughly should needle localization breast biopsies be sampled for microscopic examination? A prospective mammographic/pathologic correlative study.

To investigate the relationships between mammographic calcifications and pathologic lesions, and to develop guidelines for specimen sampling, we prospectively studied 157 consecutive needle localization breast biopsies (NLBB) using a technique in which radiographic findings in sectioned specimens were correlated with the histologic findings. All NLBBs were performed because of mammographic microcalcifications without a soft tissue density, and macroscopic examination in each case failed to reveal a gross lesion. All specimens were submitted in their entirety.

Autologous blood donations prior to elective cardiac surgery. Safety and effect on subsequent blood use.

Blood transfusions are frequently necessary for patients having open heart surgery. Although autologous blood is free of such risks as transfusion-transmitted diseases, the safety and effectiveness of autologous donations by cardiac patients are debated. We analyzed the records of 291 consecutive patients undergoing elective open heart surgery.

Passive transfusion of human chorionic gonadotropin from plasma donated during pregnancy.

Although fresh frozen plasma (FFP) prepared from autologous blood donated during pregnancy has frequently been given to homologous recipients at our institution, one transfusion resulted in an unanticipated diagnostic dilemma. A 31-year-old woman with disseminated intravascular coagulation of unclear etiology was transfused with multiple units of FFP, including 2 from pregnant autologous donors. A serum human chorionic gonadotropin (HCG) assay, performed because of the possibility that the patient's illness was a complication of unrecognized pregnancy, was positive using a blood sample drawn 7 h after the transfusions.

Increased subepithelial collagen deposition is not specific for collagenous colitis.

To refine the pathologic diagnosis of collagenous colitis and to determine whether increased subepithelial collagen deposition (SCD) is specific for collagenous colitis (CC), we reviewed histologic sections of 1549 colonic mucosal biopsy procedures obtained from 1332 patients and 157 consecutive colonic resections. Quantitative evaluation of SCD was performed for those patients who showed thickness of SCD that was 5 microns or greater in either biopsies or resections, and the overall histologic and clinical features were correlated. A focal or diffuse increase of SCD greater than or equal to 5 microns was noted in 22 (1.

Mean airway pressure--significance during mechanical ventilation in neonates.

Variations in PEEP with concomitant changes of DPP while MAP, PIP, flow, FIO2, and ventilator rate remained constant were investigated in nine neonates with RDS during the first and second days of life. After stabilization on baseline ventilator settings, PEEP was increased by 3 cm of H2O and DPP decreased in order to maintain balance MAP. Following a return to baseline settings, the PEEP was decreased by 3 cm of H2O and DPP increased sufficiently to maintain constant MAP.