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1. Aye-aye’s middle finger kinematic modeling during tap-scanning

   https://doi.org/10.1117/12.2612943  

   Kang, Jiming ; Nemati, Hamidreza ; Dehghan-Niri, Ehsan ( April 2022 , SPIE, Smart Structures/NDE, 300 Long Beach Blvd, Long Beach, CA, 2022)

   Lakhtakia, Akhlesh ; Martín-Palma, Raúl J. ; Knez, Mato (Ed.)

   The aye-aye (Daubentonia madagascariensis) is a nocturnal lemur native to the island of Madagascar with a special thin middle finger. The aye-aye’s third digit (the slenderest one) has a remarkably specific adaptation, allowing it to perform tap-scanning (Finger tapping) to locate small cavities beneath tree bark and extract woodboring larvae from it. This finger, as an exceptional active acoustic actuator, makes an aye-aye’s biological system an attractive model for Nondestructive Evaluation (NDE) methods and robotic systems. Despite the important aspects of the topic in engineering sensory and NDE, little is known about the mechanism and movement of this unique finger. In this paper a simplified kinematic model was proposed to simulate the aye-aye’s middle finger motion. 

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2. DiceCT Analysis of the Extreme Gouging Adaptations Within the Masticatory Apparatus of the Aye‐Aye ( Daubentonia madagascariensis )

   https://doi.org/10.1002/ar.24303  

   Dickinson, Edwin ; Kolli, Shruti ; Schwenk, Alysa ; Davis, Cassidy E. ; Hartstone‐Rose, Adam ( November 2019 , The Anatomical Record)

   Relative to all other primates, the aye‐aye (Daubentonia madagascariensis) exists at the extremes of both morphology and behavior. Its specialized anatomy—which includes hypselodont incisors and highly derived manual digits—reflects a dietary niche, unique among primates, which combines tap‐foraging with gouging to locate and extract wood‐boring larvae. Here, we explore the impact of this extreme dietary ecology upon the masticatory musculature of this taxon with reference to a second, similarly sized but highly generalist lemuriform—the mongoose lemur (Eulemur mongoz). Using non‐destructive, high‐resolution diffusible iodine‐based contrast‐enhanced computed tomography techniques, we reconstruct the three‐dimensional volumes of eight masticatory muscles, and, for the first time in strepsirrhines, isolate and visualize their constituent muscle fasciclesin situand in three dimensions. Using these data, we report muscle volumes, forces, and fascicle lengths from each muscle portion, as well as their orientation relative to two standardized anatomical planes. Our findings demonstrate the overbuilt nature of the aye‐aye's masticatory apparatus, in which each muscle possesses an absolutely and relatively larger muscle volume and PCSA than its counterpart in the mongoose lemur. Likewise, for several adductor muscles, aye‐ayes also possess relatively greater fascicle lengths. Finally, we note several unusual features within the lateral pterygoid of the aye‐aye—the muscle most responsible for jaw protrusion—that relate to force maximization and reorientation. As this jaw motion is critical to gouging, we interpret these differences to reflect highly specific specializations that facilitate the aye‐aye's extreme subsistence strategy. Anat Rec, 2019. © 2019 American Association for Anatomy Anat Rec, 303:282–294, 2020. © 2019 American Association for Anatomy

    

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3. Fossil lemurs from Egypt and Kenya suggest an African origin for Madagascar’s aye-aye

   https://doi.org/10.1038/s41467-018-05648-w  

   Gunnell, Gregg F. ; Boyer, Doug M. ; Friscia, Anthony R. ; Heritage, Steven ; Manthi, Fredrick Kyalo ; Miller, Ellen R. ; Sallam, Hesham M. ; Simmons, Nancy B. ; Stevens, Nancy J. ; Seiffert, Erik R. ( August 2018 , Nature Communications)

   In 1967 G.G. Simpson described three partial mandibles from early Miocene deposits in Kenya that he interpreted as belonging to a new strepsirrhine primate,Propotto. This interpretation was quickly challenged, with the assertion thatPropottowas not a primate, but rather a pteropodid fruit bat. The latter interpretation has not been questioned for almost half a century. Here we re-evaluate the affinities ofPropotto, drawing upon diverse lines of evidence to establish that this strange mammal is a strepsirrhine primate as originally suggested by Simpson. Moreover, our phylogenetic analyses support the recognition ofPropotto, together with late EocenePlesiopithecusfrom Egypt, as African stem chiromyiform lemurs that are exclusively related to the extant aye-aye (Daubentonia) from Madagascar. Our results challenge the long-held view that all lemurs are descended from a single ancient colonization of Madagascar, and present an intriguing alternative scenario in which two lemur lineages dispersed from Africa to Madagascar independently, possibly during the later Cenozoic.

    

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4. Wide-field, high-resolution lensless on-chip microscopy via near-field blind ptychographic modulation

   https://doi.org/10.1039/C9LC01027K  

   Jiang, Shaowei ; Zhu, Jiakai ; Song, Pengming ; Guo, Chengfei ; Bian, Zichao ; Wang, Ruihai ; Huang, Yikun ; Wang, Shiyao ; Zhang, He ; Zheng, Guoan ( March 2020 , Lab on a Chip)

   We report a novel lensless on-chip microscopy platform based on near-field blind ptychographic modulation. In this platform, we place a thin diffuser in between the object and the image sensor for light wave modulation. By blindly scanning the unknown diffuser to different x – y positions, we acquire a sequence of modulated intensity images for quantitative object recovery. Different from previous ptychographic implementations, we employ a unit magnification configuration with a Fresnel number of ∼50 000, which is orders of magnitude higher than those of previous ptychographic setups. The unit magnification configuration allows us to have the entire sensor area, 6.4 mm by 4.6 mm, as the imaging field of view. The ultra-high Fresnel number enables us to directly recover the positional shift of the diffuser in the phase retrieval process, addressing the positioning accuracy issue plaguing regular ptychographic experiments. In our implementation, we use a low-cost, DIY scanning stage to perform blind diffuser modulation. Precise mechanical scanning that is critical in conventional ptychography experiments is no longer needed in our setup. We further employ an up-sampling phase retrieval scheme to bypass the resolution limit set by the imager pixel size and demonstrate a half-pitch resolution of 0.78 μm. We validate the imaging performance via in vitro cell cultures, transparent and stained tissue sections, and a thick biological sample. We show that the recovered quantitative phase map can be used to perform effective cell segmentation of a dense yeast culture. We also demonstrate 3D digital refocusing of the thick biological sample based on the recovered wavefront. The reported platform provides a cost-effective and turnkey solution for large field-of-view, high-resolution, and quantitative on-chip microscopy. It is adaptable for a wide range of point-of-care-, global-health-, and telemedicine-related applications. 

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5. A primate with a Panda's thumb: The anatomy of the pseudothumb of Daubentonia madagascariensis

   https://doi.org/10.1002/ajpa.23936  

   Hartstone‐Rose, Adam ; Dickinson, Edwin ; Boettcher, Marissa L. ; Herrel, Anthony ( October 2019 , American Journal of Physical Anthropology)

   Accessory digits have evolved independently within several mammalian lineages. Most notable among these is the pseudothumb of the giant panda, which has long been considered one of the most extraordinary examples of contingent evolution. To date, no primate has been documented to possess such an adaptation. Here, we investigate the presence of this structure within the aye‐aye (Daubentonia madagascariensis), a species renowned for several other specialized morphological adaptations in the hand, including a morphologically unique third digit.

   We combine physical dissection techniques with digital imaging processes across a sample of seven individuals (six adults and one immature individual) to describe and visualize the anatomy of the wrist and hand within the aye‐aye.

   A distinct pseudothumb, which consists of both a bony component (an expanded radial sesamoid) and a dense cartilaginous extension (the “prepollex”) was observed in all specimens. We demonstrate that this pseudodigit receives muscular attachments from three muscles, which collectively have the potential to enable abduction, adduction, and opposition. Finally, we demonstrate that the pseudothumb possesses its own distinct pad within the palm, complete with independent dermatoglyphs.

   Pseudothumbs have been suggested to improve palmar dexterity in taxa with overly ‐generalized first digits (e.g., pandas) and to widen the hand for digging (e.g., some fossorial moles), but the aye‐aye's pseudothumb represents what we believe is a heretofore unrecognized third functional role: its accessory digit compensates for overspecialization of its fingers for non‐gripping functions (in this case, the aye‐aye's unique “tap foraging” practices).

    

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