Position-squared coupling in a tunable photonic crystal optomechanical cavity

We present the design, fabrication, and characterization of a planar silicon photonic crystal cavity in which large position-squared optomechanical coupling is realized. The device consists of a double-slotted photonic crystal structure in which motion of a central beam mode couples to two high-Q optical modes localized around each slot. Electrostatic tuning of the structure is used to controllably hybridize the optical modes into supermodes which couple in a quadratic fashion to the motion of the beam. From independent measurements of the anti-crossing of the optical modes and of the optical spring effect, the position-squared vacuum coupling rate is measured to be as large as 245 Hz to the fundamental in-plane mechanical resonance of the structure at 8.7MHz, which in displacement units corresponds to a coupling coefficient of 1 THz/nm$^2$. This level of position-squared coupling is approximately five orders of magnitude larger than in conventional Fabry-Perot cavity systems.Comment: 11 pages, 6 figure

A frameshift insertion in SGK3 leads to recessive hairlessness in Scottish Deerhounds : a candidate gene for human alopecia conditions

Hairlessness is a breed-specific feature selected for in some dog breeds but a rare abnormality in some others such as Scottish Deerhounds (SD). In SDs, the affected puppies are born with sparse hair but lose it within the first 2months leaving the dogs completely hairless. The previous studies have implicated variants in FOXI3 and SGK3 in hairlessness; however, the known variants do not explain hairlessness in all breeds such as SDs. We investigated the genetic cause in 66 SDs, including a litter with two hairless dogs. We utilized a combined approach of genome-wide homozygosity mapping and whole-genome sequencing of a hairless SD followed by recessive filtering according to a recessive model against 340 control genomes. Only two homozygous-coding variants were discovered in the homozygosity regions, including a 1-bp insertion in exon 2 of SGK3. This results in a predicted frameshift and very early truncation (49/490 amino acids) of the SGK3 protein. Additional screening of the recessive variant demonstrated a full segregation with the hairlessness and a 12% carrier frequency in the SD breed. The variant was not found in the related Irish Wolfhound breed. This study identifies the second hairless variant in the SGK3 gene in dogs and further highlights its role as a candidate gene for androgen-independent hair loss or alopecia in human.Peer reviewe

Extension, disruption, and translation of an orogenic wedge by exhumation of large ultrahigh-pressure terranes: Examples from the Norwegian Caledonides

Far-traveled allochthons (greater than 100 km) within collisional orogenic wedges may have undergone significant lateral movement by passive transport (in addition to thrusting) where they lie tectonically above large, exhumed, high-pressure/ultrahigh-pressure (HP/UHP) metamorphic terranes. Continental collision results in the subduction of one craton beneath another into the mantle. The subducted craton undergoes HP/UHP metamorphism, while an accretionary orogenic wedge develops simultaneously at its junction with the overlying craton. The subsequent exhumation of a large HP/UHP terrane by either far-field extension or buoyancy-driven extrusion, or both, reverses the shear traction along its upper boundary from foreland-directed thrust motion to hinterland-directed normal displacement. This normal-sense shear can stretch, thin, and fragment the overlying wedge and even carry a detached frontal fragment passively toward the foreland on top of the exhuming plate. The total “piggyback” displacement would be a function of the amount of exhumation of the HP/UHP terrane and the timing of its breakoff from the hinterland portion of the wedge. This model is applied to the Trondheim and Jotun nappe complexes of the Caledonides of southern Scandinavia, which were translated greater than 300 km to the E and SE, respectively, during the 430–385 Ma Scandian orogeny. Their hinterland boundaries rest on top of the HP/UHP Western Gneiss Complex. Kinematic indicators along their basal décollements indicate a change in shear sense from top-E/SE to top-W/NW at the same time (ca. 405 Ma) that radiometric ages indicate the Western Gneiss Complex began to exhume from the mantle. Displacements of tens of kilometers along these décollements stretched and thinned the Trondheim nappe complex and fragmented the Jotun nappe complex. Ultimately, this basal traction led to the breakaway of the frontal segments of the allochthons, allowing them to be carried passively to the E/SE as the Western Gneiss Complex continued to exhume. Top-W/NW shear continued between the Western Gneiss Complex and the stranded rearward segments of the allochthons, resulting in the opening up of the Western Gneiss Region tectonic window between the E/SE-translating nappes and their relatively “fixed” equivalents in the W/NW. The total displacement of the traveled frontal allochthons could have been considerably farther than that accomplished by thrusting alone

Early weaning increases aggression and stereotypic behaviour in cats

Behaviour problems are common in companion felines, and problematic behaviour may be a sign of chronic stress. In laboratory animals, early weaning increases the risk for aggression, anxiety, and stereotypic behaviour. However, very few studies have focused on early weaning in one of the world's most popular pets, the domestic cat, although weaning soon after the critical period of socialisation is common practice. To study the effects of early weaning (<12 weeks) on behaviour, a large data set (N = 5726, 40 breeds) was collected from home-living domestic cats through a questionnaire survey. The results show that weaning before 8 weeks of age increases the risk for aggression, but not fearful behaviour. Moreover, cats weaned after 14 weeks of age have a lower probability for aggression towards strangers than early weaned cats and a lower probability for stereotypic behaviour (excessive grooming) than cats weaned at 12 weeks. The effect of weaning age on stereotypic behaviour is partially explained by the effects on aggression. These findings indicate that early weaning has a detrimental effect on behaviour, and suggest delayed weaning as a simple and inexpensive approach to significantly improve the welfare of millions of domestic cats.Peer reviewe

Mini-Intein Structures from Extremophiles Suggest a Strategy for Finding Novel Robust Inteins

Inteins are prevalent among extremophiles. Mini-inteins with robust splicing properties are of particular interest for biotechnological applications due to their small size. However, biochemical and structural characterization has still been limited to a small number of inteins, and only a few serve as widely used tools in protein engineering. We determined the crystal structure of a naturally occurring Pol-II mini-intein from Pyrococcus horikoshii and compared all three mini-inteins found in the genome of P. horikoshii. Despite their similar sizes, the comparison revealed distinct differences in the insertions and deletions, implying specific evolutionary pathways from distinct ancestral origins. Our studies suggest that sporadically distributed mini-inteins might be more promising for further protein engineering applications than highly conserved mini-inteins. Structural investigations of additional inteins could guide the shortest path to finding novel robust mini-inteins suitable for various protein engineering purposes

Mini-Intein Structures from Extremophiles Suggest a Strategy for Finding Novel Robust Inteins

Inteins are prevalent among extremophiles. Mini-inteins with robust splicing properties are of particular interest for biotechnological applications due to their small size. However, biochemical and structural characterization has still been limited to a small number of inteins, and only a few serve as widely used tools in protein engineering. We determined the crystal structure of a naturally occurring Pol-II mini-intein from Pyrococcus horikoshii and compared all three mini-inteins found in the genome of P. horikoshii. Despite their similar sizes, the comparison revealed distinct differences in the insertions and deletions, implying specific evolutionary pathways from distinct ancestral origins. Our studies suggest that sporadically distributed mini-inteins might be more promising for further protein engineering applications than highly conserved mini-inteins. Structural investigations of additional inteins could guide the shortest path to finding novel robust mini-inteins suitable for various protein engineering purposes