Abstract A reconnaissance mission was organized by the American Concrete Institute, Committee 133, to visit the Los Grillos Bridge in Colombia on September 13, 2023. The bridge is a post-tensioned cast-in-place segmental cantilever structure featuring a box girder spanning 180 m. Situated on a slow-moving landslide, the bridge failed on August 20, 2023. Analyses indicated that the concrete crushing of the bottom slab of the 180-m-long box girder triggered the failure. This case study demonstrates that similar structures can withstand large relative deformations in the transverse direction and differential settlements, yet they remain quite vulnerable to displacement in the longitudinal direction. It also highlights the susceptibility of bridge structures in unstable geological regions.
PURPOSE OF REVIEW:This review examines both historical and recent evidence to clarify the current understanding of the relationship between B vitamin deficiencies and neuropathies. RECENT FINDINGS:Vitamin B1 (thiamine) deficiency can lead to neurological disorders such as beriberi and Wernicke's encephalopathy, conditions with significant prevalence and mortality rates. Vitamin B12 (Cobalamin) is crucial for DNA synthesis, fatty acid metabolism, and myelin production, with its deficiency leading to neuropathies and cognitive disorders. Excess vitamin B6 (pyridoxine), rather than deficiency, appears to be associated with neuropathy. TAKEAWAYS/CONCLUSIONS:Vitamin B1 and B12 deficiencies are linked to classic neuropathies, while the connection between vitamin B6 deficiency and neuropathy is less clear, though excess B6 is associated with neurotoxicity. Nutritional deficiencies are less common in developed countries but remain significant in developing nations. In developed countries, factors like alcohol consumption, bariatric surgery, and metformin use are increasing these deficiencies in clinical practice.
Frequency-modulated continuous wave (FMCW) radars are widely used in applications such as automotive sensing and remote monitoring. Implementing these systems on software-defined radio (SDR) platforms offers flexibility but also introduces challenges, such as synchronization and isolation between the transmitter and receiver, processing large volumes of data, and digital signal processing. This paper proposes two methods for range detection in FMCW radars using unsynchronized SDR platforms for the transmitter and receiver. In both approaches, a direct signal between the transmitting and receiving antennas, positioned a few centimeters apart, serves as a reference. The first method employs FFT on the squared magnitude of the received signal to estimate the range, while the second method adapts the classical matched filter technique. The proposed methods also enable the receiver to operate with a lower sampling rate than the transmitter. Tests were conducted using LimeSDR platforms with a frequency deviation of 58 MHz (corresponding to the sweep bandwidth), an output power of 10 dBm, and a central frequency of 2.4 GHz, targeting distances between 5.27 m and 28.45 m. The first method achieved an average error of 3.5% with matching sampling rates, while the second method reduced the error to 2.15%. When halving the receiver's sampling rate, the average errors increased to 4.28% and 2.33%, respectively. These results demonstrate the potential of the proposed methods for flexible and efficient radar implementations on SDR platforms.
Exact solutions for trapped modes in a planar waveguide with a small rigid obstacle are derived through the application of the Fourier transform and boundary integral equations.
Obesity has been a systemic disease that has been underrecognized for years. Obesity-related chronic kidney disease (Ob-CKD) is a multifaceted disorder that affects patients with CKD to varying degrees. Among the structural changes associated with obesity, obesity-related glomerulopathy (ORG) stands out (glomerular hypertrophy, podocytopathy, mesangial matrix expansion, focal segmental glomerulosclerosis, tubulointerstitial fibrosis, vascular lesions, and tubular atrophy) associated with other kidney diseases. There are direct and indirect mechanisms that affect the kidneys of obese patients. Among the direct mechanisms, several effects may occur: hyperfiltration, activation of the renin-angiotensin-aldosterone system (RAAS), inflammation, lipotoxicity, and neurohormonal activation. This is a narrative review that will detail the inflammatory and lipotoxicity mechanisms involved in the genesis of Ob-CKD.
