ABSTRACT
Numerous types of biological branching networks, with varying shapes and sizes, are used to acquire and distribute resources. Here, we show that plant root and shoot architectures share a fundamental design property. We studied the spatial density function of plant architectures, which specifies the probability of finding a branch at each location in the 3-dimensional volume occupied by the plant. We analyzed 1645 root architectures from four species and discovered that the spatial density functions of all architectures are population-similar. This means that despite their apparent visual diversity, all of the roots studied share the same basic shape, aside from stretching and compression along orthogonal directions. Moreover, the spatial density of all architectures can be described as variations on a single underlying function: a Gaussian density truncated at a boundary of roughly three standard deviations. Thus, the root density of any architecture requires only four parameters to specify: the total mass of the architecture and the standard deviations of the Gaussian in the three (x, y, z) growth directions. Plant shoot architectures also follow this design form, suggesting that two basic plant transport systems may use similar growth strategies.
ABSTRACT
BACKGROUND: The concept of a minimally invasive live donor nephrectomy developed over 20 years ago. Surgeons gained expertise with the laparoscopic technique and utilized multiple variations that are now utilized in transplant centers throughout the world. Recent modifications include laparoendoscopic single-site and robotic approaches that have been adopted by an additional smaller set of programs. PURPOSE: Review was performed of the following eight different surgical approaches to a "minimally invasive" live donor nephrectomy: laparoscopic (LDN), hand-assisted laparoscopic (HALDN), retroperitoneoscopic (RLDN), hand-assisted retroperitoneoscopic (HARS), single-port laparoscopic (LESS), robotic-assisted laparoscopic (RALDN), mini open, and natural orifice transluminal endoscopic (NOTES). The techniques are described and summaries of available outcomes and complications are presented. CONCLUSIONS: Traditional surgical techniques of open donor nephrectomy have transitioned to minimally invasive techniques. With adoption of these techniques as the preferred approach, several variations have and continue to evolve. The current minimally invasive donor nephrectomy techniques share low complication rates and excellent outcomes.
