Desert ants of the genus
Cataglyphis
are renowned for their navigation abilities, especially for their beeline homing after meandering foraging excursions reaching several hundreds of meters in ...length. A spiralling nest search is performed when an ant misses the nest entrance upon completing its homebound travel. We examined the nest search behaviours of two desert ant species dwelling in different habitats—
Cataglyphis bombycina
living in the dunes of the Sahara and
Cataglyphis fortis
found in the salt pans of North Africa. The two species show distinct differences in walking behaviour.
C. bombycina
performs a strict tripod gait with pronounced aerial phases, high stride frequencies, and extremely brief ground contact times. In view of these peculiarities and the yielding sand dune substrate, we hypothesised that homing accuracy, and namely distance measurement by stride integration, should be lower in
C. bombycina
, compared to the well-studied
C. fortis
with less specialised walking behaviour. We tested this hypothesis in ants’ homebound runs from a feeding site in a linear channel setup. Surprisingly, the accuracies of nest searches were similar in the two ant species, and search accuracy was also independent of the walking substrate, soft dune sand or a hard floor. The spread of the nest search, by contrast, differed significantly between the two species,
C. bombycina
exhibiting a larger search spread. This may be interpreted as an increased path integration uncertainty due to the above locomotor specialisations, or as a compensation strategy accounting for the silver ants’ particular environmental and behavioural situation.
“Smart devices” and “smart applications” open up a wide range of opportunities for the individual. Today, the vast majority of the population in Europe uses electronic devices with a multitude of ...“smart applications” as an aid in everyday life. One part of society that could arguably benefit more from these types of technology is that part comprised of persons with disabilities. Statistics show that persons with disabilities, especially those with intellectual disabilities, own and use fewer electronic devices than other parts of the population. Several authors have addressed this issue, referring to it as the “digital divide.” In this argumentative article, we advocate a social‐relational understanding of disability and conceptualise “smartness” as an attribute for situations (and neither for devices and applications nor for people). Through what we call “smart socio‐technical arrangements,” persons with intellectual disabilities potentially gain a higher level of activity and more independence. It appears that an individualised technology environment can contribute to the enablement and increase of participation of each person. The article links up with an applied research project analysing the establishment of socio‐technical arrangements not only for, but also with persons with intellectual disabilities. Our main question here is how to adequately conceptualise the “smartness” of situations for persons with intellectual disabilities. We argue that the use of devices as components of socio‐technical arrangements can optimally lead to smart situations in which persons with intellectual disabilities are more active and less restricted in their activities and participation. “Smartness” then is a synonym for functioning and an antonym of disability.
Air-cushioned spheres are widely used as treadmills to study behavioural and neurophysiological questions in numerous species. We describe an improved spherical treadmill design that reliably ...registers the path and walking behaviour of an animal walking on top of the sphere. The simple and robust set-up consists of a very light hollowed styrofoam ball supported by an air stream in a hollow half sphere and can be used indoors and outdoors. Two optical mouse sensors provided with lenses of 4.6 mm focal length detect the motion of the sphere with a temporal resolution of more than 200 frames s
and a spatial resolution of less than 0.2 mm. The treadmill can be used in an open- or closed-loop configuration with respect to yaw of the animal. The tethering allows animals to freely adjust their body posture and in the closed-loop configuration to quickly rotate around their yaw axis with their own moment of inertia. In this account, we present the first evidence of naturalistic homing navigation on a spherical treadmill for two species of
desert ants. We were able to evaluate with good precision the walking speed and angular orientation at any time. During homing the ants showed a significant difference in walking speed between the approach and search phases; moreover, they slowed down significantly as soon as they reached zero vector state, the fictive nest position.
For insects, flexibility in the performance of terrestrial locomotion is a vital part of facing the challenges of their often unpredictable environment. Arthropods such as scorpions and crustaceans ...can switch readily from forward to backward locomotion, but in insects this behaviour seems to be less common and, therefore, is only poorly understood. Here we present an example of spontaneous and persistent backward walking in Cataglyphis desert ants that allows us to investigate rearward locomotion within a natural context. When ants find a food item that is too large to be lifted up and to be carried in a normal forward-faced orientation, they will drag the load walking backwards to their home nest. A detailed examination of this behaviour reveals a surprising flexibility of the locomotor output. Compared with forward walks with regular tripod coordination, no main coordination pattern can be assigned to rearward walks. However, we often observed leg-pair-specific stepping patterns. The front legs frequently step with small stride lengths, while the middle and the hind legs are characterized by less numerous but larger strides. But still, these specializations show no rigidly fixed leg coupling, nor are they strictly embedded within a temporal context; therefore, they do not result in a repetitive coordination pattern. The individual legs act as separate units, most likely to better maintain stability during backward dragging.
The diurnal thermophilic Saharan silver ant,
, is the fastest of the North African
desert ant species. These highly mobile ants endure the extreme temperatures of their sand dune environment with ...outstanding behavioural, physiological and morphological adaptations. Surprisingly,
has comparatively shorter legs than its well-studied sister species
from salt pan habitats. This holds despite the somewhat hotter surface temperatures and the more yielding sand substrate. Here, we report that
employs a different strategy in reaching high running speeds, outperforming the fastest known runs of the longer-legged
ants. Video analysis across a broad range of locomotor speeds revealed several differences to
Shorter leg lengths are compensated for by high stride frequencies, ranging beyond 40 Hz. This is mainly achieved by a combination of short stance phases (down to 7 ms) and fast leg swing movements (up to 1400 mm s
). The legs of one tripod group exhibit almost perfect synchrony in the timings of their lift-offs and touch-downs, and good tripod coordination is present over the entire walking speed range (tripod coordination strength values around 0.8). This near synchrony in leg movement may facilitate locomotion across the yielding sand dune substrate.
•Solid-state protein investigations were performed.•The lot-to-lot variabilities in lyophilized protein powders were determined.•The molecular, particulate, and bulk properties of protein powders ...were studied.•The structural properties and chemical stability of protein pharmaceuticals were explored.•Analytical methods for batch-to-batch variability in lyophilized materials were proposed.
Lyophilization of proteins can introduce lot-to-lot variabilities in different product properties that are crucial in terms of product performance and stability. As these variations can raise several issues related to product quality, the characterization of the physical and chemical properties of protein lots is necessary, to identify critical deviations between the lots and to rationally control the process to yield an acceptable product. The critical concerns are potential quality issues of the drug product and (negative) effects on the reconstitution behavior of the solid-state lyophilized proteins. This review provides an overview of powder properties and physicochemical attributes of solid protein formulations manufactured by lyophilization that are potentially associated with lot-to-lot variabilities. Brief descriptions of various conventional, as well as novel, analytical techniques, which are suitable for characterizing the properties of the pharmaceutical protein powder, are discussed.
Path integration, although inherently error-prone, is a common navigation strategy in animals, particularly where environmental orientation cues are rare. The desert ant Cataglyphis fortis is a ...prominent example, covering large distances on foraging excursions. The stride integrator is probably the major source of path integration errors. A detailed analysis of walking behaviour in Cataglyphis is thus of importance for assessing possible sources of errors and potential compensation strategies. Zollikofer (J Exp Biol 192:95–106, 1994a) demonstrated consistent use of the tripod gait in Cataglyphis, and suggested an unexpectedly constant stride length as a possible means of reducing navigation errors. Here, we extend these studies by more detailed analyses of walking behaviour across a large range of walking speeds. Stride length increases linearly and stride amplitude of the middle legs increases slightly linearly with walking speed. An initial decrease of swing phase duration is observed at lower velocities with increasing walking speed. Then it stays constant across the behaviourally relevant range of walking speeds. Walking speed is increased by shortening of the stance phase and of the stance phase overlap. At speeds larger than 370 mms⁻¹, the stride frequency levels off, the duty factor falls below 0.5, and Cataglyphis transitions to running with aerial phases.
Summary
Background
Irritable bowel syndrome with diarrhoea (IBS‐D) is a common condition, greatly reducing the quality of life with few effective treatment options available.
Aim
To report the ...beneficial response shown in our trial with the 5‐hydroyxtryptamine (5‐HT) receptor 3 antagonist, ondansetron in IBS‐D
Methods
A randomised, placebo‐controlled, cross‐over trial of 5 weeks of ondansetron versus placebo in 125 patients meeting modified Rome III criteria for IBS‐D as previously described. Patients were compared to 21 healthy controls. 5‐HT and 5‐HIAA were measured in rectal biopsies. Whole gut transit time was assessed using a radio‐opaque marker technique. Whole blood DNA was genotyped for an insertion polymorphism in the promoter region of the serotonin transporter gene SLC6A4, as well as single nucleotide polymorphisms (SNPs) of the tryptophan hydroxylase gene TPH1 and 5‐HT3 receptor genes HTR3A, C and E.
Results
Patients’ biopsies showed significantly higher 5‐HIAA levels (2.1 (1.2‐4.2) pmol/mg protein vs 1.1 (0.4‐1.5) in controls, P < .0001). 39 patients used < 4 mg/d (“super‐responders”) while 55 required ≥ 4 mg/d. 5‐HT concentrations in rectal biopsies were significantly lower in super‐responders (21.3 (17.0‐31.8) vs 37.7 (21.4‐61.4), P = .0357) and the increase in transit time on ondansetron was significantly greater (15.6 (1.8‐31) hours vs 3.9 (−5.1‐17.9) hours). Stool consistency responders were more likely to carry the CC genotype of the SNP p.N163K rs6766410 of the HTR3C gene (33% vs 14%, P = .0066).
Conclusion
IBS‐D patients have significant abnormalities in mucosal 5‐HT metabolism. Those with the lowest concentration of 5‐HT in rectal biopsies showed the greatest responsiveness to ondansetron.
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This study aims to investigate the effect of carrier characteristics and dosator capsule filling operation on the in vitro deposition of mixtures containing salbutamol sulphate (SS) ...and lactose and mannitol as model carrier materials. The carrier surfaces of lactose and mannitol were modified via wet decantation. The impact of the decantation process on the properties of carriers was investigated by laser diffraction, density and powder flow measurements, N2 physisorption, small and wide angle X-ray scattering (SWAXS) and scanning electron microscopy (SEM). Differences in carrier type and untreated and decanted materials were identified and the SAXS measurements proved to be a promising technology confirming the successful removal of fines. Adhesive carrier API mixtures with carrier-to-API ratio of 99:1wt% were prepared, mixture homogeneity was tested and subsequently the mixtures were filled into capsules at different process settings. Finally, the influence of the decantation process on the in vitro performance of the adhesive mixtures was tested with a next generation impactor. For lactose, the decantation decreased the fine particle fraction (FPF) of SS, whereas the FPF of mannitol as a carrier was only affected by the capsule filling process.
In summary, the DPI formulation based on untreated lactose, especially by capsule filling using a dosing chamber to powder layer (compression) ratio of 1:2, proved to be superior in terms of the dosing accuracy (RSD<0.8%) and the in vitro aerodynamic performance (FPF of 12%).
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